THE SOLAR-NEUTRINO CAPTURE CROSS-SECTION FOR NA-23

A coincidence (electron, gamma-ray) experiment designed to identify on e or more components of the solar neutrino spectrum has been proposed based on a large array of NaBr detectors. In support of the design of this detector, we calculate the solar neutrino absorption rate for v Na-23 --> Mg-23 + e- within the Standard Solar Model making use of bo th experimental and theoretical data for the structure of the two nucl ei involved. It is found that the inclusion of excited states in Mg-23 enhances the absorption cross section by almost-equal-to 30%, with ap proximately one third of this enhancement coming from excited states f or which experimental data does not exist. The solar neutrino absorpti on rate is calculated to be 3.5 +/- 1.3 SNU, which amounts to about on e count every six days for the proposed detector.