Electrical characterization of the amplification plate of a thick-GEM detector for low energy X radiation dosimetry

Abstract

To evaluate the possible use of Thick-GEM detectors as dosimeters in standard mammography radiation qualities, a prototype is under development for tests. This is a collaboration project between the IPEN Calibration Laboratory and the High Energy Physics and Instrumentation Center (HEPIC-IFUSP). The prototype design takes into consideration many parameters that were obtained in an exploratory work using the Monte Carlo simulation code MCNP5. Using simulations, parameters such as typical dimensions and materials were optimized to match the characteristics of the detector to the requirements of a dosimeter for this purpose. At the present status of the project, electrical tests were undertaken to evaluate the quality of the amplification plate produced in-house. The amplification plate is composed of fiberglass with a thickness of 0.5 mm and 0.03 mm of copper on each side. The average diameter of the orifices in the plate is 0.25 mm, and the distance between centers is 1.00 mm. During the electrical tests, the amplification plate was in a gas chamber filled with Argon at atmospheric pressure. The leakage current was measured as a function of the applied voltage between the copper cladding of both sides. The electrical resistance of 15.3GΩ was obtained. Additionally, the breakdown voltage was observed at approximately 1.0 kV, limiting the maximum amplification voltages to this value.