Results from Solar Neutrino Radiochemical Experiments with main

Results from Solar Neutrino Radiochemical Experiments (with main emphasis on Gallium) Neutrino 2004, Paris 13 -18 June 2004 Carla Maria Cattadori INFN Milano and Milano Bicocca Physics Department

Results from Solar Neutrino Radiochemical Experiments ØGeneralities about solar neutrinos and radiochemical experiments ØResults of Chlorine, SAGE, GALLEX/GNO ØImpact on üNeutrino Physics üAstrophysics ü“Technological” results ØAre precision measurements possible, with radiochemical experiments ? ØConclusions Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 2

Generalities on radiochemical experiments Radiochemical experiments provided at the end of the ´ 60 the first indication of solar neutrino flux anomaly at Earth. (22 years after the Pontecorvo idea to exploit the reaction ne(N, N´)e-) to detect neutrinos. ) Since then, they have continuously performed measurements of solar neutrino capture rate at Earth that, until year 2000 (before SNO), were of invaluable importance both to determine (Dm 2, sin 22 q 12) and for solar astrophysics. Nowadays, in the SNO + Kam. LAND era, their role is changed; having almost no weight in the neutrino oscillation parameters determination (3 values over 44 SK+ 34 SNO + 13 KL +3 Rchem= 94) they are still the only experiments that have detected sub-Me. V (7 Be, pp) ne. Sun. Therefore they are the experimental verification at low energy of Neutrino 2004, solar Paris 13 -18 June Carla Maria Cattadori 3 models neutrino oscillation mechanism

Generalities on radiochemical experiments Nowadays, in the neutrino community, radiochemical experiment are considered like turtles (“protected” ancient animals): • they are slow, low statistic experiment • they are sensitive only to ne • they measure only one quantity (the integral solar neutrino interaction rate). • they do not measure spectrum or incoming direction of solar neutrinos. It is common opinion that having reached a statistical accuracy almost equal to the systematic accuracy they have almost accomplished their role. Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 4

Generalities on radiochemical experiments • CC experiments sensitive only to ne. Proposed by Pontecorvo in 1946. N' (unstable) is then separated from the target with physicalchemical techniques and then quantitatively measured observing its decay back in N. as 1 Solar Neutrino Unit [SNU] = 1 n interaction/sec each 1036 target atoms. 29 -1030 nuclei, namely O(10 -100) tons of target to have NNeutrino 10 target = 2004, Paris 13 -18 June Carla Maria Cattadori 5 O(1) n interaction/day

The Pioneer: Chlorine Experiment 37 Cl(n The interaction n Signal Composition: (BP 04+N 14 SSM+ n osc) 37 Ar (E = 813 ke. V) , e) e thr Kshell EC t = 50. 5 d 37 Cl + 2. 82 ke. V (Auger e-, X) pep+hep 7 Be 8 B CNO Tot Expected Signal (BP 04 + N 14) Neutrino 2004, Paris 13 -18 June 8. 2 SNU Carla Maria Cattadori 0. 15 0. 65 2. 30 0. 13 SNU SNU ( 4. 6%) (20. 0%) (71. 0%) ( 4. 0%) 3. 23 SNU ± 0. 68 1 +1. 8 – 1. 8 1 6

The Chlorine experiment Name Location ne interaction reaction t [d] Data taking 60 -120 50. 5 19641994 Target comp. and mass Exp. Time [d] Lab overburden Chlorine (Homestake Mine); South Dakota USA Name Location Chlorine (Homestake Mine); South Dakota USA ne(37 Cl, 37 Ar)e- C 2 Cl 4 615 tons Liquid 4200 mwe Data used for R determinat ion N runs Average efficiency Hot chem check Source calib 19701994 108 <e>extr = 95 % <e>synth = (95. 8 ± 0. 7) % <e>count = 42 % 36 Cl No Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 7

Results of Chlorine experiment 1. First measurement of solar neutrino interaction rate 2. Raised the problem of missing neutrinos 3. Opened a field of research that is not yet closed. Davis awarded in 2002, with the Nobel prize together with Koshiba and R. Giacconi 4. “for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos" R = 2. 56 ± 0. 16 SNU = 2. 56 ± 0. 23 Constancy of the solar neutrino flux (over 23 years): no correlation has been found between Rn Sun and the solar cycle (many speculation Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 8 on this item in the ‘ 90)

