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

The new type of micro-pattern gaseous detector (MPGD) like the gas electron multiplier (GEM), features the advantage of good spatial resolution ( 100 m). 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 66 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 mm6 mm. The surface resistivity of the pads and the strips are 150 k/□ and 1 k/□, respectively. The performances of the detector, especially the two-dimensional imaging performance, are studied by using a 55Fe (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 80 m () by using the imaging of a 40 m 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.