Simulation Study On The Neutron Radiation Field From Heavy Ion Nuclear Reaction Of LEAF

Heavy ion physics and heavy ion application technology are the frontier research fields that have been widely concerned in recent years.Heavy ion accelerators is the basis of heavy ion physics and heavy ion application technology research,and the development of heavy current heavy ion accelerator is to carry out heavy ion physics and heavy ion technology of the urgent need.Under this background,the Institute of Modern Physics(IMP)of the Chinese Academy of Sciences undertook the task of developing a low-energy high-current high-charge state heavy ion research device(LEAF),a special project of a national major scientific instrument.The low-energy high-current high-charge state heavy ion bombard target or the loss beam bombard accelerator wall accelerated by the LEAF device will generate secondary radiation fields(including X-rays,gamma rays,protons,neutrons,etc.),of which the neutron radiation field is the most shielded difficulties are one of the important issues that require research and evaluation.The research goal of this paper is to develop the simulation of the characteristics of the neutron radiation field produced by the typical heavy ion beams(H2+,4He2+,16O6+,40Ar12+,58Ni28+,129Xe45+,209Bi55+,238U56+)produced by the LEAF device bombarding Al,Fe,Cu and other targets.Study and calculate the dose equivalent of the neutron field to provide basic data for neutron dose evaluation and shield design around the LEAF device.The main research contents?research results and conclusions of this paper are summarized as follows:This paper carried out theoretical research related to heavy ion nuclear reaction.The reaction types?reaction processes and related theories and models related to Rutherford scattering?Coulomb excitation,?deep inelastic scattering and complete fusion reaction caused by heavy ions are briefly summarized and elaborated.This paper carried out the PHITS program simulation test research.Using the PHITS program,the neutron energy spectra of Am-Be neutron source and D-Be neutron source were simulated,then the simulated data are compared with the experimental data of Am-Be neutron source standard energy spectrum and D-Be neutron source neutron energy spectrum.By comparison,the results show that the PHITS program simulation results can well reflect the characteristics of the neutron source spectrum of charged particle nuclear reactions,which prepares the conditions for the PHITS program to carry out the neutron field simulation study of the LEAF device.Using the PHITS program,the neutron radiation field simulation and neutron dose-equivalent simulation of the lighter ions such as H2+,D+,He2+involved in the LEAF device bombarding Al,Fe,and Cu were carried out,and different beam energy conditions were given The data such as the lower average neutron energy spectrum?the neutron yield change trend with the beam energy?the neutron dose equivalent in water change trend with the beam energy and other data,through data fitting and extrapolation to the low energy region,carry out LEAF The evaluation of the neutron yield and dose equivalent of device beam parameters.The results show that for the light beams with the highest beam parameters(H2+@1emA/1MeV,D+@lemA/1MeV,He2+@1.5mA/2MeV)of the LEAF device bombarding Al?Fe and Cu targets,the maximum neutron amount is not more than 2.13×103n/s;the dose equivalent of neutron in water is not more than 5.97×10-9Sv/s.Using the PHITS program,the neutron radiation field simulation and neutr on dose equivalent simulation of heavy ions bombard Al.Fe and Cu targets such as 1606+?40Ar12+?58Ni28+?129Xe45+?209Bi55+?238U56+involved in the LE AF device were carried out The study gives the average neutron energy spect rum?the trend of neutron yield with beam energy under different beam energ y conditions and the trend of neutron dose equivalent in water with beam en ergy.Through data fitting and extrapolating to the low-energy region,carry out the evaluation of the neutron yield and dose equivalent of the beam paramet er conditions of the LEAF device.The results show that the heavy ion beam bombarding Al?Fe and Cu targets,which corresponds to the highest beam par ameters of the LEAF device(1606+@1emA/8MeV,40Ar12+@2emA/20MeV,129Xe45+@2mA/64.5MeV,209Bi55+@2emA/104.5MeV,238U56+@2emA/119MeV),the maxi-mum neutron yield is no more than 6.86×101n/s;the dose equivalent of neut-ron in water is no more than 2.02×10-8Sv/s.Overall evaluation,under the current beam conditions of the LEAF device,the low neutron yield will not resul-t in a significant environmental dose.606+and 40Ar12+bombard A1 target,the neutron dose is high,it is worthy of attention,if necessary,it should be pro perly shielded.