arXiv:0705.0116v2 [hep-ph] 29 May 2007 - arXiv.org e-Print archive · olp e V 29 ter Win 15 M urm W...

arX

iv0

705

0116

v2 [

hep-

ph]

29

May

200

7

Large underground liquid based dete13tors for

astro-parti13le physi13s in Europe s13ienti13 13ase and

prospe13ts

D Autiero

1 J Aumlystouml

2 A Baderts13her

3 L Bezrukov

4

J Bou13hez

5 A Bueno

6 J Busto

7 J-E Campagne

8

Ch Cavata

9 L Chaussard

1 A de Bellefon

10 Y Deacute13lais

1

J Dumar13hez

11 J Ebert

12 T Enqvist

13 A Ereditato

14

F von Feilitzs13h

15 P Fileviez Perez

16 M Goumlger-Ne

17

S Gninenko

4 W Gruber

3 C Hagner

12 M Hess

14

K A Ho13hmuth

17 J Kisiel

18 L Kne13ht

3 I Kreslo

14

V A Kudryavtsev

19 P Kuusiniemi

13 T La13henmaier

15

M Laran13hi

3 B Leevre

10 P K Lightfoot

19

M Lindner

20 J Maalampi

2 M Maltoni

21 A Mar13hionni

3

T Marrodaacuten Undagoitia

15 J Marteau

1 A Meregaglia

3

M Messina

14 M Mezzetto

22 A Mirizzi

1723 L Mos13a

9

U Moser

14 A Muumlller

3 G Natterer

3 L Oberauer

15

P Otiougova

3 T Patzak

10 J Peltoniemi

13 W Potzel

15

C Pistillo

14 G G Raelt

17 E Rondio

24 M Roos

25

B Rossi

14 A Rubbia

3 N Savvinov

14 T S13hwetz

26

J Sob13zyk

27 N J C Spooner

19 D Stefan

28 A Tonazzo

10

W Trzaska

2 J Ulbri13ht

3 C Volpe

29 J Winter

15

M Wurm

15 A Zalewska

28and R Zimmermann

12

1IPNL Universiteacute Claude Bernard Lyon 1 CNRSIN2P3 69622 Villeurbanne

Fran13e

2Department of Physi13s University of Jyvaumlskylauml Finland

3Institut fuumlr Teil13henphysik ETHZ Zuumlri13h Switzerland

4Institute for Nu13lear Resear13h Russian A13ademy of S13ien13es Mos13ow Russia

5CEA - Sa13lay Gif sur Yvette and APC Paris Fran13e

6Dpto Fisi13a Teori13a y del Cosmos amp CAFPE Universidad de Granada

Spain

7Centre de Physique des Parti13ules de Marseille (CPPM) IN2P3-CNRS et

Universiteacute dAix-Marseille II Marseille Fran13e

8LAL Universiteacute Paris-Sud IN2P3CNRS Orsay Fran13e

9CEA - Sa13lay Gif sur Yvette Fran13e

10Astroparti13ule et Cosmologie (APC) CNRS Universiteacute Paris VII CEA

Observatoire de Paris Paris Fran13e

11Laboratoire de Physique Nu13leacuteaire et des Hautes Energies (LPNHE)

IN2P3-CNRS et Universiteacutes Paris VI et Paris VII Paris Fran13e

12Universitaumlt Hamburg Institut fuumlr Experimentalphysik Hamburg Germany

13CUPP University of Oulu Finland

14Laboratorium fuumlr Ho13henergie Physik Bern Universitaumlt Bern Switzerland

15Te13hnis13he Universitaumlt Muumln13hen Physik-Department E15 Gar13hing

Germany

16Centro de Fisi13a Teori13a de Parti13ulas Instituto Superior Te13ni13o

Departamento de Fisi13a Lisboa Portugal

17Max-Plan13k-Institut fuumlr Physik (Werner-Heisenberg-Institut) Muumln13hen

Germany

Large underground liquid based dete13tors for astro-parti13le physi13s in Europe 2

18Institute of Physi13s University of Silesia Katowi13e Poland

19Department of Physi13s and Astronomy University of Sheeld Sheeld

United Kingdom

20Max-Plan13k-Institut fuer Kernphysik Heidelberg Germany

21Departamento de Fiacutesi13a Teoacuteri13a amp Instituto de Fiacutesi13a Teoacuteri13a Fa13ultad de

Cien13ias C-XI Universidad Autoacutenoma de Madrid Cantoblan13o Madrid Spain

22INFN Sezione di Padova Padova Italy

23INFN Sezione di Bari and Dipartimento di Fisi13a Universitagrave di Bari Bari

Italy

24A Soltan Institute for Nu13lear Studies Warsaw Poland

25Department of Physi13al S13ien13es University of Helsinki Finland

26CERN Physi13s Department Theory Division Geneva Switzerland

27Institute of Theoreti13al Physi13s Wro13law University Wro13law Poland

28H Niewodni13zanski Institute of Nu13lear Physi13s Krakow Poland

29Institut de Physique Nu13leaire dOrsay (IPNO) Groupe de Physique

Theorique Universiteacute de Paris-Sud XI Orsay Fran13e

E-mail 13ampagnelalin2p3fr

Abstra13t

This do13ument reports on a series of experimental and theoreti13al studies

13ondu13ted to assess the astro-parti13le physi13s potential of three future large-s13ale

parti13le dete13tors proposed in Europe as next generation underground observato-

ries The proposed apparatus employ three dierent and to some extent 13om-

plementary dete13tion te13hniques GLACIER (liquid Argon TPC) LENA (liquid

s13intillator) and MEMPHYS (water Cherenkov) based on the use of large mass of

liquids as a13tive dete13tion media The results of these studies are presented along

with a 13riti13al dis13ussion of the performan13e attainable by the three proposed

approa13hes 13oupled to existing or planned underground laboratories in relation

to open and outstanding physi13s issues su13h as the sear13h for matter instability

the dete13tion of astrophysi13al- and geo-neutrinos and to the possible use of these

dete13tors in future high-intensity neutrino beams

Keywords neutrino dete13tors neutrino experiments neutrino properties solar

and atmospheri13 neutrinos supernova neutrinos proton de13ay wimp

PACS numbers 1330a1420Dh1460Pq2665t+2940Gx2940Ka2940M139555Vj9585Ry

9760Bw

Submitted to Journal of Cosmology and Astroparti13le Physi13s

1 Physi13s motivation

Several outstanding physi13s goals 13ould be a13hieved by the next generation of

large underground observatories in the domain of astro-parti13le and parti13le physi13s

neutrino astronomy and 13osmology Proton de13ay [1 in parti13ular is one of the

most ex13iting predi13tion of Grand Unied Theories (for a review see [2) aiming at

the uni13ation of fundamental for13es in Nature It remains today one of the most

relevant open questions of parti13le physi13s Its dis13overy would 13ertainly represent a

fundamental milestone 13ontributing to 13larifying our understanding of the past and

future evolution of the Universe

Several experiments have been built and 13ondu13ted to sear13h for proton de13ay

but they only yielded lower limits to the proton lifetime The window between the

predi13ted proton lifetime (in the simplest models typi13ally below 1037 years) and that

ex13luded by experiments [3 (O(1033) years depending on the 13hannel) is within rea13hand the demand to ll the gap grows with the progress in other domains of parti13le

physi13s astro-parti13le physi13s and 13osmology To some extent also a negative result

from next generation high-sensitivity experiments would be relevant to rule-out some

of the theoreti13al models based on SU(5) and SO(10) gauge symmetry or to further

13onstrain the range of allowed parameters Identifying unambiguously proton de13ay

and measuring its lifetime would set a rm s13ale for any Unied Theory narrowing the

phase spa13e for possible models and their parameters This will be a mandatory step

to go forward beyond the Standard Model of elementary parti13les and intera13tions

Another important physi13s subje13t is the physi13s of astrophysi13al neutrinos as

those from supernovae from the Sun and from the intera13tion of primary 13osmi13-

rays with the Earths atmosphere Neutrinos are above all important messengers

from stars Neutrino astronomy has a glorious although re13ent history from the

dete13tion of solar neutrinos [4 5 6 7 8 9 10 to the observation of neutrinos from

supernova explosion [11 12 13 a13knowledged by the Nobel Prizes awarded to M

Koshiba and R Davis These observations have given valuable information for a

better understanding of the fun13tioning of stars and of the properties of neutrinos

However mu13h more information 13ould be obtained if the energy spe13tra of stellar

neutrinos were known with higher a1313ura13y Spe13i13 neutrino observations 13ould give

detailed information on the 13onditions of the produ13tion zone whether in the Sun or

in a supernova A supernova explosion in our galaxy would be extremely important

as the evolution me13hanism of the 13ollapsed star is still a puzzle for astrophysi13s

An even more fas13inating 13hallenge would be observing neutrinos from extragala13ti13

supernovae either from identied sour13es or from a diuse ux due to unidentied

past supernova explosions

Observing neutrinos produ13ed in the atmosphere as 13osmi13-ray se13ondaries

[14 15 16 17 18 19 20 gave the rst 13ompelling eviden13e for neutrino os13illation

[21 22 a pro13ess that unambiguously points to the existen13e of new physi13s

While today the puzzle of missing atmospheri13 neutrinos 13an be 13onsidered solved

there remain 13hallenges related to the sub-dominant os13illation phenomena In

parti13ular pre13ise measurements of atmospheri13 neutrinos with high statisti13s and

small systemati13 errors [23 would help in resolving ambiguities and degenera13ies

that hamper the interpretation of other experiments as those planned for future long

baseline neutrino os13illation measurements

Another example of outstanding open questions is that of the knowledge of the

interior of the Earth It may look hard to believe but we know mu13h better what

happens inside the Sun than inside our own planet There are very few messengers that

13an provide information while a mere theory is not su13ient for building a 13redible

model for the Earth However there is a new unexploited window to the Earths

interior by observing neutrinos produ13ed in the radioa13tive de13ays of heavy elements

in the matter Until now only the KamLAND experiment [24 has been able to study

these so-13alled geo-neutrinos opening the way to a 13ompletely new eld of resear13h

The small event rate however does not allow to draw signi13ant 13on13lusions

The fas13inating physi13s phenomena outlined above in addition to other important

subje13ts that we will address in the following 13ould be investigated by a new

generation of multipurpose experiments based on improved dete13tion te13hniques The

envisioned dete13tors must ne13essarily be very massive (and 13onsequently large) due

to the smallness of the 13ross-se13tions and to the low rate of signal events and able

to provide very low experimental ba13kground The required signal to noise ratio 13an

only be a13hieved in underground laboratories suitably shielded against 13osmi13-rays

and environmental radioa13tivity We 13an identify three dierent and to large extent

13omplementary te13hnologies 13apable to meet the 13hallenge based on large s13ale use

of liquids for building large-size volume-instrumented dete13tors

bull Water Cherenkov As the 13heapest available (a13tive) target material water is the

only liquid that is realisti13 for extremely large dete13tors up to several hundreds or

thousands of ktons water Cherenkov dete13tors have su13iently good resolution

in energy position and angle The te13hnology is well proven as previously used

for the IMB Kamiokande and Super-Kamiokande experiments

bull Liquid s13intillator Experiments using a liquid s13intillator as a13tive target provide

high-energy resolution and oer low-energy threshold They are parti13ularly

attra13tive for low energy parti13le dete13tion as for example solar neutrinos and geo-

neutrinos Also liquid s13intillator dete13tors feature a well established te13hnology

already su1313essfully applied at relatively large s13ale to the Borexino [25 and

KamLAND [26 experiments

bull Liquid Argon Time Proje13tion Chambers (LAr TPC) This dete13tion te13hnology

has among the three the best performan13e in identifying the topology of

intera13tions and de13ays of parti13les thanks to the bubble-13hamber-like imaging

performan13e Liquid Argon TPCs are very versatile and work well with a wide

parti13le energy range Experien13e on su13h dete13tors has been gained within the

ICARUS proje13t [27 28

Three experiments are proposed to employ the above dete13tion te13hniques

MEMPHYS [29 for water Cherenkov LENA [30 31 for liquid s13intillator and

GLACIER [32 33 34 35 36 for Liquid Argon In this paper we report on the study

of the physi13s potential of the experiments and identify features of 13omplementarity

amongst the three te13hniques

Needless to say the availability of future neutrino beams from parti13le a1313elerators

would provide an additional bonus to the above experiments Measuring os13illations

with arti13ial neutrinos (of well known kinemati13al features) with a su13iently long

baseline would allow to a1313urately determine the os13illation parameters (in parti13ular

the mixing angle θ13 and the possible CP violating phase in the mixing matrix) The

envisaged dete13tors may then be used for observing neutrinos from the future Beta

Beams and Super Beams in the optimal energy range for ea13h experiment A 13ommon

example is a low-energy Beta Beam from CERN to MEMPHYS at Frejus 130 km

Table 1 Basi13 parameters of the three dete13tor (baseline) design

GLACIER LENA MEMPHYS

Dete13tor dimensions

type of 13ylinder 1 vert 1 horiz 3divide 5 vert

diam (m) 70 30 65length (m) 20 100 65typi13al mass (kton) 100 50 600divide 800

A13tive target and readout

type of target liq Argon liq s13intillator water

(boiling) (opt 02 GdCl3)

readout type eminus drift 2 perp

views 105 13hannelsampli in gas phase

Cher light 27 0008 PMTs sim 2013overage

S13int light 10008 PMTs

12 00020 PMTs

amp 30 13overage

81 00012 PMTs

sim 30 13overage

away [37 High energy beams have been suggested [38 favoring longer baselines of

up to O(2000 km) The ultimate Neutrino Fa13tory fa13ility will require a magnetized

dete13tor to fully exploit the simultaneous availability of neutrinos and antineutrinos

This subje13t is however beyond the s13ope of the present study

Finally there is a possibility of (and the hope for) unexpe13ted dis13overies The

history of physi13s has shown that several experiments have made their glory with

dis13overies in resear13h elds that were outside the original goals of the experiments

Just to quote an example we 13an mention the Kamiokande dete13tor mainly designed

to sear13h for proton de13ay and a13tually 13ontributing to the observation of atmospheri13

neutrino os13illations to the 13lari13ation of the solar neutrino puzzle and to the

rst observation of supernova neutrinos [11 39 5 15 21 All the three proposed

experiments thanks to their outstanding boost in mass and performan13e will 13ertainly

provide a signi13ant potential for surprises and unexpe13ted dis13overies

2 Des13ription of the three dete13tors

The three dete13tors basi13 parameters are listed in Tab 1 All of them have a13tive

targets of tens to hundreds kton mass and are to be installed in underground

laboratories to be prote13ted against ba13kground indu13ed by 13osmi13-rays As already

said the large size of the dete13tors is motivated by the extremely low 13ross-se13tion of

neutrinos andor by the rareness of the interesting events sear13hed for Some details of

the dete13tors are dis13ussed in the following while the matters related to the possible

underground site are presented in Se13tion 3

Figure 1 Artisti13 view of a 100 kton single-tank liquid Argon TPC dete13tor

The ele13troni13 13rates are lo13ated at the top of the dewar

21 Liquid Argon TPC

GLACIER (Fig 1) is the foreseen extrapolation up to 100 kton of the liquid Argon

Time Proje13tion Chamber te13hnique The dete13tor 13an be me13hani13ally subdivided

into two parts the liquid Argon tank and the inner dete13tor instrumentation For

simpli13ity we assume at this stage that the two aspe13ts 13an be largely de13oupled

The basi13 idea behind this dete13tor is to use a single 100 kton boiling liquid Argon

13ryogeni13 tank with 13ooling dire13tly performed with liquid Argon (self-refrigerating)

Events are re13onstru13ted in 3D by using the information provided by ionization in

liquid The imaging 13apabilities and the ex13ellent spa13e resolution of the devi13e

make this dete13tor an ele13troni13 bubble 13hamber The signal from s13intillation

and Cherenkov light readout 13omplete the information 13ontributing to the event

re13onstru13tion

As far as light 13olle13tion is 13on13erned one 13an prot from the ICARUS RampD

program that has shown that it is possible to operate photomultipliers (PMTs) dire13tly

immersed in the liquid Argon [27 In order to be sensitive to DUV s13intillation

PMTs are 13oated with a wavelength shifter (WLS) for instan13e tetraphenyl-butadiene

About 1000 immersed phototubes with WLS would be used to identify the (isotropi13

and bright) s13intillation light To dete13t Cherenkov radiation about 27 000 8-

phototubes without WLS would provide a 20 13overage of the dete13tor surfa13e The

latter PMTs should have single photon 13ounting 13apabilities in order to 13ount the

number of Cherenkov photons

Charge ampli13ation and an extreme liquid purity against ele13tronegative

13ompounds (although attainable by 13ommer13ial puri13ation systems) is needed to

allow long drift distan13es of the ionizationimaging ele13trons (asymp 20 m) For this

reason the dete13tor will run in the so-13alled bi-phase mode Namely drifting ele13trons

produ13ed in the liquid phase are extra13ted into the gas phase with the help of an

ele13tri13 eld and amplied in order to 13ompensate the 13harge loss due to attenuation

along the drift path The nal 13harge signal is then read out by means of Large

Ele13tron Multiplier (LEM) devi13es providing X-Y information The Z 13oordinate is

given by the drift time measurement proportional to the drift length A possible

extension of the present dete13tor design envisages the immersion of the sensitive

Figure 2 S13hemati13 drawing of the LENA dete13tor Reprinted gure with the

permission from [40

volume in an external magneti13 eld [36 Existing experien13e from spe13ialized

Liquied Natural Gases (LNG) 13ompanies and studies 13ondu13ted in 13ollaboration with

Te13hnodyne LtD UK have been ingredients for a rst step in assessing the feasibility

of the dete13tor and of its operation in an underground site

22 Liquid s13intillator dete13tor

The LENA dete13tor is 13ylindri13al in shape with a length of about 100m and 30m

diameter (Fig 2) The inner volume 13orresponding to a radius of 13m 13ontains

approximately 5 times 104m3of liquid s13intillator The outer part of the volume is lled

with water a13ting as a veto for identifying muons entering the dete13tor from outside

