Results from SNO and Other Solar Neutrino Experiments

Home , GALLEX

R.G. Hamish Robertson University of Washington for The Sudbury Neutrino Observatory Collaboration

1 Solar Neutrino Program

1998 1999 2000 2001 2002 2003 2004 2005 2006

Comm.

D2O Salt SNO D2O

3 PRL 87, 071301, 2001 He Counters PRL 89, 011301, 2002Current PRL 89, 011302, 2002analysis

Cl-Ar Borexino

SAGE, Gallex, GNO

KamLAND & KamLAND Solar Borexino 100-tonne Liquid Scintillator at LNGS

3 SSAAGGEE (January 1990 – March 2003) L-peak: 65.8 +6.6/-6.3 SNU With Weight Factors K-peak:71.5 +5.8/-5.6 SNU Overall: 69.1 +4.3/-4.2 SNU

4 GALLEX - GNO Davis plot

GALLEX GNO 65 solar runs 58 solar runs

5 GNOGNO –– ResResultultss completed 58 solar runs 1713 days still counting 5 solar runs (30 days) blanks 12

GNO (31/08/2003) 62.9 ± 5.4 ± 2.5 SNU (L 68. ± 9. K 60. ± 7.)

+4.3 GALLEX 77.5 ± 6.2 -4.7 SNU GALLEX+GNO 69.3 ± 4.1 ± 3.6 SNU

+4.3 SAGE 69.1 -4.2 SNU Further minor improvements expected in a short time ( analysis of counter calibration data…)

6 New Low-energy Solar n Detectors

MOON CLEAN

Hellaz

LENS

7 Recent Super-K Analysis

Full zenith-angle dependence 1496-day dataset hep-ex/0309011 (Michael Smy, TAUP)

8 Sudbury Neutrino Observatory

1000 tonnes D2O

Support Structure for 9500 PMTs, 60% coverage 12 m Diameter Acrylic Vessel 1700 tonnes Inner

Shielding H2O 5300 tonnes Outer

Shield H2O Urylon Liner and Radon Seal

9 n Reactions in SNO

- CC n e + d ﬁ p+ p+ e

-Gives ne energy spectrum well -Weak direction sensitivity µ 1-1/3cos(q)

- ne only.

NC n x + d ﬁ p+ n +n x -Measure total 8B n flux from the sun. - Equal cross section for all n types

ES - - nx + e ﬁ nx + e -Low Statistics

-Mainly sensitive to ne,, some -sensitivity to nm and nt -Strong direction sensitivity

10 Neutrino Flavor Composition of 8B Flux

Fluxes (106 cm-2 s-1) ne: 1.76(11) nmt: 3.41(66) ntotal: 5.09(64) nSSM: 5.05

11 Total spectrum (NC + CC + ES)

12 2 2 tan q12-Dm12

Ê CC ˆ f +0.06 Á NC ˜ = 0.38-0.03 (99% CL) Ë f ¯S NO

†

Ê CC ˆ f +0.11 Á NC ˜ = 0.33-0.06 (99% CL) Ë f ¯S NO Solar Only Solar+KL rate Solar+KL spect. †

de Holanda & Smirnov, hep-ph/0205241, hep-ph/0212270

13 Advantages of NaCl for Neutron Detection

• Higher capture cross section n g • Higher energy release 36Cl* • Many gammas 35Cl 36Cl

s = 44 b 35Cl+n s = 0.0005 b 8.6 MeV 2H+n 6.0 MeV

3H 36Cl

14 Neutron Capture Efficiency in SNO

35Cl(n,g)36Cl Average Eff. = 0.399

Te ≥ 5.5 MeV and Rg ≤ 550 cm

2H(n,g)3H Average Eff. = 0.144

Te ≥ 5.0 MeV and Rg ≤ 550 cm Radial Position of 252Cf Source, cm

15 Cherenkov light and b14

Charged particle, Hollow cone of v > c/n emitted photons qij ) 43o Energy & Direction

b14 = b1 + 4b4

16 - Use of b14 to distinguish neutrons and e

17 Addition of Mott scattering to EGS4

Angular Distribution of 5 MeV electrons after passing through ~1 mm of water

18 Blind Analysis

Three blindfolds for the analysts:

• Include unknown fraction of neutrons that follow muons

• Spoil the NC cross section in MC

• Veto an unknown fraction of candidate events

19 b14 Distributions for SNO Salt Data

Data from July 26, 2001 to Oct. 10, 2002

254.2 live days

3055 candidate events:

+63.8 1339.6 -61.5 CC

+69.8 1344.2 -69.0 NC

+23.9 170.3 -20.1 ES

20 Sun-angle distributions

Toward sun Away from sun

21 Energy spectra

Electron kinetic energy

22 Sources of Background

• 2H(g,n)p by 214Bi, 208Tl • Cosmic rays: neutrons, spallation products • Atmospheric neutrinos, reactors, CNO • Fission • (a,n) reactions • 24Na activation (neck, calibration, recirc, muons) • AV events

