Session 26 - Neutrinos & Stellar Abundances.
Oral session, Wednesday, January 07
Jefferson,

## [26.01] Gallium solar neutrino experiments

J. Bahcall (Inst. for Advanced Study)

Neutrino absorption cross sections for \rm^71Ga are calculated for all solar neutrino sources with standard energy spectra, and for laboratory sources of \rm^51Cr and \rm^37Ar; the calculations include, where appropriate, the thermal energy of decaying solar ions and use improved nuclear and atomic data. The ratio, R, of measured (in GALLEX and SAGE) to calculated ^51Cr capture rate is R = 0.95 \pm 0.07 (exp) + ^+0.04_-0.03 (theory). Cross sections are also calculated for specific neutrino energies chosen so that a spline fit determines accurately the event rates in a gallium detector even if new physics changes the energy spectrum of solar neutrinos. Theoretical uncertainties are estimated for cross sections at specific energies and for standard neutrino energy spectra. Standard energy spectra are presented for pp and CNO neutrino sources in the appendices. Neutrino fluxes predicted by standard solar models, and minimal standard electroweak theory, when corrected for diffusion, have been in the range 120 SNU to 141 SNU since 1968. The measured rate is 70.5 \pm 7 SNU.