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
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-03-25
Abstract： [Background]: Photonuclear reactions and compact neutron sources have emerged as promising tools for the production of medical isotopes, providing alternatives to conventional reactor-based high-enriched uranium methods. East China University of Technology (ECUT) is currently constructing an electron accelerator-driven photoneutron source(ECANS) for medical isotope production research. [Purpose]: Investigate the photonuclear reaction with 100Mo isotope and utilize the generated neutrons for isotopic production. [Methods]: The study involves analyzing the photonuclear reactions of 100Mo and investigating the neutron spectrum and activation yield of 99Mo within a high purity 100Mo target. Based on this photonuclear source, a new model to produce medical isotopes is established, comprising neutron energy modulation layer and neutron reflection layer. The study calculates the production yields of 99Mo, 177Lu, and 90Y in various natural oxides and assesses the feasibility of using photonuclear sources for medical isotope production. [Results]: The research results demonstrate that photo-nuclear reactions can effectively produce medical isotopes such as 99Mo, 177Lu, and 90Y, with respective activities of 17.4/day, 18.2 Ci/day, and 57.0 Ci/day. And in the high purity 100Mo target, the daily output of 99Mo reaches 54.1 Ci/day. [Conclusions]: The study demonstrates the feasibility of using the photodisintegration reaction of 100Mo as a neutron source for secondary production of medical isotopes. This approach offers the potential to enhance the economic viability of isotope production. The study analyzed the content of radioactive impurities in natural oxides under irradiation conditions, providing preliminary insights for subsequent separation and purification processes. Therefore, this research has certain reference value for the development of tools for radioactive isotope production.
Subjects: Biology >> Zoology submitted time 2017-10-11 Cooperative journals: 《动物营养学报》
Abstract：本试验旨在研究种母鸡饲粮不同硒源及添加水平对后代肉鸡生长性能、肉品质、硒沉积和抗氧化功能的影响。将540只48周龄的健康岭南黄父母代肉用种母鸡随机分为6个组，每组3个重复，每重复30只鸡。试验采用3(硒源)×2(水平)双因素随机试验设计，饲粮硒源分别为亚硒酸钠(SS)、酵母硒(SY)、硒代蛋氨酸(SM)，硒添加水平分别为0.15和0.30 mg/kg（以硒计）。预试期4周，正试期8周。结果表明：1）与SS组相比，SM组显著降低了1~21日龄后代肉鸡的料重比（P<0.05）；SM和SY组显著提高了1日龄后代肉鸡肝脏、肾脏和肌肉的硒含量以及肾脏过氧化氢酶（CAT）活性（P<0.05），显著降低了肝脏丙二醛（MDA）含量（P<0.05）。与SY组相比，SM组显著提高了后代肉鸡16 h胸肌的pH和肾脏、肌肉的硒含量（P<0.05）。2）0.30 mg/kg组的后代肉鸡肝脏、肾脏和肌肉的硒含量显著高于0.15 mg/kg组（P<0.05）。与0.30 mg/kg组相比，0.15 mg/kg组显著提高了后代肉鸡8 h胸肌Hunter a及pH（P<0.05），显著降低了后代肉鸡24、48 h胸肌滴水损失（P<0.05），显著提高了1日龄后代肉鸡肝脏谷胱甘肽过氧化物酶、总超氧化物歧化酶（T-SOD）活性和总抗氧化能力（T-AOC）及肾脏T-SOD、CAT活性和T-AOC（P<0.05），显著降低了1日龄后代肉鸡肾脏MDA含量（P<0.05）。由此可见，在本试验条件下，种母鸡饲粮中添加0.15 mg/kg SM效果最佳。
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