Application of spin conversion reactions of positronium for analyzing the atomic scatterings

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H03703
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Atomic/Molecular/Quantum electronics
• Research Institution: The University of Tokyo
• Principal Investigator: Saito Haruo 東京大学, 大学院総合文化研究科, 教授 (60235059)
• Co-Investigator(Kenkyū-buntansha): 澁谷 憲悟 東京大学, 大学院総合文化研究科, 助教 (20415425)
• Research Collaborator: HOSOTANI Ryosuke
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 陽電子 / ポジトロニウム / スピン軌道相互作用 / スピン転換 / 原子衝突 / 散乱長 / 部分波解析

Outline of Final Research Achievements

We have studied atomic scatterings of positronium (Ps) in the ultra-low-energy region less than 100 meV by using Ps spin-conversion reaction which is forbidden in the s-wave scatterings (L=0). We have analyzed the data of the Ps annihilation rates and the momentum transfer cross-section in gaseous xenon obtained by our new positron annihilation spectrometer by means of a partial-wave expansion method. We have determined the Ps-Xe scattering length to be 2.06 a.u., which indicates that the Xe potential push out the Ps wave and delays the phase while the long-range interaction is van der Waals force. This results are qualitatively consistent with some theoretical predictions; however, some quantitative discrepancies are remained to be studied in the future works.

Free Research Field

陽電子物理学