Angular Distribution of Bremsstrahlung from Copper and Tungsten Targets Bombarded by 18, 28, and 38MeV Electrons

We measured the angular distribution of bremsstrahlung photons between 0 and 120 degrees from copper and tungsten targets bombarded by 18, 28, and 38 MeV electrons at the electron linac of Hokkaido University.Activation detectors and two types of dosimeters were applied for the measurement.The measured results were compared with those calculated with the Monte Carlo code MCNP5 to verify the calculated results.The calculated results of both the reaction rates and ambient dose equivalent rates gave good agreement with the measured ones in the case of 18 MeV electrons.A good agreement between the measurement and calculation was also observed for relative angular distributions of dose rates from 38 MeV electrons; however, the calculation overestimated the measured data by a factor of 1.2 to 2.0.To achieve further accuracy of calculation, improvement of photonuclear reaction data and absorbed dose measurement are necessary for bremsstrahlung radiation dosimetry.