International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators

4-8 May 2009, Vienna
AP/IE-03

Nuclear Cross-Section Measurements at the Manuel Lujan Jr. Neutron Scattering
Center

M. Mocko, G. Muhrer, F. Tovesson, and J. Ullmann

Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America

Corresponding Author: mmocko@lanl.gov

The Los Alamos Neutron Science Center (LANSCE) is a versatile user facility built around a
proton linear accelerator. The 800-MeV proton beam is used to generate spallation neutrons in the Weapons Neutron Research (WNR) facility and the Lujan Center (LC) optimized for nuclear physics and materials science research, respectively. Even though the LC facility is used extensively for material research, two out of sixteen neutron flight paths (FP-5, FP-14) are devoted to nuclear physics experiments. The nuclear physics experiments (fission, neutron capture) carried out at these flight paths provide vital contributions to the nuclear data evaluation efforts. Better understanding of the systematic uncertainties of the experiments provides higher-quality data sets to the evaluators and allows for generation of reliable covariance matrices to be included in next releases of nuclear data libraries.

LC facility’s target is a rather complex system consisting of many different materials, requiring a very detailed geometry description in our calculation model. We will discuss our extensive Monte Carlo study carried out for the nuclear flight paths of the LC facility. The influence of the time distribution of the primary beam on the final response function of the LC target system will be presented. Our results will be compared to the experimental data showing a direction of actual implementation in the real data analysis.