Study On Production Of Nuclear Isomers Using Intense ?-ray Source

Nuclear isomers have potential applications in astrophysics,energy storage,and medical diagnosis and treatment.The production of isomers relies on reactors,cyclotrons and radionuclide generators.In recent years,experimental reactors for isotope generation are approaching the end of their useful lives and the limited generation methods make the amount of nuclear isomers generation unable to meet the medical demand,and research on new generation methods is urgently needed.The search for more nuclear isomers with imaging and therapeutic potential is also a solution to alleviate the isomer crisis.This paper analyzes the decay properties of several isomers and their related application prospects,proposes to generate isomers by photoexcitation or photonuclear reaction driven by high-intensity gamma source,combines the reaction cross sections of isomers by(?,?')and(?,xn)reaction,simulates and calculates the yield of them,and discusses the influence of different reaction channels on the activity of isomers generation.Firstly,the isomers production based on Laser Compton Scattering(LCS)gamma source was investigated.Since the isomers ^103mRh,^113m,115mIn and ^176mLu cannot be obtained by(?,n)reaction considering the availability of activation targets,the above four isomers are chosen to be produced by the(?,?')reaction.The cross sections of these four isomers produced by the(?,?')reaction were calculated,and the yield of them were calculated by combining with the gamma ray spectrum.And then the activities of these isomers were evaluated by beam and target optimization.The results show that the specific activities of isomers ^103mRh,^113m,115mIn and ^176mLu can exceed?0.2 GBq/g after continuous irradiation of the isotope target by gamma source with an intensity of 10¹³?/s for 6 h,which can basically meet the needs of some basic research and development.Secondly,isomers production by an electron-bremsstrahlung source was studied.The bremsstrahlung source is briefly described as obtained by bombarding the conversion target of a high-atomic number with monoenergetic electrons emitted from an electron linear accelerates,and the effect of the conversion target material on the bremsstrahlung source was discussed.The nuclear isomers ^69mZn,^87mSr,^93mMo,^117mSn and ^193m,195mPt are produced by(?,?')and(?,xn)reaction,and the cross sections of each reaction channel are calculated separately to obtain the isomers yields and to clarify the effect of the activation target shape on the production.The result show that the cross section of(?,n)reaction is the largest among the different reaction channels,and the production of isomers ^69mZn,^87mSr,^93mMo,^117mSn and ^193m,195mPt depends mainly on the(?,n)reaction.The effect of the activation target shape on the yield of isomers was also discussed.The result shows that the density of the density of the beam contributes more to the improvement of the specific activity than the dispersion and attenuation of the beam.Finally,an experimental simulation of ^113m,115mIn production by a laser accelerated electron source was carried out.The effect of different electron temperatures on the electron energy spectrum and the effect of different conversion target thicknesses on the generated bremsstrahlung sources are simulated.A laser-accelerated electron source is used to bombard the indium target to produce ^113m,115mIn.The nuclear reactions that can occur in this process are discussed,and the corresponding reaction section and yield are calculated respectively.The detection efficiency of the detector during off-line measurements is simulated,and thus the radioactive indium isotope detection counts after irradiation with the laser-accelerated electron source are simulated,so that the characteristic gamma peaks of the experimentally detected degenerate radiation can be inferred,which are in general agreement with the experimental results.This leads to the conclusion that the scheme of producing isomers ^113m,115mIn by laser accelerated electron source is feasible.The present work provides the theoretical guidance for revolutionizing isomers production and finding more isomers with imaging and therapeutic potential,and basically validates the feasibility of isomers production using high intensity gamma sources.