Both the outer and the inner volume are en13losed in steel tanks of 3 to 4 13m wall

thi13kness For most purposes a du13ial volume is dened by ex13luding the volume

13orresponding to 1m distan13e to the inner tank walls The du13ial volume so dened

amounts to 88 of the total dete13tor volume

The main axis of the 13ylinder is pla13ed horizontally A tunnel-shaped 13avern

housing the dete13tor is 13onsidered as realisti13ally feasible for most of the envisioned

dete13tor lo13ations In respe13t to a1313elerator physi13s the axis 13ould be oriented towards

the neutrino sour13e in order to 13ontain the full length of muon and ele13tron tra13ks

produ13ed in 13harged-13urrent neutrino intera13tions in the liquid s13intillator

The baseline 13onguration for the light dete13tion in the inner volume foresees

12 000 PMTs of 20 diameter mounted onto the inner 13ylinder wall and 13overing

about 30 of the surfa13e As an option light 13on13entrators 13an be installed in front

of the PMTs hen13e in13reasing the surfa13e 13overage c to values larger than 50

Alternatively c = 30 13an be rea13hed by equipping 8 PMTs with light 13on13entrators

thereby redu13ing the 13ost when 13omparing to the baseline 13onguration Additional

PMTs are supplied in the outer veto to dete13t (and reje13t) the Cherenkov light from

events due to in13oming 13osmi13 muons Possible 13andidates as liquid s13intillator

material are pure phenyl-o-xylylethane (PXE) a mixture of 20 PXE and 80Dode13ane and linear Alkylbenzene (LAB) All three liquids exhibit low toxi13ity and

provide high ash and inammation points

Figure 3 Layout of the MEMPHYS dete13tor in the future Freacutejus laboratory

23 Water Cherenkov

The MEMPHYS dete13tor (Fig 3) is an extrapolation of the water Cherenkov Super-

Kamiokande dete13tor to a mass as large as 730 kton The dete13tor is 13omposed of up to5 shafts 13ontaining separate tanks 3 tanks are enough to total 440 kton du13ial mass

This is the 13onguration whi13h is used hereafter Ea13h shaft has 65 m diameter and

65 m height representing an in13rease by a fa13tor 8 with respe13t to Super-Kamiokande

The Cherenkov light rings produ13ed by fast parti13les moving within the inner

water volume are re13onstru13ted by PMTs pla13ed on the inner tank wall The PMT

housing surfa13e starts at 2 m from the outer wall and is 13overed with about 81 000 12PMTs to rea13h a 30 surfa13e 13overage in or alternatively equivalent to a 40 13overage

with 20 PMTs The du13ial volume is dened by an additional 13onservative guard of

2 m The outer volume between the PMT surfa13e and the water vessel is instrumented

with 8 PMTs If not otherwise stated the Super-Kamiokande analysis pro13edures for

e13ien13y 13al13ulations ba13kground redu13tion et13 are used in 13omputing the physi13s

potential of MEMPHYS In USA and Japan two analogous proje13ts (UNO and Hyper-

Kamiokande) have been proposed These dete13tors are similar in many respe13ts and

the physi13s potential presented hereafter may well be transposed to them Spe13i13

13hara13teristi13s that are not identi13al in the proposed proje13ts are the distan13e from

available or envisaged a1313elerators and nu13lear rea13tors sour13es of arti13ial neutrino

uxes and the and the depth of the host laboratory

Currently there is a very promising ongoing RampD a13tivity 13on13erning the

possibility of introdu13ing Gadolinium salt (GdCl3) inside Super-Kamiokande The

physi13s goal is to de13rease the ba13kground for many physi13s 13hannels by dete13ting

and tagging neutrons produ13ed in the Inverse Beta De13ay (IBD) intera13tion of νe onfree protons For instan13e 100 tons of GdCl3 in Super-Kamiokande would yield more

then 90 neutron 13aptures on Gd [41

3 Underground sites

The proposed large dete13tors require underground laboratories of adequate size and

depth naturally prote13ted against 13osmi13-rays that represent a potential sour13e of

ba13kground events mainly for non-a1313elerator experiments that 13annot exploit the

pe13uliar time stamp provided by the a1313elerator beam spill

Additional 13hara13teristi13s of these sites 13ontributing to their quali13ation as

13andidates for the proposed experiments are the type and quality of the ro13k allowing

the pra13ti13al feasibility of large 13averns at reasonable 13ost and within reasonable time

the distan13e from existing (or future) a1313elerators and nu13lear rea13tors the type and

quality of the a1313ess the geographi13al position the environmental 13onditions et13

The presently identied worldwide 13andidate sites are lo13ated in three

geographi13al regions North-Ameri13a far-east Asia and Europe In this paper we

13onsider the European region where at this stage the following sites are assumed

as 13andidates Boulby (UK) Canfran13 (Spain) Freacutejus (Fran13eItaly) Gran Sasso

(Italy) Pyhaumlsalmi (Finland) and Sieroszewi13e (Poland) Most of the sites are existing

national or international underground laboratories with asso13iated infrastru13ture and

experimental halls already used for experiments The basi13 features of the sites are

presented on Tab 2 For the Gran Sasso Laboratory a possible new (additional) site is

envisaged to be lo13ated 10 km away from the present underground laboratory outside

the prote13ted area of the neighboring Gran Sasso National Park The possibility of

under-water solutions su13h as for instan13e Pylos for the LENA proje13t is not taken

into a1313ount here The identi13ation and measurement of the dierent ba13kground

13omponents in the 13andidate sites (muons fast neutrons from muon intera13tions slow

neutrons from nu13lear rea13tions in the ro13k gammas ele13tronspositrons and alphas

from radioa13tive de13ays ) is underway mainly in the 13ontext of the ILIAS European

(JRA) Network (httpiliasin2p3fr)

None of the existing sites has yet a su13iently large 13avity able to a1313ommodate

the foreseen dete13tors For two of the sites (Freacutejus and Pyhaumlsalmi) a preliminary

feasibility study for large ex13avation at deep depth has already been performed For

the Freacutejus site the main 13on13lusion drawn from simulations 13onstrained by a series

of ro13k parameter measurements made during the Freacutejus road tunnel ex13avation is

that the shaft shape is strongly preferred 13ompared to the tunnel shape as long

as large 13avities are required As mentioned above several (up to 5) of su13h shaft

13avities with a diameter of about 65 m (for a 13orresponding volume of 250 000 m

3)

ea13h seem feasible in the region around the middle of the Freacutejus tunnel at a depth

of 4800 mwe For the Pyhaumlsalmi site the preliminary study has been performed

for two main 13avities with tunnel shape and dimensions of (20 times 20 times 120) m3and

(20times 20times 50) m3 respe13tively and for one shaft-shaped 13avity with 25 m in diameter

and 25 m in height all at a depth of about 1430 m of ro13k (4000 mwe)

4 Matter instability sensitivity to proton de13ay

For all relevant aspe13ts of the proton stability in Grand Unied Theories in strings

and in branes we refer to [2 Sin13e proton de13ay is the most dramati13 predi13tion

13oming from theories of the uni13ation of fundamental intera13tions there is a realisti13

hope to be able to test these s13enarios with next generation experiments exploiting the

above mentioned large mass underground dete13tors For this reason the knowledge

of a theoreti13al upper bound on the lifetime of the proton is very helpful in assessing

the potential of future experiments Re13ently a model-independent upper bound on

the proton de13ay lifetime has been worked out [42

τupperp =

60times 1039 (Majorana)28times 1037 (Dirac)

times(

MX1016GeV)4

α2GUT

times(

0003GeV 3

α

)2

years(1)

Largeundergroundliquidbaseddete13torsforastro-parti13lephysi13sinEurope

10

Table 2 Summary of 13hara13teristi13s of some underground sites envisioned for the proposed dete13tors

Site Boulby Canfran13 Freacutejus Gran Sasso Pyhaumlsalmi Sieroszowi13e

Lo13ation UK Spain Italy-Fran13e border Italy Finland Poland

Dist from CERN (km) 1050 630 130 730 2300 950

Type of a1313ess Mine Somport tunnel Freacutejus tunnel Highway

tunnel Mine Shaft

Vert depth (mwe) 2800 2450 4800 3700 4000 2200

Type of ro13k salt hard ro13k hard ro13k hard ro13k hard ro13k salt amp ro13k

Type of 13avity shafts tunnel shafts

Size of 13avity Φ = 65 m (20times 20times 120)m3 Φ = 74 mH = 80 m H = 37 m

micro Flux (m

minus2

day

minus1

) 34 406 4 24 9 not available

1014

1015

1016

1017

M (GeV)X

160150

140

130

125

120

115

110

αG

UT

1014

1015

1016

1017

1034

1036

1038

1040

1042

1044

Figure 4 Isoplot for the upper bounds on the total proton lifetime in years in

the Majorana neutrino 13ase in the MXαGUT plane The value of the unifying

13oupling 13onstant is varied from 160 to 110 The 13onventional values for MX

and αGUT in SUSY GUTs are marked with thi13k lines The experimentally

ex13luded region is given in bla13k Reprinted gure with permission from [42

where MX is the mass of the superheavy gauge bosons mediating proton de13ay the

parameter αGUT = g2GUT 4π with gGUT the gauge 13oupling at the grand unied

s13ale and α is the relevant matrix element Fig 4 shows the present parameter spa13e

allowed by experiments in the 13ase of Majorana neutrinos

Most of the models (Super-symmetri13 or non Super-symmetri13) predi13t a proton

lifetime τp below those upper bounds (1033minus37years) This is parti13ularly interesting

sin13e this falls within the possible range of the proposed experiments In order to have

a better idea of the proton de13ay predi13tions we list the results from dierent models

in Tab 3

No spe13i13 simulations for MEMPHYS have been 13arried out yet Therefore

here we rely on the studies done for the similar UNO dete13tor adapting the results

to MEMPHYS whi13h however features an overall better PMT 13overage

In order to assess the physi13s potential of a large liquid Argon Time Proje13tion

Chambers su13h as GLACIER a detailed simulation of signal e13ien13y and ba13kground

sour13es in13luding atmospheri13 neutrinos and 13osmogeni13 ba13kgrounds was 13arried

out [58 Liquid Argon TPCs oering high spa13e granularity and energy resolution

low-energy dete13tion threshold and ex13ellent ba13kground dis13rimination should yield

large signal over ba13kground ratio for many of the possible proton de13ay modes hen13e

allowing rea13hing partial lifetime sensitivities in the range of 1034 minus 1035 years for

Table 3 Summary of several predi13tions for the proton partial lifetimes (years)

Referen13es for the dierent models are (1) [43 (2) [44 45 (3) [46 (4)

[47 48 49 50 (5) [51 52 53 54 (6) [55 (7) [56 (8) [57

Model De13ay modes Predi13tion Referen13es

Georgi-Glashow model - ruled out (1)

Minimal realisti13

non-SUSY SU(5)all 13hannels τupperp = 14times 1036 (2)

Two Step Non-SUSY SO(10) prarr e+π0 asymp 1033minus38(3)

Minimal SUSY SU(5) prarr νK+ asymp 1032minus34(4)

SUSY SO(10)with 10H and 126H

prarr νK+ asymp 1033minus36(5)

M-Theory(G2) prarr e+π0 asymp 1033minus37(6)

SU(5) with 24F prarr π0e+ asymp 1035minus36(7)

Renormalizable Adjoint SU(5) prarr π0e+ asymp 1035minus36(8)

exposures up to 1000 kton year This 13an often be a1313omplished in quasi ba13kground-

free 13onditions optimal for dis13overies at the few events level 13orresponding to

atmospheri13 neutrino ba13kground reje13tions of the order of 105Multi-prong de13ay modes like p rarr microminusπ+K+

or p rarr e+π+πminusand 13hannels

involving kaons like prarr K+ν prarr e+K0and prarr micro+K0

are parti13ularly appealing

sin13e liquid Argon imaging provides typi13ally one order of magnitude e13ien13y in13rease

for similar or better ba13kground 13onditions 13ompared to water Cherenkov dete13tors

Up to a fa13tor of two improvement in e13ien13y is expe13ted for modes like prarr e+γ and

prarr micro+γ thanks to the 13lean photon identi13ation and separation from π0 Channels

su13h as prarr e+π0and prarr micro+π0

dominated by intrinsi13 nu13lear ee13ts yield similar

performan13e as water Cherenkov dete13tors

An important feature of GLACIER is that thanks to the self-shielding and 3D-

imaging properties the above expe13ted performan13e remains valid even at shallow

depths where 13osmogeni13 ba13kground sour13es are important The possibility of using

a very large-area annular muon-veto a13tive shielding to further suppress 13osmogeni13

ba13kgrounds at shallow depths is also a very promising option to 13omplement the

GLACIER dete13tor

In order to quantitatively estimate the potential of the LENA dete13tor in

measuring proton lifetime a Monte Carlo simulation for the de13ay 13hannel prarr K+νhas been performed For this purpose the GEANT4 simulation toolkit [59 has been

used in13luding opti13al pro13esses as s13intillation Cherenkov light produ13tion Rayleigh

s13attering and light absorption From these simulations one obtains a light yield of

sim 110 peMeV for an event in the 13enter of the dete13tor In addition the semi-

empiri13al Birks formula has been introdu13ed into the 13ode in order to take into a1313ount

the so-13alled quen13hing ee13ts

10 32

10 33

10 34

10 35

10 36

10 37

102

103

104

105

106

Exposure (kton year)

Par

tial

Lif

etim

e (y

ears

)

prarreπ0 sensitivity (90 CL)

current status

79ktyr 50 x 1033 yrs

detector (A) (Super-K)effSK=44BGSKasymp22evMtyr

eff=34 x effSKSN=34 x (SN)SK

Figure 5 Sensitivity to the e+π0proton de13ay mode 13ompiled by the UNO

13ollaboration MEMPHYS 13orresponds to 13ase (A) Reprinted gure with

permission from [60

Following studies performed for the UNO dete13tor the dete13tion e13ien13y for

p rarr e+π0is 43 for a 20 PMT 13overage of 40 or its equivalent as envisioned for

MEMPHYS The 13orresponding estimated atmospheri13 neutrino indu13ed ba13kground

is at the level of 225 eventsMton year From these e13ien13ies and ba13kground levels

proton de13ay sensitivity as a fun13tion of dete13tor exposure 13an be estimated A 1035

years partial lifetime (τpB) 13ould be rea13hed at the 90 CL for a 5 Mton year

exposure (10 years) with MEMPHYS (similar to 13ase A in Fig 5 13ompiled by the

UNO 13ollaboration [60) Beyond that exposure tighter 13uts may be envisaged to

further redu13e the atmospheri13 neutrino ba13kground to 015 eventsMton year by

sele13ting quasi ex13lusively the free proton de13ays

The positron and the two photons issued from the π0gives 13lear events in the

GLACIER dete13tor The π0is absorbed by the nu13leus in 45 of the 13ases Assuming

a perfe13t parti13le and tra13k identi13ation one may expe13t a 45 e13ien13y and a

ba13kground level of 1 eventMton year For a 1 Mton year (10 years) exposure with

GLACIER one rea13hes τpB gt 04times 1035 years at the 90 CL (Fig 6)

In a liquid s13intillator dete13tor su13h as LENA the de13ay prarr e+π0would produ13e

a 938 MeV signal 13oming from the e+ and the π0shower Only atmospheri13 neutrinos

are expe13ted to 13ause ba13kground events in this energy range Using the fa13t that

showers from both e+ and π0propagate 4 m in opposite dire13tions before being

stopped atmospheri13 neutrino ba13kground 13an be redu13ed Applying this method

the 13urrent limit for this 13hannel (τpB = 54 1033 years [61) 13ould be improved

In LENA proton de13ay events via the mode p rarr K+ν have a very 13lear signature

Exposure (kton x years)

1 102

103

104

10

Lim

it 9

0

CL

(years

)

3210

3310

3410

3510

3610

p g K+

ν micro- π

+ K

+

p g e+

γ micro+

γ+

n g e- K

+

p g micro+

K0 e

+ K

0

p g e+

π0

p g micro+

π0

n g micro- π

+

p g e+

π+ π

-

n g π0 ν

p g π+ ν

n g e+

π-

proton

neutron

Figure 6 Expe13ted proton de13ay lifetime limits (τB at 90 CL) as a fun13tion

of exposure for GLACIER Only atmospheri13 neutrino ba13kground has been taken

into a1313ount Reprinted gure with permission from [58

The kaon 13auses a prompt monoenergeti13 signal of 105 MeV together with a larger

delayed signal from its de13ay The kaon has a lifetime of 128 ns and two main de13ay

13hannels with a probability of 6343 it de13ays via K+ rarr micro+νmicro and with 2113

via K+ rarr π+π0

Simulations of proton de13ay events and atmospheri13 neutrino ba13kground have

been performed and a pulse shape analysis has been applied From this analysis

an e13ien13y of 65 for the dete13tion of a proton de13ay has been determined and

a ba13kground suppression of sim 2 times 104 has been a13hieved [62 A detail study of

ba13kground implying pion and kaon produ13tion in atmospheri13 neutrino rea13tions has

been performed leading to a ba13kground rate of 0064 yearminus1due to the rea13tion

νmicro + prarr microminus +K+ + pFor the 13urrent proton lifetime limit for the 13hannel 13onsidered (τpB = 23 times

1033 year) [3 about 407 proton de13ay events would be observed in LENA after ten

years with less than 1 ba13kground event If no signal is seen in the dete13tor within ten

years the lower limit for the lifetime of the proton will be set at τpB gt 4 times1034 yearsat the 90 CL

For GLACIER the latter is a quite 13lean 13hannel due to the presen13e of a strange

meson and no other parti13les in the nal state Using dEdx versus range as the

dis13riminating variable in a Neural Network algorithm less than 1 of the kaons are

mis-identied as protons For this 13hannel the sele13tion e13ien13y is high (97) for

an atmospheri13 neutrino ba13kground lt 1 eventMton year In 13ase of absen13e of

signal and for a dete13tor lo13ation at a depth of 1 kmwe one expe13ts for 1 Mton year

