Laser enrichment of Gd-157 based on polarization selection rules

基于偏振选择规则的Gd-157激光富集

• 批准号: 07558187
• 负责人: IZAWA Yasukazu
• 金额: $ 4.22万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07558187/
• 关键词: laser isotope separation; gadolinium; selective excitation; linear polarization; polarization selection rule; three-step photoionization

In the absorption spectrum of atomic Gd, the isotope shifts are very small compared with the widths of hyperfine structures of the odd isotopic elements. Therefore the selective photoionization scheme based on the polarization selection rules seems to be suitable to separate Gd-157. In this scheme three linearly polarized laser pulses are used to prepare aligned states. Ionization of the even isotopes in inhibited by the selection rules, while the hyperfine interactions in the odd isotopes allow selective ionization.The absorption spectrum of Gd for the transitions applicable to the 1st and 2nd steps in the 3-step photoionization scheme were measured and the isotope shifts and the hyperfine structure constants were determined. By using the excitation pathway with J=2*2*1*0, the enrichment of Gd-157 up to 80% was demonstrated. The selectivity of this method, however, will be lost by an external magnetic field because the intermediate-state alignment is destroyed by the magnetic field that finally leads to ionization of the even isotopes. The effects of magnetic field on isotope selectively was analyzed and the condition for high selectivity was discussed.The charge transfer collision cross section between the selectivity photoionized Gd ions and Gd atoms were experimentally evaluated. The atomic vapor density to maintain high selectivity was also discussed.

在Gd原子的吸收光谱中，同位素位移与奇同位素元素的超精细结构的宽度相比是非常小的。因此，基于偏振选择规则的选择性光电离方案似乎适合于Gd-157的分离。在该方案中，使用三个线偏振激光脉冲来制备对准态。偶同位素的电离受到选择规则的抑制，而奇同位素的超精细相互作用允许选择性电离.测量了Gd在三步光电离方案中第一步和第二步跃迁的吸收光谱，确定了同位素位移和超精细结构常数.采用J=2*2*1*0的激发途径，Gd-157的富集率可达80%。然而，这种方法的选择性将被外部磁场所破坏，因为中间态的排列被磁场破坏，最终导致偶同位素的电离。分析了磁场对Gd同位素选择性的影响，讨论了高选择性的条件，实验测量了选择性光电离Gd离子与Gd原子之间的电荷转移碰撞截面。讨论了维持高选择性的原子蒸气密度。

项目成果

M.Hashida, Y.Izawa et al.: "Cross section of charge transfer between a Gd atom and its single charged positive ions in metastable state close to the ground state" Physical Review A. Vol.54. 4573-4576 (1996)

M.Hashida、Y.Izawa 等人：“Gd 原子与其处于接近基态的亚稳态的单带电正离子之间的电荷转移截面”《物理评论 A》第 54 卷。

K.Nomaru and Y.Izawa: "Spatial Effects on Propagation of Laser Pulses in a Multilevel Photoionization System" Jpn.J.Appl.Phys.Vol.36. 2386-2393 (1997)

K.Nomaru 和 Y.Izawa：“多级光电离系统中激光脉冲传播的空间效应”Jpn.J.Appl.Phys.Vol.36。

M.Hashida, Y.Izawa et al.: ""Cross-section of charge transfer between a Gd atom and its single charged positive ions in metastable state close to the ground state"" Physical Review A. 54. 4573-4576 (1996)

M.Hashida、Y.Izawa 等人：“接近基态的亚稳态中 Gd 原子与其单带电正离子之间的电荷转移横截面”物理评论 A. 54. 4573-4576 (1996

M.Hashida, Y.Izawa et al.: "Cross-section of symmetric charge transfer between Gd and Gd^+ in the energy range 30-1000eV" Physical Review A. Vol.53. 1487-1491 (1996)

M.Hashida、Y.Izawa 等人：“能量范围 30-1000eV 内 Gd 和 Gd^ 之间对称电荷转移的横截面”Physical Review A. Vol.53。

K.Nomaru and Y.Izawa: ""Spatial Effects on Propagation of Laser Pulses in a Multilevel Photoionization System"" Jpn.J.Appl.Phys.(印刷中). (1997)

K. Nomaru 和 Y. Izawa：“多级光电离系统中激光脉冲传播的空间效应”Jpn.J.Appl.Phys（出版中）。