Development of a portable gas-filled ionization chamber

Abstract

A new portable gas-filled ionization chamber has been designed and constructed at the Physics Department of Sung Kyun Kwan University. To overcome the maximum count rate of similar to 10(5) particles per second of a conventional ionization chamber, which utilizes a Frisch grid, and to enhance the portability of a detector, we adopted the design of multiple electrodes and modified it from the original designs by Kimura et al. and Chae et al. The new design utilizes a stack of multiple electrodes installed perpendicular to the optical beam axis. This configuration provides a fast response time for the detector, which is essential for high-rate counting. The device has been tested with a Am-241 (t (1/2) = 432.2 years) radioactive alpha source, which mainly emits 5.486-MeV (branching ratio of 85%) and 5.443-MeV (branching ratio of 13%) alpha particles. An energy resolution of 6.3% was achieved.