Ne–Ca K壳空心原子Kαα线伴线结构的实验研究

K-shell hollow atoms with additional vacancies in the L shell are very special atoms, which are in exotic-excited states. The two-electron one-photon (TEOP) transition Kαα lines and their satellite lines provide a useful tool for investigating the energy levels, the decay properties and the electron-electron correlation effects of these kind of atoms. High intensity of these kind of atoms cannot be obtained by conventional experimental methods, and hence a comprehensive measurement on the Kαα satellites with high-resolution has not been obtained so far. The high-resolution spectra are highly needed to understand the atomic structure and other properties of these atoms. The superconducting electron-cyclotron-resonance ion source II of HIRFL can supply the highest current fully stripped heavy ions in the world, which provides an unprecedented opportunity for a comprehensive measurement on Kαα satellite lines with high-resolution. By using the fully stripped Ne–Ca ions extracted from this source with a current of as high as microampere and then bombarding the Be and C target cooled by liquid nitrogen, one aim of the present program is to obtain high intensity Ne–Ca K-shell hollow atoms with additional vacancies in the L shell. By using a high-resolution X-ray wavelength dispersive spectrometer, the energy spectra of the Kαα satellite lines and the branching ratio (to the related satellite lines of the hypersatellite transition Kαh) will be obtained. Emphases will be given to understand the energy levels, decay properties and electron-electron correlation effects of these atoms.

L壳携带旁观空穴的K壳双空穴原子是一类奇异激发态原子。该类原子双电子单光子（TEOP）跃迁Kαα线及其伴线，是研究这类原子能级结构、退激性质及电子-电子关联效应的一种有效“探针”。由于常规的实验手段难以产生高强度的此类原子，高精度Kαα线伴线谱至今尚无有效的实验测量。对这类原子结构和性质的理论认知，急需新的高精度实验数据的推动和检验。HIRFL大科学装置的超导电子回旋共振离子源II能够提供世界上最强的全裸重离子束，为获得高精度Kαα线伴线谱提供了前所未有的机遇。本项目拟利用该装置提供的微安量级的Ne–Ca等全裸离子束，轰击液氮冷却的Be、C靶，得到高强度、K壳双空穴且L壳携带旁观空穴的Ne–Ca原子。采用高分辨X射线晶体谱议，获得这些原子TEOP跃迁Kαα线伴线的能谱结构及分支比（相对于Kαh线伴线），提取这些原子的能级结构和退激性质，研究奇异激发态原子中的电子-电子关联效应。

利用HIRFL大科学装置中SECRALII提供的全裸Ar离子，轰击Be、Al和Fe等靶，制备了大量K壳双空穴且L壳携带旁观空穴的Ar原子；使用晶体谱仪，获得了这些Ar原子OEOP（单电子单光子）辐射退激的Kα超伴线及其伴线的高精度能谱。设计加工了与直线导入器相连的金属丝靶装置，使丝靶可在离子束前进方向上来回移动。通过改变丝靶位置、晶体角度和CCD位置，可在一次实验中，使用高衍射率的石墨晶体，涵盖Ar原子OEOP和TEOP（双电子单光子）跃迁出射的Kα超伴线及其伴线、Kαα线及其伴线的能区，将有效地提高测量效率，为今后系统地获取K壳双空穴且L壳携带旁观空穴原子辐射退激产生的Kα超伴线及其伴线、Kαα线及其伴线的高精度能谱、分支比带来了极大的方便。计算得到了Z=2–120类氦离子OEOP（2s2p-1s2s及1s2p-〖1s〗^2）和TEOP（2s2p-〖1s〗^2）跃迁的能量、速率和分支比，以及这些类氦离子n=2双激发态非辐射Auger单电子出射退激到1s基态的跃迁几率。计算了Z=2–133类氦离子〖1s〗^2、(〖1s,2s)〗_0,1、(〖1s,〖np〗_(1/2))〗_0,1、(〖1s,〖np〗_(3/2))〗_1,2、(〖2s,〖np〗_(1/2))〗_0,1和(〖2s,〖np〗_(3/2))〗_1,2（n≤5）电子组态对应能级中的“纯”电子-电子相互作用能，分析了电子间相互作用的具体来源和贡献。计算了类氦Ar离子、类锂Ar离子和类铍Ar离子对应的、从n=2轨道通过TEOP退激到基态的跃迁能级和跃迁速率对应关系；研究了Ar离子M壳电子数为0和8、深内壳2p–1s轨道电子跃迁的单光子辐射过程（包括OEOP和TEOP），获得了不同旁观电子（1s、2s、2p）数对前述过程的影响规律。