Measurement Of 238un Ngamma And 7li N Ngamma Gamma Ray Production Cross Sections

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Download or read book Partial [gamma]-Ray Cross Sections for the Reaction 239Pu(n,2n(gamma)i) and the 239Pu(n,2n) Cross Section written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Absolute partial [gamma]-ray cross sections for production of discrete [gamma] rays in the 239Pu(n,2n[gamma]i)238Pu reaction have been measured. The experiments were performed at LANSCE/WNR on the 60R flight line. Reaction [gamma]-rays were measured using the large-scale Compton-suppressed array of Ge detectors, GEANIE. The motivation for this experiment, an overview of the partial [gamma]-ray cross-section measurement, and an introduction to the main experimental issues will be presented. The energy resolution of the Ge detectors allowed identification of reaction [gamma] rays above the background of sample radioactivity and fission [gamma] rays. The use of planar Ge detectors with their reduced sensitivity to neutron interactions and improved line shape was also important to the success of this experiment. Absolute partial [gamma]-ray cross sections are presented for the 61 2!41 member of the ground state rotational band in 238Pu, together with miscellaneous other [gamma]-ray partial cross sections. The n,2n reaction cross section shape and magnitude as a function of neutron energy was extracted from these partial cross sections using nuclear modeling (enhanced Hauser-Feshbach) to relate partial [gamma]-ray cross sections to the n,2n cross section. The critical nuclear modeling issue is the ratio of a partial cross section to the reaction channel cross section, and not the prediction of the absolute magnitude.