Gallium experiments SAGE - The Russian-American Gallium Experiment Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 9

Collaboration ne interaction reaction Target comp. and mass Exp. Time [d] Data taking ne(71 Ga, 71 Ge)e- Ga. Cl 3 • HCl in H 2 O 103 t (30 t Ga) 3500 mwe 0. 6 m [h m 2]-1 21 -28 28 19912003 28 1990 ongoing Lab overburden GALLEX/ GNO LNGS Italy D (MPIK, TUM), I (INFN), F (CEA), USA (BNL), Israel SAGE Baksan Kabardino Balkaria RU (INR, RAS) USA (LNL, BNL) Neutrino 2004, Paris 13 -18 June ne(71 Ga, 71 Ge)e 4800 mwe 0. 1 m [h m 2]-1 Carla Maria Cattadori Metallic Ga 50 tons 10

Gallium Experiments GALLIUM Experiments 71 Ga(n The interaction e, e) 71 Ge K, L shell EC (proposed by Kuzmin in 1966) (Ethr = 233 ke. V) t = 16. 5 d 71 Ga + 10 ke. V, 1 ke. V (Auger e-, X) pp + pep 7 Be n Signal Composition: CNO (BP 04 +N 14 SSM+ n osc) 8 B Tot No osc Expected Signal (SSM +Paris n osc) Neutrino 2004, 13 -18 June 41. 7 SNU 19. 0 SNU 2. 6 SNU 4. 1 SNU ( 62 %) (28 %) ( 3. 9 %) ( 6. 1 %) 67. 4 SNU +2. 6– 2. 3 1 127 SNU +12 – 10 0. 6 n int. per day in GNO (1 in SAGE), but due to decay during exposure + ineff. , 4. 7 71 Ge decay Carla Maria Cattadori detected per extraction (28 days exposure). 11

New !! Gallium Experiments GALLEX /GNO LNGS Italy SAGE Baksan Kabardino Balkaria Data taking N runs 19912003 stopped 123 1990 ongoing 121 Average Hot Source Efficieny chem calib Tank to check counter 97 % 90 % New combined value Neutrino 2004, Paris 13 -18 June 71 As No Rex [SNU] Yes twice 51 Cr source 69. 3 ± 4. 1 ± 3. 6 5. 9% 5. 2% Yes 51 Cr 37 Ar 66. 9 ± 3. 6 5. 8% 5. 2% 69. 3 ± 5. 5 66. 9 +5. 3 – 5. 0 68. 1 ± 3. 75 (5. 5%) Carla Maria Cattadori 12

SAGE January 1990 – December 2003 14 years – 121 runs ! n o i ss e s r e +5. 3 ost p e 66. 9 e S -5. 0 SNU 51 Cr Neutrino 2004, Paris 13 -18 June source experiments Carla Maria Cattadori 13

GALLEX 65 Solar runs = 1594 d 23 Blank runs 77. 5 ± 6. 2 ± 4. 5 SNU 51 Cr Neutrino 2004, Paris 13 -18 June GNO 58 Solar runs = 1713 d 12 Blank runs 62. 9 +5. 5 – 5. 3 ± 2. 5 SNU ! n o ssi source, 71 As experiments Carla Maria Cattadori See e s r te s o p 14

Balance of the signal in L/K region L K L+K 74. 4 ± 10 79. 5 ± 8. 2 77. 5 ± 6. 2 GNO 68. 2 +8. 9 – 8. 5 59. 5 +6. 9 – 6. 6 62. 9 +5. 5 – 5. 3 GALLEX/ GNO 70. 9 ± 6. 6 67. 8 ± 5. 3 69. 3 ± 4. 1 SAGE 64. 0 +5. 9 -5. 7 69. 1 +5. 3 -5. 1 66. 9 +3. 9 -3. 8 GALLEX within 1 , events are equally distributed between L and K window, as 13 -18 expected from Carla counting efficiencies Neutrino 2004, Paris June Maria Cattadori 15

