Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-06-30
Abstract： [Background]: Boron Neutron Capture Therapy (BNCT) is a binary radiation therapy with strong targeting and high energy transfer line density at the cellular scale.It has the advantages of short treatment cycle and minimal damage to surrounding healthy tissues,making it a promising cancer treatment method. [Purpose]: This study aims to design beam shaping assembly(BSA)to make the neutron beam of D-Be neutron source suitable for BNCT and ensure neutron directionality. [Methods]: This article uses Monte Carlo simulation programs GEANT4 and FLUKA to simulate the generation of 9Be(d,n)10B reaction neutron sources and subsequent neutron moderation.A feasible scheme design for BSA was carried out using a 1.45 MeV,30 mA deuterium beam to bombard a 9 μm thin beryllium target,and set a basis BSA model with a cylindrical structure as a whole. [Results]: The results show that using a 45 cm thick BiF3 and 5 cm thick TiF3 combined slowing layer,a 12 cm thick Pb reflector layer,an 11 cm thick Al2O3 supplementary slowing layer,and a 0.1 mm thick Cd thermal neutron absorption layer,the outlet is ensured to γ and fast neutron composition,Φepi/Φth, Φepi/Φfast meets the recommended values of the IAEA. [Conclusions]: This study obtained the neutron spectra and BSA specific design scheme of low-energy deuterium beams and thin beryllium targets,providing data reference for the slowing shaping of neutrons in D-Be neutron sources and supporting subsequent research on D-Be sources.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-06-06
Abstract： [Background]: Boron Neutron Capture Therapy (BNCT) is a binary radiation therapy with strong targeting and high energy transfer line density at the cellular scale.It has the advantages of short treatment cycle and minimal damage to surrounding healthy tissues,making it a promising cancer treatment method. [Purpose]: This study aims to design beam shaping assembly(BSA)to make the neutron beam of D-Be neutron source suitable for BNCT and ensure neutron directionality. [Methods]: This article uses Monte Carlo simulation programs GEANT4 and FLUKA to simulate the generation of 9Be(d,n)10B reaction neutron sources and subsequent neutron moderation.A feasible scheme design for BSA was carried out using a 1.45 MeV,30 mA deuterium beam to bombard a 9 μm thin beryllium target,and set a basis BSA model with a cylindrical structure as a whole. [Results]: The results show that using a 45 cm thick BiF3 and 5 cm thick TiF3 combined slowing layer,a 12 cm thick Pb reflector layer,an 11 cm thick Al2O3 supplementary slowing layer,and a 0.1 mm thick Cd thermal neutron absorption layer,the outlet is ensured to γ and fast neutron composition,Φepi/Φth, Φepi/Φfast meets the recommended values of the IAEA. [Conclusions]: This study obtained the neutron spectra and BSA specific design scheme of low-energy deuterium beams and thin beryllium targets,providing data reference for the slowing shaping of neutrons in D-Be neutron sources and supporting subsequent research on D-Be sources.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-04-08
Abstract： Background : The lead-free double perovskite Cs2AgBiBr6 has garnered extensive attention in the field of nuclear radiation detection as an environmentally friendly material. Experimental observations have revealed that doping Cs2AgBiBr6 with Cu+ significantly enhances the material’s stability and photoelectric conversion efficiency. Purpose :The study aims to investigate the impact of Cu+ doping on the crystal structure and electrical properties of Cs2AgBiBr6. Methods : Using first-principles calculations based on density functional theory, a simulation study was conducted to explore the effects of Cu+ doping on the structure and electrical properties of Cs2AgBiBr6. Results : The results indicate that Cu+ doping enhances the stability of Cs2AgBiBr6. The Cs2Ag1-xCuxBiBr6 compounds formed by doping, as well as the original Cs2AgBiBr6 material, exhibit an indirect bandgap semiconductor behavior. The bandgap significantly narrows with an increase in the Cu+ doping ratio. Analysis of the density of states (DOS) suggests that the bandgap narrowing is attributed to the downward shift of the conduction band minimum dominated by Bi 6p orbitals due to Cu+ doping. Conclusions : Cs2Ag1-xCuxBiBr6 exhibits higher stability and superior electrical properties compared to Cs2AgBiBr6. It emerges as a promising candidate material for semiconductor radiation detectors.
Key words First-principles calculations, Cs2Ag1-xCuxBiBr6, Electronic structure, Cu+ Doping
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