Application of Time-over-Threshold readout method to Micro Strip Gas Chamber

Linearity problem has restrained the application of Time-over-Threshold (ToT) on Micro Strip Gas Chamber (MSGC). Here, we proposed an improved ToT method, Dynamic ToT, which could achieve better linearity in a large dynamic range. Both normal ToT and Dynamic ToT module has been assembled with discrete circuits and tested with Multi-Grid MSGC (M-MSGC). In our experiments, Dynamic ToT method has shown a significant linearity improvement, whose coefficient of determination (R-Squared) is ~0.94 over 10 fC to 100 fC input charge. With a FPGA based DAQ system, the energy spectrum has been reconstructed. Utilizing Dynamic ToT readout, both 5.9 keV peak and argon escape peak could be clearly captured.