10 32

10 33

10 34

10 35

10 36

10 37

102

103

104

105

106

Par

tial

Lif

etim

e (y

ears

)

prarrνK+ sensitivity (90 CL)

current limit

793ktyr16 x 1033 yrs

combinedsensitivity

prompt γπ+π0

micro spectrum

Figure 7 Expe13ted sensitivity to the νK+proton de13ay mode as a fun13tion

of exposure 13ompiled by the UNO 13ollaboration whi13h may be applied for the

MEMPHYS dete13tor (see text for details) Reprinted gure with permission

from [60

(10 years) exposure one ba13kground event due to 13osmogeni13 sour13es This translates

into a limit τpB gt 06 times 1035 years at 90 CL This result remains valid even at

shallow depths where 13osmogeni13 ba13kground sour13es are a very important limiting

fa13tor for proton de13ay sear13hes For example the study done in [58 shows that a

three-plane a13tive veto at a shallow depth of about 200 m ro13k overburden under a

hill yields similar sensitivity for prarr K+ν as a 3000 mwe deep dete13tor

For MEMPHYS one should rely on the dete13tion of the de13ay produ13ts of the K+

sin13e its momentum (360 MeV) is below the water Cherenkov threshold of 570 MeV a

256 MeV13 muon and its de13ay ele13tron (type I) or a 205 MeV13 π+and π0

(type II)

with the possibility of a delayed (12 ns) 13oin13iden13e with the 6 MeV

15N de-ex13itation

prompt γ (Type III) Using the known imaging and timing performan13e of Super-

Kamiokande the e13ien13y for the re13onstru13tion of p rarr νK+is 33 (I) 68 (II)

and 88 (III) and the ba13kground is 2100 22 and 6 eventsMton year respe13tively

For the prompt γ method the ba13kground is dominated by miss-re13onstru13tion

As stated by the UNO Collaboration [60 there are good reasons to believe that

this ba13kground 13an be lowered by at least a fa13tor of two 13orresponding to the

atmospheri13 neutrino intera13tion νp rarr νΛK+ In these 13onditions and taking into

a1313ount the Super-Kamiokande performan13e a 5 Mton year exposure for MEMPHYS

would allow rea13hing τpB gt 2times 1034 years (Fig 7)A preliminary 13omparison between the performan13e of three dete13tors has been

13arried out (Tab 4) For the e+π013hannel the Cherenkov dete13tor gets a better

Table 4 Summary of the e+π0and νK+

de13ay dis13overy potential for the three

dete13tors The e+π013hannel is not yet simulated for LENA

e+π0

ǫ()Bkgd(Mton year) 451 - 43225τpB (90 CL 10 years) 04times 1035 - 10times 1035

νK+

ǫ()Bkgd(Mton year) 971 651 883τpB (90 CL 10 years) 06times 1035 04times 1035 02times 1035

limit due to the higher mass However it should be noted that GLACIER although

ve times smaller in mass than MEMPHYS 13an rea13h a limit that is only a fa13tor

two smaller Liquid Argon TPCs and liquid s13intillator dete13tors obtain better results

for the νK+13hannel due to their higher dete13tion e13ien13y The te13hniques look

therefore quite 13omplementary We have also seen that GLACIER does not ne13essarily

requires very deep underground laboratories like those 13urrently existing or future

planned sites in order to perform high sensitivity nu13leon de13ay sear13hes

5 Supernova neutrinos

The dete13tion of supernova (SN) neutrinos represents one of the next frontiers of

neutrino physi13s and astrophysi13s It will provide invaluable information on the

astrophysi13s of the 13ore-13ollapse explosion phenomenon and on the neutrino mixing

parameters In parti13ular neutrino avor transitions in the SN envelope might be

sensitive to the value of θ13 and to the type of mass hierar13hy These two main issues

are dis13ussed in detail in the following Se13tions

51 SN neutrino emission os13illation and dete13tion

A 13ore-13ollapse supernova marks the evolutionary end of a massive star (M amp 8M⊙)

whi13h be13omes inevitably unstable at the end of its life The star 13ollapses and eje13ts

its outer mantle in a sho13k-wave driven explosion The 13ollapse to a neutron star

(M ≃M⊙ R ≃ 10 km) liberates a gravitational binding energy of asymp 3times1053 erg 99of whi13h is transferred to (anti) neutrinos of all the avors and only 1 to the kineti13

energy of the explosion Therefore a 13ore-13ollapse SN represents one of the most

powerful sour13es of (anti) neutrinos in the Universe In general numeri13al simulations

of SN explosions provide the original neutrino spe13tra in energy and time F 0ν Su13h

initial distributions are in general modied by avor transitions in the SN envelope

in va13uum (and eventually in Earth matter) F 0νminusrarrFν and must be 13onvoluted with

the dierential intera13tion 13ross-se13tion σe for ele13tron or positron produ13tion as well

as with the dete13tor resolution fun13tion Re and the e13ien13y ε in order to nally get

observable event rates Ne = Fν otimes σe otimesRe otimes εRegarding the initial neutrino distributions F 0

ν a SN 13ollapsing 13ore is roughly

a bla13k-body sour13e of thermal neutrinos emitted on a times13ale of sim 10 s Energy

spe13tra parametrizations are typi13ally 13ast in the form of quasi-thermal distributions

with typi13al average energies 〈Eνe 〉 = 9 minus 12 MeV 〈Eνe 〉 = 14 minus 17 MeV 〈Eνx〉 =18minus 22 MeV where νx indi13ates any non-ele13tron avor

Table 5 Values of the p and p parameters used in Eq 2 in dierent s13enario of

mass hierar13hy and sin2 θ13

Mass Hierar13hy sin2 θ13 p p

Normal amp 10minus30 cos2 θ12

Inverted amp 10minus3 sin2 θ12 0

Any 10minus5 sin2 θ12 cos2 θ12

The os13illated neutrino uxes arriving on Earth may be written in terms of the

energy-dependent survival probability p (p) for neutrinos (antineutrinos) as [63

Fνe = pF 0νe

+ (1 minus p)F 0νx

Fνe = pF 0νe

+ (1 minus p)F 0νx

(2)

4Fνx = (1minus p)F 0νe

+ (1minus p)F 0νe

+ (2 + p+ p)F 0νx

where νx stands for either νmicro or ντ The probabilities p and p 13ru13ially depend

on the neutrino mass hierar13hy and on the unknown value of the mixing angle θ13 asshown in Tab 5

Gala13ti13 13ore-13ollapse supernovae are rare perhaps a few per 13entury Up to now

SN neutrinos have been dete13ted only on13e during the SN 1987A explosion in the Large

Magellani13 Cloud in 1987 (d = 50 kp13) Due to the relatively small masses of the

dete13tors operational at that time only few events were dete13ted 11 in Kamiokande

[11 39 and 8 in IMB [64 12 The three proposed large-volume neutrino observatories

13an guarantee 13ontinuous exposure for several de13ades so that a high-statisti13s SN

neutrino signal 13ould be eventually observed The expe13ted number of events for

GLACIER LENA and MEMPHYS are reported in Tab 6 for a typi13al gala13ti13 SN

distan13e of 10 kp13 The total number of events is shown in the upper panel while the

lower part refers to the νe signal dete13ted during the prompt neutronization burst

with a duration of sim 25 ms just after the 13ore boun13e

The νe dete13tion by IBD is the golden 13hannel for MEMPHYS and LENA

In addition the ele13tron neutrino signal 13an be dete13ted by LENA thanks to the

intera13tion on

12C The three 13harged-13urrent rea13tions would provide information

on νe and νe uxes and spe13tra while the three neutral-13urrent pro13esses sensitive

to all neutrino avours would give information on the total ux GLACIER has

also the opportunity to dete13t νe by 13harged-13urrent intera13tions on40Ar with a very

low energy threshold The dete13tion 13omplementarity between νe and νe is of great

interest and would assure a unique way of probing the SN explosion me13hanism as well

as assessing intrinsi13 neutrino properties Moreover the huge statisti13s would allow

spe13tral studies in time and in energy domain

We wish to stress that it will be di13ult to establish SN neutrino os13illation ee13ts

solely on the basis of a νe or νe spe13tral hardening relative to theoreti13al expe13tationsTherefore in the re13ent literature the importan13e of model-independent signatures has

been emphasized Here we fo13us mainly on signatures asso13iated to the prompt νeneutronization burst the sho13k-wave propagation and the Earth matter 13rossing

The analysis of the time stru13ture of the SN signal during the rst few tens

of millise13onds after the 13ore boun13e 13an provide a 13lean indi13ation if the full νeburst is present or absent and therefore allows distinguishing between dierent mixing

Table 6 Summary of the expe13ted neutrino intera13tion rates in the dierent

dete13tors for a typi13al SN The following notations have been used CC NC

IBD eES and pES stand for Charged Current Neutral Current Inverse Beta

De13ay ele13tron and proton Elasti13 S13attering respe13tively The nal state nu13lei

are generally unstable and de13ay either radiatively (notation

lowast) or by βminusβ+

weak intera13tion (notation

minus+) The rates of the dierent rea13tion 13hannels are

listed and for LENA they have been obtained by s13aling the predi13ted rates from

[65 66

MEMPHYS LENA GLACIER

Intera13tion Rates Intera13tion Rates Intera13tion Rates

νe IBD 2times 105 νe IBD 90times 103 νCCe (40Ar 40Klowast) 25times 104

(minus)

νeCC(16OX) 1times 104 νx pES 70times 103 νNC

x (40Arlowast) 30times 104

νx eES 1times 103 νNCx (12Clowast) 30times 103 νx eES 10times 103

νx eES 60times 102 νCCe (40Ar 40Cllowast) 54times 102

νCCe (12C 12B+) 50times 102

νCCe (12C 12Nminus) 85times 101

Neutronization Burst rates

MEMPHYS 60 νe eESLENA 70 νe eESpESGLACIER 380 νNC

x (40Arlowast)

s13enarios as indi13ated by the third 13olumn of Tab 7 For example if the mass ordering

is normal and θ13 is large the νe burst will fully os13illate into νx If θ13 turns out

to be relatively large one 13ould be able to distinguish between normal and inverted

neutrino mass hierar13hy

As dis13ussed above MEMPHYS is mostly sensitive to the IBD although the νe13hannel 13an be measured by the elasti13 s13attering rea13tion νx+ eminus rarr eminus+ νx [67 Of

13ourse the identi13ation of the neutronization burst is the 13leanest with a dete13tor

exploiting the 13harged-13urrent absorption of νe neutrinos su13h as GLACIER Using

its unique features of measuring νe CC (Charged Current) events it is possible to

probe os13illation physi13s during the early stage of the SN explosion while with NC

(Neutral Current) events one 13an de13ouple the SN me13hanism from the os13illation

physi13s [68 69

A few se13onds after 13ore boun13e the SN sho13k wave will pass the density region

in the stellar envelope relevant for os13illation matter ee13ts 13ausing a transient

modi13ation of the survival probability and thus a time-dependent signature in the

neutrino signal [70 71 This would produ13e a 13hara13teristi13 dip when the sho13k wave

passes [72 or a double-dip if a reverse sho13k o1313urs [73 The dete13tability of su13h a

signature has been studied in a large water Cherenkov dete13tor like MEMPHYS by the

IBD [72 and in a liquid Argon dete13tor like GLACIER by Argon CC intera13tions [74

The sho13k wave ee13ts would 13ertainly be visible also in a large volume s13intillator

su13h as LENA Su13h observations would test our theoreti13al understanding of the

13ore-13ollapse SN phenomenon in addition to identifying the a13tual neutrino mixing

s13enario

Nevertheless the supernova matter prole need not be smooth Behind the sho13k-

wave 13onve13tion and turbulen13e 13an 13ause signi13ant sto13hasti13 density u13tuations

whi13h tend to 13ast a shadow by making other features su13h as the sho13k front

unobservable in the density range 13overed by the turbulen13e [75 76 The quantitative

relevan13e of this ee13t remains to be understood

A unambiguous indi13ation of os13illation ee13ts would be the energy-dependent

modulation of the survival probability p(E) 13aused by Earth matter ee13ts [77 Theseee13ts 13an be revealed by pe13uliar wiggles in the energy spe13tra due to neutrino

os13illations in Earth 13rossing In this respe13t LENA benets from a better energy

resolution than MEMPHYS whi13h may be partially 13ompensated by 10 times more

statisti13s [78 The Earth ee13t would show up in the νe 13hannel for the normal masshierar13hy assuming that θ13 is large (Tab 7) Another possibility to establish the

presen13e of Earth ee13ts is to use the signal from two dete13tors if one of them sees

the SN shadowed by the Earth and the other not A 13omparison between the signal

normalization in the two dete13tors might reveal Earth ee13ts [79 The probability

for observing a Gala13ti13 SN shadowed by the Earth as a fun13tion of the dete13tors

geographi13 latitude depends only mildly on details of the Gala13ti13 SN distribution

[80 A lo13ation at the North Pole would be optimal with a shadowing probability of

about 60 but a far-northern lo13ation su13h as Pyhaumlsalmi in Finland the proposed

site for LENA is almost equivalent (58) One parti13ular s13enario 13onsists of a large-

volume s13intillator dete13tor lo13ated in Pyhaumlsalmi to measure the geo-neutrino ux

in a 13ontinental lo13ation and another dete13tor in Hawaii to measure it in an o13eani13

lo13ation The probability that only one of them is shadowed ex13eeds 50 whereas the

probability that at least one is shadowed is about 80

As an important 13aveat we mention that very re13ently it has been re13ognized

that nonlinear os13illation ee13ts 13aused by neutrino-neutrino intera13tions 13an have a

dramati13 impa13t on the neutrino avor evolution for approximately the rst 100 km

above the neutrino sphere [81 82 The impa13t of these novel ee13ts and of their

observable signatures is 13urrently under investigation However from re13ent numeri13al

simulations [81 and analyti13al studies [83 it results that the ee13ts of these non-

linear ee13ts would produ13e a spe13tral swap νeνe larr νxνx at r 400 km for invertedneutrino mass hierar13hy One would observe a 13omplete spe13tral swapping while

ν spe13tra would show a pe13uliar bimodal split These ee13t would appear also for

astonishingly small values of θ13 These new results suggests on13e more that one

needs 13omplementary dete13tion te13hniques to be sensitive to both neutrino and anti

neutrino 13hannels

Other interesting ideas have been studied in the literature as the pointing of a SN

by neutrinos [84 determining its distan13e from the deleptonization burst that plays

the role of a standard 13andle [67 an early alert for an SN observatory exploiting

the neutrino signal [85 and the dete13tion of neutrinos from the last phases of a

presupernova star [86

So far we have investigated SN in our Galaxy but the 13al13ulated rate of supernova

explosions within a distan13e of 10 Mp13 is about 1year Although the number of events

from a single explosion at su13h large distan13es would be small the signal 13ould be

separated from the ba13kground with the 13ondition to observe at least two events within

a time window 13omparable to the neutrino emission time-s13ale (sim 10 se13) together

with the full energy and time distribution of the events [87 In the MEMPHYS

dete13tor with at least two neutrinos observed a SN 13ould be identied without opti13al

13onrmation so that the start of the light 13urve 13ould be fore13ast by a few hours

along with a short list of probable host galaxies This would also allow the dete13tion

of supernovae whi13h are either heavily obs13ured by dust or are opti13ally faint due to

prompt bla13k hole formation

Table 7 Summary of the ee13t of the neutrino properties on νe and νe signals

Mass

Hierar13hy sin2 θ13

νe neutronizationpeak Sho13k wave Earth ee13t

Normal amp 10minus3Absent νe νe

Inverted amp 10minus3Present νe νe

Any 10minus5Present - both νe νe

Table 8 DSNB expe13ted rates The larger numbers of expe13ted signal events

are 13omputed with the present limit on the ux by the Super-Kamiokande

Collaboration The smaller numbers are 13omputed for typi13al models The

ba13kground from rea13tor plants has been 13omputed for spe13i13 sites for LENA

and MEMPHYS For MEMPHYS the Super-Kamiokande ba13kground has been

s13aled by the exposure

Intera13tion Exposure Energy Window SignalBkgd

GLACIER

νe +40Ar rarr eminus + 40Klowast 05 Mton year

5 years

[16minus 40] MeV (40-60)30

LENA at Pyhaumlsalmi

νe + prarr n+ e+

n + p rarr d + γ(2 MeV 200 micros)

04 Mton year

10 years

[95minus 30] MeV (20-230)8

1 MEMPHYS module + 02 Gd (with bkgd at Kamioka)

νe + prarr n+ e+

n+Gdrarr γ(8 MeV 20 micros)

07 Mton year

5 years

[15minus 30] MeV (43-109)47

52 Diuse supernova neutrino ba13kground

As mentioned above a gala13ti13 SN explosion would be a spe13ta13ular sour13e of

neutrinos so that a variety of neutrino and SN properties 13ould be assessed However

only one su13h explosion is expe13ted in 20 to 100 years by now Waiting for the next

gala13ti13 SN one 13an dete13t the 13umulative neutrino ux from all the past SN in the

Universe the so-13alled Diuse Supernova Neutrino Ba13kground (DSNB) In parti13ular

there is an energy window around 10 minus 40 MeV where the DSNB signal 13an emerge

above other sour13es so that the proposed dete13tors may well measure this ux after

some years of exposure

The DSNB signal although weak is not only guaranteed but 13an also allow

probing physi13s dierent from that of a gala13ti13 SN in13luding pro13esses whi13h o1313ur

on 13osmologi13al s13ales in time or spa13e For instan13e the DSNB signal is sensitive

to the evolution of the SN rate whi13h in turn is 13losely related to the star formation

rate [88 89 In addition neutrino de13ay s13enarios with 13osmologi13al lifetimes 13ould

be analyzed and 13onstrained [90 as proposed in [91 An upper limit on the DSNB

ux has been set by the Super-Kamiokande experiment [92

φDSNBνe

lt 12 cmminus2 sminus1(Eν gt 193 MeV) (3)

An upper limit based on the non observation of distortions of the expe13ted

Figure 8 DSNB signal and ba13kground in the LENA dete13tor in 10 years

of exposure The shaded regions give the un13ertainties of all 13urves An

observational window between sim 95 to 25 MeV that is almost free of ba13kground

13an be identied (for the Pyhaumlsalmi site) Reprinted gure with permission

from [40

ba13kground spe13tra in the same energy range The most re13ent theoreti13al estimates