The signal is validated for both SAGE and GALLEX/GNO by 1 ke. V Event energy distribution Important! No other peaks appear in the spectrum 10 ke. V tfit = 16. 6 ± 2. 1 days t 76 Ge = 16. 5 days Event time distribution. Analysis: M. L. analysis. Null hypothesys: 1 decaying isotope + flat backgrd (independent /each run) Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 16

GALLEX/GNO seasonal variation analysis aphelion perihelion bi-monthly binning of the whole data set Flat: c 2= 2. 7 (5 d. o. f. ), C. L. : 75% Elliptical: c 2= 3. 0 (5 d. o. f. ) C. L. : 70% Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 17

GALLEX +GNO Seasonal variations Winter-Summer (statistical error only): GNO only (58 SRs): y b s i s ly a an he t in si d e Li d u d l n Inc gli a Fo Winter (32 SR): 58. 7+7. 1 -6. 8 SNU Summer (26 SR): 69. 0+8. 8 -8. 3 SNU W-S: -10 ± 11 SNU (expected from 1/d 2: +2. 5) GNO + Gallex (123 SRs): Winter (66 SR): 66. 5+5. 6 -5. 4 SNU Summer (57 SR): 74. 1+6. 4 -6. 2 SNU W-S: -7. 6 ± 9 SNU Neutrino 2004, Paris 13 -18 June (expected from 1/d 2: +2. 5) Carla in Maria Cattadori No excess W-S, as expected for LMA !! 18

SAGE survey of time modulations No evidence of time modulation binning the all data set monthly, bimonthly, yearly. Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 19

Search for time modulations in GALLEX/GNO data Claim from Sturrock and Caldwell of a significant peak in the periodogram plot of GALLEX data (and also SK) astro-ph/0103154 and subsequent (1 / years) Lomb–Scargle analysis is a Fourier analysis for data not equally spaced in time. We have repeated the analysis, found the same periodogram, but we don’t agree on the significance of the signal at 13. 5 y-1 Neutrino 2004, Paris 13 -18 June Random gaussian fluctuations Carla Maria Cattadori 20

Lomb-Scargle analysis power L. -S. time series analysis of 58 simulated GNO-like runs 0. 1% CL 40 SNU error on single sun power frequency (y-1) Neutrino 2004, Paris 13 -18 June 0. 1% CL Carla Maria Cattadori frequency (y-1) 25 SNU error on single sun 21

Time modulation exclusion plot from GALLEX/GNO data 1 = 69. 3 SNU Rule out modulations with frequency < 12 y-1 and amplitude > 40% of signal Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 22

GALLEX GNO The capture rate published by both experiments has monotonically decreased in the last 5 -6 years Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 23

m = 63 = 43 GNO m = 89 = 55 m = 73 = 52 GALLEX +GNO SAGE Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 24

combining SAGE and GALLEX/GNO period Jan 1990 – December 2003 68. 1 ± 3. 75 (5. 5%) SAGE Period Jan `90 Oct `99 N runs 70 51 121 75. 4 +7. 0 – 6. 8 +3. 5 – 3. 0 * < 60 ? ? 66. 9 +3. 9 – 3. 8 +3. 6 – 3. 2 Rn Jan `90 Dec `03 GALLEX/GNO Period May `91 – Jan `97 N runs 65 58 123 77. 5 ± 6. 2 +4. 3 – 4. 7 62. 9 ± 5. 4 ± 2. 5 * 69. 3 ± 4. 1 ± 3. 6 Rn Apr `98 – Mar `03 May `91 – Mar `03 * this value is before the efficiencies re-evaluation Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 25 * reduction of systematic obtained in GNO has not been propagated back to GALLEX

…. all this means that • it has been of crucial importance to proceed with the data taking so long. • RGa published by both experiments, has monotonically decreased in the last 6 -7 years. The statistical significance of this decreasing in each experiment is low, but the joint probability…. . • given the relevance that Gallium capture rate has and will have once the 7 Be flux will be available from Borexino or Kamland, it is important that both collaborations investigate once more if necessary to select “golden data set”, (difficult and dangerous action!!) then perform a joint analysis to provide their joint best evaluation of Rn on Gallim (debate in the collaborations about this item) Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 26

