SAGE:SAGE:status and status and

futurefuture

SAGE:SAGE:status and status and

futurefutureV.N. GavrinV.N. GavrinInstitute for Nuclear Research Institute for Nuclear Research

of the Russian Academy of Sciencesof the Russian Academy of Sciences, , MoscowMoscow

OutlineOutline• Introduction and a little historyIntroduction and a little history• SAGESAGE• Source experimentsSource experiments• Comparison of Ga result to prediction SSMComparison of Ga result to prediction SSM• Is the neutrino capture rate in Ga constant?Is the neutrino capture rate in Ga constant?• FutureFuture

OutlineOutline• Introduction and a little historyIntroduction and a little history• SAGESAGE• Source experimentsSource experiments• Comparison of Ga result to prediction SSMComparison of Ga result to prediction SSM• Is the neutrino capture rate in Ga constant?Is the neutrino capture rate in Ga constant?• FutureFuture

37Cl + νe 37Ar + e- Cl-Ar (0,81 MeV) 0,30 ± 0,03

νe, CC, NC SNO (5 MeV) 0,90 ± 0,08

νe Kamiokande II (7,5 MeV) 0,48 ± 0,08

71Ga + νe 71Ge + e- Ga-Ge (0,23 MeV) 0,52 ± 0,03

νe SuperK (5 MeV) 0,406 ± 0,04

SAGESAGEBaksan Neutrino Observatory, northern Caucasus, 3.5 km from entrance of horizontal adit,

2100 m depth (4700 m.w.e.) Data taking: Jan 1990 - till present, 50 tons of metallic Ga.Atoms of 71Ge chemical are extracted and its decay is counted.Sensitivity: One 71Ge atom from 5·1029 atoms Gawith efficiency ~90%

B - Gallium-Germanium Neutrino Telescope

T1/2 = 11,43 d

7171Ga + Ga + ννee 7171Ge + eGe + e--

SAGESAGEMeasurement of the solar neutrino capture rate with gallium metal.Measurement of the solar neutrino capture rate with gallium metal.

7171Ga(Ga(vv, e, e--))7171Ge, EGe, Eth th = 0.233 keV= 0.233 keV

It is one of the longest almost uninterrupted time of measurements among solar neutrino experiments

17 year period (1990 – 2006): 157 runs, 288 separate counting sets

Results: 66.266.2+3.3-3.2

+3.5-3.2 SNU or 66.266.2+4.8+4.8

-4.5-4.5 SNU

Presently Presently SAGESAGE is the only experiment sensitive to the is the only experiment sensitive to the pppp neutrinosneutrinos

Combined results for each yearCombined results for each year

SAGE continues to perform regular solar neutrino extractions every four weeks with ~50 t of GaSAGE continues to perform regular solar neutrino extractions every four weeks with ~50 t of Ga

All extractions as function of timeAll extractions as function of time

6464 +24/-22 SNU

GALLEX (05.91-01.97, 65 runs)→ 77.5 ±77.5 ± 7.7 7.7 SNUSNU GNO (05.98 – 09.03, 58 runs) → 62.9 ± 5.9 SNU62.9 ± 5.9 SNUGALLEX + GNO (123 runs) → 69.3 ± 5.5 SNU69.3 ± 5.5 SNU

SAGE + GALLEX + GNO → 67.6 ± 3.7 SNU67.6 ± 3.7 SNU

SAGE (45 runs) → 79.4 ±79.4 ± 9.4 SNU9.4 SNUSAGE (49 runs) → 65.0 ±65.0 ± 6.06.0SAGE (01.90 – 12.06, 157 runs) → 66.2 ±66.2 ± 4.6 4.6 SNUSNU

Source experimentsSource experiments

5151CrCr5151CrCrGallium chloride solution Gallium chloride solution Gallium metal Gallium metal (SAGE)(SAGE)

(GALLEX)(GALLEX)(1) (2) 

mGa (tons) 30.4 30.4 13.1 13.1 mof target (kg) 35,5 35,5 0,513 330 enrichment (% 50Cr) 38,6 38,6 92,4 96,94% 40Ca (natural Ca) source specific activity (KCi/g) 0,048 0,052 1,01 92,7 source activity (MCi) 1,71 1,87 0,52 0,41 expected rate 11,7 12,7 14,0 13,9

R = pmeasured/ppredicted 1.0±0.11 0.81±0.10 0.95±0.12 0.79±0.1

3737ArAr3737ArAr

RRcombined combined 0.90±0.07 0.86±0.08 0.90±0.07 0.86±0.08

Weighted Weighted averageaverage

0.88±0.05

320 keV

51V

51Cr (27.7 days)

