Development of new technology of positron annihilation defect spectroscopy under ion-bem irradiation

离子束辐照下正电子湮没缺陷光谱新技术研究进展

• 批准号: 13480141
• 负责人: ITO Yasuo
• 金额: $ 7.94万
• 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 (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13480141/
• 关键词: slow positron beam; short pulse; irradiation induced defects; pulse bunching; pulse chopping

A slow positron beam line was constructed at the neutron production room of HIT (High Fluence Irradiation Facility of University of Tokyo). The beam line was merged with the ion-beam line from the van de Graaf accelerator so that simultaneous irradiation of ion-beam and slow positron beam is possible. Evaluation of ion-beam induced defects is possible by measurements of Doppler Broadening of the positron annihilation radiation. Further improvement of the facility was aimed by making the slow positron beam. By chopping the DC positron beam into 5ns pulse width, and then bunching with 40MHz RF, short pulses of 500psec were created. These pulsed positrons were used to measure the formation and lifetime of ortho-positronium, whose lifetime is normally longer than 500psec. A trial to improve the pulse width shorter than 500psec has not been successful without sacrificing the counting efficiency. But further study for obtaining shorter pulses are under way.

在东京大学高通量辐照设施的中子产生室建造了一条慢正电子束流线。该束线与范格拉夫加速器的离子束线合并，从而使离子束和慢正电子束同时辐照成为可能。通过测量正电子湮灭辐射的多普勒展宽，可以评价离子束诱导缺陷。进一步改进设备的目的是制造慢正电子束。通过将直流正电子束切割成5ns脉冲宽度，然后与40MHz射频聚束，产生500psec的短脉冲。这些脉冲正电子被用来测量正电子的形成和寿命，正电子的寿命通常长于500psec。在不牺牲计数效率的情况下，将脉冲宽度提高到500psec以下的试验没有成功。但获得更短脉冲的进一步研究正在进行中。

项目成果

Y.Ito: "Comments on electric field experiments of positronium formation"Radiation Physics and Chemistry. in press. (2003)

Y.Ito：《正电子素形成电场实验评述》《辐射物理与化学》。

C-Q.He, E.Hamada, T.Suzuki, Ho.Kobayashi, K.Kondo, Y.ITO: "Development of a pulsed slow positron beam : moderator and bunching signal waveform"Nucl. Instr. Methods in Physics Research B. (In press). (2003)

C-Q.He、E.Hamada、T.Suzuki、Ho.Kobayashi、K.Kondo、Y.ITO：“脉冲慢正电子束的发展：慢化剂和聚束信号波形”Nucl。

C.He, T.Suzuki, V.P.Shantarovich, Y.Ito: "Positron annihilation in hypercrosslinked polystyrenes"Chemical Physics. 286. 249-256 (2003)

C.He、T.Suzuki、V.P.Shantarovich、Y.Ito：“超交联聚苯乙烯中的正电子湮灭”化学物理。

A.Shimazu, T. Miyazaki, S. Katayama, and Y. Ito: "Permeability, permselectivity, and penetrant-induced plasticization in fluorinated polyimides studied by positron lifetime measurements"Journal of Polymer Science. 41. 308-318 (2003)

A.Shimazu、T. Miyazaki、S. Katayama 和 Y. Ito：“通过正电子寿命测量研究氟化聚酰亚胺的渗透性、选择性渗透和渗透剂诱导塑化”《聚合物科学杂志》。

A.Shimazu, T.Miyazaki, S.Katayama, Y Ito: "Permeability, permselectivity, and penetrant-induced plasticization in fluorinated polyimides studied by positron lifetime meastuements"Journal of Polymer Science. 41. 308-318 (2003)

A.Shimazu、T.Miyazaki、S.Katayama、Y Ito：“通过正电子寿命测量研究氟化聚酰亚胺的渗透性、选择性渗透和渗透剂诱导的塑化”聚合物科学杂志。