Experimental Study On Proton-induced Reactions On ^natMo Up To 100 MeV And High Energy Neutron Transport In ²³⁸U & ^natPb

Accelerator-driven sub-critical system（ADS）has strong transmutation capability,considerable neutron economy and reliable system safety.It can not only transmutates high-level radioactive waste,but also has the potential of breeding nuclear fuel and generating electricity.Therefore,ADS has good energy economy and is an important research area in nuclear energy.The construction of China’s ADS system is in the critical stage of technology and needs a lot of nuclear data support.Mo,²³⁸U and Pb are the key materials of ADS system.The nuclear data of proton-induced reactions on Mo and neutron transport in ²³⁸U&Pb are the important foundation of ADS system and advanced nuclear fuel cycle system.In addition,accurate and reliable experimental data of cross-sections and yields for p+Mo nuclear reaction are also crucial to promote the development of medical isotope industry.However,for p+Mo nuclear reactions,existing experimental data are often scattered and inconsistent,and mainly concentrated below 40 Me V,and experimental data in the range of medium and high energy are scarce.For neutron transport in ²³⁸U and Pb,the evaluated nuclear data below 20 Me V are quite different and high energy neutron data are scarce,which is difficult to apply to the complex conditions of high flux and wide energy spectrum of ADS.Therefore,it is necessary to conduct detailed and reliable experimental measurements and theoretical studies on the nuclear data related to the above reactions.In this work,experimental studies of proton-induced reactions on ^natMo up to 100 Me V and high-energy neutrons transport in ²³⁸U and ^natPb were carried out.Based on the experimental terminal of ADS superconducting linear accelerator prototype in the Institute of Modern Physics,Chinese Academy of Sciences,an irradiation experimental measuring device for proton-induced reaction on stacked-foils was designed and built,and low-background HPGeγdetection spectrometer was used to measure the activity off-line.More accurate and reliable cross-sections and yields of ^natMo（p,x）^{93m+g,94g,95g,95m,96m+g}Tc,¹⁰⁰Mo（p,pn）⁹⁹Mo and ¹⁰⁰Mo（p,2n）^99mTc reactions below 20 Me V were obtained by considering various disturbance effects on radioactivity in detail.Meanwhile,TALYS code with six level density models was used to calculate the excitation function for the above reactions.Our results were also compared with the experimental data taken from EXFOR and TENDL-2019 databases.The results show that our measruements are in good agreement with most of the previous published data.However,when the energy level density model is larger than15 Me V,there is a divergence between TALYS code and experimental data,the calculation ability of TALYS code for higher energy excitation functions needs to be further improved.This work can strengthen and expand the database of proton-induced nuclear reactions.Accurate and reliable experimental data of cross-sections and yields are of important reference to the basic research in the field of nuclear medicine and the construction for ADS system.Based on SSC experiment platform of Heavy Ion Research Facility in Lanzhou（HIRFL）of the Institute of Modern Physics,Chinese Academy of Sciences,a stacked-foil activation technique was used to measure the cross-sections of ^natMo（p,x）^{93g（m+）,94g,}95g,95m,96g（m+）Tc,natMo（p,x）90（cum）,93m,99（cum）Mo,natMo（p,x）90g（m+,cum）,91m（cum）,92m,95m,96Nb and ^natMo（p,x）^{86（cum）,88g（m+,cum）,89g（m+,cum）}Nb reactions with the energy range of 75 Me V-100 Me V.TALYS code was used to calculate the nuclear reactions.The results show that the calculations can reproduce most of the experimental excitation functions of nuclear reactions,but some of them have deviation compared with the experimental data.At present,no experimental data have been reported in this energy region.Our experimental measurements fill the gap of nuclear data for proton-induced reactions on nature Mo targets in the energy region of 75-100 Me V,which is beneficial to the development and optimization of evaluation database and the improvement of theoretical model.Based on the experimental terminal of RIBLL 1 of HIRFL,high energy white neutron source was produced by 80.5 Me V/u ¹²C bombared on W target.The leakage neutron spectrum of high-energy broad-spectrum neutrons interacting with ²³⁸U&^natPb targets in the direction of 0°were measured by time-of-flight method.Meanwhile,Geant4 code combined with INCL,BIC and BERT physics models as well as ENDF/B-Ⅷ.0,JEFF-3.3 and JENDL-4.0 evaluated nuclear data libraries were used to simulate the experiment,and the calculation results of leakage neutron energy spectrum under the same experimental conditions were obtained.The results show that Geant4 code is reliable to simulate high-energy neutron transport in ²³⁸U&^natPb.