Measurement and calculation of gamma ray transport in concrete

A gamma-ray spectroscopy system using a 5-cm by 5-cm NE-213 organic scintillator was used for the measurement of gamma-ray pulse-height spectra behind four concrete slabs of different thickness. The pulse-height data was fed to the Tsing-Hua gamma-ray response matrix coupled with FORIST code to evaluate the experimental spectra. The experimental results were compared to ANISN discrete ordinates calculations. The ANISN calculations used DLC-23E data library with 22 neutron and 18 gamma-ray groups. The experimental and numerical results were in good agreement for 30 cm and 40 cm concrete slabs in the energy ranging from 0.1 MeV to 0.7 MeV, and large disagreement was evident for 10 cm and 20 cm slabs. The calculated fluxes overpredicted the measurements. At upper energies namely between 0.4 - 0.7 MeV, very good agreement was obtained for the four concrete slabs. The main source of disagreement was due to Tsing-Hua response matrix and poor modeling of one dimensional code. 36 Ref