Tungsten mesh as positron transmission moderator in a monoenergetic positron beam

被引：15
作者：
Weng, HM
Ling, CC
Beling, CD
Fung, S
Cheung, C
Kwan, PY
Hui, IP
机构：
[1] Univ Hong Kong, Dept Phys, Hong Kong, Hong Kong, Peoples R China
[2] Univ Sci & Technol China, Dept Modern Phys, Hefei 230026, Peoples R China
来源：
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS | 2004年 / 225卷 / 03期
关键词：
positron emission; positron moderation; tungsten mesh; positron annihilation;
D O I：
10.1016/j.nimb.2004.05.002
中图分类号：
TH7 [仪器、仪表];
学科分类号：
0804 ; 080401 ; 081102 ;
摘要：
The slow positron yield has been measured for various tungsten (W) moderator samples from a Na-22 radioactive source. Multi-folded W mesh, W(1 0 0) single crystal foil and W polycrystalline foil samples have been investigated. It is found that the fast to slow conversion efficiency of the W mesh moderator depends on: (1) the annealing pretreatments, (2) the chemical etching duration and (3) the number of the folding layers. With the raw W mesh material having a wire diameter of 20 mum and transmission efficiency of 92.5%, an optimal efficiency of 1.2 x 10(-3) was achieved with 5 min etching duration and a folding number of 12 layers. (C) 2004 Elsevier B.V. All rights reserved.
引用
收藏
页码：397 / 401
页数：5
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