Data Analysis of Neutron Capture Measurements on arsenic-75 using DANCE

Paul Ellison, University of Califoria, Berkeley

During the summer of 2008, I performed my practicum under the supervision of Dr. David Vieira as part of the Nuclear Chemistry team in the Nuclear and Radiochemistry group at Los Alamos National Laboratory. For my research project, I analyzed data taken on 75As with the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center (LANSCE).

Arsenic has been used as a radiochemical detector in the Nevada Test Site test program to obtain neutron fluence and device performance information. It is also relevant to the rapid and slow processes of nucleosynthesis. For these reasons it is desirable to have precise measurements of the neutron-induced reaction cross sections on both its stable and radioactive isotopes.

In September 2007, an initial neutron capture measurement on 75As was taken using the DANCE at LANSCE. Since then, the data has only been analyzed in a preliminary fashion to study background and determine optimal acquisition settings for the irradiation of a thicker 75As target to take place in 2008. It was my practicum.s research goal to thoroughly analyze this 75As neutron capture data taken in 2007.

The thorough analysis of this data involves several steps. First, each of the 160BaF2 detectors must be properly calibrated in both energy and time. Then, the background rates in the detectors must be determined by the analysis of data taken under the same experimental conditions as the 75As target, but without the 75As target material. Analysis of the individual neutron energy resonances allows for the calculation of the efficiency of the DANCE array for a given set of conditions.

Upon completion, this data will be used in conjunction with the measurements of thicker 75As targets taken in 2008 to get the best experimental value for its neutron capture cross section.

Abstract Author(s): Paul Ellison