carla maria cattadori infn milano and milano bicocca physics department
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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
Carla Maria Cattadori 2Neutrino 2004, Paris 13-18 June
Results from Solar Neutrino Radiochemical Experiments
Generalities about solar neutrinos and radiochemical experimentsResults of Chlorine, SAGE, GALLEX/GNOImpact on
Neutrino PhysicsAstrophysics“Technological” results
Are precision measurements possible,with radiochemical experiments ?Conclusions
Carla Maria Cattadori 3Neutrino 2004, Paris 13-18 June
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 e(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 (m2,sin22) and for solar astrophysics.
Nowadays, in the SNO + KamLAND 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-MeV (7Be, pp) e
Sun. Therefore they are the experimental verification at low energy of
solar models neutrino oscillation mechanism
Sune
R
Carla Maria Cattadori 4Neutrino 2004, Paris 13-18 June
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 e
• 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.
Carla Maria Cattadori 5Neutrino 2004, Paris 13-18 June
Generalities on radiochemical experiments
• CC experiments sensitive only to e. Proposed by Pontecorvo in 1946.
N' (unstable) is then separated from the target with physical-chemical techniques and then quantitatively measured
observing its decay back in N.
as
1 Solar Neutrino Unit [SNU] = 1 interaction/sec each 1036 target atoms.
Ntarget = 1029-1030 nuclei, namely O(10-100) tons of target to have O(1) interaction/day
eNNe
-1210i
2-46i ][ 106 ~ ; 10 ~ s cmcm
)()(
)(i)( target dEPdE
EdENRRatenInteractio ee
ii
Carla Maria Cattadori 6Neutrino 2004, Paris 13-18 June
The interactionThe interaction
Signal Composition:(BP04+N14 SSM+ osc) Signal Composition:(BP04+N14 SSM+ osc)
pep+hep 0.15 SNU ( 4.6%)7Be 0.65 SNU (20.0%)8B 2.30 SNU (71.0%)CNO 0.13 SNU ( 4.0%)Tot 3.23 SNU ± 0.68 1
pep+hep 0.15 SNU ( 4.6%)7Be 0.65 SNU (20.0%)8B 2.30 SNU (71.0%)CNO 0.13 SNU ( 4.0%)Tot 3.23 SNU ± 0.68 1
Expected Signal (BP04 + N14)Expected Signal (BP04 + N14)
8.2 SNU +1.8–1.8 1 8.2 SNU +1.8–1.8 1
37Cl(e,e)37Ar (Ethr = 813 keV) Kshell EC = 50.5 d
37Cl + 2.82 keV (Auger e-, X)
37Cl(e,e)37Ar (Ethr = 813 keV) Kshell EC = 50.5 d
37Cl + 2.82 keV (Auger e-, X)
The Pioneer: Chlorine Experiment
Carla Maria Cattadori 7Neutrino 2004, Paris 13-18 June
The Chlorine experimentName
Location
e interaction reaction
Target comp. and mass
Exp. Time [d]
[d]
Data taking
Lab overburden
Chlorine
(Homestake Mine);South Dakota USA
e(37Cl,37Ar)e- C2Cl4
615 tons
Liquid
60-120 50.5 1964- 19944200 mwe
Name
LocationData used
for R determinat
ion
N runs
Average
efficiency
Hot chem check
Source calib
Chlorine(Homestake Mine);South Dakota USA
1970-1994