23 Radioassay

• Bottom of vessel • 2/3 way up • Top of vessel

• MnOx • HTiO

• MnOx • HTiO Backgrounds Radial distributions

0 550 600 700 cm

(Reconstructed radius, cm/ 600)3

26 Uncertainties in Fluxes (%) 0 1 2 3 4 5 6 7 8 9 10

Energy scale Resolution Radial accuracy CC uncert. Angular res. Isotropy mean Isotropy width NC uncert. Radial E bias Internal neutrons ES uncert. Cher. bkds “AV” events Neutron capture Total CC, ES, and NC fluxes from Pure D2O Phase

Shape of 8B spectrum in CC and ES not constrained:

Standard (Ortiz et al.) shape of 8B spectrum in CC and ES:

28 Salt Phase: “Box” Opened Aug. 13, 2003

Shape of 8B spectrum in CC and ES not constrained:

Standard (Ortiz et al.) shape of 8B spectrum in CC and ES:

29 Total Active 8B Fluxes

In units of Bahcall, Pinsonneault, Basu SSM, 5.05 x 106 cm-2 s-1

+0.20 BPB01 SSM 1.00 -0.16

Junghans et al. 1.16 ± 0.16 nucl-ex/0308003 SNO D20 1.01 ± 0.13 (constrained) SNO Salt 1.03 ± 0.09 (unconstrained)

30 2-n oscillation region defined by SNO

31 2 2 tan q12-Dm12 before Salt Phase

Ê CC ˆ f +0.06 Á NC ˜ = 0.38-0.03 (99% CL) Ë f ¯S NO

†

Ê CC ˆ f +0.11 Á NC ˜ = 0.33-0.06 (99% CL) Ë f ¯S NO Solar Only Solar+KL rate Solar+KL spect. †

de Holanda & Smirnov, hep-ph/0205241, hep-ph/0212270

32 From the Salt Phase…

Ratio:

33 Closing in on Dm2, q

--90% --95% --99% --99.73%

LMA I only at > 99% CL

34 One-dimensional marginalized limits on Dm2 and q

Maximal mixing rejected at 5.4 s

LMA 1 Results from SNO -- Salt Phase

Oscillation Parameters, 2-D joint 1-s boundary < 1% probability of LMA II

Marginalized 1-D 1-s errors

Maximal mixing rejected at 5.4 s

A paper plus a “companion” guide can be found at sno.phy.queensu.ca this morning. Submitted to PRL; nucl-ex/0309004.

36 Summary

• Salt phase of SNO now complete. 254 days analyzed, another

150 to go.

• Model-independent determination of total active flux of 8B solar n.

• fx = 5.21± 0.27 (stat) ± 0.38 (syst).

6 -2 -1 • fB = 1.03 ± 0.09 (relative to 5.05 x 10 cm s , BPB01).

• Uncertainties now smaller than theoretical.

• LMA I selected. LMA II remains only at 99.73% Confidence Level.

• Maximal mixing ruled out at 5.4 s.

37 SNO gratefully acknowledges…

Canada: Natural Sciences and Engineering Research Council Northern Ontario Heritage Fund Corporation Inco Atomic Energy of Canada, Ltd. Ontario Power Generation High Performance Computing Virtual Laboratory National Research Council Canada Foundation for Innovation

US: Department of Energy

UK: Particle Physics and Astronomy Research Council

38 The SNO Collaboration S.D. Biller, M.G. Bowler, B.T. Cleveland, G. Doucas, J.A. Dunmore, H. Fergani, K. Frame, N.A. Jelley, S. Majerus, G. McGregor, S.J.M. Peeters, C.J. Sims, M. Thorman, H. Wan Chan Tseung, N. West, J.R. Wilson, K. Zuber T. Kutter, C.W. Nally, S.M. Oser, C.E. Waltham Oxford University University of British Columbia E.W. Beier, M. Dunford, W.J. Heintzelman, C.C.M. Kyba, J. Boger, R.L. Hahn, R. Lange, M. Yeh N. McCauley, V.L. Rusu, R. Van Berg Brookhaven National Laboratory University of Pennsylvania

