Primary Ionization Simulation for Different Gas Mixtures

The primary ionization in a gas mixture is crucial in nuclear and particle physics experiments. In many particle physics experiments, the primary ionization is utilized in understanding the charge density and discharge formation studies. We present the simulation of primary ionization in argon based gas mixtures to get the number of primaries, energy and spatial information with geant4 and heed++ toolkits that have been used to simulate the passage of particles through the matter. The geant4 toolkit has an advantage of obtaining the particle information like energy deposition and position co-ordinates after each step i.e., at which the particle has done some interactions in a complex, realistic, three-dimensional geometry. These steps generate each interactions after computing the cross-sections of physics processes that were taken into account for this simulation in a gas volume. The number of primaries generated with the geant4 toolkit were also compared with those obtained using heed+ +. Alpha and muons were simulated to study the primary ionization. A similar study of primary ionization was carried out with 55Fe which is radioactive in nature and captures electron. 55Mn (X-rays), νe, auger electrons and gammas were produced in this process. Gamma simulation has also been carried out. The responses of alpha, muon, 55Fe and gamma in the argon based gas mixtures were found to be distinct due to their different properties.