747 keV (81.6%)

752 keV(8.5%)

427 keV (9.0%)

432 keV(0.9%)

37Ar (35.4 days)

37Cl (stable)

813 keV (9.8%)

811 keV(90.2%)

GALLEX Cr-1 GALLEX Cr-1 1.001.00+0.11+0.11

-0.10-0.10

GALLEX Cr-2GALLEX Cr-20.81 ± 0.100.81 ± 0.10

SAGE CrSAGE Cr0.95 ± 0.120.95 ± 0.12

SAGE ArSAGE Ar0.790.79+0.09+0.09

-0.10-0.10

W. Haxton, 1988

V. Kuzmin, 1965

The source experiments with GaThe source experiments with Ga * The weighted average value of RR is 0.88 ± 0.88 ± 00.05.05, more than two SD less than unity. * If the contribution of these two excited states to the predicted rate is set to zero, then R = 0.93 ± 0.05R = 0.93 ± 0.05, reasonably consistent with unity. * We believe that, although not statistically conclusive, the combination of these experiments suggests that the predicted rates is overestimated. The most likely hypothesis is that the cross sections for neutrino capture to the lowest two states in 71Ge, both of which can be reached using either 51Cr or 37Ar sources, have overestimated. * A new experiment with a considerably higher rate from the neutrino source is planned now to settle this question.

5151CrCr5151CrCrGallium chloride solution Gallium chloride solution Gallium metal Gallium metal (SAGE)(SAGE)

(GALLEX)(GALLEX)(1) (2) 

mGa (tons) 30.4 30.4 13.1 13.1 mof target (kg) 35,5 35,5 0,513 330 enrichment (% 50Cr) 38,6 38,6 92,4 96,94% 40Ca (natural Ca) source specific activity (KCi/g) 0,048 0,052 1,01 92,7 source activity (MCi) 1,71 1,87 0,52 0,41 expected rate 11,7 12,7 14,0 13,9

R = pmeasured/ppredicted 1.0±0.11 0.90±0.09 0.95±0.12 0.79±0.1

3737ArAr3737ArAr

RRcombined combined 0.94±0.07 0.86±0.08 0.94±0.07 0.86±0.08

320 keV

51V

51Cr (27.7 days)

747 keV (81.6%)

752 keV(8.5%)

427 keV (9.0%)

432 keV(0.9%)

37Ar (35.4 days)

37Cl (stable)

813 keV (9.8%)

811 keV(90.2%)

R = pmeasured/ppredicted 1.0±0.11 0.90±0.09 0.95±0.12 0.79±0.1

Weighted Weighted averageaverage

0.90±0.05IncludingIncluding contributions from the contributions from the first two excited states first two excited states

WWithout contributions from the ithout contributions from the first two excited states first two excited states

0.95±0.05

RRcombined combined 0.94±0.07 0.86±0.08 0.94±0.07 0.86±0.08

320 keV

51V

51Cr (27.7 days)

747 keV (81.6%)

752 keV(8.5%)

427 keV (9.0%)

432 keV(0.9%)

37Ar (35.4 days)

37Cl (stable)

813 keV (9.8%)

811 keV(90.2%)

GALLEX GALLEX 7171As experimentAs experiment!!

4 5

3 2

D8

D10 D4

D6

D7

D9

D2

D5

10 11

7 8

9 12

13

D1 D3

8

19 20

17

16

21

14 15

18

SR1SR2

SR3 SR4

ASR

ASR

30 Irradiation Cells

28 Fuel Assemblies

Special Fuel Assembly

4 Shim Rods with Additional Fuel Assembly

Central Neutron Trap

2 Automatic Shim Rods

Beryllium Reflector

Reactor SM Reactor SM Cross-sectionCross-section

Thermal neutron flux – 1.66 x 1015 сm-2 sec-1

Thermal neutron flux – (1.08-3.44) x 1014 сm-2 sec-1

Research Institute of Atomic ReactorsResearch Institute of Atomic Reactors

0

500

1000

1500

2000

2500

3000

3500

4000

0 50 100 150 200Time of irradiation, day

Sp

ec

ific

ac

tiv

ity

of

Cr-

51

, C

i/g 1

2

3

4

Density of thermal neutron flux (сm-2 sec-1): 1 - 1,5 x 1015; 2 - 1,0 x 1015; 3 - 5,0 x 1014; 4 - 1,0 x 1014

Dependence of Dependence of 5151ССrr specific activityspecific activity on time of on time of irradiationirradiation

Comparison of gallium result Comparison of gallium result to predictions standard of solar modelto predictions standard of solar model

ieeiPiiR ¤

Table of factors needed to compute the capture rate in 71Ga solar neutrino experiments calculated by B.T.Cleveland. * The units of flux are 1010 (pp),109 (7Be), 108 (pep, 13N, 15O), 106 (8B, 17F), 103 (hep) cm-2 s-1.The uncertainty values are at 68% confidence.