(see for example [93 94) predi13t a DSNB ux very 13lose to the SK upper limit

suggesting that the DSNB is on the verge of the dete13tion if a signi13ant ba13kground

redu13tion is a13hieved su13h as Gd loading [41 With a 13areful redu13tion of ba13kgrounds

the proposed large dete13tors would not only be able to dete13t the DSNB but to study

its spe13tral properties with some pre13ision In parti13ular MEMPHYS and LENA

would be sensitive mostly to the νe 13omponent of DSNB through νe IBD while

GLACIER would probe νe ux trough νe +40Ar rarr eminus + 40Klowast

(and the asso13iated

gamma 13as13ade) [95

The DSNB signal energy window is 13onstrained from above by the atmospheri13

neutrinos and from below by either the nu13lear rea13tor νe (I) the spallation produ13tionof unstable radionu13lei by 13osmi13-ray muons (II) the de13ay of invisible muons into

ele13trons (III) solar νe neutrinos (IV) and low energy atmospheri13 νe and νe neutrinosintera13tions (V) The three dete13tors are ae13ted dierently by these ba13kgrounds

GLACIER looking at νe is mainly ae13ted by types IV and V MEMPHYS lled with

pure water is ae13ted by types I II V and III due to the fa13t that the muons may

not have enough energy to produ13e Cherenkov light As pointed out in [72 with the

addition of Gadolinium [41 the dete13tion of the 13aptured neutron releasing 8 MeV

gamma after sim 20 micros (10 times faster than in pure water) would give the possibility

to reje13t the invisible muon (type III) as well as the spallation ba13kground (type

II) LENA taking benet from the delayed neutron 13apture in νe + p rarr n + e+ ismainly 13on13erned with rea13tor neutrinos (I) whi13h impose to 13hoose an underground

Figure 9 Possible 90 CL measurements of the emission parameters of

supernova ele13tron antineutrino emission after 5 years running of a Gadolinium-

enhan13ed SK dete13tor or 1 year of one Gadolinium-enhan13ed MEMPHYS tanks

Reprinted gure with permission from [96

site far from nu13lear plants If LENA was installed at the Center for Underground

Physi13s in Pyhaumlsalmi (CUPP Finland) there would be an observational window from

sim 97 to 25 MeV that is almost free of ba13kground The expe13ted rates of signal and

ba13kground are presented in Tab 8 A1313ording to 13urrent DSNB models [89 that are

using dierent SN simulations ([97 98 99) for the predi13tion of the DSNB energy

spe13trum and ux the dete13tion of sim10 DSNB events per year is realisti13 for LENA

Signal rates 13orresponding to dierent DSNB models and the ba13kground rates due to

rea13tor and atmospheri13 neutrinos are shown in Fig 8 for 10 years exposure at CUPP

Apart from the mere dete13tion spe13tros13opy of DSNB events in LENA will

13onstrain the parameter spa13e of 13ore-13ollapse models If the SN rate signal is known

with su13ient pre13ision the spe13tral slope of the DSNB 13an be used to determine

the hardness of the initial SN neutrino spe13trum For the 13urrently favoured value of

the SN rate the dis13rimination between 13ore-13ollapse models will be possible at 26σafter 10 years of measuring time [40 In addition by the analysis of the ux in the

energy region from 10 to 14 MeV the SN rate for z lt 2 13ould be 13onstrained with

high signi13an13e as in this energy regime the DSNB ux is only weakly dependent on

the assumed SN model The dete13tion of the redshifted DSNB from z gt 1 is limited

by the ux of the rea13tor νe ba13kground In Pyhaumlsalmi a lower threshold of 95 MeV

resuls in a spe13tral 13ontribution of 25 DSNB from z gt 1The analysis of the expe13ted DSNB spe13trum that would be observed with a

Gadolinium-loaded water Cherenkov dete13tor has been 13arried out in [96 The

possible measurements of the parameters (integrated luminosity and average energy)

of SN νe emission have been 13omputed for 5 years running of a Gd-enhan13ed

Super-Kamiokande dete13tor whi13h would 13orrespond to 1 year of one Gd-enhan13ed

MEMPHYS tank The results are shown in Fig 9 Even if detailed studies on the

13hara13terization of the ba13kground are needed the DSNB events provide the rst

neutrino dete13tion originating from 13osmologi13al distan13es

6 Solar neutrinos

In the past years water Cherenkov dete13tors have measured the high energy tail

(E gt 5 MeV) of the solar

8B neutrino ux using ele13tron-neutrino elasti13 s13attering

[8 Sin13e su13h dete13tors 13ould re13ord the time of an intera13tion and re13onstru13t the

energy and dire13tion of the re13oiling ele13tron unique information on the spe13trum and

time variation of the solar neutrino ux were extra13ted This provided further insights

into the solar neutrino problem the de13it of the neutrino ux (measured by several

experiments) with respe13t to the ux expe13ted by solar models 13ontributing to the

assessment of the os13illation s13enario for solar neutrinos [4 5 6 7 8 9 10

With MEMPHYS Super-Kamiokandes measurements obtained from 1258 days

of data taking 13ould be repeated in about half a year while the seasonal ux

variation measurement will obviously require a full year In parti13ular the rst

measurement of the ux of the rare hep neutrinos may be possible Elasti13 neutrino-

ele13tron s13attering is strongly forward peaked In order to separate the solar neutrino

signal from the isotropi13 ba13kground events (mainly due to low radioa13tivity) this

dire13tional 13orrelation is exploited although the angular resolution is limited by

multiple s13attering The re13onstru13tion algorithms rst re13onstru13t the vertex from

the PMT timing information and then the dire13tion by assuming a single Cherenkov

13one originating from the re13onstru13ted vertex Re13onstru13ting 7 MeV events in

MEMPHYS seems not to be a problem but de13reasing this threshold would imply

serious 13onsideration of the PMT dark 13urrent rate as well as the laboratory and

dete13tor radioa13tivity level

With LENA a large amount of neutrinos from

7Be (around sim 54 times 103day

sim 20 times 106year) would be dete13ted Depending on the signal to ba13kground

ratio this 13ould provide a sensitivity to time variations in the

7Be neutrino ux of

sim 05 during one month of measuring time Su13h a sensitivity 13an give unique

information on helioseismology (pressure or temperature u13tuations in the 13enter of

the Sun) and on a possible magneti13 moment intera13tion with a timely varying solar

magneti13 eld The pep neutrinos are expe13ted to be re13orded at a rate of 210day(sim 77times104y) These events would provide a better understanding of the global solarneutrino luminosity allowing to probe (due to their pe13uliar energy) the transition

region of va13uum to matter-dominated neutrino os13illation

The neutrino ux from the CNO 13y13le is theoreti13ally predi13ted with a large

un13ertainty (30) Therefore LENA would provide a new opportunity for a detailed

study of solar physi13s However the observation of su13h solar neutrinos in these

dete13tors ie through elasti13 s13attering is not a simple task sin13e neutrino events

13annot be separated from the ba13kground and it 13an be a1313omplished only if the

dete13tor 13ontamination will be kept very low [100 101 Moreover only mono-energeti13

sour13es as those mentioned 13an be dete13ted taking advantage of the Compton-like

shoulder edge produ13ed in the event spe13trum

Re13ently the possibility to dete13t

8B solar neutrinos by means of 13harged-13urrent

intera13tion with the

13C [102 nu13lei naturally 13ontained in organi13 s13intillators has

Table 9 Number of events expe13ted in GLACIER per year 13ompared with

the 13omputed ba13kground (no os13illation) from the Gran Sasso ro13k radioa13tivity

(032 10minus6n cmminus2 sminus1

(gt 25 MeV) The absorption 13hannel has been split into

the 13ontributions of events from Fermi and Gamow-Teller transitions of the

40Ar

to the dierent

40K ex13ited levels and that 13an be separated using the emitted

gamma energy and multipli13ity

Eventsyear

Elasti13 13hannel (E ge 5 MeV) 45 300Neutron ba13kground 1400Absorption events 13ontamination 1100

Absorption 13hannel (Gamow-Teller transition) 101 700Absorption 13hannel (Fermi transition) 59 900Neutron ba13kground 5500Elasti13 events 13ontamination 1700

been investigated Even if signal events do not keep the dire13tionality of the neutrino

they 13an be separated from ba13kground by exploiting the time and spa13e 13oin13iden13e

with the subsequent de13ay of the produ13ed

13N nu13lei The residual ba13kground

amounts to about 60year 13orresponding to a redu13tion fa13tor of sim 3 times 10minus4) [102

Around 360 events of this type per year 13an be estimated for LENA A deformation

due to the MSW matter ee13t should be observable in the low-energy regime after a

13ouple of years of measurements

For the proposed lo13ation of LENA in Pyhaumlsalmi (sim 4000mwe) the 13osmogeni13ba13kground will be su13iently low for the above mentioned measurements Noti13e that

the Freacutejus site would also be adequate for this 13ase (sim 4800 mwe) The radioa13tivityof the dete13tor would have to be kept very low (10minus17

gg level U-Th) as in the

KamLAND dete13tor

Solar neutrinos 13an be dete13ted by GLACIER through the elasti13 s13attering

νx + eminus rarr νx + eminus (ES) and the absorption rea13tion νe +40Ar rarr eminus + 40Klowast

(ABS)

followed by γ-ray emission Even if these rea13tions have low energy threshold (15MeV

for the se13ond one) one expe13ts to operate in pra13ti13e with a threshold set at 5 MeV

on the primary ele13tron kineti13 energy in order to reje13t ba13kground from neutron

13apture followed by gamma emission whi13h 13onstitutes the main ba13kground for some

of the underground laboratories [28 These neutrons are indu13ed by the spontaneous

ssion and (αn) rea13tions in ro13k In the 13ase of a salt mine this ba13kground 13an

be smaller The fa13t that salt has smaller UTh 13on13entrations does not ne13essarily

mean that the neutron ux is smaller The ux depends on the ro13k 13omposition sin13e

(alphan) rea13tions may 13ontribute signi13antly to the ux The expe13ted raw event

rate is 330 000year (66 from ABS 25 from ES and 9 from neutron ba13kground

indu13ed events) assuming the above mentioned threshold on the nal ele13tron energy

By applying further oine 13uts to purify separately the ES sample and the ABS

sample one obtains the rates shown on Tab 9

A possible way to 13ombine the ES and the ABS 13hannels similar to the NCCC

ux ratio measured by SNO 13ollaboration [9 is to 13ompute the following ratio

R =NESNES

0

1

2

(

NAbsminusGT NAbsminusGT0 +NAbsminusF NAbsminusF

0

)(4)

where the numbers of expe13ted events without neutrino os13illations are labeled

04 05 06

true value of sin2θ

23

0

10

20

30

40

50

04 05 060

10

20

30

40

50∆χ

2 of

the

wro

ng o

ctan

t

2σ

3σ

AT

M-only

SPLT

2HK

Sensitivity of LBL+ATM data to the octant of θ23

Figure 10 Dis13rimination of the wrong o13tant solution as a fun13tion of

sin2 θtrue23

for θtrue13

= 0 We have assumed 10 years of data taking with a 440

kton dete13tor Reprinted gure with permission from [37

with a 0) This double ratio has two advantages First it is independent of the

8B

total neutrino ux predi13ted by dierent solar models and se13ond it is free from

experimental threshold energy bias and of the adopted 13ross-se13tions for the dierent

13hannels With the present t to solar neutrino experiments and KamLAND data

one expe13ts a value of R = 130plusmn 001 after one year of data taking with GLACIER

The quoted error for R only takes into a1313ount statisti13s

7 Atmospheri13 neutrinos

Atmospheri13 neutrinos originate from the de13ay 13hain initiated by the 13ollision of

primary 13osmi13-rays with the upper layers of Earths atmosphere The primary 13osmi13-

rays are mainly protons and helium nu13lei produ13ing se13ondary parti13les su13h π and

K whi13h in turn de13ay produ13ing ele13tron- and muon- neutrinos and antineutrinos

At low energies the main 13ontribution 13omes from π mesons and the de13ay 13hain

π rarr micro+ νmicro followed by micro rarr e + νe + νmicro produ13es essentially two νmicro for ea13h νe Asthe energy in13reases more and more muons rea13h the ground before de13aying and

therefore the νmicroνe ratio in13reases For Eν amp 1 GeV the dependen13e of the total

neutrino ux on the neutrino energy is well des13ribed by a power law dΦdE prop Eminusγ

with γ = 3 for νmicro and γ = 35 for νe whereas for sub-GeV energies the dependen13e

be13omes more 13ompli13ated be13ause of the ee13ts of the solar wind and of Earths

magneti13 eld [103 As for the zenith dependen13e for energies larger than a few

GeV the neutrino ux is enhan13ed in the horizontal dire13tion sin13e pions and muons

13an travel a longer distan13e before losing energy in intera13tions (pions) or rea13hing

the ground (muons) and therefore have more 13han13es to de13ay produ13ing energeti13

neutrinos

Histori13ally the atmospheri13 neutrino problem originated in the 80s as

a dis13repan13y between the atmospheri13 neutrino ux measured with dierent

experimental te13hniques and the expe13tations In the last years a number of dete13tors

had been built whi13h 13ould dete13t neutrinos through the observation of the 13harged

lepton produ13ed in 13harged-13urrent neutrino-nu13leon intera13tions inside the dete13tor

material These dete13tors 13ould be divided into two 13lasses iron 13alorimeters whi13h

re13onstru13t the tra13k or the ele13tromagneti13 shower indu13ed by the lepton and water

Cherenkov whi13h measure the Cherenkov light emitted by the lepton as it moved

faster than light in water lling the dete13tor volume The rst iron 13alorimeters

Frejus [18 and NUSEX [14 found no dis13repan13y between the observed ux and

the theoreti13al predi13tions whereas the two water Cherenkov dete13tors IMB [17 and

Kamiokande [16 observed a 13lear de13it 13ompared to the predi13ted νmicroνe ratio Theproblem was nally solved in 1998 when the already mentioned water Cherenkov

Super-Kamiokande dete13tor [21 allowed to establish with high statisti13al a1313ura13y

that there was indeed a zenith- and energy-dependent de13it in the muon-neutrino

ux with respe13t to the theoreti13al predi13tions and that this de13it was 13ompatible

with the hypothesis of νmicro rarr ντ os13illations The independent 13onrmation of this

ee13t from the 13alorimeter experiments Soudan-II [19 and MACRO [104 eliminated

the original dis13repan13y between the two experimental te13hniques

Despite providing the rst solid eviden13e for neutrino os13illations atmospheri13

neutrino experiments suer from two important limitations Firstly the sensitivity of

an atmospheri13 neutrino experiments is strongly limited by the large un13ertainties

in the knowledge of neutrino uxes and neutrino-nu13leon 13ross-se13tion Su13h

un13ertainties 13an be as large as 20 Se13ondly water Cherenkov dete13tors do not

allow an a1313urate re13onstru13tion of the neutrino energy and dire13tion if none of the

two is known a priori This strongly limits the sensitivity to ∆m2 whi13h is very

sensitive to the resolution of LEDuring its phase-I Super-Kamiokande has 13olle13ted 4099 ele13tron-like and 5436

muon-like 13ontained neutrino events [20 With only about one hundred events ea13h

the a1313elerator experiments K2K [105 and MINOS [106 already provide a stronger

bound on the atmospheri13 mass-squared dieren13e ∆m231 The present value of the

mixing angle θ23 is still dominated by Super-Kamiokande data being statisti13ally the

most important fa13tor for su13h a measurement However large improvements are

expe13ted from the next generation of long-baseline experiments su13h as T2K [107

and NOνA [108 sensitive to the same os13illation parameters as atmospheri13 neutrino

experiments

Despite the above limitations atmospheri13 neutrino dete13tors 13an still play a

leading role in the future of neutrino physi13s due to the huge range in energy (from

100 MeV to 10 TeV and above) and distan13e (from 20 km to more than 12 000 km)

13overed by the data This unique feature as well as the very large statisti13s expe13ted

for a dete13tor su13h as MEMPHYS (20divide30 times the present Super-Kamiokande eventrate) will allow a very a1313urate study of the subdominant modi13ation to the leading

os13illation pattern thus providing 13omplementary information to a1313elerator-based

experiments More 13on13retely atmospheri13 neutrino data will be extremely valuable

for

0 π2 π 3π2 2πtrue δ

CP

0

001

002

003

004

005tr

ue s

in2 2θ

13

0 025 05 075 1fraction of true δ

CP values

2σ sensitivity to normal hierarchy from LBL + ATM data

βB

T2HK

SPL βB

T2HKSPL

NOνA NOνA(pdr) +

T2K4 MW

βB+SPLβB+SPL

Figure 11 Sensitivity to the mass hierar13hy at 2σ (∆χ2 = 4) as a fun13tion

of sin2 2θtrue13

and δtrueCP

(left) and the fra13tion of true values of δtrueCP

(right)

The solid 13urves are the sensitivities from the 13ombination of long-baseline and

atmospheri13 neutrino data the dashed 13urves 13orrespond to long-baseline data

only We have assumed 10 years of data taking with a 440 kton mass dete13tor

03 04 05 06

True value of sin2θ23

00

0005

001

0015

Sen

sitiv

ity to

sin

2 2θ13

right octant of θ23

1σ

2σ3σ

03 04 05 06

wrong octant of θ23

1σ

2σ

3σ

2σ03 04 05 06 07

combined

1σ

2σ3σ

Figure 12 Sensitivity to sin2 2θ13 as a fun13tion of sin2 θtrue23

for LBL data only

(dashed) and the 13ombination beam and atmospheri13 neutrino data (solid) In

the left and 13entral panels we restri13t the t of θ23 to the o13tant 13orresponding

to θtrue23 and π2 minus θtrue23 respe13tively whereas the right panel shows the overall

sensitivity taking into a1313ount both o13tants We have assumed 8 years of beam

and 9 years of atmospheri13 neutrino data taking with the T2HK beam and a

1 Mton dete13tor Reprinted gure with permission from [109

bull Resolving the o13tant ambiguity Although future a1313elerator experiments are

expe13ted to 13onsiderably improve the measurement of the absolute value of the

small quantity D23 equiv sin2 θ23 minus 12 they will have pra13ti13ally no sensitivity

on its sign On the other hands it has been pointed out [110 111 that the

νmicro rarr νe 13onversion signal indu13ed by the small but nite value of ∆m221 13an

resolve this degenera13y However observing su13h a 13onversion requires a very

long baseline and low energy neutrinos and atmospheri13 sub-GeV ele13tron-like

events are parti13ularly suitable for this purpose In Fig 10 we show the potential

of dierent experiments to ex13lude the o13tant degenerate solution

bull Resolving the hierar13hy degenera13y If θ13 is not too small matter ee13t will

produ13e resonant 13onversion in the νmicro harr νe 13hannel for neutrinos (antineutrinos)if the mass hierar13hy is normal (inverted) The observation of this enhan13ed

