Solar neutrinos Recent results Daniel Vignaud (APC Paris) Neutrinos at the forefront of particle physics and astrophysics 23 October 2012

1.Solar neutrinos, witnesses of the core of the Sun 2.Archaeology ( ) : the solar neutrino problem 3.Towards solar neutrino spectroscopy 4.Solar neutrinos and particle physics 5.Is there any future ? Solar neutrinos : Recent results

1.Solar neutrinos, witnesses of the core of the Sun 2.Archaeology ( ) : the solar neutrino problem 3.Towards solar neutrino spectroscopy 4.Solar neutrinos and particle physics 5.Is there any future ? Solar neutrinos : Recent results

température T (10 6 K) The Sun  Composition : 73% hydrogen (H) 25% helium (He) 2% other elements Central temperature: degrees p + p  d + e + + e core radiative zone convective zone Energy production in the Sun: cycles of nuclear reactions Energy balance : 4 protons + 2 electrons  helium neutrinos W

Nuclear reactions in the Sun p + p  2 H + e + + e B pp 3 He + 3 He  4 He + 2p 3 He + 4 He  7 Be +  2 H + p  3 He +  100% 85% 15% 7 Be + e -  7 Li + e 7 Li + p  4 He + 4 He 15% Be 7 Be + p  8 B +  8 B  8 Be + e + + e 8 Be  4 He + 4 He 0,02% B B

Nuclear reactions in the Sun p + p  2 H + e + + e 3 He + 3 He  4 He + 2p 3 He + 4 He  7 Be +  7 Be + e -  7 Li + e 7 Li + p  4 He + 4 He 7 Be + p  8 B +  8 B  8 Be + e + + e 8 Be  4 He + 4 He 2 H + p  3 He +  100% 85% 15% 0,02% 15% B B pp Be p + e - + p  2 H + e 0,4% pep 3 He + p  4 He + e + + e hep

Nuclear reactions in the Sun CNO cycle 12 C + p  13 N +  13 N  13 C + e + + e 13 C + p  14 N +  14 N + p  15 O +  15 O  15 N + e + + e 15 N + p  12 C + 4 He B N O 12 C : catalyst

Energy production in stars cycle CNO cycle pp Temperature of the star (10 6 K) Competition between the pp chain and the CNO cycle as a function of the stellar temperature. For the Sun, the pp chain is still dominant.

pp 8B8B pep 7 Be Neutrino energy (MeV) Flux Spectres continus : cm -2 s -1 MeV -1 Raies monoénergétiques : cm -2 s ,1 Energy spectrum of solar neutrinos hep SuperK, SNO Chlorine Borexino Gallium LENS TPC 13 N 15 O

 J.N.Bahcall, M.Pinsonneault, S.Basu, astro-ph/ , Ap. J. 555 (2001) 990 A.M. Serenelli, W.C. Haxton, C. Pena-Garay, arXiv:  S.Turck-Chièze et al., Ap. J. Lett. 555 (2001) L69 S. Turck-Chièze and S. Couvidat, Rep. Prog. Phys. 74 (2011) SSM and Seismic model SNO Predictions of the solar models Z/X Best determination of the Sun metallicity, but disagreement with héliosismology 40 years of solar modeling Flux (cm -2 s -1 ) GS98 (High met.) AGS09 (Low met.) Seismic (AGS09) Error (~) pp (10 10 ) % pep (10 8 ) % 7 Be (10 9 ) % 8 B (10 6 ) % 13 N (10 8 ) % 15 O (10 8 ) % Radioch. (SNU) Chlorine % Gallium %

1.Solar neutrinos, witnesses of the core of the Sun 2.Archaeology ( ) : the solar neutrino problem 3.Towards solar neutrino spectroscopy 4.Solar neutrinos and particle physics 5.Is there any future ? Solar neutrinos : Recent results