* http://arXiv.org/abs/nucl-ex/0703012

SAGE + GALLEX + GNO → 67.6 ± 3.7 SNU67.6 ± 3.7 SNUExcellent agreementExcellent agreement

[pp+7Be+CNO+pep+8B|Ga] = 67.6 ± 3.6 SNU from 288 solar neutrino extractions in the SAGE and GALLEX/GNO experiments

[8B|SNO] = (1.68 ± 0.11) ×106 νe/(cm2 s-1) → [8B|Ga] = 3.7 +1.2 -0.7 SNU

[pp+7Be+CNO+pep|Ga] = 64.0 +3.7-3.3 SNU

[7Be+CNO+pep+8B|Cl] = 2.56 ± 0.23 SNU [8B|Cl] = 1.72 ± 0.14 SNU →[7Be+CNO+pep|Cl] = 0.84 ± 0.27 SNU

[7Be+CNO+pep|Ga] = [7Be+CNO+pep|Cl] × = 23.9+7.9-7.6 SNU

[7Be+CNO+pep|Ga] = 23.9+8.1 -8.0 SNU

[pp|Ga] = [pp+7Be+CNO+pep|Ga] - [7Be+CNO+pep|Ga] = 40.1 +6.6 -9.0 SNU →

the measured electron neutrino pp flux at Earth of (3.41 +0.76-0.77) × 1010/(cm2 s-1)

(5.94 ± 0.06) × 1010/(cm2 s-1) (SSM) ×( ) = (3.30 +013-0.14) × 1010/(cm2 s-1)

Excellent agreementExcellent agreement

THE THE pp pp NEUTRINO FLUXNEUTRINO FLUX

)..(.ee

iP 0380040015550

),(/),( 77 ClGaBeBe

Is the neutrino capture rate Is the neutrino capture rate in Ga constant?in Ga constant?

Time periodTime period 05/14/91-01/23/9705/14/91-01/23/97 05/20/98-04/09/0305/20/98-04/09/03 05/14/91- 4/09/0305/14/91- 4/09/03Full data setFull data set

01/90-12/0601/90-12/06

Number runsNumber runs 65 58 123

GALLEX/GNOGALLEX/GNO 77.5 ± 6.2 +4.3-4.7 62.9 +5.5

-5.3 ± 2.5 69.3 ± 4.1± 3.6 –

77.5 +7.6-7.8 62.9 +6.0

-5.9 69.3 ± 5.5

Number runsNumber runs 45 49 94 157

SAGESAGE 79.4 +8.8-8.4 ± 3.9 65.0 +5.1

-4.9± 3.4 68.9 +4.5-4.3 ± 3.4 66.3 +3.3

-3.2 +3.5

-3.2

79.4 +9.6-9.3 65.0 +6.1

-6.0 68.9 +5.6-5.5 66.3 +4.8

-4.5

Number runsNumber runs (110) (107) (217) (288)

SAGE+GALLEX/GNOSAGE+GALLEX/GNO 78.3 ± 5.9 63.9 ± 4.2 69.1 ± 3.9 67.6 ± 3.6

ΔΔ ~ 2~ 2σσΔΔ ~ 2~ 2σσ

If one assumes the rate in Gallex-GNO varies linearly in time then the best fit gives [Capture rate = 82 ± 10 - (1.7 ± 1.1) × [t(year) - 1990] Altmann M et al. 2005 Phys Lett B 616]

time variationtime variation χχ22/dof/dof prob prob χχ22/dof/dof prob probwithwith 10.8/5 5.6% 10.8/5 5.6% 11.7/1611.7/16 76% 76%without without 13.2/6 4.0% 13.2/6 4.0% 11.4/1711.4/17 83% 83%

At the present time we cannot differentiate between these two At the present time we cannot differentiate between these two hypotheses, but it should become possible to do so with additional data.hypotheses, but it should become possible to do so with additional data.

FutureFuture• Further running for the next three years.Further running for the next three years.

• Measurement of the response of a Ga solar Measurement of the response of a Ga solar neutrino experiment to neutrinos from a neutrino experiment to neutrinos from a 5151Cr Cr source with accuracy better than 5%.source with accuracy better than 5%.