13onversion would allow the determination of the mass hierar13hy Although a

magnetized dete13tor would be the best solution for this task it is possible to

extra13t useful information also with a 13onventional dete13tor sin13e the event

rates expe13ted for atmospheri13 neutrinos and antineutrinos are quite dierent

This is 13learly visible from Fig 11 where we show how the sensitivity to the

mass hierar13hy of dierent beam experiments is drasti13ally in13reased when the

atmospheri13 neutrino data 13olle13ted by the same dete13tor are also in13luded in the

t

bull Measuring or improving the bound on θ13 Although atmospheri13 data alone

are not expe13ted to be 13ompetitive with the next generation of long-baseline

experiments in the sensitivity to θ13 they will 13ontribute indire13tly by eliminatingthe o13tant degenera13y whi13h is an important sour13e of un13ertainty for beam

experiments In parti13ular if θtrue23 is larger than 45 then the in13lusion of

atmospheri13 data will 13onsiderably improve the a1313elerator experiment sensitivity

to θ13 as 13an be seen from the right panel of Fig 12 [109

In GLACIER the sear13h for ντ appearan13e is based on the information provided

by the event kinemati13s and takes advantage of the spe13ial 13hara13teristi13s of ντ CC

and the subsequent de13ay of the produ13ed τ lepton when 13ompared to CC and NC

intera13tions of νmicro and νe ie by making use of ~Pcandidate and~Phadron Due to the large

ba13kground indu13ed by atmospheri13 muon and ele13tron neutrinos and antineutrinos

the measurement of a statisti13ally signi13ant ex13ess of ντ events is very unlikely for

the τ rarr e and τ rarr micro de13ay modes

The situation is mu13h more advantageous for the hadroni13 13hannels One 13an

13onsider tau-de13ays to one prong (single pion ρ) and to three prongs (πplusmnπ0π0and

three 13harged pions) In order to sele13t the signal one 13an exploit the kinemati13al

variables Evisible ybj (the ratio between the total hadroni13 energy and Evisible) and

QT (dened as the transverse momentum of the τ 13andidate with respe13t to the total

measured momentum) that are not 13ompletely independent one from another but show

some 13orrelation These 13orrelations 13an be exploited to redu13e the ba13kground In

order to maximize the separation between signal and ba13kground one 13an use three

dimensional likelihood fun13tions L(QT Evisible ybj) where 13orrelations are taken into

a1313ount For ea13h 13hannel three dimensional likelihood fun13tions are built for both

signal (LSπ LSρ LS3π) and ba13kground (LBπ LBρ LB3π) In order to enhan13e the

separation of ντ indu13ed events from νmicro νe intera13tions the ratio of likelihoods is

taken as the sole dis13riminant variable lnλi equiv ln(LSi LBi ) where i = π ρ 3πTo further improve the sensitivity of the ντ appearan13e sear13h one 13an 13ombine

the three independent hadroni13 analyses into a single one Events that are 13ommon to

at least two analyses are 13ounted only on13e and a survey of all possible 13ombinations

for a restri13ted set of values of the likelihood ratios is performed Table 10 illustrates

the statisti13al signi13an13e a13hieved by several sele13ted 13ombinations of the likelihood

ratios for an exposure equivalent to 100 kton year

The best 13ombination for a 100 kton year exposure is a13hieved for the following

set of 13uts lnλπ gt 3 lnλρ gt 05 and lnλ3π gt 0 The expe13ted number of NC

ba13kground events amounts to 25 (top) while 25+22 = 47 are expe13ted Pβ is the

Poisson probability for the measured ex13ess of upward going events to be due to

a statisti13al u13tuation as a fun13tion of the exposure An ee13t larger than 4σ is

obtained for an exposure of 100 kton year (one year of data taking with GLACIER)

Last but not least it is worth noting that atmospheri13 neutrino uxes are

Table 10 Expe13ted GLACIER ba13kground and signal events for dierent

13ombinations of the π ρ and 3π analyses The 13onsidered statisti13al sample

13orresponds to an exposure of 100 kton year

lnλπ lnλρ lnλ3π Top Bottom Pβ ()

Cut Cut Cut Events Events

00 05 00 223 223 + 43 = 266 2times 10minus1(31σ)

15 15 00 92 92 + 35 = 127 2times 10minus2(37σ)

30 minus10 00 87 87 + 33 = 120 3times 10minus2(36σ)

30 05 00 25 25 + 22 = 47 2times 10minus3 (43σ)30 15 00 20 20 + 19 = 39 4times 10minus3

(41σ)30 05 minus10 59 59 + 30 = 89 9times 10minus3

(39σ)30 05 10 18 18 + 17 = 35 1times 10minus2

(38σ)

themselves an important subje13t of investigation and in the light of the pre13ise

determination of the os13illation parameters provided by long baseline experiments

the atmospheri13 neutrino data a1313umulated by the proposed dete13tors 13ould be used

as a dire13t measurement of the in13oming neutrino ux and therefore as an indire13t

measurement of the primary 13osmi13-rays ux

The appearan13e of subleading features in the main os13illation pattern 13an also be

a hint for New Physi13s The huge range of energies probed by atmospheri13 data will

allow to set very strong bounds on me13hanisms whi13h predi13t deviation from the 1Elaw behavior For example the bound on non-standard neutrino-matter intera13tions

and on other types of New Physi13s (su13h as violation of the equivalen13e prin13iple or

violation of the Lorentz invarian13e) whi13h 13an be derived from present data is already

the strongest whi13h 13an be put on these me13hanisms [112

8 Geo-neutrinos

The total power dissipated from the Earth (heat ow) has been measured with thermal

te13hniques to be 442 plusmn 10 TW Despite this small quoted error a more re13ent

evaluation of the same data (assuming mu13h lower hydrothermal heat ow near mid-

o13ean ridges) has led to a lower gure of 31 plusmn 1 TW On the basis of studies of

13hondriti13 meteorites the 13al13ulated radiogeni13 power is thought to be 19 TW (about

half of the total power) 84 of whi13h is produ13ed by

238U and

232Th de13ay whi13h

in turn produ13e νe by beta-de13ays (geo-neutrinos) It is then of prime importan13e

to measure the νe ux 13oming from the Earth to get geophysi13al information with

possible appli13ations in the interpretation of the geomagnetism

The KamLAND 13ollaboration has re13ently reported the rst observation of the

geo-neutrinos [24 The events are identied by the time and distan13e 13oin13iden13e

between the prompt e+ and the delayed (200 micros) neutron 13apture produ13ed by

νe + p rarr n + e+ and emiting a 22 MeV gamma The energy window to sear13h for

the geo-neutrino events is [17 34]MeV The lower bound 13orresponds to the rea13tion

threshold while the upper bound is 13onstrained by nu13lear rea13tor indu13ed ba13kground

events The measured rate in the 1 kton liquid s13intillator dete13tor lo13ated at the

Kamioka mine where the Kamiokande dete13tor was previously installed is 25+19minus18 for

a total ba13kground of 127plusmn 13 eventsThe ba13kground is 13omposed by 23 of νe events from the nu13lear rea13tors in

Japan and Korea These events have been a13tually used by KamLAND to 13onrm

and pre13isely measure the Solar driven neutrino os13illation parameters (see Se13tion

6) The residual 13 of the events originates from neutrons of 73 MeV produ13ed in

13C(α n)16O rea13tions and 13aptured as in the IBD rea13tion The α parti13les 13ome

from the

210Po de13ays a

222Rn daughter whi13h is of natural radioa13tivity origin The

measured geo-neutrino events 13an be 13onverted in a rate of 51+39minus36 times 10minus31 νe per

target proton per year 13orresponding to a mean ux of 57times 106cmminus2 sminus1 or this 13an

be transformed into a 99 CL upper bound of 145times 10minus30 νe per target proton peryear (162times 107cmminus2 sminus1

and 60 TW for the radiogeni13 power)

In MEMPHYS one expe13ts 10 times more geo-neutrino events but this would

imply to de13rease the trigger threshold to 2 MeV whi13h seems very 13hallenging with

respe13t to the present Super-Kamiokande threshold set to 46 MeV due to high level

of raw trigger rate [113 This trigger rate is driven by a number of fa13tors as dark

13urrent of the PMTs γs from the ro13k surrounding the dete13tor radioa13tive de13ay in

the PMT glass itself and Radon 13ontamination in the water

In LENA at CUPP a geo-neutrino rate of roughly 1000year [114 from the

dominant νe + p rarr e+ + n IBD rea13tion is expe13ted The delayed 13oin13iden13e

measurement of the positron and the 22 MeV gamma event following neutron 13apture

on protons in the s13intillator provides a very e13ient tool to reje13t ba13kground events

The threshold energy of 18 MeV allows the measurement of geo-neutrinos from the

Uranium and Thorium series but not from

40K A rea13tor ba13kground rate of about

240 events per year for LENA at CUPP in the relevant energy window from 18 MeV

to 32 MeV has been 13al13ulated This ba13kground 13an be subtra13ted statisti13ally using

the information on the entire rea13tor neutrino spe13trum up to ≃ 8 MeV

As it was shown in KamLAND a serious ba13kground sour13e may 13ome from radio

impurities There the 13orrelated ba13kground from the isotope

210Po is dominating

However with an enhan13ed radiopurity of the s13intillator the ba13kground 13an be

signi13antly redu13ed Taking the radio purity levels of the Borexino CTF dete13tor at

Gran Sasso where a

210Po a13tivity of 35plusmn 12m3day in PXE has been observed this

ba13kground would be redu13ed by a fa13tor of about 150 13ompared to KamLAND and

would a1313ount to less than 10 events per year in the LENA dete13tor

An additional ba13kground that fakes the geo-neutrino signal is due to

9Li whi13h is

produ13ed by 13osmi13-muons in spallation rea13tions with

12C and de13ays in a β-neutron

13as13ade Only a small part of the

9Li de13ays falls into the energy window whi13h is

relevant for geo-neutrinos KamLAND estimates this ba13kground to be 030 plusmn 005[24

At CUPP the muon rea13tion rate would be redu13ed by a fa13tor ≃ 10 due to

better shielding and this ba13kground rate should be at the negligible level of ≃ 1 event

per year in LENA From these 13onsiderations it follows that LENA would be a very

13apable dete13tor for measuring geo-neutrinos Dierent Earth models 13ould be tested

with great signi13an13e The sensitivity of LENA for probing the unorthodox idea

of a geo-rea13tor in the Earths 13ore was estimated too At the CUPP underground

laboratory the neutrino ba13kground with energies up to ≃ 8 MeV due to nu13lear

power plants was 13al13ulated to be around 2200 events per year A 2 TW geo-rea13tor

in the Earths 13ore would 13ontribute 420 events per year and 13ould be identied at a

statisti13al level of better than 3σ after only one year of measurement

Finally in GLACIER the νe +40Ar rarr e+ + 40Cllowast has a threshold of 75 MeV

whi13h is too high for geo-neutrino dete13tion

10-2

10-1

1

10

10 2

10 3

10-6

10-5

10-4

10-3

10-2

10-1

Atmospheric Neutrino Background

100 kton LAr 10 years of data taking

Elastic Scattering Cross Section (pb)

E

vent

s

Eν min = 10 GeV

MWIMP = 20 GeV

MWIMP = 50 GeV

MWIMP = 100 GeV

Figure 13 Expe13ted number of signal and ba13kground events as a fun13tion

of the WIMP elasti13 s13attering produ13tion 13ross-se13tion in the Sun with a 13ut

of 10 GeV on the minimum neutrino energy Reprinted gure with permission

from [115

9 Indire13t sear13hes for the Dark Matter of the Universe

The Weakly Intera13ting Massive Parti13les (WIMPs) that likely 13onstitute the halo of

the Milky Way 13an o1313asionally intera13t with massive obje13ts su13h as stars or planets

When they s13atter o su13h an obje13t they 13an potentially lose enough energy that they

be13ome gravitationally bound and eventually will settle in the 13enter of the 13elestial

body In parti13ular WIMPs 13an be 13aptured by and a1313umulate in the 13ore of the

Sun

As far as the next generation of large underground observatories is 13on13erned

although not spe13i13ally dedi13ated to the sear13h for WIMP parti13les one 13ould dis13uss

the 13apability of GLACIER in identifying in a model-independent way neutrino

signatures 13oming from the produ13ts of WIMP annihilations in the 13ore of the Sun

[115

Signal events will 13onsist of energeti13 ele13tron- (anti)neutrinos 13oming from the

de13ay of τ leptons and b quarks produ13ed in WIMP annihilation in the 13ore of the Sun

Ba13kground 13ontamination from atmospheri13 neutrinos is expe13ted to be low One

13annot 13onsider the possibility of observing neutrinos fromWIMPs a1313umulated in the

Earth Given the smaller mass of the Earth and the fa13t that only s13alar intera13tions

13ontribute the 13apture rates for our planet are not enough to produ13e a statisti13ally

signi13ant signal in GLACIER

The sear13h method takes advantage of the ex13ellent angular re13onstru13tion and

10-2

10-1

1

10

10 2

10 3

10-5

10-4

10-3

10-2

10-1

Yea

rs o

f da

ta ta

king

for

Dis

cove

ry 100 kTon Liquid Argon Detector

MWIMP = 100 GeV

MWIMP = 50 GeV

MWIMP = 20 GeV

Eν min = 10 GeV

5 σ and 50 CL

Figure 14 Minimum number of years required to 13laim a dis13overy WIMP signal

from the Sun in a 100 kton LAr dete13tor as fun13tion of σelastic for three values of

the WIMP mass Reprinted gure with permission from [115

superb ele13tron identi13ation 13apabilities GLACIER oers in looking for an ex13ess of

energeti13 ele13tron- (anti)neutrinos pointing in the dire13tion of the Sun The expe13ted

signal and ba13kground event rates have been evaluated as said above in a model

independent way as a fun13tion of the WIMP elasti13 s13attering 13ross-se13tion for a

range of masses up to 100 GeV The dete13tor dis13overy potential namely the number

of years needed to 13laim a WIMP signal has been dis13overed is shown in Figs 13

and 14 With the assumed set-up and thanks to the low ba13kground environment

provided by the LAr TPC a 13lear WIMP signal would be dete13ted provided the

elasti13 s13attering 13ross-se13tion in the Sun is above sim 10minus4pb

10 Neutrinos from nu13lear rea13tors

The KamLAND 1 kton liquid s13intillator dete13tor lo13ated at Kamioka measured the

neutrino ux from 53 power rea13tors 13orresponding to 701 Joule13m

2[26 An event

rate of 3652plusmn 237 above 26 MeV for an exposure of 766 ton year from the nu13lear

rea13tors was expe13ted The observed rate was 258 events with a total ba13kground of

178plusmn73 The signi13ant de13it interpreted in terms of neutrino os13illations enablesa measurement of θ12 the neutrino 1-2 family mixing angle (sin2 θ12 = 031+002

minus003) as

well as the mass squared dieren13e ∆m212 = (79plusmn 03) times 10minus5

eV

2

Future pre13ision measurements are 13urrently being investigated Running

KamLAND for 2-3 more years would gain 30 (4) redu13tion in the spread of ∆m212

3 4 5 6 7 8 9 10 11 12E

p [MeV]

0

02

04

06

08

1N

osc

Nno

-osc

147 kt yr MEMPHYS-Gd

44 kt yr LENA

Figure 15 The ratio of the event spe13tra in positron energy in the 13ase of

os13illations with ∆m221 = 79times 10minus5

eV

2and sin2 θ12 = 030 and in the absen13e

of os13illations determined using one year data of MEMPHYS-Gd and LENA

lo13ated at Frejus The error bars 13orrespond to 1σ statisti13al error Reprinted

gure with permission from [116

(θ12) Although it has been shown in Se13tions 5 and 8 that νe originated from nu13lear

rea13tors 13an be a serious ba13kground for diuse supernova neutrino and geo-neutrino

dete13tion the Freacutejus site 13an take benet of the nu13lear rea13tors lo13ated in the Rhne

valley to measure ∆m221 and sin2 θ12 In fa13t approximately 67 of the total rea13tor

νe ux at Freacutejus originates from four nu13lear power plants in the Rhone valley lo13ated

at distan13es between 115 km and 160 km The indi13ated baselines are parti13ularly

suitable for the study of the νe os13illations driven by ∆m221 The authors of [116

have investigated the possibility of using one module of MEMPHYS (147 kton du13ial

mass) doped with Gadolinium or the LENA dete13tor updating the previous work

of [117 Above 3 MeV (26 MeV) the event rate is 59 980 (16 670) eventsyear forMEMPHYS (LENA) whi13h is 2 orders of magnitude larger than the KamLAND event

rate

In order to test the sensitivity of the experiments the prompt energy spe13trum is

subdivided into 20 bins between 3 MeV and 12 MeV for MEMPHYS-Gd and Super-

Kamiokande-Gd and into 25 bins between 26 MeV and 10 MeV for LENA (Fig 15) A

χ2analysis taking into a1313ount the statisti13al and systemati13al errors shows that ea13h

of the two dete13tors MEMPHYS-Gd and LENA if pla13ed at Freacutejus 13an be exploited

to yield a pre13ise determination of the solar neutrino os13illation parameters ∆m221 and

sin2 θ12 Within one year the 3σ un13ertainties on ∆m221 and sin2 θ12 13an be redu13ed

respe13tively to less than 3 and to approximately 20 (Fig 16) In 13omparison

the Gadolinium doped Super-Kamiokande dete13tor that might be envisaged in a near

future would rea13h a similar pre13ision only with a mu13h longer data taking time

Several years of rea13tor νe data 13olle13ted by MEMPHYS-Gd or LENA would allow a

determination of ∆m221 and sin2 θ12 with un13ertainties of approximately 1 and 10

at 3σ respe13tively

01 02 03 04 05

sin2θ

12

7

8

9

∆m2 21

[10

-5 e

V2 ]

