| There are many types of neutron sources,each with its own advantages.Highflux neutron sources of medium-energy high-current linac have higher neutron yield and lower cost,which has attracted extensive attention in recent years.For example,many countries are developing an IFMIF device for the study of fast neutron radiation damage of structural materials of international thermonuclear fusion reactor;A high flux neutron source based on linear accelerator for neutron scattering diffraction research is under construction at the Eulich Research Center in Germany.The Institute of Modern Physics of the Chinese Academy of Sciences is constructing a neutron source for the ADS project.In addition,the high-flux neutron source of high-current linac has important application value in the fields of fast neutron physics,neutron activation analysis,neutron photography,and neutron irradiation breeding.The neutron source of medium-energy high-current linac involves three key problems: the technology of medium-energy high-current linac,the technology of high-power target,the design of target station and experimental terminal.Among them,the design of the target station and experimental terminal is closely related to the nuclear reaction and the characteristic parameters of the neutron generated by the beam bombarding target.There are mainly 9Be(d,xn)reaction,9Be(p,xn)reaction,7Li(d,xn)reaction and 7Li(p,xn)reaction available for the neutron source of the medium energy high current linear accelerator.Compared with Li target,Be target has the advantages of high melting point,high thermal conductivity,stable chemical properties and easy processing.Considering the difficulty of target design,It is more reasonable to choose 9Be(d,xn)reaction and 9Be(p,xn)reaction.In this paper,the simulation of neutron properties of 9Be(d,xn)and 9Be(p,xn)reactions will be carried out,aiming to provide basic data of neutron source characteristic parameters for the next stage of the project.Firstly,this paper uses PHITS program to calculate the neutron energy spectrum under the condition of 9Be(d,xn)reaction double differential cross section and thick target based on the JQMD model,INCL model and INCL/ DWBA coupling model,and compares it with the existing experimental data.The results show that,The calculated results of INCL/ DWBA coupling model are in good agreement with the experimental data,which means that the INCL/ DWBA coupling model can better reflect the nuclear reaction process of 9Be(d,xn).Secondly,the 9Be(d,xn)reaction double differential cross sections with the Dbeam energy range of 5-25 Me V are calculated using the PHITS program and the coupled model of INCL/ DWBA,and a database is established.Based on the established double differential cross section database and the developed muti-layer thin target approximation method,the neutron energy spectrum,neutron Angle distribution and neutron yield of deuterium beam energy in the range of 5-25 Me V for thick Be targets are calculated.The results are compared with the experimental data and the direct simulation results of PHITS program.The calculated data of the mutilayer thin target approximation method coincide with the PHITS direct simulation results,and are well combined with the experimental data,which further verifies the feasibility of the calculation method and the reliability of the calculated data.Finally,using the PHITS program and the INCL/ DWBA coupling model,the neutron energy spectrum,neutron angle distribution and neutron yield of the 9Be(p,xn)reaction are simulated under the condition of the proton beam energy range of 5-25 Me V and the thick Be target.The results are compared with the PHITS simulation results of the 9Be(p,xn)reaction of the same deuterium beam energy range and thick Be target.The neutron source characteristics of the two reaction are evaluated and analyzed.The basic data are prepared for the further development of the physical design of the neutron source based on the strong current linac. |
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