108 <>extr = 95 %
<>synth = (95.8 ± 0.7) %
<>count = 42 %
36Cl No
Carla Maria Cattadori 8Neutrino 2004, Paris 13-18 June
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
“for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos"
R = 2.56 R = 2.56 ± ± 0.16 0.16 ±± 0.16 SNU 0.16 SNU = 2.56 = 2.56 ± 0.23± 0.23
Constancy of the solar neutrino flux (over 23 years): no correlation has been found between R Sun and the solar cycle (many speculation on this item in the ‘90)
Carla Maria Cattadori 9Neutrino 2004, Paris 13-18 June
Gallium experiments
SAGE - The Russian-American Gallium Experiment
Carla Maria Cattadori 10Neutrino 2004, Paris 13-18 June
Collaboration e interaction reaction
Target comp. and mass
Exp. Time [d]
Data taking
Lab overburden
GALLEX/
GNO
LNGS Italy
D (MPIK,TUM),
I (INFN),
F (CEA), USA (BNL), Israel
e(71Ga,71Ge)e- GaCl3• HCl in H2O
103 t (30 t Ga)
21-28
28
1991-2003
3500 mwe
0.6 [h m2]-1
SAGE
Baksan
Kabardino Balkaria
RU (INR, RAS)
USA (LNL,BNL)e(71Ga,71Ge)e- Metallic Ga
50 tons
28 1990-ongoing
4800 mwe
0.1 [h m2]-1
Carla Maria Cattadori 11Neutrino 2004, Paris 13-18 June
The interaction(proposed by Kuzmin in 1966)
The interaction(proposed by Kuzmin in 1966)
71Ga(e,e)71Ge (Ethr = 233 keV)K,L shell EC = 16.5 d
71Ga + 10 keV, 1 keV (Auger e-, X)
71Ga(e,e)71Ge (Ethr = 233 keV)K,L shell EC = 16.5 d
71Ga + 10 keV, 1 keV (Auger e-, X)
Signal Composition:(BP04 +N14 SSM+ osc) Signal Composition:(BP04 +N14 SSM+ osc)
pp + pep 41.7 SNU ( 62 %)7Be 19.0 SNU (28 %)CNO 2.6 SNU ( 3.9 %)8B 4.1 SNU ( 6.1 %)Tot 67.4 SNU +2.6
–2.3 1
No osc 127 SNU +12 –10
pp + pep 41.7 SNU ( 62 %)7Be 19.0 SNU (28 %)CNO 2.6 SNU ( 3.9 %)8B 4.1 SNU ( 6.1 %)Tot 67.4 SNU +2.6
–2.3 1
No osc 127 SNU +12 –10
Expected Signal (SSM + osc)Expected Signal (SSM + osc)
0.6 int. per day in GNO (1 in SAGE), but due to decay during exposure + ineff., 4.7 71Ge decay
detected per extraction (28 days exposure).
0.6 int. per day in GNO (1 in SAGE), but due to decay during exposure + ineff., 4.7 71Ge decay
detected per extraction (28 days exposure).
Gallium ExperimentsGALLIUM ExperimentsGALLIUM Experiments
Carla Maria Cattadori 12Neutrino 2004, Paris 13-18 June
Gallium ExperimentsGallium Experiments
Data taking
N runs
Average
Efficieny
Tank to counter
Hot chem check
Source calib
Rex
[SNU]
GALLEXGALLEX/GNO/GNOLNGS Italy
1991-2003
stopped
123 97 % 71As Yes
twice51Cr
source
69.3 ± 4.1 ± 3.6
5.9% 5.2%
69.3 69.3 ± ± 5.55.5
SAGESAGEBaksan
Kabardino Balkaria
1990-ongoing
121 90 % No Yes51Cr37Ar
66.9 ± 3.9 ± 3.6
5.8% 5.2%
66.9 66.9 +5.3+5.3 –5.0–5.0
New !!New !!
68.1 68.1 ± 3.75 ± 3.75 (5.5%)(5.5%)New combined valueNew combined value
Carla Maria Cattadori 13Neutrino 2004, Paris 13-18 June
SAGESAGE January 1990 – December2003
14 years – 121 runs
66.9 66.9 +5.3+5.3-5.0-5.0 SNU SNUSee poster session !