Determination of Gallium-ne capture cross section Ga-ne capture cross sections are needed to compute fluxes from rate At low energy ( < 410 ke. V, namely for pp ns) only g. s. -g. s. transitions are present; for this transition cross sections are evaluated from 71 Ge E. C. good accuracy ( 2. 3% at 1 ) At the 7 Be energies, the first two excited state (at 175 and 500 ke. V) must be considered; BGT estimated from (p, n) reactions; estimated accuracy – 3% +5% Direct measurement desirable Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 27

Experimental situation Two GALLEX and one SAGE calibrations, with strong 51 Cr sources Rmeas = 0. 93 ± 0. 07 Rtheo Improvements are well possible irradiating with a 2 MCi source f. i. 20 tons of metallic gallium Final accuracy 5% or better = theoretical accuracy to addrees the question: corrections to g. s. -e. s. only or to g. s. -g. s. also? Neutrino 2004, Paris 13 -18 June GALLEX sources: 1. 71 MCi 1. 87 MCi Carla Maria Cattadori SAGE source 0. 52 MCi 28

SAGE 37 Ar source: see details in SAGE poster SAGE is at the moment irradiating 13. 2 tons of its metallic Gallium with a 37 Ar n source 614 k. Ci strenght: En (37 Ar) > En (51 Cr) improved sensitivity for second 71 Ge e. s. 330 Kg of Ca 2 O 3 Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 29

Gas processing efficiencies evaluation Data from neutrino source experiments can be used to infer on the cross section only once the extraction + gas processing efficiencies are exactly determined, and “hot chemistry” effect are excluded. This has been done by the GALLEX collaboration, spiking the target with O(10000) atoms of 37 As, that beta decay to 76 Ge, kinematically mimicking the n interaction. The processing efficiency has been found to be correctly extimated (from the methods routinely adopted at each run) =100% with 1% error. Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 30

Impact of Gallium experimental results on neutrino oscillation parameters determination. Almost irrelevant with the actual experimental accuracy in the actual experimental scenario Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 31

Allowed (Dm 2, tan 2 q 12) regions from Radiochemical experiments -4 10 -3 10 -2 10 -1 1 10 10 -4 10 -3 10 -2 10 -1 1 10 Ga experiments are more sensitive to tan 2 q 12 than to Dm 2 Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 32

Th e Thta= et 37 Th a=. 5° 35 e t Th a= ° e 3 Th ta= 2. 5 et 30 ° a= ° 28. 5 ° Oscillation parameters vs (Ga rate + SSM) 0. 954 Fpp 0. 970 0. 983 1. 000 1. 016 Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori Comments: No sensitivity within the presently allowed oscillation parameter region 33

Impact of Gallium Results on Astrophysics Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 34

Solar Models R previsions for Radiochemical experiments from LUNA experiment on 14 N(p, g)15 O New S 0(14 N+p) = 1. 77 ke. V ± 0. 2 Flux (cm-2 s-1) BP 00 BP 04 + N 14 BP 04+ + N 14 Pee Dm 2 = 7. 1 x 10 -5 e. V 2 q 12 = 32. 5 pp (109) 59. 5 (± 1%) 5. 94 (± 1%) 59. 8 60. 3 0. 578 (vac) pep (108) 1. 40 (± 2%) 1. 42 1. 44 0. 531(vac) hep (103) 9. 24 7. 88 (± 16%) 7. 93 8. 09 ~ 0. 3 matter 4. 77 (± 10%) 4. 86 (± 12%) 4. 86 4. 65 0. 557 vac 5. 05 +20%-16% 5. 79 (± 23%) 5. 77 5. 24 0. 324 matter 7 Be 8 B (109) (106) 13 N (108) 5. 48 +21%-17% 5. 71 2. 30 0. 557 vac 15 O (108) 4. 80 +25%-19% 5. 03 1. 79 0. 541 vac 17 F (106) 5. 63 +25%-25% 5. 91 3. 93 Neutrino 2004, Paris 13 -18 June Columns 2, 3, 4 from BP 0435 Carla Maria Cattadori increased accuracy in 7 Be(p, g)8 B measurement

