Development of the air shower core detector for the primary cosmic-ray observation at the knee.

爆发探测器的开发是为了测量由重宇宙线（如铁成分）产生的空气簇射核的能量流，以解析宇宙线在膝区（10^<15>eV至10^<16>eV）的主要成分，这是宇宙线起源的关键信息。于2003年建立了一个由40cm × 50cm × 3.5cm铅和1cm厚闪烁体组成的原型型爆发探测器。猝发信号通过波长移动光纤由光电倍增管读出。通过使用两个不同增益的光电倍增管，获得了宽的动态范围。通过对西藏羊八井（海拔4300 m）空气簇射的模拟研究表明，用这种探测器以3.75 m的格网间距对空气簇射核进行观测，可以很好地研究其主要成分。数据分析是基于人工神经网络来分离核种的（见59届<th>物理学会年会报告）。 ...更多信息 2004年对原型探测器的线性度、动态范围和位置均匀性进行了系统的检查和改进。研制了数据采集系统，并在西藏空气簇射阵中心布设了4个探测器。新的爆发探测器自2004年10月开始运行，触发条件是爆发大小大于40个粒子。触发率完全在预期值范围内，观察成功持续到现在。对实验数据的初步分析结果与模拟结果吻合较好，表明该仪器能够有效地实现预期目标（2005年<th>日本物理学会第60届年会上的报告），从而保证了本研究所开发的爆发探测器可以用于下一步膝能区的初级成分观测。通过几年的观察，预计20 x 20通道网格的放大仪器将为膝关节组成提供高统计数据。少

The development of the burst detector was made to measure the energy flow of the air shower core originated by heavy cosmic rays such as iron component in order to resolve the primary composition of the cosmic rays at the knee region (10^<15>eV〜10^<16>eV) which is a key information on the cosmic ray origin. A proto type burst detector consisting of 40cm x 50cm x 3.5 cm lead and scintillator of 1cm thick was setup in 2003. The burst signal is read out by photomultiplier through wavelength shifting fiber. Wide dynamic range is obtained by using two photomultipliers of the different gain. From the air shower simulation study, it was shown that the primary composition can be well studied through the observation of the air shower core by this kind of the detectors placed at Tibet Yangbajing (4300 m above sea level) with 3.75m spacing in a grid. The data analysis is based on artificial neural network to separate the nuclear species (reported on 59^<th> annual conference of the Physical Socie … More ty of Japan 2004 and Autumn conference 2004).Systematic checks and improvements were made on the proto type detector in 2004 for the linearity, the dynamic range and the positional uniformity. Data acquisition system was also developed and 4 detectors were set up in the center of the Tibet air shower array. The new burst detector is under operation since Oct. 2004 with trigger condition of burst size greater than 40 particles. The trigger rate is well within the expected value and the observation is successfully continued until now. The result of an early analysis of the experimental data is in a good agreement with the simulation showing that the instrument is working efficiently for the aimed purpose (reported on 60^<th> annual conference of the Physical Society of Japan 2005).It is ensured that the burst detector developed in this research can be used in the next step to observe the primary composition at the knee energy range. It is expected that the enlarged instrument of 20 x 20 channels in a grid will provide the knee composition with high statistics through a few years observation. Less