CONCLUSION

The mica window of a Gm tube allows passage of alpha, beta and gamma radiations. The radiations ionize the gas inside the tube. The electrons move to the anode while the positive ions move to the cathode. As the ions are produced, there are collisions which produce small currents which are in turn amplified and passed to the scale. The scale counts the pulses and shows the total on a display screen. After each pulse, the gas returns to normal ready for the next particle to enter. A small presence of halogen gas in the tube helps in absorbing the positive ions to reduce further ionization and hence a quick return to normal. This is called quenching the tube.