…… to summarize BP 00 with Z/Xold= 0. 0229 BP 04 = BP 00 + New data on EOS, Nucl Phys. (Cross sections) N 14 = BP 04 + S 0(14 N+p) = 1. 77 ke. V ± 0. 2 BP 04+ = BP 04 + Z/Xnew=0. 0176 to be compared with Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 36

Solar Models R previsions for Radiochemical experiments Experiment Dm 2, al tan 2 q 12 from experiments SNO/ 7. 1, 0. 45 † 1. 00 +6% -6% SK 7. 3, 0. 42 * 1. 01 +6% -6% 5. 21 ± 0. 27 no osc BP 00 BP 04 + N 14 BP 04+ + N 14 5. 77 5. 24 3. 35 (± 21%) 3. 23 2. 95 8. 5 +1. 8 – 1. 8 8. 2 7. 7 5. 05 +20% 5. 79 (± 23%) -16% (cm-2 s-1) Cl 7. 1, 0. 45 † 3. 06 ± 0. 04 2. 56 ± 0. 23 7. 3, 0. 42 * 2. 79 ± 0. 18 [SNU] no osc 7. 6 +1. 3 – 1. 1 Ga 7. 1, 0. 45 † 68. 1 ± 3. 75 7. 3, 0. 42 * [SNU] no osc BP 04 69. 4 ± 2. 6 65. 8 ± 4. 5 128 +9 -7 67. 7 ± 5. 5 69. 3 ± 5. 3 67. 7 ± 5. 3 131 +12 – 10 127 +12 – 10 (best fit point all solar + Kam. LAND data. 8 B flux free, other fluxes from BP 00) Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 37 * (best fit point all solar + Kam. LAND data; all n fluxes free + lum. constr. ) †

Comparison of solar model predictions with experimental results • Neutrinos prefer a Sun having “low metallicity” solar interior, as the recent photospheric measurements indicate • when this data are included in the SSM tension with helioseismology as the depth of the convective zone goes to 0. 726 Rsun (instead of 0. 713 as measured i. e. 18% discrepancy). Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 38

LCNO estimate from Gallium experimental results imposing the luminosity constraint Assumption: nuclear fusion reactions are the only source of energy in the Sun and knowing from experiments RGa which is given by the sum of all the neutrino components, weighted by the cross section and Pee Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 39

Gallium Uncertainties for evaluation of pp and CNO n flux Parameter Uncertainty Rga Uncertainty (SNU) Theta +/- 2. 5° SNO+kam+SK 2. 9 7 Be 10% SSM 1. 9 Cross section GS -GS 2. 3% 1. 5 Cross section GS –ES(1, 2) 50% 0. 7 Cross section GS-ES>2 35% 1. 5 8 B 9% SNO 0. 4 pep 1. 5 % SSM 0. 1 4. 2 Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 40

…. . it is possible to estimate at the same time Fpp and FCNO once we know the 8 B, 7 Be, pep fluxes • 8 B take from experiments • 7 Be take from SSM • pep strictly related to pp Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 41

Important! Here the solar model N 14 (Bahcall nomenclature) is used as reference, i. e. the unity on the Y axis take already into account the reduced flux due to new S 0(14 N) measurement 3 limit 3 best fit Neutrino 2004, Paris 13 -18 June 2 1 Carla Maria Cattadori luminosity constraint 42

Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 43

Finally with the listed assumptions and from the capture rate measured in Gallium experiments it is possible to determine RGa Fpp [109 cm-2 s-1 ] Fpp / Fpp (BP 04+N 14) 69. 3 Old 59. 9 (1± 0. 02 ± 0. 01 theo) 1. 00(2) 68. 1 New 58. 8 (1± 0. 02) 0. 98(4) Fantastic agreement !! Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 44

…. for 8 B and 7 Be F(8 B)meas = (0. 89 ± 0. 04 ex ± 0. 23 theo) F(8 B) BP 04 + N 14 F(7 Be)meas = (0. 91+0. 24 -0. 62 ex ± 0. 11 theo) F(7 Be) BP 04+N 14 from BP 04 Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 45

