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Development of a high-rate MUSIC for particle identifications of unstable nuclei

开发用于不稳定核粒子识别的高速 MUSIC

基本信息

批准号：
10640288
负责人：
KIMURA Kikuo
金额：
$ 2.11万
依托单位：
Nagasaki Institute of Applied Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

A high-rate and stable particle identification detector for heavy ions was developed for using as a beam monitor in the unstable nuclear beam experiment like at the forthcoming RI-beam Factory. A multi-layered parallel plate gas ionization chamber having no grid was tried for this detector. The multi-layered configuration enables to make each unit of the chamber very thin and thus to operate it at high speed. However, because of the grid less construction, anode pulses of this ionization chamber are formed not only by the rapid current due to drifting electrons but also by the extremely show positive ion current. The existence of the latter current causes a great problem when operating at high rate. This problem was found to be avoided by applying the special pulse shaping to the anode pulses. The slowness of the positive ion current can be utilized to effectively reject the contribution of this current from the anode pulses. The multi-layered ionization chamber (high-rate MUSIC) thus constructed was tested using secondary beams containing various different heavy ions. It was found that the particle identification capability of this detector was almost equal to the limiting value determined by the statistical fluctuations of energy loss of the incident particles. That is to say, electric noises or detector properties did not at all affect it. The resolution can be improved indefinitely by increasing energy loss. As for the high-rate performance, no deterioration of the resolution was observed up to the maximum counting rate, 150kcps, of the test experiment. As a result of this, a highly practical detector could be developed.

研制了一种高速率、稳定的重离子粒子鉴别探测器，用于即将建成的放射性离子束工厂等非稳定核束实验中的束流监测。该探测器采用了无栅网的多层平行板气体电离室。多层构造使得腔室的每个单元能够非常薄，从而使其以高速运行。然而，由于无栅极结构，该电离室的阳极脉冲不仅由漂移电子引起的快速电流形成，而且还由极端显示的正离子电流形成。后一种电流的存在在高速率操作时引起很大的问题。发现通过对阳极脉冲施加特殊的脉冲整形可以避免这个问题。可以利用正离子电流的缓慢性来有效地拒绝来自阳极脉冲的该电流的贡献。多层电离室（高速率MUSIC），从而构建了测试使用含有各种不同的重离子的次级束。发现该探测器的粒子识别能力几乎等于由入射粒子能量损失的统计涨落所确定的极限值。也就是说，电噪声或探测器特性对分辨率没有任何影响，通过增加能量损失，可以无限提高分辨率。至于高速率性能，没有观察到分辨率的恶化，直到测试实验的最大计数率150kcps。因此，可以开发高度实用的检测器。