Evidence for the non-statistical population of the 1s2s2p ⁴P metastable state by electron capture in 4 MeV collisions of B³⁺(1s2s ³S) with H₂ targets

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• 作者：E.P. Benis^a ; ; S. Doukas^b ; T.J.M. Zouros^c ; ^d
• 关键词：Non-statistical population ; Electron capture ; Cascade feeding ; Metastable states ; Effective solid angle
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：2016
• 出版时间：15 February 2016
• 年：2016
• 卷：369
• 期：Complete
• 页码：83-86
• 全文大小：516 K

文摘

We have revisited previously published data involving collisions of mixed 4 MeV ${\text{B}}^{3+}(1s^2{}^{1}S\text{,}1s2s{}^{3}S)$ with H₂ targets (Benis et al., 2002) in search of evidence for the non-statistical production of the $1s2s2p{}^{4}P$ long-lived metastable state by single electron capture. Using our recently published method for the accurate determination of the effective solid angle of Auger decaying metastable projectile states in combination with knowledge of the $1s2s{}^{3}S$ metastable beam fraction allowed us to determine the ratio $R={}^{4}P/{}^{2}P$ of 1s2s2p$1s2s2p$ quartet to doublet production cross sections both formed by electron capture. Our present determination of R=2.8±0.5$R=2.8\pm 0.5$, clearly departs from the expected value of R=2$R=2$ based on statistical spin recoupling arguments and thus provides evidence for the active presence of additional population mechanisms in a new collision system.