0

10

20

30

40∆χ

2

current solar +Kamland225 kt yr SK-Gd147 kt yr MEMPHYS-Gd44 kt yr LENA

0 10 20 30 40

∆χ2

3σ contours

Figure 16 A1313ura13y of the determination of ∆m221

and sin2 θ12 for one year

data taking of MEMPHYS-Gd and LENA at Frejus and Super-Kamiokande-

Gd 13ompared to the 13urrent pre13ision from solar neutrino and KamLAND data

The allowed regions at 3σ (2 dof) in the ∆m221 minus sin2 θ12 plane as well as

the proje13tions of the χ2for ea13h parameter are shown Reprinted gure with

permission from [116

However some 13aveat are worth to be mentioned The prompt energy trigger

of 3 MeV requires a very low PMT dark 13urrent rate in the 13ase of the MEMPHYS

dete13tor If the energy threshold is higher the parameter pre13ision de13reases as 13an

be seen in Fig 17 The systemati13 un13ertainties are also an important fa13tor in the

experiments under 13onsideration espe13ially the determination of the mixing angle as

those on the energy s13ale and the overall normalization

Anyhow the a1313ura13y in the knowledge of the solar neutrino os13illation

parameters whi13h 13an be obtained in the high statisti13s experiments 13onsidered here

are 13omparable to those that 13an be rea13hed for the atmospheri13 neutrino os13illation

parameters ∆m231 and sin2 θ23 with the future long-baseline Super beam experiments

su13h as T2HK or T2KK [118 in Japan or SPL from CERN to MEMPHYS

Hen13e su13h rea13tor measurements would 13omplete the program of the high pre13ision

determination of the leading neutrino os13illation parameters

11 Neutrinos from parti13le a1313elerator beams

Although the main physi13s goals of the proposed liquid-based dete13tors will be in

the domain of astro-parti13le physi13s it would be e13onomi13al and also very interesting

from the physi13s point of view 13onsidering their possible use as far dete13tors for

the future neutrino fa13ilities planned or under dis13ussion in Europe also given the

large nan13ial investment represented by the dete13tors In this Se13tion we review

24 26 28 3 32 34 36 38 4threshold of E

vis [MeV]

0

005

01

015

02

025sp

read

3

σ C

L

24 26 28 3 32 34 36 38 40

005

01

015

02

025

sin2θ

12

∆m2

21

Memphys-Gd 147 kt yr

Figure 17 The a1313ura13y of the determination of ∆m221

and sin2 θ12 whi13h 13an

be obtained using one year of data from MEMPHYS-Gd as a fun13tion of the

prompt energy threshold

the physi13s program of the proposed observatories when using dierent a1313elerator

neutrino beams The main goals will be pushing the sear13h for a non-zero (although

very small) θ13 angle or its measurement in the 13ase of a dis13overy previously made

by one of the planned rea13tor or a1313elerator experiments (Double-CHOOZ or T2K)

sear13hing for possible leptoni13 CP violation (δCP) determining the mass hierar13hy

(the sign of ∆m231) and the θ23 o13tant (θ23 gt 45 or θ23 lt 45) For this purpose

we 13onsider here the potentiality of a liquid Argon dete13tor in an upgraded version

of the existing CERN to Gran Sasso (CNGS) neutrino beam and of the MEMPHYS

dete13tor at the Freacutejus using a possible new CERN proton driver (SPL) to upgrade to 4

MW the 13onventional neutrino beams (Super Beams) Another s13heme 13ontemplates

a pure ele13tron- (anti)neutrino produ13tion by radioa13tive ion de13ays (Beta Beam)

Note that LENA is also a good 13andidate dete13tor for the latter beam option Finally

as an ultimate beam fa13ility one may think of produ13ing very intense neutrino beams

by means of muon de13ays (Neutrino Fa13tory) that may well be dete13ted with a liquid

Argon dete13tor su13h as GLACIER

The determination of the missing Ue3 (θ13 ) element of the neutrino mixing matrixis possible via the dete13tion of νmicro rarr νe os13illations at a baseline L and energy Egiven by the atmospheri13 neutrino signal 13orresponding to a mass squared dieren13e

EL sim ∆m2 ≃ 25 times 10minus3 eV 2 The 13urrent layout of the CNGS beam from CERN

to the Gran Sasso Laboratory has been optimized for a τ -neutrino appearan13e sear13hto be performed by the OPERA experiment [119 This beam 13onguration provides

limited sensitivity to the measurement of Ue3

Therefore we dis13uss the physi13s potential of an intensity-upgraded and energy-

reoptimized CNGS neutrino beam 13oupled to an o-axis GLACIER dete13tor [120

This idea is based on the possible upgrade of the CERN PS or on a new ma13hine

(PS+) to deliver protons of 50 GeV13 with a power of 200 kW Post a1313eleration to

SPS energies followed by extra13tion to the CNGS target region should allow to rea13h

MW power with neutrino energies peaked around 2 GeV In order to evaluate the

physi13s potential one assumes ve years of running in the neutrino horn polarity plus

ve additional years in the anti-neutrino mode A systemati13 error on the knowledge

of the νe 13omponent of 5 is assumed Given the ex13ellent π0parti13le identi13ation

13apabilities of GLACIER the 13ontamination of π0is negligible

An o-axis beam sear13h for νe appearan13e is performed with the GLACIER

dete13tor lo13ated at 850 km from CERN For an o-axis angle of 075

o θ13 13an be

dis13overed for full δCP 13overage for sin2 2θ13 gt 0004 at 3σ (Fig 18) At this rather

modest baseline the ee13t of CP violation and matter ee13ts 13annot be disentangled

In fa13t the determination of the mass hierar13hy with half-13overage (50) is rea13hed

only for sin2 2θ13 gt 003 at 3σ A longer baseline (1050 km) and a larger o-axis angle

(15

o) would allow the dete13tor to be sensitive to the rst minimum and the se13ond

maximum of the os13illation This is the key to resolve the issue of mass hierar13hy With

this dete13tor 13onguration full 13overage for δCP to determine the mass hierar13hy 13an

be rea13hed for sin2 2θ13 gt 004 at 3σ The sensitivity to mass hierar13hy determination13an be improved by 13onsidering two o-axis dete13tors one of 30 kton at 850 km

and o-axis angle 075

o a se13ond one of 70 kton at 1050 km and 15

0o-axis Full

13overage for δCP to determine the mass hierar13hy 13an be rea13hed for sin2 2θ13 gt 002at 3σ (Fig 19) This two-dete13tor 13onguration rea13hes very similar sensitivities to

the ones of the T2KK proposal [118

Another notable possibility is the CERN-SPL Super Beam proje13t It is a

13onventional neutrino beam featuring a 4 MW SPL (Super-13ondu13ting Proton Lina13)

[122 driver delivering protons onto a liquid Mer13ury target to generate an intense π+

(πminus) beam with small 13ontamination of kaons The use of near and far dete13tors will

allow both νmicro disappearan13e and νmicro rarr νe appearan13e studies The physi13s potentialof the SPL Super Beam with MEMPHYS has been extensively studied [37 123 124

However the beam simulations will need some retuning after the forth13oming results

of the CERN HARP experiment [125 on hadro-produ13tion

After 5 years exposure in νmicro disappearan13e mode a 3σ a1313ura13y of (3-4) 13an

be a13hieved on ∆m231 and an a1313ura13y of 22 (5) on sin2 θ23 if the true value is

05 (037) namely in 13ase of maximal or non-maximal mixing (Fig 20) The use of

atmospheri13 neutrinos 13an 13ontribute to solving the o13tant ambiguity in 13ase of non-

maximal mixing as it is shown in Fig 20 Note however that thanks to a higher energy

beam (sim 750 MeV) the T2HK proje13tDagger 13an benet from a mu13h lower dependen13e on

the Fermi motion to obtain a better energy resolution

In appearan13e mode (2 years νmicro plus 8 years νmicro) a 3σ dis13overy of non-zero

θ13 irrespe13tive of the a13tual true value of δCP is a13hieved for sin2 2θ13 amp 4 10minus3

(θ13 amp 36) as shown in Fig 21 For maximal CP violation (δtrueCP = π2 3π2) thesame dis13overy level 13an be a13hieved for sin2 2θ13 amp 8 10minus4

(θ13 amp 08) The best

sensitivity for testing CP violation (ie the data 13annot be tted with δCP = 0 nor

δCP = π) is a13hieved for sin2 2θ13 asymp 10minus3(θ13 asymp 09) as shown in Fig 22 The

Dagger Here we to the proje13t where a 4 MW proton driver is built at KEK to deliver an intense neutrino

beam dete13ted by a large water Cherenkov dete13tor

)13

θ (22sin

-410-3

10 -210 -110

CP

co

vera

ge

δfr

ac

tio

n

0

01

02

03

04

05

06

07

08

09

1

CNGS - θ13 Discovery90 CL 3σ CL

anti ν run only

ν run only

(ν+anti ν) run

free parameters

(ν+anti ν) run

fixed parameters

(ν+anti ν) run

no systematics

Figure 18 GLACIER in the upgraded CNGS beam Sensitivity to the dis13overy

of θ13 fra13tion of δCP 13overage as a fun13tion of sin2 2θ13 Reprinted gure with

)13

θ (22

sin

-410-3

10 -210 -110

CP

co

ve

rag

eδ

fra

cti

on

0

01

02

03

04

05

06

07

08

09

1

CNGS - 2 detectors - Mass hierarchy exclusion

(ν+anti ν) run

fixed parameters

anti ν run only

ν run only

(ν+anti ν) run

no systematics

90 CL 3σ CL

(ν+anti ν) run

free parameters

Figure 19 Upgraded CNGS beam mass hierar13hy determination for a two

dete13tor 13onguration at baselines of 850 km and 1050 km Reprinted gure with

03 04 05 06 07

sin2θ

23

15

2

25

3

∆m2 31

[10

-3 e

V2 ]

T2K-IT2HKSPLSPL+ATM

5 yrs ν-data 99 CL (2 dof)

SK + K

2K allow

ed

test point 1

test point 2

Figure 20 Allowed regions of ∆m231

and sin2 θ23 at 99 CL (2 dof) after

5 years of neutrino data taking for ATM+SPL T2K phase I ATM+T2HK

and the 13ombination of SPL with 5 years of atmospheri13 neutrino data in the

MEMPHYS dete13tor For the true parameter values we use ∆m231 = 22 (26) times

10minus3 eV2and sin2 θ23 = 05 (037) for the test point 1 (2) and θ13 = 0 and

the solar parameters as ∆m221

= 79 times 10minus5 eV2 sin2 θ12 = 03 The shaded

region 13orresponds to the 99 CL region from present SK and K2K data [121

maximum sensitivity is a13hieved for sin2 2θ13 sim 10minus2where the CP violation 13an be

established at 3σ for 73 of all the δtrueCP

Although quite powerful the proposed SPL Super Beam is a 13onventional

neutrino beam with known limitations due to the low produ13tion rate of anti-neutrinos

13ompared to neutrinos whi13h in addition to a smaller 13harged-13urrent 13ross-se13tion

imposes to run 4 times longer in anti-neutrino mode and implies di13ulty to set up an

a1313urate beam simulation and to design a non-trivial near dete13tor setup mastering

the ba13kground level Thus a new type of neutrino beam the so-13alled Beta Beam

is being 13onsidered The idea is to generate pure well 13ollimated and intense νe(νe)beams by produ13ing 13olle13ting and a1313elerating radioa13tive ions [126 The resulting

Beta Beam spe13tra 13an be easily 13omputed knowing the beta-de13ay spe13trum of the

parent ion and the Lorentz boost fa13tor γ and these beams are virtually free from

other ba13kground avors The best ion 13andidates so far are

18Ne and

6He for νeand

νe respe13tively A baseline study for the Beta Beam has been initiated at CERN and

is now going on within the European FP6 design study for EURISOL

The potential of su13h Beta Beam sent to MEMPHYS has been studied in the

13ontext of the baseline s13enario using referen13e uxes of 58 times 1018 6He useful

de13aysyear and 22times 1018 18Ne de13aysyear 13orresponding to a reasonable estimate

CP

10-4

10-3

10-2

sin2 2θ

13

CP values

Sensitivity to a non-zero θ13 at 3σ

βB

T2HK

SPL

βB

T2HK

SPLβB

+SPL

βB+SPL

σsyst

= 2minus5

Figure 21 3σ dis13overy sensitivity to sin2 2θ13 for Beta Beam SPL and T2HK

as a fun13tion of the true value of δCP (left panel) and as a fun13tion of the fra13tion

of all possible values of δCP (right panel) The width of the bands 13orresponds

to values for the systemati13al errors between 2 and 5 The dashed 13urve

13orresponds to the Beta Beam sensitivity with the uxes redu13ed by a fa13tor 2

10-4

10-3

10-2

10-1

true sin22θ

13

0

π2

π

3π2

2π

true

δC

P

T2HKSPLβB

Sensitivity to CP violation at 3σ

σsyst

= 2minus5

∆χ2 (δ

CP = 0 π) = 9

Figure 22 CP violation dis13overy potential for Beta Beam SPL and T2HK

For parameter values inside the ellipse-shaped 13urves CP 13onserving values of δCP

13an be ex13luded at 3σ (∆χ2 gt 9) The width of the bands 13orresponds to values

for the systemati13 errors from 2 to 5 The dashed 13urve is des13ribed in Fig 21

by experts in the eld of the ultimately a13hievable uxes The optimal values is

a13tually γ = 100 for both spe13ies and the 13orresponding performan13e have been

re13ently reviewed in [37 123 124

In Figs 2122 the results of running a Beta Beam during 10 years (5 years

with neutrinos and 5 years with anti-neutrinos) is shown and prove to be far better

13ompared to an SPL Super beam run espe13ially for maximal CP violation where a

non-zero θ13 value 13an be stated at 3σ for sin2 2θ13 amp 2 10minus4(θ13 amp 04) Moreover it

is noti13eable that the Beta Beam is less ae13ted by systemati13 errors of the ba13kground

13ompared to the SPL Super beam and T2HK

Before 13ombining the two possible CERN beam options relevant for the proposed

European underground observatories let us 13onsider LENA as potential dete13tor

LENA with a du13ial volume of sim 45 kton 13an as well be used as dete13tor for a

low-energy Beta Beam os13illation experiment In the energy range 02 minus 12 GeV

the performed simulations show that muon events are separable from ele13tron events

due to their dierent tra13k lengths in the dete13tor and due to the ele13tron emitted in

the muon de13ay For high energies muons travel longer than ele13trons as the latter

undergo s13attering and bremsstrahlung This results in dierent distributions of the

number of photons and the timing pattern whi13h 13an be used to distinguish between

the two 13lasses of events For low energies muons 13an be re13ognized by observing the

ele13tron of its su1313eeding de13ay after a mean time of 22 micros By using both 13riteria

an e13ien13y of sim 90 for muon appearan13e has been 13al13ulated with a1313eptan13e of

1 ele13tron ba13kground The advantage of using a liquid s13intillator dete13tor for

su13h an experiment is the good energy re13onstru13tion of the neutrino beam However

neutrinos of these energies 13an produ13e ∆ resonan13es whi13h subsequently de13ay into

a nu13leon and a pion In water Cherenkov dete13tors pions with energies under the

Cherenkov threshold 13ontribute to the un13ertainty of the neutrino energy In LENA

these parti13les 13an be dete13ted The ee13t of pion produ13tion and similar rea13tions is

13urrently under investigation in order to estimate the a13tual energy resolution

We also mention a very re13ent development of the Beta Beam 13on13ept [38 based

on a very promising alternative for the produ13tion of ions and on the possibility of

having mono13hromati13 single-avor neutrino beams by using ions de13aying through

the ele13tron 13apture pro13ess [127 128 In parti13ular su13h beams would be suitable to

pre13isely measure neutrino 13ross-se13tions in a near dete13tor with the possibility of an

energy s13an by varying the γ value of the ions Sin13e a Beta Beam uses only a small

fra13tion of the protons available from the SPL Super and Beta Beams 13an be run at

the same time The 13ombination of a Super Beam and a Beta Beam oers advantages

from the experimental point of view sin13e the same parameters θ13 and δCP 13an be

measured in many dierent ways using 2 pairs of CP related 13hannels 2 pairs of T

related 13hannels and 2 pairs of CPT related 13hannels whi13h should all give 13oherent

results In this way the estimates of systemati13 errors dierent for ea13h beam will

be experimentally 13ross-13he13ked Needless to say the unos13illated data for a given

beam will provide a large sample of events 13orresponding to the small sear13hed-for

signal with the other beam adding more handles to the understanding of the dete13tor

response

The 13ombination of the Beta Beam and the Super Beam will allow to use neutrino

modes only νmicro for SPL and νe for Beta Beam If CPT symmetry is assumed all the

information 13an be obtained as Pνerarrνmicro = Pνmicrorarrνe and Pνmicrorarrνe = Pνerarrνmicro We illustrate

this synergy in Fig 23 In this s13enario time 13onsuming anti-neutrino running 13an be

avoided keeping the same physi13s dis13overy potential

CP

10-4

10-3

10-2

sin2 2θ

13

CP values

3σ discovery of a non-zero θ13 within 5 yrs

T2HK 10y

βB 5ySP

L 5y

βB +

SPL

5y

SPL 5

yβB

5y

T2HK 10y

βB + SPL 5y

Figure 23 Dis13overy potential of a nite value of sin2 2θ13 at 3σ (∆χ2 gt 9)for 5 years neutrino data from Beta Beam SPL and the 13ombination of Beta

Beam + SPL 13ompared to 10 years data from T2HK (2 years neutrinos + 8 years

antineutrinos) Reprinted gure with permission from [37

One 13an also 13ombine SPL Beta Beam and the atmospheri13 neutrino experiments

to redu13e the parameter degenera13ies whi13h lead to dis13onne13ted regions on the multi-

dimensional spa13e of os13illation parameters One 13an look at [129 130 131 for the

denitions of intrinsi13 hierar13hy and o13tant degenera13ies As we have seen above

atmospheri13 neutrinos mainly multi-GeV e-like events are sensitive to the neutrino

mass hierar13hy if θ13 is su13iently large due to Earth matter ee13ts whilst sub-GeV

e-like events provide sensitivity to the o13tant of θ23 due to os13illations with ∆m221

