Cross section measurements of the $^{152}$Sm($\gamma$,n)$^{151}$Sm reaction near threshold

Neutron capture cross sections of the unstable nucleus $^{151}$Sm (t$_{1/2}$=90~yr) are the fundamental data for nuclear transmutation and nuclear astrophysics. The $^{151}$Sm is one of radioactive fission products in the nuclear waste. In order to determine the (n,$\gamma$) transmutation rate of this nucleus, the experimental data are desired to be available in the energy range from thermal to MeV. On the other hand, the branching point nucleus $^{151}$Sm is important for characterizing the s-process nucleosynthesis in AGB stars. The inverse $^{152}$Sm($\gamma$,n)$^{151}$Sm reaction was measured near threshold at the AIST facility. Beams of quasi-monochromatic photons from laser Compton scattering (LCS) irradiated an enriched $^{152}$Sm sample. We present the experimental method with the LCS $\gamma$ beam and photoneutron cross sections for $^{152}$Sm. The present data will be used to evaluate the capture cross section of $^{151}$Sm with the Hauser-Fechbach statical model.