Three-Electrode Organic-Type G.M. Counter Design and Performance

The sensitivity of the organic-type G.M. tube is increased by introducing a third electrode (grid) between the cylindrical steel cathode and a concentric tungsten wire anode and applying positive potential to that grid. The optimum position of the grid inside the cathode corresponding to the minimum capacitance of the counter is determined by using the simulation technique. Plateau curves of this tube are obtained for different grid positions. It is justified that the best performance of the tube is determined with the optimum grid position. Plateau curves of the three-electrode G. M. tube are also reported, with optimum grid position, for different values of grid potential. It is found that the sensitivity of the counter can be controlled by variation of the grid potential.