类氦C离子诱发不同金属厚靶原子的K-X射线

K-X rays induced by helium-like C ions in thick target atoms of different metals

利用中国原子能科学研究院HI-13MV串列加速器上提供的动能为15—55 MeV的类氦C离子分别轰击Fe,Ni,Nb和Mo金属厚靶,采用HpGe探测器测量了K-X射线,获得了相应的K-X射线的发射截面.本文中由于各个靶原子外壳层电离度的不同,类氦C离子与Fe,Ni靶原子相互作用发射的K_(β)与K_(α)X射线的分支强度比随入射离子动能增加而减小,而Nb,Mo靶原子发射的K-X射线分支强度比变化不明显.利用厚靶截面公式计算了靶原子K-X射线的发射截面,并与不同的理论模型及质子的结果进行了对比.结果表明随类氦C离子动能的增大,Fe,Ni靶原子发射的K_(β)与K_(α)X射线的总产生截面与考虑多电离的两体碰撞近似修正模型最为符合Nb,Mo靶原子发射的K_(β)与K_(α)X射线的总产生截面与平面波恩近似模型的理论值最为接近.质子与单核子C离子能量相同时,质子比类氦C离子激发不同靶的K-X射线产生截面约小3个数量级.

The physical process and experimental phenomena of the interaction between highly charged heavy ions and atoms are very complex,particularly in the intermediate energy region,because of the limitation of accelerator and existing theoretical analysis,less systematic researches,incomplete atomic data,and not so high accuracy.The research of celestial element X-ray data is more scarce and the research of X-ray data of celestial elements is even more scarce.Helium-like C ions with 15–55 MeV kinetic energy provided by the HI-13 MV series accelerator of the China Institute of Atomic Energy are used to bombard Fe,Ni,Nb and Mo thick targets.The HpGe detectors are used to measure the K-X ray emission,and the corresponding K-X ray emission cross sections are obtained.Due to the different ionization degrees of the shell layers of various target atoms,the branching intensity ratio of K_(β)to K_(α)X rays emitted by Helium-like C ions interacting with Fe and Ni target atoms decreases with the increase of the kinetic energy of the incident ions,while the branching intensity ratio of K-X rays emitted by Nb and Mo target atoms does not change significantly.The K-X ray emission cross section of target atom is calculated by using the formula of thick target cross section,and compared with the results of different theoretical models and proton.The results show that with the increase of the kinetic energy of helium-like C ions,the total emission cross section of the K_(β)and K_(α)X ray emitted from Fe and Ni target atoms are most consistent with the BEA correction model considering multiple ionization,and the total emission cross section of K_(β)and K_(α)X ray emitted from Nb and Mo target atoms are closest to the theoretical values of PWBA model.When the energy of proton is the same as that of single nucleon C ion,the cross section of K-X ray produced by proton is about three orders of magnitude smaller than that produced by helium-like C ion.