Measurement of the Tm168(n,n’) and Tm168(n,2n) cross section using surrogate reactions*

The direct reaction Tm169(a,a’)Tm169 was used as a surrogate reaction for Tm169(n,n’) and Tm169(n,2n). A 55 MeV alpha beam was used to induce reactions on Tm169, C12 and a mylar target. The (a,a’xn) reactions on these targets were measured using the LLNL NeutronSTARS array located at the Texas A&M Cyclotron Institute. Particle singles events were measured for each target over an angle range of approximately 32 to 60 degrees with respect to the beam direction. Neutrons were detected in coincidence with the scattered particles using a 2.2-ton Gd doped liquid scintillator detector that surrounded the main reaction chamber. The surrogate cross sections of the Tm168(n,xn) reactions will be compared to the known Gd155(n,xn) cross sections. Progress on the surrogate Tm168(n,xn) cross sections and the measurement technique will be presented.