Neutron Capture Cross Section Measurements of 243Am For Neutron Energies up to 1 MeV at Dance With a Novel Technique on the Preparation of Actinide Targets

Abstract

Neutron capture reactions of actinides are of great importance for different applications in nuclear physics and stockpile stewardship. In the absence of underground testing, the safety, security, and reliability of the nuclear stockpile resides in the use of simulations and the application of scientific knowledge about the physical and chemical properties of the actinides to the specific problems of weapons aging. ^243Am has proven to be an important actinide whose neutron capture cross section is especially important. However, due to the actinides’ characteristics (radioactive, limited quantity, price, etc.), acquiring appropriate targets for these experiments has proven to be challenging. This thesis is divided into two parts. The first part contains a detailed description of a neutron capture cross-section measurement on ^243Am that took place at LANSCE, using the DANCE (Detector for Advanced Neutron Capture Experiments) array during the 2007 run cycle. The analysis and results from this experiment showcase the importance of appropriate targets, without which reliable cross-sectional data cannot be produced. The second part describes the development of a new target preparation method using spraying-assisted solution combustion synthesis. With this method, robust actinide targets of desired thicknesses and with the desired properties can be produced. Additionally, a complete characterization process was also developed, in order to fully characterize the produced targets regarding their thickness, composition, microstructure and uniformity. Finally, two new targets of ^243Am and ^243Am/^235U were produced for a new neutron capture cross-section measurement that will take place at LANSCE using the DANCE detector array and the new spallation source MARK – IV.