Preliminary results of new GELINA data for natural cadmium

The total neutron cross section of cadmium (Cd) is very large in the thermal neutron energy region which determines its special role in reactor technology. The first resonance of ¹¹³Cd at 0.178 eV is of high importance in the interpretation of Cd neutron cross section structure in the thermal region. The evaluated data files for Cd isotopes and particularly the resonance parameters do not correspond to the requirements of the advanced reactor technologies. To provide data for a new evaluation, a set of top quality transmission experiments has been designed and performed at the neutron time-of-flight facility GELINA at the Institute for Reference Materials and Measurements (IRMM) in Geel, Belgium. The measurements have been carried out at 26.45 m and 50 m flight paths of GELINA at 50 Hz, 400 Hz and 800 Hz working frequencies of the LINAC, using natural Cd samples with various thicknesses (purity 99.99% in Cd). The experiments at 50 Hz provide high quality data in the thermal energy region, from which we could extract the resonance parameters for the first resonance of ¹¹³Cd at 0.178 eV with high accuracy.

Considering the transmission data obtained with various sample thicknesses as a source of additional information for low level cross section we validate a new approach for cross section description in this energy region.