1970 : the detector Homestake mine (South Dakota) 600 tons of C 2 Cl 4 e + 37 Cl  37 Ar + e - 37 Cl (T 1/2 =35 d) The « pionneering » chlorine experiment  Radiochemical  Sensitive to 7 Be and 8 B B.T.Cleveland et al., Ap. J. 496 (1998) 505 Result : 2.56 ± 0.20 SNU 1/3 of solar models ( SNU)

30.3 tons of gallium in aqueous solution (GaCl 3 + HCl) GALLEX / GNO : radiochemical detection of primordial solar e + 71 Ga  71 Ge + e - threshold = 233 keV sensitive to all W.Hampel et al., Phys. Lett. B447 (1999) 127 M.Altmann et al., Phys. Lett. B616 (2005) 174 F.Kaether et al., Phys. Lett. B685 (2010) 47 GALLEX : 77.5 ± 7.8 SNU (73.4 ± 7.2 SNU) GNO : 62.9 ± 6.0 SNU GALLEX/GNO : 69.3 ± 5.5 SNU (67.6 ± 5.1 SNU) Solar models : SNU ~60% of solar models SAGE Baksan (Russie) 50 tons Ga metal Similar results

electron  tons of water PMTs e + e -  e + e - SuperKamiokande cos  E > 5 MeV sensitive to 8 B S. Fukuda et al. : hep-ex/ Flux measured for 8 B : (2.32 ± 0.03 (stat.) ± 0.08 (syst.)) 10 6 cm -2 s -1 45% of solar models (5 ±1) 10 6 cm -2 s -1

Solar neutrinos: results and predictions chlore chlorine SuperK gallium Spring 2001

(CC) (NC) (elastic sc.)  1000 tons D 2 O (target)  7000 tons H 2 0 (shield)  ’’ PM for Cerenkov light  Canada-USA-GB Collaboration Sudbury Neutrino Observatory (SNO) n detection E > 4-5 MeV sensitive to 8 B cos  June 2001

CC : 1.76 ± 0.11 ES : 2.39 ± 0.27 ES(SK) : 2.32 ± 0.08 No oscillation : Total flux = ES = CC = NC Oscillation Total flux = CC + (ES-CC)*6 = NC NC : 5.09 ± 0.63 e pp d e W ee e e, W,Z n (p) d Z Summary of SNO results (2006) [units : 10 6 cm -2 s -1 ] Sun : 5 ± 1 NC : 4.94 ± 0.43 CC : 1.68 ± 0.10 ES : 2.35 ± 0.27 Salt phase arXiv:

Experimental results after SNO

The problem is solved  Nuclear reactions in the Sun produce only e  Until SNO, solar neutrino detectors were sensitive only (mainly) to e SNO has shown that : a)solar  e have been (partially) transformed into  or  and the oscillation mechanism explains the observed deficit b) the SSM is (at first order) right !

1.Solar neutrinos, witnesses of the core of the Sun 2.Archaeology ( ) : the solar neutrino problem 3.Towards solar neutrino spectroscopy 4.Solar neutrinos and particle physics 5.Is there any future ? Solar neutrinos : Recent results

2. SuperK, new results on 8 B 1.Borexino : 7 Be, pep, CNO, 8 B 3. SNO, final results on 8 B

Elastic diffusion  e   e Target n° 1 : 7 Be neutrinos Proposal : 60 events / day (no oscillation) (oscillation) Gran Sasso (Italy) Borexino (2007-…) Bq/kg 1 verre d’eau : 10 Bq Objectif : Gagner 10 ordres de grandeur Bq/kg 1 glass of water: 10 Bq Purpose: Improve by 10 orders of mag. 50 times more light than Cherenkov  No directionality M No discrimination e - Sun and e - radioactivity Scintillator

 Borexino is underground the Gran Sasso mountain (3800 m.w.e.) Target: 300 tons of liquid scintillator in a nylon vessel (4,25 m radius) 1 er shielding: 900 tons of liquid scintillator 2200 photomultipliers looking at the center 2 nd shielding: 2100 tons of water 208 PMTs to sign muons (veto) 2 nd nylon vessel (against radon)

visible energy (MeV) events / (day x 100 tons) Expected signal in Borexino (SSM+ oscillation [LMA] ) pp Be B CNO total 14 C pep pep window Be window e  e

