Neutron Scattering Cross Section Measurements for $^{169}$TM via the Time-of-Flight Technique

This research entails the first direct neutron scattering cross section measurements for $^{169}$Tm via the time-of-flight technique. Neutron elastic and inelastic cross-section angular distributions were measured at 590-keV and 1000-keV incident neutron energies. Differential cross-section excitation functions were also measured in 0.1-MeV steps at 125$^{o}$ (scattering angle) from 495-keV to 1000-keV incident energy. The elastic measurements in the 0.5-MeV to 1.0-MeV incident neutron energy range compare favorably with the JENDL-4.0 evaluation based on nuclear reaction model calculations in the Japanese Evaluated Nuclear Data Library. The inelastic measurements are compared to JENDL-4.0 and to earlier measurements by Ko \textit{et al}. (\textit{Nucl. Phys.} \textbf{A679}, 147-162 (2000)) who used the (n,~n'~$\gamma )$ technique for states above 100 keV in excitation. The measurements were made using the UMass Lowell 5.5-MV Van de Graaff accelerator, operated in the pulsed and bunched beam mode, producing subnanosecond proton pulses at a 5-MHz repetition rate to generate neutrons via the $^{7}$Li(p,n)$^{7}$Be reaction in a thin metallic elemental lithium target.