GALLEX/GNO - all uncertainties 0. 954 0. 970 0. 983 Fpp Experimental constraint SSM prediction Experimental constraint Comments: perfect agreement of Ga rate with SSM + oscillation scenario F(pp) probed at 2% level (1 sigma) F(CNO) < 3. 5 SSM (2 sigma) But to be totally model independent we need a measurement of F(Be) at 10% 1. 000 1. 016 Neutrino 2004, Paris 13 -18 June Measured Carla Maria Cattadori R = 69. 3 +- 5. 5 SNU 46

GNO- all uncertainties Comments: GNO is compatible with SSM + oscillation scenario at the level of 1 low values of the CNO flux are favored 0. 954 0. 983 Fpp 0. 970 1. 000 1. 016 Neutrino 2004, Paris 13 -18 June Measured Carla Maria Cattadori R = 62. 9 +- 6. 0 SNU GNO is at border 47 of physical region

GALLEX- all uncertainties Comments: GALLEX is compatible with SSM + oscillation scenario within 2 The effect of GNO is important in the probe of the solar luminosity 0. 954 0. 983 Fpp 0. 970 1. 000 1. 016 Neutrino 2004, Paris 13 -18 June Measured Carla Maria Cattadori R = 77. 5 +- 7. 7 SNU 48

Gallium- 5% error 0. 970 0. 983 Fpp BP 00 0. 954 1. 000 1. 016 Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori R = 70. 0 +- 3. 5 SNU 49

Are precision measurements possible with Gallium radiochemical experiments? Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 50

Gallium- 3% error Delta theta 1. 5° - cross section measured at 1% Comments: Errors at the level of SSM uncertainties in pp flux 0. 954 0. 983 Fpp 0. 970 1. 000 1. 016 Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 51

Achievable accuracies 3 years of running; 4 weeks runs; 60% efficency; 70 SNU signal Systematic error: 2. 5 SNU ( GNO); not large improvements possible 30 tons 80 tons (GNO) (available gallium) 160 tons Det. evt. s 195 519 1040 Total accuracy 7 SNU 4 SNU 3 SNU Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 52

Technological results • Few atoms chemistry • Low level counting techniques • Intense neutrino sources production (intensity calibration, know-how to produce and manipulate safely etc. . ) • Radiochemistry techniques • Radon counting and quantitative determination at level of few atoms. • Ultra-low activity miniaturized proportional counters Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 53

Conclusions • Radiochemical experiments have provided along the last 40 years measurements of solar ne interaction rate on 37 Cl and on 71 Ga • they confirm at sub-Mev energies the neutrino oscillation scenario and the standard solar model • The update value for the neutrino capture rate on Gallium is 68. 1 ± 3. 7 from 244 GALLEX+GNO+SAGE runs • Gallium experiments have demonstrated to be reliable and have been calibrated with high intensity neutrino sources. Chlorine and GALLEX experiments has experimentally excluded hot chenistry effects • No time modulations (seasonal, monthly, bimonthly, yearly) have been found with the actual accuracy we can state that the neutrino flux constant Neutrino 2004, Paris is 13 -18 June Carla Maria Cattadori 54

Taking F(8 B)meas = (0. 89 ± 0. 04 ex ± 0. 23 theo) F(8 B) BP 04 + N 14 F(7 Be)meas = (0. 91+0. 24 -0. 62 ex ± 0. 11 theo) F(7 Be) BP 04+N 14 RGa Fpp [109 cm-2 s-1 ] Fpp (BP 04+N 14) 69. 3 Old 59. 9 (1± 0. 02 ± 0. 01 theo) 1. 00(2) 68. 1 New 58. 8 (1± 0. 02) 0. 98(4) Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori Fpp / 55

Extra slides Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 56

Radiochemical experimental technique Add carrier 2. Extracted gas 1 mg 72, 74, 76 Ge in GALLEX 250 mg 72, 74, 76 Ge in SAGE in counter 0. 1 cc STP 36, 38 Ar in Chlorine exp. Extraction Ga: Ge. Cl 4 with N 2 Cl: Ar with He stream 1. Exposure Wait Exposure time t 0 3. Counter in shielding 6 months for 76 Ge 12 months for 37 Ar Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori In Gallium synthesis(Ge. H lab 4 + Xe), Chlorine (Ar + CH 4) in counter V =1 cc Stop counting Remove counter 57

