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Neutrinos from the sun, earth and SN’s: a brief excursion. Aldo Ianni @ 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 n e beam Low energy

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  • Solar neutrinos: established facts
  • Solar neutrinos: the future
  • Neutrinos from the Earth: present & future
  • Neutrinos from SN
solar neutrinos
Solar neutrinos
  • Pure ne beam
  • Low energy
  • Long baseline (1013 cm)
  • Moving through high density matter (at sun’s core ~150 g/cm3)
solar neutrinos observations
Solar neutrinos: observations

* Super-Kamiokande recovers full detector performances this year

** SNO is planned to be shut down end of this year

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

Taken from V. Barger et al hep-ph/0501247

Taken from G.L.Fogli et al hep-ph/0506083

established facts
Established facts
  • 0.01% of solar neutrinos measured in real time
  • Data explained by the MSW LMA
  • MWS defines mass hierarchy (m2 > m1)
  • SNO CC/NC sets tan2q12<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
a look at the future for solar neutrinos
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
borexino @ gran sasso
Borexino @ Gran Sasso

A pioneering experiment to search for sub-MeV

7Be solar neutrinos

  • Target medium : 100tons of high radiopurity organic liquid scintillator
  • Detection channel: neutrino-electron elastic scattering (about 30cpd expected)
  • Signature : seasonal variation + Compton-like threshold due to monoenergetic 7Be neutrinos
  • Challenge : reduce background sources (238U, 232Th, 40K, 222Rn, 85Kr, 39Ar, 210Pb, 210Po) to get S/N>1
  • Lower detection energy : 250 keV limited to intrinsic 14C contamination
  • Experimental strategies to reduce background : established by a 4-ton scale prototype
pep neutrinos with borexino
pep neutrinos with Borexino
  • Basic idea : reduce 11C cosmogenic background
  • Method: tagging 11C by tackling the produced (95%) neutrons in spallation interactions

Taken from C. Galbiati et al PRC 71, 055805 (2005)

Remark: a pep measurement gives the same information of a pp one

reduction of background for pep neutrinos

Spherical cut


Capture to reject 11C event

Cylindrical cut

Around muon-track

Reduction of background forpep neutrinos

Muon track

Neutron production

11 c tagged with the borexino prototype
11C tagged with the Borexino prototype

11C decays b+ with Qb~1MeV and t~30min

Measured production rate ~0.14 events/day/ton at Gran

Sasso depth

Taken from Borexino coll. hep-ex/0601035

predictions to falsify with borexino
Predictions to falsify with Borexino

Bahcall et al, JHEP 8 (2004) 016, hep-ph/04060294

2 monoenergetic beams to test solar physics and

neutrino physics

pep new goal for kamland ii
pep new goal for KamLAND-II

Taken from Nakajima, La Thuile

pep for sno
pep for SNO+
  • Main physics goal for 1kton organic liquid scintillator after SNO
  • At SNOlab 11C is reduced by a factor of about 10 with respect to Gran Sasso and 70 to Kamioka
searching for pp solar neutrinos
Searching for pp solar neutrinos
  • Goal : no 14C or a strong tagging
  • Solution-I : liquid Ne(CLEAN) or Xe(XMASS), detection channel = ES
  • Solution-II : loaded 115In liquid scintillator (LENS)
  • Solution-III : 100Mo sheets + plastic scintillator
  • Time scale : due to experimental difficulties >2010
conclusions on solar neutrinos
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
Neutrinos from the earth: geoneutrinos
  • Goals:
  • determine distribution of U, Th and K in earth interior
  • measure total heat due to radioactivity [earth gives 30-44 TW]
  • determine hot spots (geo-reactor etc) if any
detection of geoneutrinos
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
The earth looked through geoneutrinos

Geoneutrino flux (Fiorentini et al)

Middle oceanic crust



Lena 30kt


present observations @ kamland
Present observations @ KamLAND
  • Energy window: 0.9<E<2.6 MeV
  • Observed : 152 events
  • Background : 127 ± 13 events
  • Geoneutrino signal : 25+19-18 events
  • Main sources of background : reactors and 13C(a,n)16O with a’s from 210Po
geoneutrinos @ gran sasso
Geoneutrinos @ Gran Sasso

Borexino 300t target mass : S/N~1

lena in finland
LENA in Finland
  • Proposeda 30kt multi-puspose liquid scintillator based on PXE
  • PXE tested with the Borexino prototype
  • High statistics and angular resolution (26°) may allow 40K neutrino measurement looking toward the earth’s nucleus (if any hidden K in there!)
conclusions on geoneutrinos
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 (2s) evidence of geoneutrinos from KamLAND
  • Hope : detect K neutrinos somehow. See M. Chen talk at Neutrino Geophysics, Honolulu, Hawaii December 15, 2005
detection of sn neutrinos 1
Detection of SN neutrinos [1]
  • SN neutrinos are affected by oscillations:
  • In the standard figure each flavor has a peculiar mean energy and temperature (Te~3.5MeV, Tanti-e~5MeV, Tx~8MeV with <E>~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




detection of sn neutrinos 2
Detection of SN neutrinos [2]
  • SuperKamiokande will play a crucial role with ~8000 events for inverse-beta decay and ~700 for NC on 16O @10kpc
  • SuperKamiokande will see ~300 events of antineutrino @50kpc 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
conclusions on sn neutrinos
Conclusions on SN neutrinos
  • A future galactic SN will yield 100-1000 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