Development of a crystal installing SQUID's for the detection of charged particles

一个弱磁场跟随着一个移动的带电粒子，磁场的强度随着粒子的速度而增加。根据我们运用狭义相对论理论的计算，我们预测了以相对论速度运动的带电粒子所产生的磁场强度具有SQUID可以探测到的数量级。这一事实开启了在不直接“接触”的情况下探测带电粒子的可能性。作为第一步，我们开发了一种用于SQUID安装的晶体，该晶体应在氦温度下运行。这种晶体的特点是有一个洞，带电粒子可以通过这个洞进出。考虑到未来的发展，我们决定使用FRP材料代替不锈钢等金属。为了获得较好的耐低温性能和良好的磁性能，对其进行了性能测试。对于液体密封和真空密封，测试和开发了一种螺杆系统，使其易于组装和拆卸。在初步测试中，我们成功地密封了液氮和液氦。原型晶体可以保持液氮一段时间，但不可能达到保持液氦的阶段。泄漏的原因已经检测出来了，我们希望在现在的改进进展后可以保留它们。

A weak magnetic field follows a moving charged particle and the strength of the field increases with the velocity of the particle. Accoridng to our calculation using the theory of special relativity, it is predicted that the strength of the magnetic field induced by a charged prticle moving with a relativistic speed have an order of magnitude detectable by a SQUID. This fact opens a possibility of detecting a charged particle without directly "touching". As a first step we develop a crystal for the installation of the SQUID which should be operated at the helium temperature. The crystal is characterized with a hole through which charged particles can come and go.Thinking of the future development, we decided to use FRP material instead of metal such as stainless steel. The type of the FRP was examined in order to survive the low temperature and to achieve good magnetic character. For the liquid and the vacuum seal, a screw system has been tested and developed, which makes the assembling and the deassembling easy. In a preliminary test we succeeded in sealing the liquid nitrogen and also the liquid helium. The prototype crystal could keep the liquid nitrogen for a while, but it was not possible to reach the stage of keeping the liquid helium. The cause of the leakage was detected and we hope we can keep them after the improvement progressing now.