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Development of an air shower array for accurate determination of the arrival direction of cosmic rays in the 10^<15>eV region.

开发用于精确确定10 15 eV区域宇宙射线到达方向的空气喷淋阵列。

基本信息

批准号：
61460016
负责人：
KASAHARA Katsuaki
金额：
$ 4.29万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

The array constructed in 1986 has been updated in 1987 to have the final system used for test experiment as follows: 16 fast timing detectors are placed in a 4x4 matrix with 15 m separation. Each consists of a plastic scintillater of 500x 500x35 size and a fast photomultiplier accomodated in a steinless steal box of whcih inner surface is painted white. A lead plate of 0.5 cm thick is placed on the top of the box to have better time resolution by converting high energy gamma rays into election pairs. A cammac system is used for the data taking which is controlled by a micor-computer. The data is recorded in an optical disk with a frequency of about 1 Hz. In addition to these, 8 detectors dedicated to the electron number measurement are distributed in the center and peripheral part of the array.The two main purposes of the test experiment, i.e., 1) establishing the stability for a long time (especially for heavy weather conditions) and 2) acquiring the augular resolution better then 1゜, have been achieved successfully. The angular resolution is estimated and its dependence on the shower size, the number of detector and the timing accuracy of the detectors has been clarified. The present system give -0.7゜ for 10^<15>eV cosmic rays where means that the estimated arrival direction falls in within from the true direction for 50 % cases. Increasing the number of detectors and upgrading the quality of scintillaters will give us better resuolution than the present one; better than 1゜ for 10^<14>eV region showers better than 0.3゜ for 10^<15>eV showers.Thus we have established the basis for a full scale experiment at Yambatin (4300m) in Tibet and expect that a reliable gamma-ray astronomy in the 10^<15>eV region can be explored.

在1986年建造的阵列已经在1987年更新，有用于测试实验的最终系统如下：16个快速定时探测器放置在4x4矩阵中，间隔15米。每个都由一个500x 500x35尺寸的塑料闪烁体和一个快速光电倍增管组成，该光电倍增管被安置在一个内表面涂成白色的不锈钢盒中。盒子顶部放置了0.5 cm厚的引线板，通过将高能伽马射线转换为选举对，具有更好的时间分辨率。cammac系统用于数据采集，由微机控制。数据以1hz左右的频率记录在光盘中。此外，阵列的中心和外围还分布着8个专用于电子数测量的探测器。测试实验的两个主要目的，即1)建立长时间的稳定性（特别是在恶劣天气条件下）和2)获得优于1的惯性分辨率，已成功实现。估计了角分辨率，并阐明了角分辨率与星雨大小、探测器数量和探测器定时精度的关系。目前的系统对10^<15>eV宇宙射线给出-0.7，这意味着估计到达方向在50%的情况下落在真实方向以内。增加探测器的数量和提高闪烁体的质量将使我们获得比现在更好的分辨率；10^<14>eV区域阵雨优于1 10^<15>eV阵雨优于0.3。