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T: Fachverband Teilchenphysik

T 74: Gaseous Detectors II

T 74.6: Vortrag

Donnerstag, 19. März 2026, 17:30–17:45, KH 01.014

Investigation of the protection layers used in GridPix detectors — •Felix Becker, Jochen Kaminski, Klaus Desch, Sabine Hartung, and Yevgen Bilevych — Physikalisches Institut, Universität Bonn

The GridPix detector is a gaseous detector based on the Timepix technology. It is based on a pixel readout ASIC with a grid structure applied on top of it, which grants gas amplification. In the production process of the GridPix, a high-resistive protection layer is applied on the surface of the Timepix. This protection layer helps avoiding the chip getting damaged by sparks inside the detector and increases the longevity immensely. However, the exact electric properties, such as the resistivity of the layer, are not completely known. The main goal of this investigation is to find a reliable method for measuring the layer's resistivity. To do so, the results of multiple measuring methods, are compared. The first method is using charged particles. Because electrons accumulate at the surface of the protective layer if its resistivity is non-zero, a potential builds up on its surface. This potential lowers the effective electric field between the grid and the surface of the protective layer, what lowers the gas amplification. This effect takes place, until a steady state is reached. This charge-up effect and the discharge of the protective layer can be used to calculate the material resistivity. A second method is detaching the grid and measuring the resistivity directly via an voltage-current measurement. The presentation will describe the steps taken in the analysis, including the considerations behind each measurement method.

Keywords: Particle Detectors; GridPix; TimePix; Resistivity; Charge up effects