论文标题
BESIII实验的圆柱宝石机械结构的研究和改进
Investigation and improvements of the mechanical structure of Cylindrical GEMs for the BESIII experiment
论文作者
论文摘要
气体电子乘数（宝石）可以以大型箔片生产，并以不同的形状模制。创建圆柱层的可能性为对撞机实验的内部跟踪器提供了机会。一个至关重要的项目是在活动区域的材料预算低，因此阳极和阴极的支撑结构必须很轻。 Kloe2 Collaboration已使用蜂窝状材料建造了第一个圆柱形宝石探测器，并在高温下生产了碳纤维皮。 BESIII正在开发具有充电和时间读数的创新CGEM探测器。在几种创新功能中，机械结构被设计为Rohacell和PMI泡沫Kapton的三明治。在从意大利的建筑工地运输到北京高能物理研究所的第一次生产探测器后，在其中一些探测器中观察到了一些故障，与检测器内部的宝石变形兼容。我们通过IHEP实验室中可用的工业CT扫描进行了详细的研究，并对受损的探测器进行了尸检。在这次演讲中，我们将审查施工过程，装运，调查结果。已经设计和开发了在室温下组装的碳纤维和蜂窝的新的辅助结构。碳纤维的厚度足够小，可以使单个检测器层的材料预算低于辐射长度的0.5 $ \％$，而机械鲁棒性则超出了HEP检测器的目的。本次演讲还将介绍具有这种机械结构的第一个检测器，并将其运送到IHEP上，这是探测器的操作（例如当前稳定性，放电，温度和湿度相关性）的初步结果。
Gas Electron Multipliers (GEMs) can be produced in large foils and molded in different shapes. The possibility to create cylindrical layers has opened the opportunity to use such detector as internal tracker at collider experiments. One crucial item is to have low material budget in the active area, so the supporting structure of anode and cathode must be light. KLOE2 collaboration has built the first Cylindrical GEM detector with honeycomb material with carbon fiber skins produced at high temperature. BESIII is developing an innovative CGEM detector with charge and time readout. Among several innovative features, the mechanical structure was designed to be a sandwich of Rohacell and Kapton, a PMI foam. After the transportation of a first production of the detectors from the construction site in Italy to the Institute of High Energy Physics in Beijing, some malfunctions have been observed in some of them, compatible with GEMs deformation inside the detector. We have performed a detailed study by means of an industrial CT scan available in IHEP laboratory and autopsy to the damaged detectors. In this talk, we will review the construction process, the shipment, the findings of the investigation. A new supporting structure of carbon fiber and honeycomb, assembled at room temperature, has been designed and developed. The thickness of the carbon fiber is small enough to keep the material budget of a single detector layer below 0.5$\%$ of a radiation length, while the mechanical robustness results beyond the purpose of a detector for HEP. A first detector with such a mechanical structure has been built and shipped to IHEP, preliminary results from operation (e.g. current stability, discharges, temperature and humidity correlation) of the detectors will be also presented in this talk.
