High-energy proton microbeam facilities are powerful tools in space science,biology and cancer therapy studies.The primary limitations of the 50 MeV proton microbeam system are the poor beam quality provided by the cy...High-energy proton microbeam facilities are powerful tools in space science,biology and cancer therapy studies.The primary limitations of the 50 MeV proton microbeam system are the poor beam quality provided by the cyclotron and the problem of intense scattering in the slit position.Here,we present an optical design for a cyclotron-based 50 MeV high-energy proton microbeam system with a micron-sized resolution.The microbeam system,which has an Oxford triplet lens configuration,has relatively small spherical aberrations and is insensitive to changes in the beam divergence angle and momentum spread.In addition,the energy filtration included in the system can reduce the beam momentum spread from 1 to 0.02%.The effects of lens parasitic aberrations and the lens fringe field on the beam spot resolution are also discussed.In addition,owing to the severe scattering of 50 MeV protons in slit materials,a slit system model based on the Geant4 toolkit enables the quantitative analysis of scattered protons and secondary particles.For the slit system settings under a 10-micron final beam spot,very few scattered protons can enter the quadrupole lens system and affect the focusing performance of the microbeam system,but the secondary radiation of neutrons and gamma rays generated at the collimation system should be considered for the 50 MeV proton microbeam.These data demonstrate that a 50 MeV proton microbeam system with a micron-sized beam spot based on a cyclotron is feasible.展开更多
Iron is commonly used as a structural and shielding material in nuclear devices. The accuracy of its nuclear data is critical for the design of nuclear devices. The evaluation data of ^(56)Fe isotopes in the latest ve...Iron is commonly used as a structural and shielding material in nuclear devices. The accuracy of its nuclear data is critical for the design of nuclear devices. The evaluation data of ^(56)Fe isotopes in the latest version of the CENDL-3.2 library from China was significantly updated. This new data must be tested before it can be used. To test the reliability of this data and assess the shielding effect, a shielding benchmark experiment was conducted with natural Fe spherical samples using a pulsed deuterium–tritium neutron source at the China Institute of Atomic Energy(CIAE). The leakage neutron spectra from the natural spherical iron samples with different thicknesses(4.5, 7.5, and 12 cm) were measured between 0.8 and 16 MeV after interacting with 14 MeV neutrons using the time-of-flight method. The simulation results were obtained by Monte Carlo simulations by employing the Fe data from the CENDL-3.2, ENDF/B-VIII.0, and JEDNL-5.0 libraries. The measured and simulated leakage neutron spectra and penetration rates were compared, demonstrating that the CENDL-3.2 library performs sufficiently overall. The simulation results of the other two libraries were underestimated for scattering at the continuum energy level.展开更多
基金supported by the National Natural Science Foundation of China(Nos.1197283,U1632271)the National Key R&D Program of China(No.2021YFA1601400).
文摘High-energy proton microbeam facilities are powerful tools in space science,biology and cancer therapy studies.The primary limitations of the 50 MeV proton microbeam system are the poor beam quality provided by the cyclotron and the problem of intense scattering in the slit position.Here,we present an optical design for a cyclotron-based 50 MeV high-energy proton microbeam system with a micron-sized resolution.The microbeam system,which has an Oxford triplet lens configuration,has relatively small spherical aberrations and is insensitive to changes in the beam divergence angle and momentum spread.In addition,the energy filtration included in the system can reduce the beam momentum spread from 1 to 0.02%.The effects of lens parasitic aberrations and the lens fringe field on the beam spot resolution are also discussed.In addition,owing to the severe scattering of 50 MeV protons in slit materials,a slit system model based on the Geant4 toolkit enables the quantitative analysis of scattered protons and secondary particles.For the slit system settings under a 10-micron final beam spot,very few scattered protons can enter the quadrupole lens system and affect the focusing performance of the microbeam system,but the secondary radiation of neutrons and gamma rays generated at the collimation system should be considered for the 50 MeV proton microbeam.These data demonstrate that a 50 MeV proton microbeam system with a micron-sized beam spot based on a cyclotron is feasible.
基金supported by the National Natural Science Foundation of China (No. 11775311)。
文摘Iron is commonly used as a structural and shielding material in nuclear devices. The accuracy of its nuclear data is critical for the design of nuclear devices. The evaluation data of ^(56)Fe isotopes in the latest version of the CENDL-3.2 library from China was significantly updated. This new data must be tested before it can be used. To test the reliability of this data and assess the shielding effect, a shielding benchmark experiment was conducted with natural Fe spherical samples using a pulsed deuterium–tritium neutron source at the China Institute of Atomic Energy(CIAE). The leakage neutron spectra from the natural spherical iron samples with different thicknesses(4.5, 7.5, and 12 cm) were measured between 0.8 and 16 MeV after interacting with 14 MeV neutrons using the time-of-flight method. The simulation results were obtained by Monte Carlo simulations by employing the Fe data from the CENDL-3.2, ENDF/B-VIII.0, and JEDNL-5.0 libraries. The measured and simulated leakage neutron spectra and penetration rates were compared, demonstrating that the CENDL-3.2 library performs sufficiently overall. The simulation results of the other two libraries were underestimated for scattering at the continuum energy level.