51Cr source experiments
Carla Maria Cattadori 14Neutrino 2004, Paris 13-18 June
GALLEXGALLEX65 Solar runs = 1594 d23 Blank runs
GNOGNO 58 Solar runs = 1713 d12 Blank runs
62.9 62.9 ++5.55.5 –5.3–5.3 ± 2.5 SNU ± 2.5 SNU
See poster sessio
n !
77.5 77.5 ± 6.2 ± 4.5 SNU± 6.2 ± 4.5 SNU
51Cr source, 71As experiments
Carla Maria Cattadori 15Neutrino 2004, Paris 13-18 June
Balance of the signal in L/K region
L K L+K
GALLEX 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
within 1, events are equally distributed between L and K window, as expected from counting efficiencies
Carla Maria Cattadori 16Neutrino 2004, Paris 13-18 June
Event energy distribution
Important! No other peaks appear in the spectrum
Event time distribution.
Analysis: M.L. analysis.
Null hypothesys: 1 decaying isotope + flat backgrd (independent /each run)
fit = 16.6 ± 2.1 days
76Ge = 16.5 days
The signal is validated for both SAGE and GALLEX/GNO by
1 keV
10 keV
Carla Maria Cattadori 17Neutrino 2004, Paris 13-18 June
GALLEX/GNO seasonal variation analysis
peri
helio
n
ap
helio
n
Flat: 2= 2.7 (5 d.o.f.), C.L.: 75%
Elliptical: 2= 3.0 (5 d.o.f.) C.L.: 70%
bi-monthly binning of the whole data set
Carla Maria Cattadori 18Neutrino 2004, Paris 13-18 June
GALLEX +GNO Seasonal variations
GALLEX +GNO Seasonal variations
Winter-Summer (statistical error only):
GNO only (58 SRs):
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/d2: +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 (expected from 1/d2: +2.5)
Included in the analysis
by Fogli and Lisi
No excess in W-S, as expected for LMA !!No excess in W-S, as expected for LMA !!
Carla Maria Cattadori 19Neutrino 2004, Paris 13-18 June
SAGE survey of time modulations
No evidence of time modulation binning the all data set monthly, bimonthly, yearly.
Carla Maria Cattadori 20Neutrino 2004, Paris 13-18 June
Search for time modulations in GALLEX/GNO data
Lomb–Scargle analysis is a Fourier analysis for data not equally spaced in time.
Claim from Sturrock and Caldwell of a significant peak in the periodogram plot of GALLEX data (and also SK)
(1 / years)
Random gaussian fluctuations
astro-ph/0103154 and subsequent
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
Carla Maria Cattadori 21Neutrino 2004, Paris 13-18 June
Lomb-Scargle analysisL.-S. time series analysis of 58 simulated GNO-like runs
40 SNU error on single sun
pow
er
0.1% CL
pow
er
frequency (y-
1)
frequency (y-
1)
25 SNU error on
single sun
0.1% CL
Carla Maria Cattadori 22Neutrino 2004, Paris 13-18 June
Time modulation exclusion plot from GALLEX/GNO data
Rule out modulations Rule out modulations with frequency < 12 ywith frequency < 12 y-1-1 and amplitude > 40% of and amplitude > 40% of signalsignal
1 = 69.3 SNU
Carla Maria Cattadori 23Neutrino 2004, Paris 13-18 June
GALLEX GNO
The capture rate published by both experiments has monotonically decreased in the last 5-6 years
Carla Maria Cattadori 24Neutrino 2004, Paris 13-18 June
GNO
= 63 = 43
= 89 = 55
= 73 = 52
GALLEXGALLEX+GNO
SAGE
Carla Maria Cattadori 25Neutrino 2004, Paris 13-18 June
combining SAGE and GALLEX/GNO period Jan 1990 – December 2003
68.1 ± 3.75 (5.5%)
SAGEPeriod Jan `90 Oct `99 Jan `90 Dec `03
N runs 70 51 121
R 75.4 +7.0 –6.8 +3.5 –3.0 * < 60 ?? 66.9 +3.9 –3.8 +3.6 –3.2
GALLEX/GNO
Period May `91 – Jan `97 Apr `98 – Mar `03 May `91 – Mar `03
N runs 65 58 123
R 77.5 ± 6.2 +4.3 –4.7 62.9 ± 5.4 ± 2.5 * 69.3 ± 4.1 ± 3.6
* this value is before the efficiencies re-evaluation
* reduction of systematic obtained in GNO has not been propagated back to GALLEX
Carla Maria Cattadori 26Neutrino 2004, Paris 13-18 June
…. 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 7Be 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 Ron Gallim (debate in the collaborations about this item)
Carla Maria Cattadori 27Neutrino 2004, Paris 13-18 June
Determination of Gallium-e capture cross section
Ga-e capture cross sections are needed to compute fluxes from rate
At low energy ( < 410 keV, namely for pp s) only g.s.-g.s.transitions are present;for this transition cross sections are evaluated from 71Ge E.C.
