26 research outputs found
The BNO-LNGS joint measurement of the solar neutrino capture rate in 71Ga
We describe a cooperative measurement of the capture rate of solar neutrinos
by the reaction 71Ga(\nu_e,e^-)71Ge. Extractions were made from a portion of
the gallium target in the Russian-American Gallium Experiment SAGE and the
extraction samples were transported to the Gran Sasso laboratory for synthesis
and counting at the Gallium Neutrino Observatory GNO. Six extractions of this
type were made and the resultant solar neutrino capture rate was 64
^{+24}_{-22} SNU, which agrees well with the overall result of the gallium
experiments. The major purpose of this experiment was to make it possible for
SAGE to continue their regular schedule of monthly solar neutrino extractions
without interruption while a separate experiment was underway to measure the
response of 71Ga to neutrinos from an 37Ar source. As side benefits, this
experiment proved the feasibility of long-distance sample transport in ultralow
background radiochemical experiments and familiarized each group with the
methods and techniques of the other.Comment: 7 pages, no figures; minor additions in version
Measurement of the Solar Neutrino Capture Rate by the Russian-American Gallium Solar Neutrino Experiment During One Half of the 22-Year Cycle of Solar Activity
We present the results of measurements of the solar neutrino capture rate in
gallium metal by the Russian-American Gallium Experiment SAGE during slightly
more than half of a 22-year cycle of solar activity. Combined analysis of the
data of 92 runs during the 12-year period January 1990 through December 2001
gives a capture rate of solar neutrinos with energy more than 233 keV of 70.8
+5.3/-5.2 (stat.) +3.7/-3.2 (syst.) SNU. This represents only slightly more
than half of the predicted standard solar model rate of 128 SNU. We give the
results of new runs beginning in April 1998 and the results of combined
analysis of all runs since 1990 during yearly, monthly, and bimonthly periods.
Using a simple analysis of the SAGE results combined with those from all other
solar neutrino experiments, we estimate the electron neutrino pp flux that
reaches the Earth to be (4.6 +/- 1.1) E10/(cm^2-s). Assuming that neutrinos
oscillate to active flavors the pp neutrino flux emitted in the solar fusion
reaction is approximately (7.7 +/- 1.8) E10/(cm^2-s), in agreement with the
standard solar model calculation of (5.95 +/- 0.06) E10/(cm^2-s).Comment: English translation of article submitted to Russian journal Zh. Eksp.
Teor. Fiz. (JETP); 12 pages, 5 figures. V2: Added winter-summer difference
and 2 reference
Measurement of the solar neutrino capture rate with gallium metal
The solar neutrino capture rate measured by the Russian-American Gallium
Experiment (SAGE) on metallic gallium during the period January 1990 through
December 1997 is 67.2 (+7.2-7.0) (+3.5-3.0) SNU, where the uncertainties are
statistical and systematic, respectively. This represents only about half of
the predicted Standard Solar Model rate of 129 SNU. All the experimental
procedures, including extraction of germanium from gallium, counting of 71Ge,
and data analysis are discussed in detail.Comment: 34 pages including 14 figures, Revtex, slightly shortene
The Baksan gallium solar neutrino experiment
A radiochemical 71Ga-71Ge experiment to determine the integral flux of neutrinos from the sun has been constructed at the Baksan Neutrino Observatory in the USSR. Measurements have begun with 30 tonnes of gallium. An additional 30 tonnes of gallium are being installed so as to perform the full experiment with a 60-tonne target. The motivation, experiment procedures, and present status of this experiment are described. © 1990
First results from the Soviet-American gallium experiment
The Soviet-American Gallium Experiment is the first experiment able to measure the dominant flux of low energy p-p solar neutrinos. Four extractions made during January to May 1990 from 30 tons of gallium have been counted and indicate that the flux is consistent with 0 SNU and is less than 72 SNU (68% CL) and less than 138 SNU (95% CL). This is to be compared with the flux of 132 SNU predicted by the Standard Solar Model. © 1991
Measurement of the response of a gallium metal solar neutrino experiment to neutrinos from a [Formula Presented] source
The neutrino capture rate measured by the Russian-American Gallium Experiment is well below that predicted by solar models. To check the response of this experiment to low-energy neutrinos, a 517 kCi source of [Formula Presented]Cr was produced by irradiating 512.7 g of 92.4%-enriched [Formula Presented]Cr in a high-flux fast neutron reactor. This source, which mainly emits monoenergetic 747-keV neutrinos, was placed at the center of a 13.1 ton target of liquid gallium and the cross section for the production of [Formula Presented]Ge by the inverse beta decay [Formula Presented] was measured to be [Formula Presented] The ratio of this cross section to the theoretical cross section of Bahcall for this reaction is 0.95 ±0.12 [Formula Presented] (theor) and to the cross section of Haxton is 0.87±0.11 (expt)±0.09 (theor). This good agreement between prediction and observation implies that the overall experimental efficiency is correctly determined and provides considerable evidence for the reliability of the solar neutrino measurement. © 1999 The American Physical Society
The russian-american gallium experiment (sage) cr neutrino source measurement
The solar neutrino capture rate measured by SAGE is well below that predicted by solar models. To check the overall experimental efficiency, we exposed 13 tonnes of Ga metal to a reactor-produced 517 kCi source of 51Cr. The ratio of the measured production rate to that predicted from the source activity is 0.95+/-0.11+0.05/-0.08. This agreement verifies that the experimental efficiency is measured correctly, establishes that there are no unknown systematic errors at the 10% level, and provides considerable evidence for the reliability of the solar neutrino measurement. © 1996 The American Physical Society
Measurement of the solar neutrino capture rate by SAGE and implications for neutrino oscillations in vacuum
The Russian-American solar neutrino experiment has measured the capture rate of neutrinos on metallic gallium in a radiochemical experiment at the Baksan Neutrino Observatory. Eight years of measurement give the result 67.2 (+7.2,-7.0) (+3.5,-3.0) SNU, where the uncertainties are statistical and systematic, respectively. The restrictions these results impose on vacuum neutrino oscillation parameters are given
Preliminary results from the Russian-American Gallium Experiment Cr-neutrino source measurement
The Russian-American Gallium Experiment has been collecting solar neutrino data since early 1990. The flux measurement of solar neutrinos is well below that expected from solar models. We discuss the initial results of a measurement of experimental efficiencies by exposing the gallium target to neutrinos from an artificial source. The capture rate of neutrinos from this source is very close to that which is expected. The result can be expressed as a ratio of the measured capture rate to the anticipated rate from the source activity. This ratio is 0.93 + 0.15, - 0.17 where the systematic and statistical errors have been combined. To first order the experimental efficiencies are in agreement with those determined during solar neutrino measurements and in previous auxiliary measurements. One must conclude that the discrepancy between the measured solar neutrino flux and that predicted by the solar models can not arise from an experimental artifact