Aging effect in the BESIII drift chamber

分类： 物理学 >> 核物理学 提交时间： 2016-09-13

DONG Ming-Yi XIU Qing-Lei WU Ling-Hui WU Zhi QIN Zhong-Hua SHEN Pin AN Fen-Fen JU Xu-Dong LIU Yi ZHU Kai OU-YANG Qun CHEN Yuan-Bo

摘要： As the main tracking detector of BESIII, the drift chamber works for accurate measurements of the tracking and the momentum of the charged particles decayed from the reaction of BEPCII e+ and e-. After operation six years, 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 the inner drift chamber in Jan., 2012, about 0.2% water vapor was added to MDC gas mixture to solve this cathode aging problem. These results provide an important reference for MDC operation high voltage setting and the upgrade of the inner drift chamber.

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