Measurements on branching ratios of dipole states in Ta-181 using transmission nuclear resonance fluorescence

Shizuma, Toshiyuki; Angell, C.; Hajima, Ryoichi; Ludewigt, B.*; Quiter, B. J.*; Koizumi, Mitsuo 

Quasi-monoenergetic laser Compton scattering photon beam was used for a transmission nuclear resonance fluorescence measurement on Ta-181. The experiment was carried out at Duke University. We used photon beams at energies of 2.28 and 2.75 MeV with energy width of about 4% to irradiate absorber and scattering targets of Ta-181 We measured scattered -rays from the scattering target using high-purity Ge detectors. As a result, we found three times more strength than the previously known values. In addition, we observed large branching of 75% at 2.28 MeV and 50% at 2.75 MeV going to excited states from resonances. In this presentation, we will report on the measurement method and the experimental results. We will also talk about the future plan for development of non-destructive assay using mono-energetic laser Compton scattering -ray beam.