高能脉冲C~(6+)离子束激发Ni靶的K壳层X射线
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摘要
精确测量离子与原子碰撞引起的靶原子内壳层电离截面,对研究原子内壳层过程以及建立合适的理论模型具有重要的意义.现有的实验数据和理论模型大都集中在中低能区,高能区由于受到实验条件的限制,几乎没有相关实验数据的报道,哪种理论更适合描述高能重离子入射的靶原子内壳层电离截面,还需要进行深入的实验研究.采用电子冷却存储环提供能量分别为165,300,350,430 MeV/u的C~(6+)离子束轰击Ni靶,测量Ni的K壳层X射线.分析了实验中探测到的Ni的K_β和K_α射线强度比,发现入射粒子能量的变化对该强度比影响不明显.分别应用两体碰撞近似(BEA)、平面波玻恩近似(PWBA)和ECPSSR理论对Ni的K壳层X射线的产生截面进行理论计算,并将理论结果与实验结果进行比较.
Accurate measurement of the ionization cross section of the target atom induced by collision between ions and atoms is of great significance for studying the atomic shell process and establishing a suitable theoretical model.The experimental data and the theoretical models mostly concentrate on the cases in the low energy region at present.Only a few experimental data of high energy region are reported due to the limitation of experimental conditions.Which theory is more suitable to describe the ionization cross section of the inner shell of the target atom caused by the high energy heavy ions,is necessarily studied experimentally.The C~(6+) ions provided by the Heavy Ion Research Facility in Lanzhou Electron Cooling Storage Ring,are used to bombard the Ni target,in which the K-shell X-ray of Ni is measured.The incident energies of C~(6+) ions are 165,300,350 and 430 MeV/u respectively.Through analyzing the intensity ratio of K_β/K_α X-ray of Ni,it is found that the influence of incident energy on the intensity ratio of K_β/K_α X-ray is not obvious.The intensity ratios of this experiment are greater than the experimental values of incident proton and the calculated values based on the Hartree-Slater theory,which may be caused by the multiple-ionization of the L shell.The production cross sections of Ni K-shell X-ray are calculated by the binary encounter approximation(BEA) model,the plane wave Born approximation(PWBA) model and the energy-loss coulomb-repulsion perturbed-stationary-state relativistic(ECPSSR) theory respectively,which are compared with the experimental results in this paper.It is found that the experimental cross section increases with the increasing incident energy,which is consistent with the trend of BEA model estimation,but the experimental value is obviously lower than the theoretical value.We think that BEA model needs to be modified when describing the ionization process in the high energy region.
Accurate measurement of the ionization cross section of the target atom induced by collision between ions and atoms is of great significance for studying the atomic shell process and establishing a suitable theoretical model.The experimental data and the theoretical models mostly concentrate on the cases in the low energy region at present.Only a few experimental data of high energy region are reported due to the limitation of experimental conditions.Which theory is more suitable to describe the ionization cross section of the inner shell of the target atom caused by the high energy heavy ions,is necessarily studied experimentally.The C~(6+) ions provided by the Heavy Ion Research Facility in Lanzhou Electron Cooling Storage Ring,are used to bombard the Ni target,in which the K-shell X-ray of Ni is measured.The incident energies of C~(6+) ions are 165,300,350 and 430 MeV/u respectively.Through analyzing the intensity ratio of K_β/K_α X-ray of Ni,it is found that the influence of incident energy on the intensity ratio of K_β/K_α X-ray is not obvious.The intensity ratios of this experiment are greater than the experimental values of incident proton and the calculated values based on the Hartree-Slater theory,which may be caused by the multiple-ionization of the L shell.The production cross sections of Ni K-shell X-ray are calculated by the binary encounter approximation(BEA) model,the plane wave Born approximation(PWBA) model and the energy-loss coulomb-repulsion perturbed-stationary-state relativistic(ECPSSR) theory respectively,which are compared with the experimental results in this paper.It is found that the experimental cross section increases with the increasing incident energy,which is consistent with the trend of BEA model estimation,but the experimental value is obviously lower than the theoretical value.We think that BEA model needs to be modified when describing the ionization process in the high energy region.
引文
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[5]Wang X,Zhao Y T,Chen R,Zhou X M,Xu G,Sun Y B,Lei Y,Wang Y Y,Ren J R,Yu Y,Li Y F,Zhang X A,Li Y Z,Liang C H,Xiao G Q 2012 Phys.Lett.A 3761197
[6]Liang C H,Zhang X A,Li Y Z,Zhao Y T,Mei C X,Zhou X M,Xiao G Q 2013 Acta.Phys.Sin.62 063202(in Chinese)[梁昌慧,张小安,李耀宗,赵永涛,梅策香,周贤明,肖国青2013物理学报62 063202]
[7]Mei C X,Zhao Y T,Zhang X A,Ren J R,Zhou X M,Wang X,Lei Y,Liang C H,Li Y Z,Xiao G Q 2012 Laser Part.Beams 30 665
[8]Merzbacher E,Lewis H W 1958 Handbuch der Physik 6166
[9]Lapicki G,Laubert R,Brandt W 1980 Phys.Rev.A 221889
[10]Brandt W,Lapicki G 1981 Phys.Rev.A 23 1717
[11]Lapicki G,Zander A R 1981 Phys.Rev.A 23 2072
[12]Lapicki G 2002 Nucl.Instr.Meth.B 19 8
[13]Kocbach L,Hansteen J M,Gundersen R 1980 Nucl.Instr.Meth.B 169 281
[14]McGuire J H,Richard P 1973 Phys.Rev.A 8 1374
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[16]LISE 10.0.8.http://lise.nscl.msu.edu/lise.html[2017-01-30]
[17]Kessler J E G,Deslatts R D,Girard D,Schwitz W,Jacobs L,Renner O 1982 Phys.Rev.A 26 2696
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[19]Scofleld J H 1974 Phys.Rev.A 9 1041
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[22]Gryzinski M 1965 Phys.Rev.A 138 336
[23]Liu Z,Cipolla S J 1996 Comp.Phys.Comm.97 315
[24]Benka O,Kropf A 1978 Atomic Data and Nuclear Data Tables 22 219
[25]Krause M O 1979 J.Phys.Chem.Ref.8 307
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[27]Czamota M,Banas D,Braziewicz J,Semaniak J,Pajek M 2009 Phys.Rev.A 79 032710