The result of running during 5 years in neutrino mode for SPL and Beta Beam

adding further the atmospheri13 neutrino data is shown in Fig 24 [37 One 13an

appre13iate that pra13ti13ally all degenera13ies 13an be eliminated as only the solution with

the wrong sign survives with a ∆χ2 = 33 This last degenera13y 13an be 13ompletely

eliminated by using a neutrino running mode 13ombined with anti-neutrino mode and

ATM data [37 However the example shown is a favorable 13ase with sin2 θ23 = 06and in general for sin2 θ23 lt 05 the impa13t of the atmospheri13 data is weaker So

as a generi13 13ase for the CERN-MEMPHYS proje13t one is left with the four intrinsi13

degenera13ies However the important observation in Fig 24 is that degenera13ies

have only a very small impa13t on the CP violation dis13overy in the sense that if

the true solution is CP violating also the fake solutions are lo13ated at CP violating

values of δCP Therefore thanks to the relatively short baseline without matter ee13t

even if degenera13ies ae13t the pre13ise determination of θ13 and δCP they have only a

small impa13t on the CP violation dis13overy potential Furthermore one would quote

expli13itly the four possible sets of parameters with their respe13tive 13ondential level

It is also 13lear from the gure that the sign(∆m231) degenera13y has pra13ti13ally no ee13t

on the θ13 measurement whereas the o13tant degenera13y has very little impa13t on the

determination of δCP

Some other features of the atmospheri13 neutrino data are presented in Se13 7 In

order to fully exploit the possibilities oered by a Neutrino Fa13tory the dete13tor

should be 13apable of identifying and measuring all three 13harged lepton avors

produ13ed in 13harged-13urrent intera13tions and of measuring their 13harges in order to

identify the in13oming neutrino heli13ity The GLACIER 13on13ept in its non-magnetized

option provides a ba13kground-free identi13ation of ele13tron-neutrino 13harged-13urrent

0 002 004 006 008

sin22θ

13

-π

-π2

0

π2

πδ C

P

0 002 004 006 008

002 004 006 008

sin22θ

13

002 004 006 008

sin22θ

13

002 004 006 008

βB + SPL 5y βB 5y SPL 5y

95 CL regions for the (HtrO

tr) (H

trO

wr) (H

wrO

tr) (H

wrO

wr) solutions

Figure 24 Allowed regions in sin2 2θ13 and δCP for 5 years data (neutrinos only)

from Beta Beam SPL and the 13ombination Htrwr(Otrwr) refers to solutions

with the truewrong mass hierar13hy (o13tant of θ23) For the 13olored regions in

the left panel also 5 years of atmospheri13 data are in13luded the solution with the

wrong hierar13hy has ∆χ2 = 33 The true parameter values are δCP = minus085πsin2 2θ13 = 003 sin2 θ23 = 06 For the Beta Beam only analysis (middle panel)

an external a1313ura13y of 2 (3) for |∆m231| (θ23) has been assumed whereas for

the left and right panel the default value of 10 has been used Reprinted gure

with permission from [37

events and a kinemati13al sele13tion of tau-neutrino 13harged-13urrent intera13tions We

13an assume that 13harge dis13rimination is available for muons rea13hing an external

magnetized-Fe spe13trometer

Another interesting and extremely 13hallenging possibility would 13onsist in

magnetizing the whole liquid Argon volume [132 36 This set-up would allow the

13lean 13lassi13ation of events into ele13trons right-sign muons wrong-sign muons and

no-lepton 13ategories In addition high granularity permits a 13lean dete13tion of quasi-

elasti13 events whi13h provide a sele13tion of the neutrino ele13tron heli13ity by dete13ting

the nal state proton without the need of an ele13tron 13harge measurement Table 11

summarizes the expe13ted rates for GLACIER and 1020 muon de13ays at a neutrino

fa13tory with stored muons having an energy of 30 GeV [133 Ntot is the total number

of events and Nqe is the number of quasi-elasti13 events

Figure 25 shows the expe13ted sensitivity in the measurement of θ13 for a baseline of7400 km The maximal sensitivity to θ13 is a13hieved for very small ba13kground levelssin13e one is looking in this 13ase for small signals most of the information is 13oming

from the 13lean wrong-sign muon 13lass and from quasi-elasti13 events On the other

hand if its value is not too small for a measurement of θ13 the signalba13kgroundratio 13ould be not so 13ru13ial and also the other event 13lasses 13an 13ontribute to this

measurement

A Neutrino Fa13tory should aim to over-13onstrain the os13illation pattern in order

to look for unexpe13ted new physi13s ee13ts This 13an be a13hieved in global ts of the

parameters where the unitarity of the mixing matrix is not stri13tly assumed Using

a dete13tor able to identify the τ lepton produ13tion via kinemati13 means it is possible

to verify the unitarity in νmicro rarr ντ and νe rarr ντ transitions

The study of CP violation in the lepton system probably is the most ambitious

goal of an experiment at a Neutrino Fa13tory Matter ee13ts 13an mimi13 CP violation

however a multi-parameter t at the right baseline 13an allow a simultaneous

determination of matter and CP violating parameters To dete13t CP violation ee13ts

the most favorable 13hoi13e of neutrino energy Eν and baseline L is in the region of

Table 11 Expe13ted events rates for GLACIER in a Neutrino Fa13tory beam

assuming no os13illations and for 1020 muon de13ays (Emicro=30 GeV) Ntot is the

total number of events and Nqe is the number of quasi-elasti13 events

Event rates for various baselines

L = 732 km L = 2900 km L = 7400 kmNtot Nqe Ntot Nqe Ntot Nqe

νmicro CC 2260 000 90 400 144 000 5760 22 700 900

microminus νmicro NC 673 000 41 200 6800

1020 de13ays νe CC 871 000 34 800 55 300 2200 8750 350

νe NC 302 000 19 900 3000

νmicro CC 1010 000 40 400 63 800 2550 10 000 400

micro+ νmicro NC 353 000 22 400 3500

1020 de13ays νe CC 1970 000 78 800 129 000 5160 19 800 800

νe NC 579 000 36 700 5800

Emicro = 30 GeV L = 7400 km

10-4

10-3

10-2

10-6 10-5 10-4 10-3 10-2 10-1 1sin2 2Θ13

∆m2 23

(eV

2 )

90 ALLOWED

SUPER-K ALLOWED

2 x 1019 micro(background)

2 x 1019 micro(no background)

Figure 25 GLACIER sensitivity to the measurement of θ13 Reprinted gure

001

002

003

004

005

006

007

008

009

01

x 10-3

-3 -2 -1 0 1 2 3

δ (rad)

m2 12

(eV

2 )

L = 730 km E = 75 GeV 10 20

L = 2900 km E = 30 GeV 1019

θ13 freeθ13 free

θ13 fixed

χ2 min

+ 46 contour lines

∆

micromicro

Figure 26 GLACIER 90 CL sensitivity on the CP -phase δCP as a fun13tion

of ∆m221 for the two 13onsidered baselines The referen13e os13illation parameters

are ∆m232 = 3 times 10minus3 eV2

sin2 θ23 = 05 sin2 θ12 = 05 sin2 2θ13 = 005 and

δCP = 0 The lower 13urves are made xing all parameters to the referen13e values

while for the upper 13urves θ13 is free Reprinted gure with permission from [134

the rst maximum given by (LEν)max ≃ 500 kmGeV for |∆m2

32| = 25times 10minus3 eV2

[134 To study os13illations in this region one has to require that the energy of

the rst-maximum be smaller than the MSW resonan13e energy 2radic2GFneE

maxν

∆m232 cos 2θ13 This xes a limit on the baseline Lmax asymp 5000 km beyond whi13h

matter ee13ts spoil the sensitivity

As an example Fig 26 shows the sensitivity to the CP violating phase δCP

for two 13on13rete 13ases The events are 13lassied in the ve 13ategories previously

mentioned assuming an ele13tron 13harge 13onfusion of 01 The ex13lusion regions

in the ∆m212 minus δCP plane are determined by tting the visible energy distributions

provided that the ele13tron dete13tion e13ien13y is sim 20 The ex13luded regions extend

up to values of |δCP | 13lose to π even when θ13 is left free

12 Con13lusions and outlook

In this paper we dis13uss the importan13e of outstanding physi13s phenomena su13h

as the possible instability of matter (proton de13ay) the produ13tion of neutrinos in

supernovae in the Sun and in the interior of the Earth as well as the re13ently

dis13overed pro13ess of neutrino os13illations also dete13table through arti13ial neutrinos

produ13ed by nu13lear rea13tors and parti13le a1313elerators

All the above physi13s subje13ts key issues for parti13le physi13s astro-parti13le

physi13s astrophysi13s and 13osmology 13all for a new generation of multipurpose

underground observatories based on improved dete13tion te13hniques

The envisioned dete13tors must ne13essarily be very massive (and 13onsequently

large) and able to provide very low experimental ba13kground The required signal to

noise ratio 13an only be a13hieved in underground laboratories suitably shielded against

13osmi13-rays and environmental radioa13tivity Some 13andidate sites in Europe have

been identied and we are progressing in assessing in detail their 13apabilities

We have identied three dierent and to a large extent 13omplementary

te13hnologies 13apable of meeting the 13hallenge based on large s13ale use of liquids for

building large-size volume-instrumented dete13tors The three proposed large-mass

liquid-based dete13tors for future underground observatories for parti13le physi13s in

Europe (GLACIER LENA and MEMPHYS) although based on 13ompletely dierent

dete13tion te13hniques (liquid Argon liquid s13intillator and water Cherenkov) share a

similar very ri13h physi13s program For some 13ases of interest their dete13tion properties

are quite 13omplementary A summary of the s13ienti13 13ase presented in this paper is

given for astro-parti13le physi13s topi13s in Table 12

A13knowledgments

We wish to warmly a13knowledge support from all the various funding agen13ies We

wish to thank the EU framework 6 proje13t ILIAS for providing assistan13e parti13ularly

regarding underground site aspe13ts (13ontra13t 8R113-CT-2004-506222)

46

Table 12 Summary of the physi13s potential of the proposed dete13tors for astro-parti13le physi13s topi13s The () stands for the 13ase where

Gadolinium salt is added to the water of one of the MEMPHYS shafts

Topi13s GLACIER LENA MEMPHYS

100 kton 50 kton 440 kton

Proton de13ay

e+π0 05times 1035 10times 1035

νK+ 11times 1035 04times 1035 02times 1035

SN ν (10 kp13)

CC 25times 104(νe) 90times 103(νe) 20times 105(νe)

NC 30times 104 30times 103

ES 10times 103(e) 70times 103(p) 10times 103(e)

DSNB ν (SB 5 years) 40-6030 9-1107 43-10947 ()

Solar ν (Evts 1 year)

8

B ES 45times 104 16times 104 11times 1058

B CC 360

7

Be 20times 106

pep 77times 104

Atmospheri13 ν (Evts 1 year) 11times 104 40times 104 (1-ring only)

Geo ν (Evts 1 year) below threshold asymp 1000 need 2 MeV threshold

Rea13tor ν (Evts 1 year)) 17times 104 60times 104 ()

Dark Matter (Evts 10 years) 3 events

(σES = 10minus4

M gt 20 GeV)

Referen13es

[1 J C Pati and A Salam Is Baryon Number Conserved Phys Rev Lett 31 (1973) 661664

[2 P Nath and P F Perez Proton stability in grand unied theories in strings and in branes

Phys Rept 441 (2007) 191317 [hep-ph0601023

[3 Super-Kamiokande Collaboration K Kobayashi et al Sear13h for nu13leon de13ay via

modes favored by supersymmetri13 grand uni13ation models in Super-Kamiokande-I Phys

Rev D72 (2005) 052007 [hep-ex0502026

[4 J Davis Raymond D S Harmer and K C Homan Sear13h for neutrinos from the sun

Phys Rev Lett 20 (1968) 12051209

[5 Kamiokande-II Collaboration K S Hirata et al Observation of B-8 solar neutrinos in

the Kamiokande-II dete13tor Phys Rev Lett 63 (1989) 16

[6 GALLEX Collaboration P Anselmann et al Solar neutrinos observed by GALLEX at

Gran Sasso Phys Lett B285 (1992) 376389

[7 D N Abdurashitov et al Results from SAGE Phys Lett B328 (1994) 234248

[8 Super-Kamiokande Collaboration M B Smy Solar neutrino pre13ision measurements

using all 1496 days of Super-Kamiokande-I data Nu13l Phys Pro13 Suppl 118 (2003)

2532 [hep-ex0208004

[9 SNO Collaboration B Aharmim et al Ele13tron energy spe13tra uxes and day-night

asymmetries of B-8 solar neutrinos from the 391-day salt phase SNO data set Phys Rev

C72 (2005) 055502 [nu13l-ex0502021

[10 GNO Collaboration M Altmann et al Complete results for ve years of GNO solar

neutrino observations Phys Lett B616 (2005) 174190 [hep-ex0504037

[11 Kamiokande-II Collaboration K Hirata et al Observation of a neutrino burs from the

supernova SN1987a Phys Rev Lett 58 (1987) 14901493

[12 R M Bionta et al Observation of a neutrino burst in 13oin13iden13e with supernova SN1987A

in the Large Magellani13 Clound Phys Rev Lett 58 (1987) 1494

[13 E N Alekseev L N Alekseeva I V Krivosheina and V I Vol13henko Dete13tion of the

neutrino signal from SN1987A in the LMC using the INR Baksan underground s13intillator

teles13ope Phys Lett B205 (1988) 209214

[14 The NUSEX Collaboration M Aglietta et al Experimental study of atmospheri13

neutrino ux in the NUSEX experiment Europhys Lett 8 (1989) 611614

[15 Kamiokande-II Collaboration K S Hirata et al Experimental study of the atmospheri13

neutrino ux Phys Lett B205 (1988) 416

[16 Kamiokande-II Collaboration K S Hirata et al Observation of a small atmospheri13

νmicroνe ratio in Kamiokande Phys Lett B280 (1992) 146152

[17 R Be13ker-Szendy et al The Ele13tron-neutrino and muon-neutrino 13ontent of the

atmospheri13 ux Phys Rev D46 (1992) 37203724

[18 Freacutejus Collaboration K Daum et al Determination of the atmospheri13 neutrino spe13tra

with the Freacutejus dete13tor Z Phys C66 (1995) 417428

[19 Soudan-2 Collaboration W W M Allison et al The atmospheri13 neutrino avor ratio

from a 39 du13ial kiloton-year exposure of Soudan 2 Phys Lett B449 (1999) 137144

[hep-ex9901024

[20 Super-Kamiokande Collaboration Y Ashie et al A measurement of atmospheri13

neutrino os13illation parameters by Super-Kamiokande I Phys Rev D71 (2005) 112005

[hep-ex0501064

[21 Super-Kamiokande Collaboration Y Fukuda et al Eviden13e for os13illation of

atmospheri13 neutrinos Phys Rev Lett 81 (1998) 15621567 [hep-ex9807003

[22 T Kajita Dis13overy of neutrino os13illations Rept Prog Phys 69 (2006) 16071635

[23 T Tabarelli de Fatis Prospe13ts of measuring sin2(2θ13) and the sign of ∆m2with a massive

magnetized dete13tor for atmospheri13 neutrinos Eur Phys J C24 (2002) 4350

[hep-ph0202232

[24 T Araki et al Experimental investigation of geologi13ally produ13ed antineutrinos with

KamLAND Nature 436 (2005) 499503

[25 Borexino Collaboration H O Ba13k et al Phenylxylylethane (PXE) A high-density

high-ashpoint organi13 liquid s13intillator for appli13ations in low-energy parti13le and

astrophysi13s experiments physi13s0408032

[26 KamLAND Collaboration T Araki et al Measurement of neutrino os13illation with

KamLAND Eviden13e of spe13tral distortion Phys Rev Lett 94 (2005) 081801

[hep-ex0406035

[27 ICARUS Collaboration S Amerio et al Design 13onstru13tion and tests of the ICARUS

T600 dete13tor Nu13l Instrum Meth A527 (2004) 329410

[28 ICARUS Collaboration F Arneodo et al The ICARUS experiment a se13ond-generation

proton de13ay experiment and neutrino observatory at the Gran Sasso Laboratory

hep-ex0103008

[29 A de Bellefon et al MEMPHYS A large s13ale water Cherenkov dete13tor at Freacutejus

hep-ex0607026

[30 L Oberauer F von Feilitzs13h and W Potzel A large liquid s13intillator dete13tor for

low-energy neutrino astronomy Nu13l Phys Pro13 Suppl 138 (2005) 108111

[31 T Marrodaacuten Undagoitia et al Low energy neutrino astronomy with the large liquid

s13intillator dete13tor LENA Prog Part Nu13l Phys 57 (2006) 283 [hep-ph0605229

[32 A Rubbia Experiments for CP-violation A giant liquid argon s13intillation Cherenkov and

13harge imaging experiment hep-ph0402110

[33 A Rubbia Review of massive underground dete13tors hep-ph0407297

[34 A Ereditato and A Rubbia Ideas for future liquid argon dete13tors Nu13l Phys Pro13

Suppl 139 (2005) 301310 [hep-ph0409143

[35 A Ereditato and A Rubbia The liquid argon TPC A powerful dete13tor for future neutrino

experiments and proton de13ay sear13hes Nu13l Phys Pro13 Suppl 154 (2006) 163178

[hep-ph0509022

[36 A Ereditato and A Rubbia Con13eptual design of a s13alable multi-kton super13ondu13ting

magnetized liquid argon TPC Nu13l Phys Pro13 Suppl 155 (2006) 233236

[hep-ph0510131

[37 J E Campagne M Maltoni M Mezzetto and T S13hwetz Physi13s potential of the

CERN-MEMPHYS neutrino os13illation proje13t JHEP 04 (2007) 003 [hep-ph0603172

[38 C Rubbia A Ferrari Y Kadi and V Vla13houdis Beam 13ooling with ionisation losses

hep-ph0602032

[39 K S Hirata et al Observation in the Kamiokande-II dete13tor of the neutrino burst from

supernova SN1987A Phys Rev D38 (1988) 448458

[40 M Wurm et al Dete13tion potential for the diuse supernova neutrino ba13kground in the

large liquid-s13intillator dete13tor LENA Phys Rev D75 (2007) 023007

[astro-ph0701305

[41 J F Bea13om and M R Vagins GADZOOKS Antineutrino spe13tros13opy with large water