good accuracy ( 2.3% at 1)
At the 7Be energies, the first two excited state (at 175 and 500 keV) must be considered; BGT estimated from (p,n) reactions;
estimated accuracy –3% +5%
Direct measurement desirable
Carla Maria Cattadori 28Neutrino 2004, Paris 13-18 June
Experimental situationTwo GALLEX and one SAGE calibrations,
with strong 51Cr sources
RRmeasmeas = 0.9= 0.93 3 ±± 0.070.07 R Rtheotheo
Improvements are well possible irradiating with a 2MCi 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?
GALLEX sources: 1.71 MCi 1.87 MCi
SAGE source 0.52 MCi
Carla Maria Cattadori 29Neutrino 2004, Paris 13-18 June
SAGE 37Ar source: see details in SAGE poster
Ca40(n,alfa)Ar37
0
50
100
150
200
250
1.E-02 1.E-01 1.E+00 1.E+01 Energy, ?eV
Cross s
ecti
on
,?b
0.000
0.005
0.010
0.015
0.020
0.025
Barnes75 Knellwolf66Guoyou93 Zhang2000Qaim79 Bormann79
Bartle77 Bartle81JENDL-3.2 ENDF/B-6FOND-2.3 ADL-3FLUX
330 Kg of Ca2O3
SAGE is at the moment irradiating 13.2 tons of its metallic Gallium with a 37Ar source 614 kCi strenght:
E (37Ar) > E (51Cr) improved sensitivity for second 71Ge e.s.
Carla Maria Cattadori 30Neutrino 2004, Paris 13-18 June
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 37As, that beta decay to 76Ge,
kinematically mimicking the interaction.The processing efficiency has been found to be correctly
extimated (from the methods routinely adopted at each run) =100% with 1% error.
Carla Maria Cattadori 31Neutrino 2004, Paris 13-18 June
Impact of Gallium experimental results on neutrino oscillation parameters determination.
