MEASUREMENT OF FISSION PRODUCT YIELDS FROM FAST-NEUTRON-INDUCED FISSION

摘要

One of the aims of the Stockpile Stewardship Program is a reduction of the uncertainties on fission data used for analyzing nuclear test data [1,2]. Fission products such as ~(147)Nd are convenient for determining fission yields because of their relatively high yield per fission (about 2%) and long half-life (10.98 days). A scientific program for measuring fission product yields from ~(235)U,~(238)U and ~(239)Pu targets as a function of bombarding neutron energy (0.1 to 15 MeV) is currently underway using monoenergetic neutron beams produced at the 10 MV Tandem Accelerator at TUNL. Dual-fission chambers are used to determine the rate of fission in targets during activation. Activated targets are counted in highly shielded HPGe detectors over a period of several weeks to identify decaying fission products. To date, data have been collected at neutron bombarding energies 4.6,9.0,14.5 and 14.8 MeV. Experimental methods and data reduction techniques are discussed, and some preliminary results are presented.