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Development of Endcap Electromagnetic Calorimete for B Factory

B厂端盖电磁热量计开发

基本信息

批准号：
06044218
负责人：
FUKUSHIMA Masaki
金额：
$ 6.91万
依托单位：
National Laboratory for High Energy Physics
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

The performance of CsI (Tl) single crystal was test for the use of high precision electromagnetic calorimeter for the BELLE experiment at the KEK asymmetric B-Factory. The radiation hardness of 30cm long crystal from Russian, Chinese and French crystal growers was tested by irradiating them by low energy gamma rays from ^<60>Co and measuring the change of average light yield and the uniformity of light collection. The radiation hardness of Chinese crystal was greatly improved by the doping of specific material. The crystals from all the vendors were finally proved to be adequate for the use in the endcap region. It was discovered that the localized radiation damage does not deteriorate the uniformity of the ligh yield, and therefore the decrease of average light yield is correctable by the calibration without sacrificing the energy resolution.We built automated optical and dimensional property measurement devices, and installed them in the crystal growth factories in Russia and China as well as at KEK for the final acceptance test of produced crystals. These devices measure the light yield and uniformity within 4 minutes, and the dimension of the crystal within 3 minutes.The performance of 6*6 crystal matrix was tested by the tagged photon beam at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. The preliminary analysis shows an excellent energy resolution of 4.0% at 40MeV and 1.8% at 800 MeV.A study will be continued for improving the performance against pileup by adopting the wave form sampling technique.

利用高精度电磁量能器对CsI（Tl）单晶的性能进行了测试，用于KEK非对称B工厂的贝儿实验。用低能γ射线辐照俄罗斯、中国和法国的30cm长晶体，<60>测量其平均光产额和聚光均匀性的变化。通过掺杂特定的材料，使单晶的抗辐照性能得到了很大的提高。所有供应商的晶体最终被证明足以用于端盖区域。结果发现，局部辐射损伤不会影响光产额的均匀性，因此，平均光产额的降低可以通过校准来校正，而不会牺牲能量分辨率。我们建立了自动光学和尺寸性能测量设备，并将其安装在俄罗斯和中国的晶体生长工厂以及KEK，用于生产的晶体的最终验收测试。这些设备在4分钟内测量光输出和均匀性，并在3分钟内测量晶体的尺寸。6*6晶体矩阵的性能在俄罗斯新西伯利亚的布德克核物理研究所用标记光子束进行了测试。初步分析表明，40 MeV和800 MeV的能量分辨率分别为4.0%和1.8%。将继续研究采用波形采样技术来提高抗堆积性能。