The effects of neutron scattering by matrix hydrogen in geological samples were examined in order to accurately determine their chemical compositions by neutron-induced prompt gamma-ray analysis (PGA). Three different matrix materials including basaltic reference rock sample (JB-2) mixed with chemical reagents including H-containing ones were analyzed by using thermal and/or cold neutron-guided beams of JRR-3 at Japan Atomic Energy Agency. The sensitivity change of elements with the variation of the H concentrations was evaluated for disk and spherical target geometries. The results show that the analytical sensitivities of B, Cl and Cd in disk samples seem to increase with increasing the matrix H concentrations by the irradiation of both thermal and cold-neutron beams. The sensitivity enhancement of B for disk-shaped JB-2 mixed with up to 2% mass H is within the analytical uncertainty associated with PGA with a thermal-neutron beam.
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