Measurement of the ⁶⁵Cu Neutron-Capture Cross Section for Constraining s-process Nucleosynthesis

Determining the origin of the elements in the observable universe requires detailed knowledge of the salient nuclear physics, such as neutron-capture cross-sections.  Recently, the neutron-capture cross-sections of two isotopes, important for the s-process, ^63,65Cu, have been called into question.  A measurement from 2008 reduced the neutron-capture cross sections of ^63,65Cu by ~65% and ~40%, respectively.  However, a more recent measurement of ⁶³Cu agrees well with the higher cross section from measurements prior to the 2008 work.   This discrepancy is understood as a systematic bias in the 2008 measurement originating from the natural Cu backing material of the neutron production target not properly accounted for when determining the neutron flux.  Moreover, it is likely the same systematic bias observed in the 2008 work for ⁶³Cu is present for their ⁶⁵Cu result as well, and the currently accepted neutron-capture cross section is far too low.   Recently, neutron capture on ⁶⁵Cu was measured using the Detector for Advanced Neutron Capture Experiments was performed at Los Alamos National Laboratory and preliminary results presently agree well with the older measurements.  Analysis and results of this most recent measurement will be presented.