A.Bellerive, X. Dai, F. Dalnoki-Veress, R.S. Dosanjh, D.R. Grant, S.N. Ahmed, M. Chen, F.A. Duncan, E.D. Earle, B.G. Fulsom, C.K. Hargrove, R.J. Hemingway, I. Levine, C. Mifflin, E. Rollin, H.C. Evans, G.T. Ewan, K. Graham, A.L. Hallin, W.B. Handler, O. Simard, D. Sinclair, N. Starinsky, G. Tesic, D. Waller P.J. Harvey, M.S. Kos, A.V. Krumins, J.R. Leslie, Carleton University R. MacLellan, H.B. Mak, J. Maneira, A.B. McDonald, B.A. Moffat, A.J. Noble, C.V. Ouellet, B.C. Robertson, P. Jagam, H. Labranche, J. Law, I.T. Lawson, B.G. Nickel, P. Skensved, M. Thomas, Y.Takeuchi R.W. Ollerhead, J.J. Simpson Queen’s University University of Guelph D.L. Wark J. Farine, F. Fleurot, E.D. Hallman, S. Luoma, Rutherford Laboratory and University of Sussex M.H. Schwendener, R. Tafirout, C.J. Virtue Laurentian University R.L. Helmer TRIUMF Y.D. Chan, X. Chen, K.M. Heeger, K.T. Lesko, A.D. Marino, E.B. Norman, C.E. Okada, A.W.P. Poon, A.E. Anthony, J.C. Hall, J.R. Klein S.S.E. Rosendahl, R.G. Stokstad University of Texas at Austin Lawrence Berkeley National Laboratory T.V. Bullard, G.A. Cox, P.J. Doe, C.A. Duba, J.A. Formaggio, M.G. Boulay, T.J. Bowles, S.J. Brice, M.R. Dragowsky, N. Gagnon, R. Hazama, M.A. Howe, S. McGee, S.R. Elliott, M.M. Fowler, A.S. Hamer, J. Heise, A. Hime, K.K.S. Miknaitis, N.S. Oblath, J.L. Orrell, R.G.H. Robertson, G.G. Miller, R.G. Van de Water, J.B. Wilhelmy, J.M. Wouters M.W.E. Smith, L.C. Stonehill, B.L. Wall, J.F. Wilkerson Los Alamos National Laboratory University of Washington 40 SNO Phase III (NCD Phase)- Begins ‘04

ÿ 3He Proportional Counters (“NC Detectors”)

40 Strings on 1-m grid 440 m total active length

Detection Principle nx

2 PMT H + nx Æ p + n + nx - 2.22 MeV (NC)

3He + n Æ p + 3H + 0.76 MeV

Physics Motivation Event-by-event separation. Measure NC NCD n and CC in separate data streams. Different systematic uncertainties than neutron capture on NaCl. NCD array removes neutrons from CC, calibrates remainder. CC spectral shape.

41 Why Event-by-Event?

Phase III Phase I Projected Source DCC/CC (%) DNC/NC (%) DNC/NC (%) Energy Scale ¶ -4.2, +4.3 -6.2, +6.1 0.0 Energy Resolution ¶ -0.9, +0.0 -0.0, +4.4 0.0 Energy Non-linearity ¶ ±0.1 ±0.4 0.0 Vertex Resolution ¶ ±0.0 ±0.1 0.0 Vertex Accuracy -2.8, +2.9 ±1.8 0.0 Angular Resolution -0.2, +0.2 -0.3, +0.3 0.0 Internal Source p-d ¶ ±0.0 -1.5, +1.6 3.0 External Source p-d ¶ ±0.1 -1.0, +1.0 1.0 D2O Cherenkov ¶ -0.1, +0.2 -2.6, +1.2 0.0 H2O Cherenkov ±0.0 -0.2, +0.4 0.0 AV Cherenkov ±0.0 -0.2, +0.2 0.0 PMT Cherenkov ¶ ±0.1 -2.1, +1.6 0.0 Neutron Capture ±0.0 -4.0, +3.6 3.0 S Systematic -5.2, +5.2 -8.5, +9.1 4.5 S Statistical -2.8, +3.4 -8.5, +8.6 4 S Uncertainties 7 12 6 ¶ CC NC anti-correlation

42 second per Counts

Time after muon, s N. Oblath 43 16 N in D2O s per Counts

A.D. Marino

44 (a,n) Reactions

45 BOREXINO: radiopurity requirements

Typical Borexino level Conc.

14C 14C/ 12C<10-12 14C/ 12C~10-18

238U, 232Th ~ 1ppm in dust ~10-16g/g(PC) ~ 1ppb stainless steel ~ 1ppt IV nylon

-13 Knat ~ 1ppm in dust <10 g/g(PC)

222Rn ~ 10Bq / m3 in air ~ 70 mBq / m3 in PC (0.3ev/day/100tons) 85Kr, (39Ar) 1.1Bq/m3 0.16mBq/m3 (0.5 m 3 (13mBq/m3 ) in air Bq/m ) in N2 0.01 events/day/ton If secular equilibrium is broken: contaminants such as 210Pb, 210Po may be a serious problem 46 GALLEGALLEXX ++GNOGNO SeasonalSeasonal variationsvariations

Winter-Summer (statistical error only): GNO only (58 SRs):

+7.1 Winter (32 SR): 58.7 -6.8 SNU

+8.8 Summer (26 SR): 69.0 -8.3 SNU W-S: -10 ± 11 SNU GNO + Gallex (123 SRs):

+5.6 Winter (66 SR): 66.5 -5.4 SNU

+6.4 Summer (57 SR): 74.1 -6.2 SNU W-S: -7.6 ± 9 SNU

47 48 49 SNO & KamLAND

3s Day – Night Contours (%) 1s

CC/NC Contours

de Holanda, Smirnov hep-ph/ 0212270 Neutron Capture Efficiency in SNO

35Cl(n,g)36Cl Average Eff. = 0.399

Te ≥ 5.5 MeV and Rg ≤ 550 cm

2H(n,g)3H Average Eff. = 0.144

Te ≥ 5.0 MeV and Rg ≤ 550 cm Radial Position of 252Cf Source, cm

51 Uncertainty Budget