Results of Chlorine experiment Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 58

Results of Chlorine experiment Learning phase of these experiments is very long ! Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 59

GALLEX – GNO Test hypothesis of time constancy of n signal: 1. Test of Likelihood Ratio C. L. 5. 6 % 2. c 2 flat fit = 13. 6 (6 d. o. f. ) C. L. 3. 4% Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 60

Improvements Many improvements resulting in a reduction of a factor of 2 in the systematic error Item Gallex GNO Target size 0. 8% Chemical yield 2. 0% Counting efficiency (active vol determination) 4. 0% 2. 2% Pulse shape cuts 2. 0% 1. 3%* Event sel. (others) 0. 3% 0. 6% Side reactions 1. 2 SNU Rn-cut inefficiency 1. 2 SNU 0. 5 SNU +1. 8 SNU -2. 6 SNU - 68 Ge contamination * Neural Neutrino 2004, Parisnetwork 13 -18 June analysis Carla Maria Cattadori 61

Composition of the Gallium signal RGa = Fpp pp Ppp + FCNO PCNO + F 8 8 P 8 + F 7 7 P 7 + Fpep Ppep LSun = Fpp app + FCNO a. CNO + F 8 a 8 + F 7 a 7 + Fpep apep F a P (SNO+SK+KAM) F P (SNU) pp 59. 8 BP 04+N 14 1. 310 11. 7 0. 578 40. 4 7 Be 4. 86 BP 04+N 14 1. 260 71. 7 0. 557 19. 4 N 0. 323 BP 04+N 14 0. 346 60. 2 0. 557 1. 1 O 0. 254 BP 04+N 14 2. 157 115 0. 541 1. 5 8 B 0. 00521 SNO 0. 663 24500 0. 324 4. 1 pep 0. 142 1. 192 15. 7 0. 531 1. 2 TOT 67. 7 BP 04+N 14 FN = 1. 14 FO RGa = 69. 3 ± 5. 5 SNU Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 62

Solar Models previsions for R (int. rate) in Radiochemical Experiments new meas. from LUNA exp. of S 0(14 N+p) = 1. 77 ke. V ± 0. 2 14 N(p, g)15 O 29 2. 0 X) o / (Z 0 = d l Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 63

Solar Models R previsions for Radiochemical experiments Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 64

Generalities on radiochemical experiments ne interaction reaction t [d] Data taking 60 -120 50. 5 19641993 Ga. Cl 3 • HCl in H 2 O 100 t (30 t Ga) 21 -28 28 16 19912003 Metallic Ga 55 -49 tons 28 16 1990 ongoing Target comp. and mass Lab overburden Chlorine (Homestake Mine); South Dakota USA ne(37 Cl, 37 Ar)e- GALLEX/ GNO LNGS Italy ne(71 Ga, 71 Ge)e- SAGE Baksan Kabardino Balkaria ne(71 Ga, 71 Ge)e- 4400 mwe 2700 mwe C 2 Cl 4 600 tons Liquid Exp. Time [d] 4800 mwe Neutrino 2004, Paris 13 -18 June Carla Maria Cattadori 65

Generalities on radiochemical experiments Chlorine (Homestake Mine); South Dakota USA GALLEX/ GNO Data used for R determinat ion N runs 19701993 106 Average Hot Source efficiency chem calib check 19912003 124 0. 958 ± 0. 007 ? ? 1990 ongoing 104 ? ? 36 Cl Baksan Kabardino Balkaria Neutrino 2004, Paris 13 -18 June 2. 55 ± 0. 17 ± 0. 18 6. 6% 7% 2. 6 ± 0. 3 37 As Yes twice 51 Cr source 69. 3 ± 4. 1 ± 3. 6 5. 9% 5% No Yes 51 Cr 37 Ar 70. 5 ± 4. 8 ± 3. 7 6. 8% 5. 2% LNGS Italy SAGE No Rex [SNU] Carla Maria Cattadori 70. 5 ± 6. 0 66