DETERMINATION OF DEAD TIME OF A G-M COUNTER USING TWO SOURCE METHOD

Abstract

This study investigates the dead time of a Geiger–Müller (GM) counter and examines how counting losses arising from detector dead time influence measured count rates. The research question addressed is whether the two-source method can reliably determine the dead time of a GM counter operating under a non paralyzable model. The dead time was determined experimentally using two gamma-emitting radioactive sources, ¹³⁷Cs and ¹³³Ba. Count rates were measured for each source individually and for the combined sources at a fixed operating voltage of 520 V. Twenty independent measurements were taken for each configuration over a counting interval of 60 seconds. Statistical parameters including average counts, standard deviations, and count rates were evaluated to assess counting losses and the randomness of nuclear decay. The results show that the observed count rate for the combined sources was consistently lower than the sum of the individual count rates, confirming the nonlinear nature of dead time effects in the GM counter. Using the two-source dead time equation for a non paralyzable system, the dead time of the GM counter was calculated to be 31.40 ms. Statistical analysis further revealed inherent fluctuations in the measurements, consistent with the random nature of radioactive disintegration. It is concluded that the two-source method provides a reliable and effective approach for determining the dead time of a GM counter, and that the measured dead time is consistent with values reported in related studies, while remaining dependent on experimental conditions and counting rate.