K T=1, yr 89%  11% c.e. E max = 1,311 MeV 85 Kr T=10,7 yr ~100%  E max = 0,687 MeV E (MeV) 14 C T 1/2 =5730 yr 100%  E max = 156 keV 210 Po T 1/2 =138 d 100%  E a = 5,3 MeV Quenching f. in PC: 13.4 E vis = 395 keV Many radioactive enemies ! The expected signal is here 11 C Cosmogenic (  ) T=20 min 100%  E max = 0.96 MeV 1.02<E vis <1.98 MeV Fortunately, Borexino could achieve exceptional low radiopurity of the scintillator and of all the components of the detector

Towards 7 Be solar  All data: 740 live days Expected 7 Be signal

Remove  +  followers (2 ms) All data: 740 live days Towards 7 Be solar 

Expected 7 Be signal Fiducial Volume Fiducial mass = 75.6 tonnes R < 3.02m |z| < 1.67m Remove  +  followers (2 ms) 210 Po  All data: 740 live days Towards 7 Be solar 

Expected 7 Be signal Statistically subtract  ’s  discrimination by pulse shape analysis using the Gatti parameter] Remove  +  followers (2 ms) All data: 740 live days Fiducial Volume Towards 7 Be solar 

2 types of fit : 1)No subtraction of  from 210 Po – Energy from number of photons 2)Subtraction of  (pulse shape method by Gatti) - Energy from total charge Events / day / 100 tons : 7 Be: 46.0 ± 1.5 ± Kr: 31.2 ± 1.7 ± Bi: 41 ± 1.5 ± C : 28.5 ± 0.2 ± 0.7 Towards 7 Be solar 

46.0 ± 1.5 (stat) ± 1.5 (syst) ev./day /100 tons for 7 Be (862 keV)   arXiv: Phys. Rev. Lett. 107, (2011) Systematic errors  ( 7 Be-862 keV) = (2.78 ± 0.13) 10 9 cm -2 s -1 SSM-High Met = (4.48 ± 0.31) 10 9 cm -2 s -1 Ratio = 0.62 ± 0.05 P ee = 0.51 ± 0.07 [  ( e )=4.5  (    )] Towards 7 Be solar 

Towards pep and CNO  85 Kr 7 Be v 210 Po 210 Bi 11 C : dominant background Cosmogenic, t 1/2 = 29 min Borexino muon rate = 4200/day Can’t veto after every muon! pep v CNO v External Backgrounds

Cosmic μ The 125 muon-neutron coincidences/day can be vetoed without excessive loss of live time. 11 C + n Most 11 C (t 1/2 =29 min) produced via  + 12 C 11 C + n  11 C 11 Be + e + + e n capture (255  s) Most 11 C (t 1/2 =29 min) produced via  + 12 C 11 C + n  11 C 11 Be + e + + e Delayed neutron capture (2.2 MeV  signal) identifies when and where 11 C was produced  geometrical cut Towards pep and CNO 

Remove 91% of 11 C with a livetime sacrifice of 51.5%. I. Three-fold coincidence : space and time veto after coinc. between  and cosmogenic n Towards pep and CNO 

II. Pulse shape discrimination between e + and e - (50% of e + give orthopositronium (t 1/2 =3 ns)) Towards pep and CNO 

III. Multidimensional fit with all the ingredients + * arXiv: Phys. Rev. Lett. 108 (2012) pep flux 3.1 ± 0.6 ± 0.3 counts/(day.100 ton)  (pep) = 1.6 ± cm -2 s -1  (SSM) = 1.45 ± cm -2 s -1 CNO flux < 7.9 counts/(day.100 ton)  (CNO) < cm -2 s -1  (SSM) = 5.2 (3.7) 10 8 cm -2 s -1 Towards pep and CNO 

Towards 8 B  Expected rate (0-14 MeV) : 0.49±0.05 c/d/100 tonnes > 5 MeV (like SK and SNO): 0.14±0.01 c/d/100 tons Contamination from 2.6 MeV  ( 208 Tl)  E>2.8 MeV: 0.26±0.03 c/d/100 tons  SSM = 5.58 ± cm -2 s -1 (High Metallicity 2011) Counting rate: 30 c/d/100 ton Spectrum ( MeV) Borexino 246 d Ratio S/B < 1/100!!!

