【作者】 董明义； 修青磊； 伍灵慧； 秦中华； 吴智； 欧阳群； 陈元柏；

【Author】 DONG Ming-yi;XIU Qing-lei;WU Ling-hui;QIN Zhong-hua;OU-YANG Qun;CHEN Yuan-bo;State Key Laboratory of Particle Detection and Electronics;Institute of High Energy Physics, CAS;

【机构】 核探测与核电子学国家重点实验室； 中国科学院高能物理研究所；

【摘要】 作为BESⅢ的中心径迹探测器,漂移室主要用来精确测量BEPCⅡ正负电子对撞产生的末态带电粒子的径迹和动量。连续运行6年以来,由于较高的束流本底漂移室经历了老化过程,前10层增益出现了明显下降,其中第一层增益下降最大,约为29%。采用Bhabha事例重建和丝单元累积电荷两种方法得到了一致的结果。对于2012年漂移室内室出现的Malter效应,通过向工作气体中添加0.2%的水蒸气而解决。老化研究结果为漂移室的工作高压设置及内室升级提供了重要依据。更多还原

【Abstract】 As the main tracking detector of BESⅢ, the drift chamber works for accurate measurements of the tracking and momentum of the charged particles decayed from the reaction of BEPCⅡ e~+ and e~-. After six years of operation, the drift chamber is suffering from aging problems due to huge beam related background. The gains of the cells in the first ten layers experience an obvious decrease, reaching a maximum of about 29% for the first layer cells. Two calculation methods for the gains change(Bhabha events and accumulated charges with 0.3% aging ratio for inner chamber cells) get almost the same results. For the Malter effect encountered by inner drift chamber in Jan., 2012, 0.2% water vapor was added to MDC gas mixture to solve this cathode aging problem. These results provide an important foundation for MDC operation high voltage setting and the upgrade of inner drift chamber.更多还原