Validating polarization effects in -rays elastic scattering by Monte Carlo simulation

モンテカルロ・シミュレーションによるガンマ線断線散乱における偏光への影響評価

Omer, M.  ; 羽島 良一*

Omer, M.; Hajima, Ryoichi*

Nuclear resonance fluorescence (NRF) is a promising technique for nondestructive assay (NDA) of nuclear materials. Its strength is improved when polarized -ray beams are used as probes because the polarized -rays provide an asymmetry in the intensity of the scattered photons. Nonetheless, NRF interaction takes place with other interactions such as elastic scattering of -rays. These interactions are unavoidable background which may limit the sensitivity of the NRF technique. Therefore, estimating polarization effects of elastic scattering is a significant factor in assessing the NRF method. Here, we implement a new Monte Carlo simulation to account for polarization effects of the elastic scattering. The simulation is based on explicit expressions driven in the Stokes parameters formalism. The scattering amplitudes of Rayleigh, nuclear Thomson, and Delbrck scattering processes have been superimposed into a two-orthogonal set of complex amplitudes. This set is then exploited to construct the core of the simulation in a way such that the simulation could handle arbitrary polarization states of the incoming beam and correspondingly generate polarization states for the outgoing beam. This work was supported by the subsidiary for promotion of strengthening nuclear security or the like of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.