 Muon energy spectrum  All  are cut (residual rate: <10 -3 c/d)  Neutron cut: 2 ms veto after each , to reject induced n (mean capture time ~250  s) (residual n rate: ~10 -4 c/d)  Fiducial volume (to eliminate surface contamination by 220 Rn and 222 Rn)  Cosmogenic cuts (to eliminate short-live radioactive induced like 12 B, 8 Li, 9 Li, 8 He, 6 He,…)  Some more cuts… 10 C, 214 Bi, 208 Tl. Towards 8 B 

> 5 MeV > 7 MeV > 5 MeV > 5.5 MeV > 6 MeV > 7 MeV> 2.8 MeV *Threshold is defined at 100% trigger efficiency Systematic errors: 3.8% (fiducial mass) 3.5% (energy threshold) d 75±13 events above 3 MeV (46±8 events above 5 MeV)  ( 8 B) = 0.22 ± 0.04 ± 0.01 cpd/100 t (  ( 8 B) = 0.13 ± 0.02 ± 0.01 cpd/100 t)  ( 8 B) = 2.4 ± 0.4 ± cm -2 s -1 (  ( 8 B) = 2.7 ± 0.4 ± cm -2 s -1 )  (SSM) High Met = 5.58 ± cm -2 s -1 arXiv: Phys. Rev. D82 (2010) Towards 8 B 

SuperKamiokande : what’s new ? K. Takeuchi : Physun 2012 I.

SuperKamiokande : what’s new ? K. Takeuchi : Physun 2012 II.

Y. Takeuchi, Physun 2012 SuperKamiokande : what’s new ? III. 8 B Energy spectrum (all)

SNO : what’s new ? I- Low Energy Threshold Phys. Rev. C81 (2010) I- LETA (Low Energy Threshold Analysis) : T eff > 3.5 MeV Low energy spectrum still consistent with no distortion

SNO : what’s new ? II- 3 phase analysis Total uncertainty : 3.6% N. Fiuza de Barros, NOW 2012 Combine data taking phases into a single analysis (to avoid double counting of common systematics)

SNO : what’s new ? III- hep neutrinos N. Fiuza de Barros, NOW 2012 hep solar neutrinos 1000 times less than 8B !  hep) SSM = (8.0 ± 1.2) 10 3 cm -2 s days of SNO data  hep) < cm -2 s -1 [preliminary]  hep) SK < cm -2 s -1 ]

pp 8B8B 7 Be pep Neutrino energy (MeV) Flux Spectres continus : cm -2 s -1 MeV -1 Raies monoénergétiques : cm -2 s ,1 Towards spectroscopy of solar neutrinos hep 13 N 15 O Borexino limit SNO limit Borexino BX, SK, SNO lowering the threshold

1.Solar neutrinos, witnesses of the core of the Sun 2.Archaeology ( ) : the solar neutrino problem 3.Towards solar neutrino spectroscopy 4.Solar neutrinos and particle physics 5.Is there any future ? Solar neutrinos : Recent results

Solar neutrinos and oscillation parameters (spring 2001) Bahcall, Krastev, Smirnov, hep-ph/ SMA LMA LOW  m 2 (eV 2 ) tan 2  VAC  m 2 12  12 SMA LMA LOW  m 2 (eV 2 ) tan 2  VAC Thanks to MSW effect

