Measurement of the 169Tm(n, 3n)167Tm cross section and the associated branching ratios in the decay of 167Tm.

The cross section for the 169Tm(n,3n) 167Tm reaction was measured from 17 to 22 MeV using quasimonoenergetic neutrons produced by the ²H(d,n) ³He reaction. This energy range was studied to resolve the discrepancy between previous (n,3n) cross-section measurements. In addition, the absolute γ -ray branching ratios following the electron-capture decay of 167Tm were measured. These results provide more reliable nuclear data for an important diagnostic that is used at the National Ignition Facility to estimate the yield of reaction-in-flight neutrons produced via the inertial-confinement-fusion plasma in deuterium-tritium capsules. [ABSTRACT FROM AUTHOR]