Application of the EXtrapolated Efficiency Method (EXEM) to infer the gamma-cascade detection efficiency in the actinide region

TL;DR

This paper applies the Extrapolated Efficiency Method (EXEM) to measure gamma-cascade detection efficiency in actinides, specifically for uranium and neptunium reactions, validating the method with statistical-model calculations.

Contribution

First application of EXEM to actinide region, demonstrating its effectiveness in inferring gamma-cascade detection efficiency in complex nuclei.

Findings

EXEM successfully inferred gamma-cascade efficiency in actinides.

Validation through Hauser-Feshbach calculations confirms the method's reliability.

Determined fission and gamma-decay probabilities of 239Np below neutron separation energy.

Abstract

The study of transfer-induced gamma-decay probabilities is very useful for understanding the surrogate-reaction method and, more generally, for constraining statistical-model calculations. One of the main difficulties in the measurement of gamma-decay probabilities is the determination of the gamma-cascade detection efficiency. In [Nucl. Instrum. Meth. A 700, 59 (2013)] we developed the Extrapolated Efficiency Method (EXEM), a new method to measure this quantity. In this work, we have applied, for the first time, the EXEM to infer the gamma-cascade detection efficiency in the actinide region. In particular, we have considered the 238U(d,p)239U and 238U(3He,d)239Np reactions. We have performed Hauser-Feshbach calculations to interpret our results and to verify the hypothesis on which the EXEM is based. The determination of fission and gamma-decay probabilities of 239Np below the neutron separation energy allowed us to validate the EXEM.