Almost irrelevant with the actual experimental accuracy in the actual experimental scenario
Carla Maria Cattadori 32Neutrino 2004, Paris 13-18 June
Allowed (m2,tan2) regions from Radiochemical experiments
-4
1010-4 10-3 10-2 10-1 11010-4 10-3 10-2 10-1 1
Ga experiments are more sensitive to tan212 than to m2
Carla Maria Cattadori 33Neutrino 2004, Paris 13-18 June
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
5
50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100
Gallium Rate (SNU)
FC
NO
N14
/BP
00
Theta=35
°
Theta=30
°
Theta=32
.5°
Theta=28
.5°
Theta=37
.5°
0.954
0.970
0.983
1.000
1.016
p
p
Comments: No sensitivity within the presently allowed oscillation parameter region
Oscillation parameters vs (Ga rate + SSM)
Carla Maria Cattadori 34Neutrino 2004, Paris 13-18 June
Impact of Gallium Results on Astrophysics
Carla Maria Cattadori 35Neutrino 2004, Paris 13-18 June
Solar Models R previsions for Radiochemical experiments
Flux
(cm-2s-1)
BP00 BP04 BP04 +
N14
BP04+
+ N14
Pee
m2 = 7.1x10-5 eV2
12 = 32.5
pp (109) 59.5 (± 1%) 5.94 (± 1%) 59.8 60.3 0.578 (vac)
pep (108) 1.40 (± 2%) 1.40 (± 2%) 1.42 1.44 0.531(vac)
hep (103) 9.24 7.88 (± 16%) 7.93 8.09 ~ 0.3 matter7Be (109) 4.77 (± 10%) 4.86 (± 12%) 4.86 4.65 0.557 vac8B (106) 5.05 +20%
-16% 5.79 (± 23%) 5.77 5.24 0.324 matter
13N (108) 5.48 +21%-17% 5.71 2.30 0.557 vac
15O (108) 4.80 +25%-19% 5.03 1.79 0.541 vac
17F (106) 5.63 +25%-25% 5.91 3.93
37%35% 3.23
%43%3954.2
%44%4485.5
from LUNA experiment on 14N(p,)15ONew S0(14N+p) = 1.77 keV ± 0.2
increased accuracy in 7Be(p,)8B measurement Columns 2,3,4 from BP04
Carla Maria Cattadori 36Neutrino 2004, Paris 13-18 June
…… to summarize
BP00 with Z/Xold= 0.0229
BP04 = BP00 + New data on EOS, Nucl Phys.(Cross sections)
N14 = BP04 + S0(14N+p) = 1.77 keV ± 0.2
BP04+ = BP04 + Z/Xnew=0.0176
to be compared with
RRCZ 715.0
RRCZ 725.0
001.0713.0 measR
Carla Maria Cattadori 37Neutrino 2004, Paris 13-18 June
Solar Models R previsions for Radiochemical experimentsExperimental
m2,
tan212
from experiments
BP00 BP04 BP04
+ N14
BP04+ + N14
SNO/
SK
5.21 ± 0.27(cm-2s-1)
7.1, 0.45 †
7.3, 0.42 *
1.00 +6% -6%
1.01 +6% -6%
no osc 5.05 +20%
-16%
5.79 (± 23%) 5.77 5.24
Cl
2.56 ± 0.23
[SNU]
7.1, 0.45 †
7.3, 0.42 *
3.06 ± 0.04
2.79 ± 0.18 3.35 (± 21%) 3.23 2.95
no osc 7.6 +1.3
–1.1
8.5 +1.8 –1.8 8.2 7.7
Ga
68.1 ± 3.75
[SNU]
7.1, 0.45 †
7.3, 0.42 *
69.4 ± 2.6
65.8 ± 4.5 67.7 ± 5.5 69.3 ± 5.3 67.7 ± 5.3
no osc 128 +9 -7
131 +12 –10 127 +12
–10 127 +12
–10
† (best fit point all solar + KamLAND data. 8B flux free, other fluxes from BP00)* (best fit point all solar + KamLAND data; all fluxes free + lum. constr.)
Carla Maria Cattadori 38Neutrino 2004, Paris 13-18 June
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).
