Neutrinos from the sun, earth and SN’s: a brief excursion Aldo IFAE 2006 Pavia April 19 th

Outline  Solar neutrinos: established facts  Solar neutrinos: the future  Neutrinos from the Earth: present & future  Neutrinos from SN

Solar neutrinos Pure e beam Low energy Long baseline (10 13 cm) Moving through high density matter (at sun’s core ~150 g/cm 3 )

Solar neutrinos: observations ExperimentTypeThres. (MeV)Start ESCCNC Homestake(Cl-Ar)Radioch (stopped) KamiokandeCherenk (stopped) SAGERadioch GALLEXRadioch (stopped) Super-KamiokandeCherenk * GNORadioch (stopped) SNOCherenk ** * Super-Kamiokande recovers full detector performances this year ** SNO is planned to be shut down end of this year

Phenomenology of solar neutrino observations 1.Observations explained by neutrino oscillations + matter effects (MSW) 2.MSW leads to energy spectrum distortion and regeneration in the earth (day-night effect) 3.After SNO with NC the space of parameters gets reduced a lot 4.After KamLAND (assuming CPT) one dominant solution is tackled, namely the LMA

The great turn with SNO (>2001)

Established dominant solution Taken from V. Barger et al hep-ph/ Taken from G.L.Fogli et al hep-ph/

Established facts 0.01% of solar neutrinos measured in real time Data explained by the MSW LMA MWS defines mass hierarchy (m 2 > m 1 ) SNO CC/NC sets tan 2  12 <1 MSW predicts up-turn of survival probability (spectral distortion) and regeneration MSW predicted effects not yet observed in SNO and SK due to high systematrics and still poor statistics

SNO data

A look at the future for Solar neutrinos  Measure in real time 99.99% of spectrum below 5 MeV : low energy detectors  Measure spectral distortion and regeneration : low energy and/or Mton water Cherenkov  Compare photon to neutrino luminosity : low energy solar neutrinos pp, pep, Be  Test new physics with sub-dominant effects : e.m. properties, mass varying neutrinos, non-standard interactions, light sterile neutrino

Gran Sasso A pioneering experiment to search for sub-MeV 7 Be solar neutrinos 1.Target medium : 100tons of high radiopurity organic liquid scintillator 2.Detection channel: neutrino-electron elastic scattering (about 30cpd expected) 3.Signature : seasonal variation + Compton-like threshold due to monoenergetic 7 Be neutrinos 4.Challenge : reduce background sources ( 238 U, 232 Th, 40 K, 222 Rn, 85 Kr, 39 Ar, 210 Pb, 210 Po) to get S/N>1 5.Lower detection energy : 250 keV limited to intrinsic 14 C contamination 6.Experimental strategies to reduce background : established by a 4-ton scale prototype

pep neutrinos with Borexino Basic idea : reduce 11 C cosmogenic background Method : tagging 11 C by tackling the produced (95%) neutrons in spallation interactions Taken from C. Galbiati et al PRC 71, (2005) Remark: a pep measurement gives the same information of a pp one

Reduction of background for pep neutrinos Cylindrical cut Around muon-track Spherical cut around neutron Capture to reject 11 C event Neutron production Muon track

11 C tagged with the Borexino prototype Taken from Borexino coll. hep-ex/ C decays  + with Q  ~1MeV and  min Measured production rate ~0.14 events/day/ton at Gran Sasso depth

Predictions to falsify with Borexino Bahcall et al, JHEP 8 (2004) 016, hep-ph/ monoenergetic beams to test solar physics and neutrino physics

pep new goal for KamLAND-II Taken from Nakajima, La Thuile

pep for SNO+ Main physics goal for 1kton organic liquid scintillator after SNO At SNOlab 11 C is reduced by a factor of about 10 with respect to Gran Sasso and 70 to Kamioka

