Reliability of prompt gamma-ray analysis for the determination of Na and Mg in rock samples.

The reliability of neutron-induced prompt gamma-ray analysis (PGA) was examined for the determination of Na and Mg in geological and cosmochemical rock samples, because they tend to have been erroneously determined for such samples. JB-1 (basalt standard rock) and Allende (chondritic meteorite) powder samples were repeatedly analyzed by using thermal or cold neutron-guided beams of the JRR-3M research reactor at Japan Atomic Energy Agency. In critically evaluating calculated values for major prompt gamma-rays of Na and Mg, it was observed that a 472.2 keV peak for Na and a 2828.2 keV peak for Mg yielded reasonable consistency with corresponding recommended values. Sodium and Mg were determined for five lunar meteorites by PGA using these prompt gamma-rays, and were found to be consistent with their data obtained by instrumental neutron activation analysis.