Cherenkov dete13tors Phys Rev Lett 93 (2004) 171101 [hep-ph0309300

[42 I Dorsner and P Fileviez Perez How long 13ould we live Phys Lett B625 (2005) 8895

[hep-ph0410198

[43 H Georgi and S L Glashow Unity of all elementary parti13le for13es Phys Rev Lett 32

(1974) 438441

[44 I Dorsner and P Fileviez Perez Uni13ation without supersymmetry Neutrino mass proton

de13ay and light leptoquarks Nu13l Phys B723 (2005) 5376 [hep-ph0504276

[45 I Dorsner P F Perez and R Gonzalez Felipe Phenomenologi13al and 13osmologi13al aspe13ts

of a minimal GUT s13enario Nu13l Phys B747 (2006) 312327 [hep-ph0512068

[46 D-G Lee R N Mohapatra M K Parida and M Rani Predi13tions for proton lifetime in

minimal nonsupersymmetri13 SO(10) models An update Phys Rev D51 (1995) 229235

[hep-ph9404238

[47 H Murayama and A Pier13e Not even de13oupling 13an save minimal supersymmetri13 SU(5)

Phys Rev D65 (2002) 055009 [hep-ph0108104

[48 B Baj13 P Fileviez Perez and G Senjanovi13 Proton de13ay in minimal supersymmetri13

SU(5) Phys Rev D66 (2002) 075005 [hep-ph0204311

[49 B Baj13 P Fileviez Perez and G Senjanovi13 Minimal supersymmetri13 SU(5) theory and

proton de13ay Where do we stand hep-ph0210374

[50 D Emmanuel-Costa and S Wiesenfeldt Proton de13ay in a 13onsistent supersymmetri13 SU(5)

GUT model Nu13l Phys B661 (2003) 6282 [hep-ph0302272

[51 K S Babu and R N Mohapatra Predi13tive neutrino spe13trum in minimal SO(10) grand

uni13ation Phys Rev Lett 70 (1993) 28452848 [hep-ph9209215

[52 C S Aulakh B Baj13 A Melfo G Senjanovi13 and F Vissani The minimal supersymmetri13

grand unied theory Phys Lett B588 (2004) 196202 [hep-ph0306242

[53 T Fukuyama A Ilakova13 T Kiku13hi S Meljana13 and N Okada Detailed analysis of

proton de13ay rate in the minimal supersymmetri13 SO(10) model JHEP 09 (2004) 052

[hep-ph0406068

[54 H S Goh R N Mohapatra S Nasri and S-P Ng Proton de13ay in a minimal SUSY

SO(10) model for neutrino mixings Phys Lett B587 (2004) 105116 [hep-ph0311330

[55 T Friedmann and E Witten Uni13ation s13ale proton de13ay and manifolds of G(2)

holonomy Adv Theor Math Phys 7 (2003) 577617 [hep-th0211269

[56 B Baj13 and G Senjanovi13 Seesaw at LHC hep-ph0612029

[57 P Fileviez Perez A minimal renormalizable grand unied theory hep-ph0702287

[58 A Bueno et al Nu13leon de13ay sear13hes with large liquid argon TPC dete13tors at shallow

depths Atmospheri13 neutrinos and 13osmogeni13 ba13kgrounds JHEP 04 (2007)

[hep-ph0701101

[59 GEANT4 Collaboration S Agostinelli et al GEANT4 A simulation toolkit Nu13l

Instrum Meth A506 (2003) 250303

[60 C K Jung Feasibility of a next generation underground water Cherenkov dete13tor UNO

AIP Conf Pro13 533 (2000) 2934 [hep-ex0005046

[61 T Nakaya Next-generation nu13leon de13ay experiments Nu13l Phys Pro13 Suppl 138 (2005)

376382

[62 T Marrodaacuten Undagoitia et al Sear13h for the proton de13ay plarr K+ + nu in the large liquid

s13intillator low energy neutrino astronomy dete13tor LENA Phys Rev D72 (2005) 075014

[hep-ph0511230

[63 A S Dighe and A Y Smirnov Identifying the neutrino mass spe13trum from the neutrino

burst from a supernova Phys Rev D62 (2000) 033007 [hep-ph9907423

[64 M Aglietta et al Comments on the two events observed in neutrino dete13tors during the

supernova 1987a outburst Europhys Lett 3 (1987) 13211324

[65 L Cadonati F P Calapri13e and M C Chen Supernova neutrino dete13tion in Borexino

Astropart Phys 16 (2002) 361372 [hep-ph0012082

[66 J F Bea13om W M Farr and P Vogel Dete13tion of supernova neutrinos by neutrino proton

elasti13 s13attering Phys Rev D66 (2002) 033001 [hep-ph0205220

[67 M Ka13helriess et al Exploiting the neutronization burst of a gala13ti13 supernova Phys

Rev D71 (2005) 063003 [astro-ph0412082

[68 I Gil-Botella and A Rubbia De13oupling supernova and neutrino os13illation physi13s with

LAr TPC dete13tors JCAP 0408 (2004) 001 [hep-ph0404151

[69 I Gil-Botella and A Rubbia Os13illation ee13ts on supernova neutrino rates and spe13tra and

dete13tion of the sho13k breakout in a liquid argon TPC JCAP 0310 (2003) 009

[hep-ph0307244

[70 R C S13hirato and G M Fuller Conne13tion between supernova sho13ks avor

transformation and the neutrino signal astro-ph0205390

[71 G L Fogli E Lisi D Montanino and A Mirizzi Analysis of energy- and time-dependen13e

of supernova sho13k ee13ts on neutrino 13rossing probabilities Phys Rev D68 (2003)

033005 [hep-ph0304056

[72 G L Fogli E Lisi A Mirizzi and D Montanino Probing supernova sho13k waves and

neutrino avor transitions in next-generation water-Cherenkov dete13tors JCAP 0504

(2005) 002 [hep-ph0412046

[73 R Tomas et al Neutrino signatures of supernova sho13k and reverse sho13k propagation

JCAP 0409 (2004) 015 [astro-ph0407132

[74 V Barger P Huber and D Marfatia Supernova neutrinos 13an tell us the neutrino mass

hierar13hy independently of ux models Phys Lett B617 (2005) 167173

[hep-ph0501184

[75 G L Fogli E Lisi A Mirizzi and D Montanino Damping of supernova neutrino transitions

in sto13hasti13 sho13k-wave density proles JCAP 0606 (2006) 012 [hep-ph0603033

[76 A Friedland and A Gruzinov Neutrino signatures of supernova turbulen13e

astro-ph0607244

[77 C Lunardini and A Y Smirnov Supernova neutrinos Earth matter ee13ts and neutrino

mass spe13trum Nu13l Phys B616 (2001) 307348 [hep-ph0106149

[78 A S Dighe M T Keil and G G Raelt Identifying earth matter ee13ts on supernova

neutrinos at a single dete13tor JCAP 0306 (2003) 006 [hep-ph0304150

[79 A S Dighe M T Keil and G G Raelt Dete13ting the neutrino mass hierar13hy with a

supernova at I13eCube JCAP 0306 (2003) 005 [hep-ph0303210

[80 A Mirizzi G G Raelt and P D Serpi13o Earth matter ee13ts in supernova neutrinos

Optimal dete13tor lo13ations JCAP 0605 (2006) 012 [astro-ph0604300

[81 H Duan G M Fuller J Carlson and Y-Z Qian Simulation of 13oherent non-linear neutrino

avor transformation in the supernova environment I Correlated neutrino traje13tories

Phys Rev D74 (2006) 105014 [astro-ph0606616

[82 S Hannestad G G Raelt G Sigl and Y Y Y Wong Self-indu13ed 13onversion in dense

neutrino gases Pendulum in avour spa13e Phys Rev D74 (2006) 105010

[astro-ph0608695

[83 G G Raelt and A Y Smirnov Self-indu13ed spe13tral splits in supernova neutrino uxes

arXiv07051830 [hep-ph

[84 R Tomas D Semikoz G G Raelt M Ka13helriess and A S Dighe Supernova pointing

with low- and high-energy neutrino dete13tors Phys Rev D68 (2003) 093013

[hep-ph0307050

[85 P Antonioli et al SNEWS The SuperNova Early Warning System New J Phys 6 (2004)

114 [astro-ph0406214

[86 A Odrzywolek M Misiaszek and M Kuts13hera Dete13tion possibility of the

pair-annihilation neutrinos from the neutrino-13ooled pre-supernova star Astropart Phys

21 (2004) 303313 [astro-ph0311012

[87 S Ando J F Bea13om and H Yuksel Dete13tion of neutrinos from supernovae in nearby

galaxies Phys Rev Lett 95 (2005) 171101 [astro-ph0503321

[88 M Fukugita and M Kawasaki Constraints on the star formation rate from supernova reli13

neutrino observations Mon Not Roy Astron So13 340 (2003) L7 [astro-ph0204376

[89 S Ando Cosmi13 star formation history and the future observation of supernova reli13

neutrinos Astrophys J 607 (2004) 2031 [astro-ph0401531

[90 S Ando De13aying neutrinos and impli13ations from the supernova reli13 neutrino observation

Phys Lett B570 (2003) 11 [hep-ph0307169

[91 G L Fogli E Lisi A Mirizzi and D Montanino Three-generation avor transitions and

de13ays of supernova reli13 neutrinos Phys Rev D70 (2004) 013001 [hep-ph0401227

[92 Super-Kamiokande Collaboration M Malek et al Sear13h for supernova reli13 neutrinos

at Super-Kamiokande Phys Rev Lett 90 (2003) 061101 [hep-ex0209028

[93 L E Strigari J F Bea13om T P Walker and P Zhang The 13on13ordan13e 13osmi13 star

formation rate Impli13ations from and for the supernova neutrino and gamma ray

ba13kgrounds JCAP 0504 (2005) 017 [astro-ph0502150

[94 A M Hopkins and J F Bea13om On the normalisation of the 13osmi13 star formation history

Astrophys J 651 (2006) 142 [astro-ph0601463

[95 A G Co1313o A Ereditato G Fiorillo G Mangano and V Pettorino Supernova reli13

neutrinos in liquid argon dete13tors JCAP 0412 (2004) 002 [hep-ph0408031

[96 H Yuksel S Ando and J F Bea13om Dire13t measurement of supernova neutrino emission

parameters with a gadolinium enhan13ed Super-Kamiokande dete13tor Phys Rev C74

(2006) 015803 [astro-ph0509297

[97 T Totani K Sato H E Dalhed and J R Wilson Future dete13tion of supernova neutrino

burst and explosion me13hanism Astrophys J 496 (1998) 216225 [astro-ph9710203

[98 T A Thompson A Burrows and P A Pinto Sho13k breakout in 13ore-13ollapse supernovae

and its neutrino signature Astrophys J 592 (2003) 434 [astro-ph0211194

[99 M T Keil G G Raelt and H-T Janka Monte Carlo study of supernova neutrino spe13tra

formation Astrophys J 590 (2003) 971991 [astro-ph0208035

[100 Borexino Collaboration G Alimonti et al Ultra-low ba13kground measurements in a large

volume underground dete13tor Astropart Phys 8 (1998) 141157

[101 G Alimonti et al A large-s13ale low-ba13kground liquid s13intillation dete13tor The 13ounting

test fa13ility at Gran Sasso Nu13l Instrum Meth A406 (1998) 411426

[102 A Ianni D Montanino and F L Villante How to observe B-8 solar neutrinos in liquid

s13intillator dete13tors Phys Lett B627 (2005) 3848 [physi13s0506171

[103 M C Gonzalez-Gar13ia and Y Nir Developments in neutrino physi13s Rev Mod Phys 75

(2003) 345402 [hep-ph0202058

[104 MACRO Collaboration M Ambrosio et al Matter ee13ts in upward-going muons and

sterile neutrino os13illations Phys Lett B517 (2001) 5966 [hep-ex0106049

[105 K2K Collaboration M H Ahn et al Measurement of neutrino os13illation by the K2K

experiment hep-ex0606032

[106 MINOS Collaboration N Tagg First MINOS results from the NuMI beam ECONF

C060409 (2006) 019 [hep-ex0605058

[107 Y Itow et al The JHF-Kamioka neutrino proje13t hep-ex0106019

[108 NOvA Collaboration D S Ayres et al NOvA proposal to build a 30-kiloton o-axis

dete13tor to study neutrino os13illations in the Fermilab NuMI beamline hep-ex0503053

[109 P Huber M Maltoni and T S13hwetz Resolving parameter degenera13ies in long-baseline

experiments by atmospheri13 neutrino data Physi13al Review D 71 (2005) 053006

[110 C W Kim and U W Lee Comment on the possible ele13tron-neutrino ex13ess in the

Super-Kamiokande atmospheri13 neutrino experiment Phys Lett B444 (1998) 204207

[hep-ph9809491

[111 O L G Peres and A Y Smirnov Testing the solar neutrino 13onversion with atmospheri13

neutrinos Phys Lett B456 (1999) 204213 [hep-ph9902312

[112 M C Gonzalez-Gar13ia and M Maltoni Atmospheri13 neutrino os13illations and new physi13s

Phys Rev D70 (2004) 033010 [hep-ph0404085

[113 Y Fukuda et al The Super-Kamiokande dete13tor Nu13l Instrum Meth A501 (2003)

418462

[114 K A Ho13hmuth et al Probing the Earths interior with a large-volume liquid s13intillator

dete13tor Astropart Phys 27 (2007) 2129 [hep-ph0509136

[115 A Bueno R Cid S Navas-Con13ha D Hooper and T J Weiler Indire13t dete13tion of dark

matter WIMPs in a Liquid Argon TPC JCAP 0501 (2005) 001 [hep-ph0410206

[116 S T Pet13ov and T S13hwetz Pre13ision measurement of solar neutrino os13illation parameters

by a long-baseline rea13tor neutrino experiment in Europe Phys Lett B642 (2006)

487494 [hep-ph0607155

[117 S Choubey and S T Pet13ov Rea13tor anti-neutrino os13illations and gadolinium loaded

Super-Kamiokande dete13tor Phys Lett B594 (2004) 333346 [hep-ph0404103

[118 M Ishitsuka T Kajita H Minakata and H Nunokawa Resolving neutrino mass hierar13hy

and CP degenera13y by two identi13al dete13tors with dierent baselines Phys Rev D72

(2005) 033003 [hep-ph0504026

[119 OPERA Collaboration R A13quafredda et al First events from the CNGS neutrino beam

dete13ted in the OPERA experiment New J Phys 8 (2006) 303 [hep-ex0611023

[120 A Meregaglia and A Rubbia Neutrino os13illation physi13s at an upgraded CNGS with large

next generation liquid argon TPC dete13tors JHEP 11 (2006) 032 [hep-ph0609106

[121 M Maltoni T S13hwetz M A Tortola and J W F Valle Status of global ts to neutrino

os13illations New J Phys 6 (2004) 122 [hep-ph0405172

[122 F Gerigk et al Con13eptual design of the SPL II a high-power super13ondu13ting H- lina13 at

CERN CERN-2006-006

[123 BENE Steering Group Collaboration A Baldini et al Beams for European Neutrino

Experiments (BENE) Midterm s13ienti13 report

[124 International S13oping Study Collaboration P Dornan et al in preparation (2006)

[125 M G Catanesi et al Proposal for hadron produ13tion measurements using the NA49

dete13tor for use in long-baseline and atmospheri13 neutrino ux 13al13ulations

CERN-SPSC-2001-017

[126 P Zu1313helli A novel 13on13ept for a νeνe neutrino fa13tory The beta beam Phys Lett B532

(2002) 166172

[127 J Bernabeu J Burguet-Castell C Espinoza and M Lindroos Mono13hromati13 neutrino

beams JHEP 12 (2005) 014 [hep-ph0505054

[128 J Sato Monoenergeti13 neutrino beam for long baseline experiments Phys Rev Lett 95

(2005) 131804 [hep-ph0503144

[129 J Burguet-Castell M B Gavela J J Gomez-Cadenas P Hernandez and O Mena On the

measurement of leptoni13 CP violation Nu13l Phys B608 (2001) 301318

[hep-ph0103258

[130 H Minakata and H Nunokawa Exploring neutrino mixing with low energy superbeams

JHEP 10 (2001) 001 [hep-ph0108085

[131 G L Fogli and E Lisi Tests of three-avor mixing in long-baseline neutrino os13illation

experiments Phys Rev D54 (1996) 36673670 [hep-ph9604415

[132 A Baderts13her M Laran13hi A Meregaglia A Muller and A Rubbia First results from a

liquid argon time proje13tion 13hamber in a magneti13 eld Nu13l Instrum Meth A555

(2005) 294309 [physi13s0505151

[133 A Bueno M Campanelli and A Rubbia Physi13s potential at a neutrino fa13tory Can we

benet from more than just dete13ting muons Nu13l Phys B589 (2000) 577608

[hep-ph0005007

[134 A Bueno M Campanelli S Navas-Con13ha and A Rubbia On the energy and baseline

optimization to study ee13ts related to the delta-phase (CP-T-violation) in neutrino

os13illations at a neutrino fa13tory Nu13l Phys B631 (2002) 239284 [hep-ph0112297

Physics motivation
Description of the three detectors
- Liquid Argon TPC
- Liquid scintillator detector
- Water Cherenkov
- - Underground sites
  - Matter instability sensitivity to proton decay
  - Supernova neutrinos
  - - SN neutrino emission oscillation and detection
    - Diffuse supernova neutrino background
    - - Solar neutrinos
      - Atmospheric neutrinos
      - Geo-neutrinos
      - Indirect searches for the Dark Matter of the Universe
      - Neutrinos from nuclear reactors
      - Neutrinos from particle accelerator beams
      - Conclusions and outlook

Page 2: arXiv:0705.0116v2 [hep-ph] 29 May 2007 - arXiv.org e-Print archive · olp e V 29 ter Win 15 M urm W 15, A a Zalewsk 28 and R Zimmermann 12 1 IPNL, ersité Univ Claude Bernard on Ly