Solar neutrinos and oscillation parameters (June 2001) Bahcall, Krastev, Smirnov, hep-ph/ SMA LMA LOW  m 2 (eV 2 ) tan 2  VAC  m 2 12  12 SMA LMA LOW  m 2 (eV 2 ) tan 2  VAC

Solar neutrinos and oscillation parameters (precision) sin 2 (2  12 ) = 0.87  m 2 = eV 2 Phys. Rev. Lett. 100 (2008) Sun KamLAND (2008)

A. Palazzo, Physun 2012 Solar neutrinos and oscillation parameters (precision)

E (MeV) P( e e ) sin 2 (2  12 ) = 0.87  m 2 = eV 2 pp - all solar 7 Be - Borexino pep – Borexino 8 B – SNO (LETA) + Borexino 8 B – SNO + SK vacuum effect sin 2 2  MSW effect sin 2  12 =0.314 MSW effect : the Sun and LMA Needs more precision in the transition region

Possible regeneration of solar v e if they cross the Earth before interacting (Cribier et al., 1986). Solar before Borexino ModelPredicted A nd (862 keV) LMA<0.001 LOW MaVaN~0.20 Day-night asymmetry of 7 Be e P( e  e ) 0 1 sin 2  E/  m2

Solar WITH Borexino LOW solution excluded at >99.73% C.L. arXiv: Phys. Lett. B707 (2012) 22 Low solution Day-night asymmetry of 7 Be e A dn (862 keV): ± stat ±0.007 sys

Y. Takeuchi, Physun 2012 D/N in SuperKamiokande

1.Solar neutrinos, witnesses of the core of the Sun 2.Archaeology ( ) : the solar neutrino problem 3.Towards solar neutrino spectroscopy 4.Solar neutrinos and particle physics 5.Is there any future ? Solar neutrinos : Recent results ?

Future for solar in Borexino  measure CNO  (if suppression of 210 Bi) ?  measure pp  ? Many astrophysical implications : - First probe of energy produced in high mass stars - Help to solve the metallicity problem - Check homogeneous young Sun (e.g. accretion during formation of planetary system),…

A. Mc Donald, Neutrino 2012 Future Solar experiments (beyond Borexino)

Liquid scintillator in the old SNO sphere G. Orebi Gann, Physun 2012

L. Oberauer, Physun 2012 M. Wurm et al. / Astrop. Phys. 35 (2012) 685  Very high statistics in 7 Be (allows to search for small flux fluctuations)  CNO and pep possible,if 210 Bi background < 10 to 100 (Borexino)  8 B spectrum from 3 MeV (elastic scattering)  8 B spectrum via 13 C charged current reaction from 4 MeV ( ∼ 425 counts/year) LENA (Low Energy Neutrino Astronomy) > 2020 ?

 Important progresses in solar neutrino spectroscopy, thanks to Borexino : 7 Be, pep, limit on CNO, low threshold for 8 B.  SuperKamiokande and SNO provide updated results on 8 B.  The experiments fix fluxes for solar models  The oscillation solution MSW-LMA has become more precise, thanks to flux, spectrum and day- night effect (and KamLAND).  Future : CNO ? pp ? Conclusion

Solar neutrinos are at the forefront of particle physics and astrophysics Solar neutrinos   are at the forefront of particle physics and astrophysics (Lugdunum, -52 BC)     

1-D binned likelihood fits in energy 7 Be, 210 Po, 85 Kr, 11 C, 210 Bi weights floated pp, pep, 8 B, and CNO fixed to SSM fluxes + LMA 222 Rn, 218 Po, and 214 Pb weights constrained by 214 Bi- 214 Po co-incidence Towards 7 Be solar 

Particles with higher ionization density produce more slow light  /  pulse shape discrimination Separate α / β using the “Gatti Parameter” Fit each energy bin with the sum of two Gaussians

Towards 8 B 

Données solaires + KamLAND 2005 : précision sur  m 2 12 Solar neutrinos and oscillation parameters (precision) M. Maltoni, Physun 2012

Survival probabilities with MSW effect How the solar neutrino spectrum is modified by the MSW effect ?