While neutrons were not discovered until 1932 [1], already in 1920 Sir Ernest Rutherford had hypothesized the "possible existence of an atom of mass 1 which has zero nucleus charge" [2] to explain the constitution of elements heavier than hydrogen. Since then we have come to understand that nuclear reactions involving the capture of a neutron touch every area of modern life. We exist because many of the elements heavier than iron were created in stars in a process that involves the rapid capture of neutrons (the r process). Our understanding of neutron capture reactions plays an important role in safe nuclear power generation and in guaranteeing the reliability of our nuclear stockpile without a return to testing. However, it is not possible to constrain important neutron-capture cross sections on many of the isotopes of interest to these processes, due either to the unstable nature of the target or the neutron. Because understanding the neutron-capture reaction is so important to our society, there has been an increased effort in recent years to develop indirect methods to constrain the cross section for this reaction on unstable nuclei. The surrogate reactions method, in which a reaction is chosen which will form the "same" compound nucleus as the desired (in this case neutron-capture) reaction, is one such technique. The decay of the compound nucleus is measured, and the resulting data are used to constrain the calculation of the neutron-capture cross section. This method has recently been benchmarked using a measurement of the 95Mo(d,p) reaction against the available 95Mo(n,γ) cross section. There is excellent agreement between the experimentally-constrained and known cross sections. A century after Sir Ernest’s first reaction, this study opens the door to exciting new measurements in the vibrant field he was instrumental in creating.

Constraining neutron-capture reactions through the surrogate reactions method

2019 Fall National Meeting

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