Development of low cost school array device for observing wide area cosmic ray air showers

一种低成本的学校阵列装置，包括用于探测宇宙线的气体密封式电阻板室、具有宇宙线触发电路和测量脉冲高度、到达时间等电路的电子电路盒以及进行总体控制的个人计算机。在这些器件中，最难研制的是气封式电阻板室。电阻板室有两种工作模式。一种是流光模式，另一种是雪崩模式。我们为这两种类型建造了测试室，并测试密封式操作以及测试室的工作时间。对于流光模式腔室，我们使用氩气、异丁烷和正丁烷的混合物。实验结果表明，流注模式电离室在一年内探测效率可达95%以上，脉冲高度无明显变化。然而，从那时起观察到老化效应，大约600天的操作，胶水出来了。雪崩模式信号具有两个较小的数量级，因此对电极和气体的影响很小。由于雪崩模式试验室比流光模式试验室建造得晚，因此试验周期较短。真空室的性能可保持一年以上。由于雪崩模式信号小于流光模式信号，并且雪崩模式室预期持续时间更长，因此我们构建了具有雪崩模式的全尺寸室。全尺寸的腔室大约大四倍。由于拾取电极的面积在全尺寸腔室中比在测试腔室中大得多，拾取噪声也大得多。为了将噪声降低到可接受的水平，我们必须将拾取电极分成六个。到目前为止，我们已经制作了六个完整的房间。为了完成探测器，我们将这些腔室放入不锈钢外壳并连接，这是我们尚未完成的。电子设备已经完成，使用低成本的部件来降低成本。

Low cost school array device consists of gas sealed type resistive plate chamber for detecting cosmic rays, an electronics circuit box which has trigger circuit for cosmic rays and circuits to measure pulse height, arrival time, etc, and a personal computer which perform the overall control. Among these components, the most difficult one to develop was gas sealed type resistive plate chamber. Resistive plate chamber has two types of operation modes. One is streamer mode and the other is avalanche mode. We built test chambers for both types and test the sealed type operation and how long do the chambers work. For the streamer mode chamber, we used argon, iso-butane, and tetrafluoroethane, mixture. As the result of the test, the streamer mode chamber could maintain 95% detection efficiency and no large difference of pulse height for one year. Aging effect, however, was observed since then and about 600 days of operation, glue came out. Avalanche mode signal has two orders of smaller signals, hence the effect to the electrodes and gas is small. Since the avalanche mode test chamber was built later than the streamer mode chamber, test period was shorter. The chamber keeps its performance for more than one year. Since the avalanche mode signals are smaller than the streamer mode signals and avalanche mode chamber is expected to last longer, we built the full size chamber with avalanche mode. The full size chamber is about four times larger. Since the area of the pickup electrode is much larger in the full size chamber than the test chamber, pickup noise was also much larger. To reduce the noise to an acceptable level, we had to divide the pickup electrode in to six. We have made six full size chambers so far. To complete the detector, we put those chambers into the stainless case and put connections, which we have not done yet. Electronics had been complete, which uses low cost parts to reduce the cost.