Effect of permanent dipole moment of molecules onpositronium thermalization in the gases

分子永久偶极矩对气体中正电子热化的影响

• 批准号: 12640384
• 负责人: NAGASHIMA Yasuyuki
• 金额: $ 2.3万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640384/
• 关键词: positron annihilation; positronium; thermalization; permanent dipole; 気体; シリカエアロジェル; 運動量移行断面積

The scattering of positronium (Ps) atoms by atoms or molecules is a fundamental process that provide an attractive testing ground for scattering theories. Recently, it has become possible to extract useful qualitative information on Ps interactions with atoms or molecules in the energy range below 1eV using the angular correlation of annihilation radiation (ACAR) method combined with the use of silica aerogel.In this project, we have observed Ps thermalization process in Ne, H_2, N_2, CH_4, and C_2H_4 gases. By analyzing the data, we determined the momentum-transfer cross sections between Ps and these molecules to be (10*7)×10^<-16>cm^2 for Ne, (17*5)×10^<-16>cm^2 for H_2, (26*8)×10^<-16>cm^2 for N_2, (17*8)×10^<-16>cm^2 for Ch_4, and (23*7)×10^<-16>cm^2 for C_2H_4. We have also compared the Ps thermalization process in neo-C_5H_<12> is slower than that in neo-C_5H_<12>. This indicates that the effect of permanent dipole of iso-C_5H_<12> is small for Ps thermalization.

正电子素（Ps）原子与原子或分子的散射是一个基本的过程，为散射理论提供了一个有吸引力的试验场。近年来，利用湮没辐射的角相关（ACAR）方法和SiO2气凝胶相结合，可以在1eV以下的能量范围内提取Ps与原子或分子相互作用的定性信息，本项目中我们观测了Ne、H_2、N_2、CH_4和C_2H_4气体中Ps的热化过程。通过对实验数据的分析，我们确定了Ps与这些分子之间的动量转移截面：Ne为（10 * 7）× 10 ^cm ^2，H_2为（17 * 5）× 10 ^cm ^2，N_2为（26 * 8）× 10 ^cm ^2，CH_4为（17 * 8）× 10 ^cm ^2，C_2H_4为（23 * 7）× 10 ^cm ^2。<-16><-16><-16><-16><-16>我们还比较了在neo-C_5H_2中Ps热化过程比在neo-C_5H_2中慢。<12><12>这表明异C_5H_3的永久偶极对Ps热化的影响很小。<12>

项目成果

Y.Nagashima: "Positronium-atom/molecule interactions : momentum-transfer cross sections and ^1Zeff"New Directions in Antimatter Chemistry and Physics. 291-301 (2001)

Y.Nagashima：“正电子原子/分子相互作用：动量传递截面和^1Zeff”反物质化学和物理的新方向。

Y.Nagashima: "Positronium-Atom/Molecule Interactions : Momentum-transfer Cross Sections and ^1Z_<eff>"New Directions in Antimatter Chemistry and Physics. 291-301 (2001)

Y.Nagashima：“正电子原子/分子相互作用：动量转移截面和^1Z_<eff>”反物质化学和物理的新方向。

Y. Nagashima: ""Positronium-Atom/Molecule Interactions : Momentum-transfer Cross Sections and ^1Z_<eff>""New Directions in Antimatter Chemistry and Physics. 291-301 (2001)

Y. Nagashima：“正电子原子/分子相互作用：动量转移截面和 ^1Z_<eff>”“反物质化学和物理学的新方向。