Study on NRF-CT Imaging by Laser Compton Backscattering Gamma-rays in UVSOR

Monochromatic gamma-ray beam in MeV energy region is suitable for non-destructive inspection of high density and massive objects because of its high penetrability. A specific nuclide can be detected by the process of Nuclear Resonance Fluorescence (NRF). A non-destructive inspection of Special Nuclear Materials hidden in a container cargo using NRF is proposed by Bertozzi*. Non-destructive detection of Pu inside of a spent nuclear fuel rod is also proposed for management of radioactive wastes, nuclear material accounting and safeguards**. We have developed 2D NRF imaging by using quasi-monochromatic gamma-ray beam in MeV energy region generated by Laser Compton Backscattering (LCS) method*** and proposed to develop an NRF-CT image in the ELI-NP where a high intensity LCS beam can be available in near future. To demonstrate and finalize the measurement system of the NRF-CT imaging by using LCS gamma-ray beam, we have started a study on NRF-CT imaging at the new LCS beamline in UVSOR. The LCS beamline can generate 5.4 MeV LCS gamma-rays with a flux of 1×10⁷ photons/s. We have measured the 5.291 MeV NRF gamma-rays from a lead target in this beamline and tried to take a NRF-CT image.