Number 57 (Story #2), November 27, 1991 by Phillip F. Schewe and Ben Stein THE SOVIET-AMERICAN GALLIUM SOLAR NEUTRINO EXPERIMENT (SAGE) collaboration reports a neutrino capture rate of less than 79 solar neutrino units (1 SNU= 10-36 solar-neutrino captures per sec. per target atom), a rate less than that predicted (132 SNU) by the so-called Standard Solar Model. The SAGE detector, located at the Baksan Neutrino Observatory in the USSR, uses 30 tons of gallium to capture neutrinos produced inside the Sun during proton-proton fusion reactions. When the neutrinos reach the detector they will occasionally convert a gallium-71 nucleus into a germanium-71 nucleus. The level of extracted germanium therefore provides a measure of the incident solar neutrino flux. These first SAGE results are based on measurements carried out in January, February, March, April, and July 1990. The neutrino-flux shortfall seen in previous solar-neutrino experiments has prompted theorists to suggest either that the Sun was at fault (e.g., its core temperature was lower than we thought) or that neutrinos were at fault (e.g., neutrinos could transform from one type into another, fooling earthly detectors). The latter explanation is favored by the SAGE results since the rate for proton-proton fusion reactions is not dependent on the sun's core temperature. (A.I. Abazov et al., Physical Review Letters, 9 December 1991; for more information, contact Kenneth Lande, University of Pennsylvania, 215-898-8176.)