Cryogenic helium as stopping medium for high-energy ions

被引：13

作者：

Purushothaman, S. ^{[1
]}

Dendooven, P. ^{[1
]}

Moore, I. ^{[2
]}

Penttila, H. ^{[2
]}

Ronkainen, J. ^{[2
]}

Saastamoinen, A. ^{[2
]}

Aysto, J. ^{[2
]}

Perajarvi, K. ^{[2
]}

Takahashi, N. ^{[3
,4
]}

Gloos, K. ^{[5
]}

机构：

[1] Univ Groningen, Kernfys Versneller Inst, NL-9747 AA Groningen, Netherlands

[2] Univ Jyvaskyla, Dept Phys, Jyvaskyla 40014, Finland

[3] Osaka Univ, Suita, Osaka 565, Japan

[4] Osaka Sci Museum, Osaka, Japan

[5] Univ Turku, Dept Phys, Wihuri Phys Lab, Turku 20014, Finland

来源：

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS | 2008年 / 266卷 / 19-20期

基金：

芬兰科学院;

关键词：

Gets catcher; Cryogenic helium gas; Ions in helium; Radioactive ion beams;

D O I：

10.1016/j.nimb.2008.05.096

中图分类号：

TH7 [仪器、仪表];

学科分类号：

0804 ; 080401 ; 081102 ;

摘要：

We have investigated the survival and transport efficiency of Ra-219 ions emitted by a Ra-223 source in high-density cryogenic helium gas, with ionisation of the gas induced by a proton beam. The combined efficiency of ion survival and transport by an applied electric field was measured as a function of ionisation rate density for electric fields up to 160 V/cm and for three temperature and density combinations: 77 K, 0.18 mg/cm(3), 10 K, 0.18 mg/cm(3) and 10 K, 0.54 mg/cm(3). At low beam intensity or high electric field, an efficiency of 30%, is obtained, confirming earlier results. A sharp drop in efficiency is observed at a "threshold" ionisation rate density which increases with the square of the applied electric field. At 160 V/cm, the efficiency stays above 10% up to an ionisation rate density of 10(12) ion-electron pairs/cm(3)/s. The observed behaviour is understood as the result of shielding of the applied field by the weak plasma created by the proton beam: it counteracts the effective transport of ions and electrons, leading to recombination between the two. We conclude that cryogenic helium gas at high-density and high electric field is a promising medium for the transformation of very high-energy ions into low-energy ones. (c) 2008 Elsevier B.V. All rights reserved.

引用

页码：4488 / 4492

页数：5