Photo Neutron Cross Sections in Na²³ and Si²⁸

Abstract

Photoneutron cross sections in Na²³ and Si²⁸ were measured using BF₃ proportional counters. In the case of Na²³, the cross section shows a rather sharp resonance at the energy of 14.4 Mev and there is evidence in favor of giant resonance splitting. The breaks are observed at 13.1, 14.2, and 15.3 Mev in the Na²³ (γ, n) Na²² yield curve. In the case of Si²⁸, the cross section seems to consist of two peaks in the vicinity of 20 Mev, but as a result of the poor statistics, the detailed shape of the cross section is uncertain.