Carla Maria Cattadori 39Neutrino 2004, Paris 13-18 June
LCNO estimate from Gallium experimental results imposing the luminosity constraint
neutrinoemittedperphotonsinMeVi
12111053.8 sMeVcmLi
iiSun
)()(
)(itarget dEPdE
EdENR ee
ii
and knowing from experiments RGa which is given by the sum of all the neutrino components, weighted by the cross section and Pee
Assumption: nuclear fusion reactions are the only source of energy in the Sun
Carla Maria Cattadori 40Neutrino 2004, Paris 13-18 June
Parameter Parameter
Uncertainty
Rga
Uncertainty
(SNU)
Theta +/- 2.5° SNO+kam+SK
2.9
7Be 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
8B 9 % SNO 0.4
pep 1.5 % SSM 0.1
4.24.2
GalliumUncertainties for evaluation of pp and CNO flux
Carla Maria Cattadori 41Neutrino 2004, Paris 13-18 June
…..it is possible to estimate at the same time pp and CNO once
we know the 8B, 7Be, pep fluxes
iii
NNOO
Sun
CNO
L
L
• 8B take from experiments
• 7Be take from SSM
• pep strictly related to pp
Carla Maria Cattadori 42Neutrino 2004, Paris 13-18 June
Important! Here the solar model N14 (Bahcall nomenclature) is used as reference, i.e. the unity on the Y axis take already into account the reduced flux due to new S0(14N) measurement
3
2 1
best fit
3 limit
luminosity constraint
Carla Maria Cattadori 43Neutrino 2004, Paris 13-18 June
)%6.06.1(04
BPSun
CNO
L
L
0414
3.22.1 6.02.1
BPSun
CNO
NSun
CNO
fitbest
Sun
CNO
L
L
L
L
L
L
GG
)3(%7
GGSun
CNO
L
L
0414
???? 5.00.1
BPSun
CNO
NSun
CNO
fitbest
Sun
CNO
L
L
L
L
L
L
GGSAGE
)3(%65
GGSAGESun
CNO
L
L
Carla Maria Cattadori 44Neutrino 2004, Paris 13-18 June
Finally with the listed assumptions and from the capture rate measured in Gallium experiments it is
possible to determine
RRGaGa pppp
[[101099 cm cm-2-2 s s-1 -1 ]]pp pp //
pp pp (BP04+N14)(BP04+N14)
69.3 69.3 OldOld 59.9 59.9 (1(1± ± 0.02 0.02 ± 0.01± 0.01theotheo)) 1.00(2)1.00(2)
68.1 68.1 NewNew 58.8 58.8 (1(1± ± 0.02)0.02) 0.98(4)0.98(4)
Fantastic agreement !!
Carla Maria Cattadori 45Neutrino 2004, Paris 13-18 June
(8B)meas = (0.89 ± 0.04ex ± 0.23theo) (8B) BP04 + N14
(7Be)meas = (0.91+0.24-0.62 ex ± 0.11theo) (7Be) BP04+N14
…. for 8B and 7Be
from BP04
Carla Maria Cattadori 46Neutrino 2004, Paris 13-18 June
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
5
50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100
Gallium Rate (SNU)
FC
NO
N14
/BP
04
0.954
0.970
0.983
1.000
1.016
Fp
p
GALLEX/GNO - all uncertainties
R = 69.3 +- 5.5 SNU
Comments: perfect agreement of Ga rate with SSM + oscillation scenario (pp) probed at 2% level (1 sigma)
(CNO) < 3.5 SSM (2 sigma)But to be totally model independent we need a measurement of (Be) at 10%
Measured
SS
M p
redi
ctio
nE
xper
imen
tal c
onst
rain
t
SSM
pre
dict
ion
Exp
erim
enta
l con
stra
int
Carla Maria Cattadori 47Neutrino 2004, Paris 13-18 June
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
5
50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100
Gallium Rate (SNU)
FC
NO
N14
/BP
00
0.954
0.970
0.983
1.000
1.016
Fp
p
GNO- all uncertainties
R = 62.9 +- 6.0 SNU
Comments: GNO is compatible with SSM + oscillation scenario at the level of 1 low values of the CNO flux are favored
GNO is at border GNO is at border of physical regionof physical region
Measured
Carla Maria Cattadori 48Neutrino 2004, Paris 13-18 June
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
5
50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100
Gallium Rate (SNU)
FC
NO
N14
/BP
00
0.954
0.970
0.983
1.000
1.016
Fp
p
GALLEX- all uncertainties
R = 77.5 +- 7.7 SNU
Comments: GALLEX is compatible with SSM + oscillation scenario within 2 The effect of GNO is important in the probe of the solar luminosity
Measured
Carla Maria Cattadori 49Neutrino 2004, Paris 13-18 June
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
5
50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100
Gallium Rate (SNU)
FC
NO
N14
/BP
00Gallium- 5% error
0.954
0.970
0.983
1.000
1.016
Fp
p B
P00
R = 70.0 +- 3.5 SNU
Carla Maria Cattadori 50Neutrino 2004, Paris 13-18 June
Are precision measurements possible with Gallium radiochemical experiments?
