Total cross-section measurements of ¹⁶⁹Tm below 100 eV

The neutron total cross-sections of thulium (¹⁶⁹Tm) were measured in the neutron energy region from 0.01 eV to 100 eV by using the time-of-flight method at the Pohang Neutron Facility, which consists of an electron linac, a water-cooled tantalum target with a water moderator, and a 12-m- long time-of flight path. Two thulium plates with different thicknesses were used for the neutron transmission measurement. The background level was determined by using a notch-filter of Co, In, and Cd sheets. The present measurement was compared with the previous ones, while a new set of resonance parameters of Tm-169 isotope was obtained from the transmission ratio by using the SAMMY code, with a comparison with the recommended parameters by Mughabghab.