Searching for pp solar neutrinos  Goal : no 14 C or a strong tagging  Solution-I : liquid Ne(CLEAN) or Xe(XMASS), detection channel = ES  Solution-II : loaded 115 In liquid scintillator (LENS)  Solution-III : 100 Mo sheets + plastic scintillator  Time scale : due to experimental difficulties >2010

Conclusions on solar neutrinos Wonderful effort made by researchers (both on experiments and theory) to collect and explain data Unique opportunity with low energy solar neutrinos both in astrophysics and neutrino physics A great challenge for experiments pep neutrinos measurable Not too much to add to oscillation parameters

Neutrinos from the earth: geoneutrinos Goals: 1.determine distribution of U, Th and K in earth interior 2.measure total heat due to radioactivity [earth gives TW] 3.determine hot spots (geo-reactor etc) if any

Detection of geoneutrinos Above 1.8MeV (only U,Th): inverse-beta decay (strong tagging) Below 1.8MeV (K as well): elastic scattering (weak tagging)

The earth looked through geoneutrinos Geoneutrino flux (Fiorentini et al) Middle oceanic crust SNO+ Borexino Lena 30kt KamLAND

Present KamLAND Energy window: 0.9<E<2.6 MeV Observed : 152 events Background : 127 ± 13 events Geoneutrino signal : events Main sources of background : reactors and 13 C( ,n) 16 O with  ’s from 210 Po

Gran Sasso Borexino 300t target mass : S/N~1

LENA in Finland Proposed a 30kt multi-puspose liquid scintillator based on PXE PXE tested with the Borexino prototype High statistics and angular resolution (26°) may allow 40 K neutrino measurement looking toward the earth’s nucleus (if any hidden K in there!)

Conclusions on geoneutrinos U and Th geoneutrinos to get information on radiogenic heat on earth and test earth formation mechanism U and Th geoneutrinos easy to detect far away from reactors and with a low background liquid scintillator More detectors in different locations to reduce uncertainties First (2  ) evidence of geoneutrinos from KamLAND Hope : detect K neutrinos somehow. See M. Chen talk at Neutrino Geophysics, Honolulu, Hawaii December 15, 2005

SN neutrinos

Detection of SN neutrinos [1] SN neutrinos are affected by oscillations: In the standard figure each flavor has a peculiar mean energy and temperature (T e ~3.5MeV, T anti-e ~5MeV, T x ~8MeV with ~3.15T) Uncertainty of standard figure ~50% SN in galaxy: 40±10 yr/SN. Long-term stability of detectors required in order to measure the temperature and energy of x ’s and their antiparticles one needs a spectral signature e anti-e x

Detection of SN neutrinos [2] SuperKamiokande will play a crucial role with ~8000 events for inverse-beta decay and ~700 for NC on 16 SuperKamiokande will see ~300 events of in the LMC SNO has a unique channel e +d  ppe- for studying the neutronization phase but it will be shut down in 2007 NC with neutrino-proton elastic scattering to measure x ’s and their antiparticles with a spectral signature in low threshold liquid scintillators (Borexino, KamLAND) Italy has a great opportunity with LVD, T600 and Borexino at the same location

Detection of SN neutrinos [3] Detection channelN, BorexinoN, LVD +e -  +e inverse-beta decay p  +p C(, ) 12 C * [E  =15.1MeV] 9(8 for anti- ) 27(25 for anti- ) 12 C(anti-,e + ) 12 B C(,e - ) 12 N Fe(,e - ) 56 Co+ 56 Fe(anti-,e + ) 56 Mn -80

Conclusions on SN neutrinos A future galactic SN will yield events in the existing detectors for the well tagged channel of inverse- beta decay (electron-antineutrino spectral signature) Neutrino-proton elastic scattering will allow to measure the energy and temperature of mu and tau (anti)neutrinos Collection of nice data for the cooling phase, not as well for the neutronization phase after SNO shut-down Future proposed LENA to see modulation of spectra due to matter effect in the earth