MEASUREMENT OF TOTAL NEUTRON CROSS SECTION FOR Sm, Gd AND Dy IN THE THERMAL ENERGY REGION
Atomic Energy Research Laboratory
Musashi Institute of Technology
Ozenji 971, Asao-ku, Kawasaki, Japan
Century Research Center Corporation
3-6-2 Nihonbashi, Hon-cho, Chuo-ku, Tokyo, Japan
The method to measure total neutron cross sections in the thermal energy region was established with the chopper and time-of-flight facility installed at the Musashi reactor (TRIGA-II, 100kW). To date, the facility was used primarily for measuring samples which were essentially scatterers. The method successfully developed in this research was newly applied to samples having very large absorption cross section. Cross sections were measured for natural Sm, Gd and Dy by using the Al powder dilution method. Comparison of the measured cross sections with published data showed satisfactory agreement, but the results obtained for Sm and Gd at 0.0253 eV showed slightly lower values than the data published in BNL-325 3rd ed. The g-factors obtained by Westcott for these absorbers, however, were independently evaluated based on the result of this research, and found to be in good agreement with the published figures.
KEYWORDS: total neutron cross section, time-of-flight, Westcott g-factor, natural Sm, Gd, Dy, dilution method