Study of Gamma Radiation from Interaction of 14.7-MeV Neutrons with208Pb

Abstract

The gamma radiation from the interaction of 14.7-MeV neutrons with {sup 208}Pb is investigated by high-resolution germanium-detector gamma-ray spectroscopy by using an enriched {sup 208}Pb sample. Cross sections for 14 gamma-ray lines from the {sup 208}Pb(n,n{prime}{gamma}) and {sup 208}Pb(n,2n{gamma}) reactions are measured at an emission angle of 124 deg. The results are compared with measurements from previous studies and with predictions based on the statistical theory of nuclear reactions (including direct and precompound contributions). The current results, especially for the {sup 208}Pb(n,n{prime}{gamma}) reaction, are considerably smaller than the results of most of the measurements of the previous studies probably because of the neglect of important sources of background, e.g., gamma-ray production in lead shielding, in the previous studies. Agreement with theory is adequate for the strong transitions between the lowest levels in {sup 207}Pb and {sup 208}Pb, but large discrepancies exist for the weaker transitions, especially for gamma-ray transitions from levels where experimental knowledge of branching ratios is missing. The study of the gamma radiation from the interaction of 14-MeV neutrons with lead is essential for accurate prediction of the gamma-ray heating in such devices. In addition, the nucleus {sup 208}Pb is especially studied as a test case for detailedmore » comparison of the predictions of nuclear reaction theory with experiments.« less