A simulation method for measurement of the cross-section of the^(14)N(n,a)^(11)B reaction with gas and solid samples using a gridded ionization chamber(GIC)has been established.Using the simulation,the experimental sp...A simulation method for measurement of the cross-section of the^(14)N(n,a)^(11)B reaction with gas and solid samples using a gridded ionization chamber(GIC)has been established.Using the simulation,the experimental spectra of both^(14)N(n,a)^(11)B events and background from other reactions can be predicted,and the experimental scheme can be optimized.According to the simulation results,the optimal experimental parameters,including the pressure of the working gas and the compositions of the working gas and the sample,can be determined.In addition,the simulation results can be used to determine the valid event area and calculate the detection efficiency for valid events.A measurement of the cross-sections of the^(14)N(n,a)^(11)B reaction at E_(n)=4.25,4.50,4.75,5.00,5.25,and 5.50 MeV,based on the 4.5-MV Van de Graff accelerator at Peking University(PKU)using a GIC as the detector for the outgoing a particles,has been performed.The good agreement of the spectra from the simulation and experiment demonstrated the universality of this simulation method,which can be used to accurately measure neutroninduced light-charged particle emission reactions.展开更多
Effect of multiple alloying elements (Ga, Nb, Zr, Hf and Pr) on microstructure and magnetic properties of nanocomposite Nd 9- x Pr x Fe 86.5- y-z-m-n Ga y Nb z Zr m Hf n B 4.5 ( ...Effect of multiple alloying elements (Ga, Nb, Zr, Hf and Pr) on microstructure and magnetic properties of nanocomposite Nd 9- x Pr x Fe 86.5- y-z-m-n Ga y Nb z Zr m Hf n B 4.5 ( x =0, 2 25; y, z, m, n =0.5, 1.0) ribbons was investigated by a L 16 (2 15 ) orthogonal experiment. The results show that the addition of multiple alloying elements can effectively reduce the grain size of Nd 2Fe 14 B and α Fe phases and promote amorphous phase to occur at low wheel speed. No inhomogeneous growth of grains was found in annealed ribbons, but a large amount of additives would results in irregularity of Nd 2Fe 14 B and α Fe grains. On the other hand, addition of multiple alloying elements has complex effects on magnetic properties due to interactions between alloying elements. When the content of Nb is 0.5%, increasing the content of Pr and Ga and decreasing the content of Zr and Hf can improve the magnetic properties effectively. The optimum magnetic properties were obtained in Nd 2.25 Pr 6.75 Fe 84.5 Ga 1.5 Nb 0.5 B 4.5 ribbons spun at 15 m·s -1 with J r=1.053 T, i H c=530.9 kA·m -1 ,( BH ) max =124 kJ·m -3 .展开更多
基金supported by the National Natural Science Foundation of China(No.12075008)Science and Technology on Nuclear Data Laboratory,China Nuclear Data Centerthe State Key Laboratory of Nuclear Physics and Technology,Peking University(No.NPT2020KFJ22)。
文摘A simulation method for measurement of the cross-section of the^(14)N(n,a)^(11)B reaction with gas and solid samples using a gridded ionization chamber(GIC)has been established.Using the simulation,the experimental spectra of both^(14)N(n,a)^(11)B events and background from other reactions can be predicted,and the experimental scheme can be optimized.According to the simulation results,the optimal experimental parameters,including the pressure of the working gas and the compositions of the working gas and the sample,can be determined.In addition,the simulation results can be used to determine the valid event area and calculate the detection efficiency for valid events.A measurement of the cross-sections of the^(14)N(n,a)^(11)B reaction at E_(n)=4.25,4.50,4.75,5.00,5.25,and 5.50 MeV,based on the 4.5-MV Van de Graff accelerator at Peking University(PKU)using a GIC as the detector for the outgoing a particles,has been performed.The good agreement of the spectra from the simulation and experiment demonstrated the universality of this simulation method,which can be used to accurately measure neutroninduced light-charged particle emission reactions.
文摘Effect of multiple alloying elements (Ga, Nb, Zr, Hf and Pr) on microstructure and magnetic properties of nanocomposite Nd 9- x Pr x Fe 86.5- y-z-m-n Ga y Nb z Zr m Hf n B 4.5 ( x =0, 2 25; y, z, m, n =0.5, 1.0) ribbons was investigated by a L 16 (2 15 ) orthogonal experiment. The results show that the addition of multiple alloying elements can effectively reduce the grain size of Nd 2Fe 14 B and α Fe phases and promote amorphous phase to occur at low wheel speed. No inhomogeneous growth of grains was found in annealed ribbons, but a large amount of additives would results in irregularity of Nd 2Fe 14 B and α Fe grains. On the other hand, addition of multiple alloying elements has complex effects on magnetic properties due to interactions between alloying elements. When the content of Nb is 0.5%, increasing the content of Pr and Ga and decreasing the content of Zr and Hf can improve the magnetic properties effectively. The optimum magnetic properties were obtained in Nd 2.25 Pr 6.75 Fe 84.5 Ga 1.5 Nb 0.5 B 4.5 ribbons spun at 15 m·s -1 with J r=1.053 T, i H c=530.9 kA·m -1 ,( BH ) max =124 kJ·m -3 .
