基于阻性阳极读出方法的气体电子倍增器二维成像性能

Study of the two dimensional imaging performance for the gas electron multiplier using the resistive anode readout method

新型微结构气体探测器,如气体电子倍增器(gas electron multiplier,GEM)等,具有非常好的位置分辨率潜力(σ<100μm),但是需要匹配大规模高密度的读出电子学,给探测器的建设、造价、功耗、空间利用等带来极大压力.阻性阳极读出方法可以在保持较高位置分辨率的前提下,大幅节省电子学.基于厚膜电阻工艺,一种新的阻性单元阵列结构被成功开发和应用于三级级联GEM探测器的读出阳极.该阻性阳极包括6×6个6 mm×6 mm的基本阻性单元,仅需匹配49路读出电子学.^(55)Fe放射源(5.9 keV)和X光机(8 keV)实验的结果显示探测器的位置分辨率(σ)可好于80μm,位置非线性好于1.5%.同时,探测器还获得了很好的实物成像效果.探测器的优良性能表明这种阻性阳极读出方法适用于大面积二维成像气体探测器的读出,并可用于其他探测器的读出.

The new type of micro-pattern gaseous detector（MPGD） like the gas electron multiplier（GEM）, features the advantage of good spatial resolution（σ 〈μm）. However, abundant and high density electronic channels are needed to obtain the high spatial resolution, which will lead to a great pressure on the detector construction, power consumption,spatial utilization, etc. The resistive anode readout method can help to obtain a good spatial resolution comparable to the pixel readout structure with an enormous reduction of the electronic channels. By using the thick film resistor technology, a new type of resistive structure, composed of high resistive square pad array with low resistive narrow border strips, is developed and applied to the readout anode of the triple GEM detector. For the resistive anode readout board used in the experiment, there are × resistive cells, which means that the detector needs only 49 electronics channels.To obtain a good spatial resolution, the cell size is set to be 6 mm × mm. The surface resistivity of the pads and the strips are 150 kΩ/□ and 1 kΩ/□, respectively. The performances of the detector, especially the two-dimensional imaging performance, are studied by using a^（55）Fe（5.9 keV） source and an X ray tube（8 keV）. The test results show that the spatial resolution of the detector is better than μm（σ） by using the imaging of a μm wide slot, and the nonlinearity is better than 1.5% by the scanning along the x-axis of the readout board in the steps of 1 mm. Furthermore, quite a good two-dimensional imaging capability is achieved by the detector. These good performances of the detector show the feasibility of the resistive anode readout method for the GEM detector with large area and other detectors with similar structures in the two-dimensional imaging applications.