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The conflict between the production capacity and demand for medical radioisotopes has become more prominent. In addition, for some new types of medical radioisotopes, neutron, and proton-induced reactions are not the best way to generate them with high specific activity. The research status of medical radioisotopes is introduced, then the gamma facility and potential new medical radioisotope candidates based on photonuclear reaction are widely surveyed. The production of medical radioisotope 186 g Re is simulated based on the Laser Compton Scattering (LCS) gamma source and bremsstrahlung gamma source. It is found that the next generation quasi-monochromatic, high-flux LCS gamma source can produce medical radioisotope 186 g Re with less than 0.05% 188Re impurity with around 400 mb cross section. Meanwhile, the bremsstrahlung gamma source can produce around 200 MBq/g specific activity medical radioisotope 186 g Re with realistic electron intensity 3.125 mA. This study and simulations show that photonuclear reaction can be regarded as an alternative route for producing medical radioisotopes. • Study on photonuclear method for high-specific-activity medical isotopes. • Provided a wide survey of potential gamma transmutation medical radioisotopes. • Explored strengths of quasi-monoenergetic and bremsstrahlung γ for 186gRe production. [ABSTRACT FROM AUTHOR]

This study aims to formulate semi-empirical processing applied to analyze simulated and experimental scattering spectra on pipeline samples for estimating the intensity of the single scattering component for the Compton scattering technique. Firstly, a procedure has been developed based on probability density functions of each scattering component, which are obtained by GEANT4. Secondly, sixteen targets are simulated with MCNP6 to validate the proposed procedure. It is shown that the relative deviation for all samples is under 3%. Thirdly, the nine calculated thickness of pipeline samples is determined with a maximum relative deviation lower than 5% in comparing to calibration thickness. [ABSTRACT FROM AUTHOR]

The production, application, and/or measurement of polarised X-/gamma rays are key to the fields of synchrotron science and X-/gamma-ray astronomy. The design, development and optimisation of experimental equipment utilised in these fields typically relies on the use of Monte Carlo radiation transport modelling toolkits such as Geant4. In this work the Geant4 "G4LowEPPhysics" electromagnetic physics constructor has been reconfigured to offer a best set of electromagnetic physics models for studies exploring the transport of low energy polarised X-/gamma rays. An overview of the physics models implemented in "G4LowEPPhysics", and it's experimental validation against Compton X-ray polarimetry measurements of the BL38B1 beamline at the SPring-8 synchrotron (Sayo, Japan) is reported. "G4LowEPPhysics" is shown to be able to reproduce the experimental results obtained at the BL38B1 beamline (SPring-8) to within a level of accuracy on the same order as Geant4's X-/gamma ray interaction cross-sectional data uncertainty (approximately ± 5 %). [ABSTRACT FROM AUTHOR]

In beam geometries where a directed γ -ray beam hits the surface of a coaxial high purity germanium detector (HPGe), the detector efficiency is sensitive to the position where γ -rays initially hit the detector surface because the structure of the detector is nonuniform. This may cause inaccuracy of the detector efficiency when measured using standard sources that are point-like sources emitting γ -rays isotropically. Obtaining a precise estimation of the full energy peak efficiency of the coaxial HPGe detector in the beam geometry for on-axis and off-axis measurements requires a Monte Carlo simulation. We performed Monte Carlo simulations that calculate the detector efficiency in the beam geometry. The effects of the off-axis distance and γ -ray beam size on the efficiency are quantitatively analyzed. We found that the intrinsic efficiency in the beam geometry is maximized when the beam hits the detector at specific off-axis distances. Our Monte Carlo calculations have been supported by nuclear resonance fluorescence experiments using laser Compton scattering γ -ray beams. • Calculating efficiency of coaxial HPGe detector for directed γ-ray beams by Geant4. • Revealing the sensitivity of efficiency to γ-ray beam size and off-axis distance. • Off-axis efficiency is higher than on-axis efficiency, depending on γ-ray energy. • Maximizing efficiency by selecting the optimum off-axis distance. • LCS γ-ray beams up to 3 MeV validate calculations experimentally. [ABSTRACT FROM AUTHOR]