BEPCⅡ束损系统研究

Study on beam loss system of BEPCⅡ

为更好掌握储存环中的束流状态,在北京正负电子对撞机二期工程的储存环上建立了以二极管为探测器的束流损失探测系统。用蒙特卡罗软件对损失束流产生簇射电子的分布情况进行了模拟,为安装束损探测器位置提供了依据。搭建了包括探头、数据获取系统、数据传输系统在内的束损系统。对束损过程进行了详细的分析与描述。对北京正负电子对撞机多年的束损数据进行了整理分析,对其在丢束诊断、束流寿命研究等多个方面应用情况进行了总结。数据显示建立的束损系统工作状态稳定,是优化机器参数、改善束流寿命、分析丢束过程的有力工具。

Background： A beam loss system that uses the PIN diode as the detector has been set up on Beijing Electron–Positron Collider II （BEPCII） storage after 8-a routine operation. Further study and analysis should been carried out based on the historical data. Purpose： This study aims to learn the beam loss process in depth and further optimize the parameters of the accelerator. Methods： Based on the machine size and beam parameter of BEPCII, the Monte Carlo simulation of the cluster electrons in the storage ring was performed to provide reference for installation position of the beam loss system. Then different methods, including adding all the beam loss monitor （BLM） counts, adding the inner detector, adding the outer detector, have been used for data analysis of the beam life time, beam loss distribution, beam envelope and dispersion, etc., under both the collider mode and synchrotron mode. Results： The results show that the BLM system is useful to study the beam life time and diagnose the beam loss processes. The beam loss system for BEPCII works stablely. The detector counts are much smaller than the dynamic range of the detector. Conclusion： Over the eight years, the response of the beam loss system does not change a lot, which implies that the radiation tolerance of beam loss system is very good. Lower than expected detector counts show that the detectors position needs to be optimized, the sensitivity is not enough. The beam loss system is an effective method to study the “dust” effect.