Carla Maria Cattadori 51Neutrino 2004, Paris 13-18 June
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
5
50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100
Gallium Rate (SNU)
FC
NO
N14
/BP
00Gallium- 3% error
0.954
0.970
0.983
1.000
1.016
Fp
p
Delta theta 1.5° - cross section measured at 1%Comments: Errors at the level of SSM uncertainties in pp flux
Carla Maria Cattadori 52Neutrino 2004, Paris 13-18 June
3 years of running; 4 weeks runs; 60% efficency; 70 SNU signal
Systematic error: 2.5 SNU ( GNO); not large improvements possible
30 tons30 tons 80 tons80 tons 160 tons160 tons
(GNO) (available gallium)
Det.evt.s 195 519 1040
Total accuracy 7 SNU7 SNU 4 SNU4 SNU 3 SNU3 SNU
Achievable accuracies
Carla Maria Cattadori 53Neutrino 2004, Paris 13-18 June
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
Carla Maria Cattadori 54Neutrino 2004, Paris 13-18 June
Conclusions
• Radiochemical experiments have provided along the last 40 years measurements of solar e interaction rate on 37Cl and on 71Ga
• 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 68.1 ± 3.7 ± 3.7 from 244 GALLEX+GNO+SAGE runsfrom 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 is constant
Carla Maria Cattadori 55Neutrino 2004, Paris 13-18 June
Taking (8B)meas = (0.89 ± 0.04ex ± 0.23theo) (8B) BP04 + N14
(7Be)meas = (0.91+0.24-0.62 ex ± 0.11theo) (7Be) BP04+N14
RRGaGa pppp
[10[1099 cm cm-2-2 s s-1 -1 ]]pp pp //
pp pp (BP04+N14)(BP04+N14)
69.3 69.3 OldOld 59.9 59.9 (1± 0.02 (1± 0.02 ± 0.01± 0.01theotheo)) 1.00(2)1.00(2)
68.1 68.1 NewNew 58.8 (1± 0.02)58.8 (1± 0.02) 0.98(4)0.98(4)
0414
3.22.1 )5.0(6.0)0.1(2.1
)( BPSun
CNO
NSun
CNO
fitbest
Sun
CNO
L
L
L
L
L
L
SGG
)3(%)6%5(%7)(
SGGSun
CNO
L
L
Carla Maria Cattadori 56Neutrino 2004, Paris 13-18 June
Extra slides
Carla Maria Cattadori 57Neutrino 2004, Paris 13-18 June
Radiochemical experimental techniqueRadiochemical experimental technique
t0
In synthesis lab
Add carrier1mg 72,74,76 Ge in GALLEX250mg 72,74,76 Ge in SAGE0.1 cc STP 36,38Ar in Chlorine exp.
ExtractionGa: GeCl4 with N2 Cl: Ar with Hestream
Wait Exposure time
Gallium (GeH4 + Xe), Chlorine (Ar + CH4)in counter V =1cc
1. Exposure
Counter in shielding
6 months for 76Ge12 months for 37Ar
Stop countingRemove counter
2. Extracted gas in counter
3.
