Background: A good knowledge of gas gain properties is of importance for the development and operation of proportional counters. Spherical tissue equivalent proportional counters (TEPC) have been widely used in the protection dosimetry applications

thus it is necessary to investigate the gas gain characterization in TEPC detectors. Because of the extremely low pressure

gas gain in the TEPC is significantly influenced by the gradient of the electric field around the anode wire. Gradient-field model was proved to be accurate enough to predict the gas gain in the TEPC. However

the formula based on the gradient-field model comprises three gas dependent constants which make it impractical for TEPC design and applications. Purpose: This work aims to develop a technical routine for the simulation of the TEPC gas gain and implement validations of the simulated results. Methods: In this work

a Benjamin type TEPC was firstly developed

then ANSYS was employed to solve the electric field strength in the detector. Garfield was used to simulate the gas gain properties in the Benjamin type TEPC with different bias voltage. At last

an internal 241Am α source was adopted to measure the absolute gas amplification factor in the TEPC. Results: It is found that

Benjamin type TEPC has a uniform electric field intensity distribution along the anode wire

which could be employed in TEPC design. Garfield simulated results agreed well with the experimental values. The deviation between the measured and simulated values increases with the applied bias of the detector. Conclusion: Given the fact that the TEPC was usually operated with gas gain to be about 40

the Garfield simulation method could be used as reference in the TEPC development and operation. Abstract