Neutron Capture Reaction Cross-section Data Processing and Resonance Parameter Analysis of ¹⁹⁷Au Based on White Light Neutron Source

Abstract

The neutron capture reaction plays an important role in reactor operation, nuclear device design, and nuclear astrophysics research. Neutron capture reaction is one of the neutron reactions that plays an important role in the use of reactor control rods and shell materials, the design of nuclear device structures, and the study of nuclear astrophysics S processes and element origins. The 4π BaF₂ detection device has advantages such as high time resolution, low neutron sensitivity, and high detection efficiency, making it suitable for measuring neutron radiation capture reaction cross-section data. In order to fill the gap in domestic neutron capture reaction data in the keV energy range and improve the accuracy of Chinese nuclear data, the Key Laboratory of Nuclear Data at the Chinese Institute of Atomic Energy (CIAE) has established a Gamma Total Absorption Facility (GTAF), which consists of 28 hexagonal BaF₂ crystals and 12 pentagonal BaF₂ crystals to form a spherical shell with an outer diameter of 25cm and an inner diameter of 10cm, covering 95.2% of the solid angles. The Back-n beam line of the Chinese Spallation Neutron Source (CSNS) is a back-streaming white beam line that covers neutron energy ranging from a few eV to several hundred MeV, making it suitable for measuring neutron capture cross-sections. The reaction cross-section data of ¹⁹⁷Au was measured using GTAF on the Back-n beam line. The measurement data was preliminarily background deducted through energy screening, PSD method, and crystal multiplicity screening. Subsequently, the background was analyzed and deducted based on the measurement data of ^natC and empty samples, and the yield of ¹⁹⁷Au capture reaction was obtained. Resonance parameters are a set of parameters extracted from experimental data to describe the resonance curve, which can eliminate the influence of experimental conditions on resonance data and are more important than the cross-section obtained from experiments. The resonance energy, neutron resonance width, and gamma resonance width parameters of ¹⁹⁷Au at 1-100eV were fitted using the SAMMY program. Comparing the resonance curves obtained from experimental measurements and the resonance parameters obtained from fitting with the ENDF/B-VIII.0 database, it can be found that the experimental measurement results are in good agreement with the database, and there are certain differences in the resonance parameters. The analysis of the reasons may be related to the GTAF energy resolution, Back-n neutron spectrum measurement accuracy, and the experimental background deduction method, which is also the focus of the next step of work.