Carla Maria Cattadori 58Neutrino 2004, Paris 13-18 June
Results of Chlorine experiment
Carla Maria Cattadori 59Neutrino 2004, Paris 13-18 June
Results of Chlorine experiment
Learning phase of these experiments is very long !
Carla Maria Cattadori 60Neutrino 2004, Paris 13-18 June
GALLEX – GNO
Test hypothesis of time constancy of signal:
1. Test of Likelihood Ratio C.L. 5.6 %
. 2 flat fit = 13.6 (6 d.o.f.) C.L. 3.4%
Carla Maria Cattadori 61Neutrino 2004, Paris 13-18 June
ImprovementsImprovements
Item Gallex GNO
Target size 0.8% 0.8%
Chemical yield 2.0% 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 1.2 SNU
Rn-cut inefficiency 1.2 SNU 0.5 SNU68Ge contamination +1.8 SNU
-2.6 SNU -
* Neural network analysis
Many improvements resulting in a reduction of a factor of 2 in the systematic error
Carla Maria Cattadori 62Neutrino 2004, Paris 13-18 June
RGa = pp pp Ppp + CNO CNO PCNO + 8 8 P8 + 7 7 P7 + pep pep Ppep
RGa = 69.3 ± 5.5 SNU
P
(SNO+SK+KAM)
P
(SNU)
pp 59.8 BP04+N14 1.310 11.7 0.578 40.4
7Be 4.86 BP04+N14 1.260 71.7 0.557 19.4
N 0.323 BP04+N14 0.346 60.2 0.557 1.1
O 0.254 BP04+N14 2.157 115 0.541 1.5
8B 0.00521 SNO 0.663 24500 0.324 4.1
pep 0.142 BP04+N14 1.192 15.7 0.531 1.2
TOT 67.7
N = 1.14 O
Composition of the Gallium signal
LSun = pp pp + CNO CNO + 8 8 + 7 7 + pep pep
Carla Maria Cattadori 63Neutrino 2004, Paris 13-18 June
Solar Models previsions for R (int.rate) in Radiochemical Experiments
RRCZ 715.0
new meas.from LUNA exp. of
S0(14N+p) =
1.77 keV ± 0.2
14N(p,)15O
(Z/X) old
=0.0229
Carla Maria Cattadori 64Neutrino 2004, Paris 13-18 June
Solar Models R previsions for Radiochemical experiments
Carla Maria Cattadori 65Neutrino 2004, Paris 13-18 June
Generalities on radiochemical experiments
e interaction reaction
Target comp. and mass
Exp. Time [d]
[d]
Data taking
Lab overburden
Chlorine
(Homestake Mine);South Dakota USA
e(37Cl,37Ar)e- C2Cl4
600 tons
Liquid
60-120 50.5 1964- 19934400 mwe
GALLEX/
GNO
LNGS Italy
e(71Ga,71Ge)e- GaCl3• HCl in H2O
100 t (30 t Ga)
21-28
28
16 1991-2003
2700 mwe
SAGE
Baksan
Kabardino Balkaria
e(71Ga,71Ge)e- Metallic Ga
55-49 tons
28 16 1990-ongoing
4800 mwe
Carla Maria Cattadori 66Neutrino 2004, Paris 13-18 June
Generalities on radiochemical experiments
Data used for R
determination
N runs
Average
efficiency
Hot chem check
Source calib
Rex
[SNU]
Chlorine(Homestake Mine);South Dakota USA
1970-1993
106 0.958
±
0.007
36Cl No 2.55 ± 0.17 ± 0.18
6.6% 7%
2.6 ± 0.3
GALLEX/GNOLNGS Italy
1991-2003
124 ?? 37As Yes
twice51Cr
source
69.3 ± 4.1 ± 3.6
5.9% 5%
SAGEBaksan
Kabardino Balkaria
1990-ongoing
104 ?? No Yes51Cr37Ar
70.5 ± 4.8 ± 3.7
6.8% 5.2%
70.5 ± 6.0