SAGE (Soviet-American Gallium Experiment)

SAGE (Soviet–American Gallium Experiment, or sometimes Russian-American Gallium Experiment) is a collaborative experiment devised by several prominent Physicists to measure the solar neutrino flux.

The Experiment

SAGE was devised to measure the radio-chemical solar neutrino flux based on the inverse beta decay reaction, $\{\}^\{71\}\; \{Ga\}\; left(\{v\}\_\{e\},e^\{-\}\; ight)\{\}^\{71\}\; \{Ge\}$. The target for the reaction was 55-57 tonnes of liquid gallium metal stored deep underground at the Baksan Neutrino Observatory in the Caucasus mountains in Russia. About once a month, the neutrino induced Ge is extracted from the Ga. $\{\}^\{71\}\; \{Ge\}$ is unstable with respect to electron capture ($t\_\{1/2\}=11.43$ days) and, therefore, the amount of extracted Ge can be determined from its activity as measured in small proportional counters. The experiment has measured the solar neutrino flux in 31 extractions between January 1990 and October 1993. The result of these experiments was 73 +16/-18 (statistical) +5/-7 (systematic) SNU. This represents only 56%-60% of the capture rate predicted by different Standard Solar Models, which predict 138 SNU. Additional extractions through the end of 1994 are awaiting analysis.

The Russian-American collaboration has used a $\{518\}-\{kCi\}$ $\{\}^\{51\}\; \{Cr\}$ neutrino source to test the experimental operation. The energy of these neutrinos is similar to the solar $\{\}^7\; \{Be\}$ neutrinos and thus makes an ideal check on the experimental procedure. The extractions for the Cr experiment took place between January and May of 1995 and the counting of the samples lasted until fall. The bulk of the analysis of the data has been completed. The result, expressed in terms of a ratio of the measured production rate to the expected production rate, is 1.0±0.15. This indicates that the discrepancy between the solar model predictions and the SAGE flux measurement cannot be an experimental artifact.

Members of SAGE

SAGE was lead by the following Physicists:

*Vladimir Gavrin
*Georgiy Zatsepin (Joint Institute for Nuclear Research, Russia)
*Tom Bowles (Los Alamos)

ee also

*Hans Bethe was the architect of the theory of nuclear fusion reactions in stars.
*The University of Washington is playing a major role in the statistical analysis of the SAGE data and in the determination of systematic uncertainties. They are very active in the remaining analysis of the Cr experiment data as well as the solar neutrino data.

External links

* [http://cat.inist.fr/?aModele=afficheN&cpsidt=4077673 Results of the experiments]
* [http://www.peoplesarchive.com/browse/movies/2119/en/ Hans Bethe talking about SAGE] on Peoples Archive