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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.

1986年建造的阵列已于1987年更新，最终系统用于测试实验如下：16个快速定时探测器放置在4x 4矩阵中，间隔为15 m。每一个都由一个500 × 500 × 35的塑料翻板和一个快速光电倍增管组成，它们装在一个内表面涂成白色的不锈钢盒子里。在盒子的顶部放置一块0.5厘米厚的铅板，通过将高能伽马射线转换成电子对来获得更好的时间分辨率。数据采集采用计算机控制的cammac系统。数据以大约1Hz的频率记录在光盘中。除此之外，8个专用于电子数测量的探测器分布在阵列的中心和外围部分。测试实验的两个主要目的，1)建立了长期稳定性（特别是在恶劣天气条件下）和2）获得了优于1 μ m的Augular分辨率。角分辨率的估计和依赖簇射的大小，探测器的数量和定时精度的探测器已经澄清。本系统给出了10^<15>eV宇宙射线的-0.7，这意味着对于50%的情况，估计的到达方向福尔斯落在真实方向内。增加探测器的数量和提高探测器的质量将使我们获得比目前更好的结果，10^ eV区簇射优于1 μ m，10 <14>^ eV区簇射优于0.3 μ m<15>，从而为在西藏羊八井（4300米）进行全尺寸实验奠定了基础，并期望在10^ eV区进行可靠的γ射线天文学<15>探索。