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T: Fachverband Teilchenphysik

T 81: Myondetektoren 2

T 81.7: Talk

Wednesday, March 26, 2014, 18:15–18:30, P12

Ageing and Charge Up Measurements for a Micromegas Detector with Resistive Strip Anode — •Helge Danger, Otmar Biebel, Jonathan Bortfeldt, and Ralf Hertenberger — LS Schaile, LMU München

A resistive strip Micromegas Detector (MICRO MEsh GAseous Structure) with 9 cm × 9 cm active area and two-dimensional x-y-strip readout was investigated for radiation damages. The upper anode layer, used for readout, is covered by resistive strips with a resistivity of 100 MΩ/cm. It is formed by 358 copper strips of 150 µm width and 250 µm pitch.

This detector irradiated locally with 7 nA of 20 MeV protons at the Tandem Accelerator in Garching for eleven hours. The proton induced current between mesh and anode was 11 µA. After irradiation the current returned instantaneously to the standard dark-current of a few nA. A total charge of 0.2 C/cm² was accumulated in the irradiated area. The gas-gain measured before and after the ageing at 25 reference-positions is compared.

We present results on the comparison of gas-gains for non-irradiated and irradiated areas, on ion back diffusion and on the time dependent behaviour of the mean pulse height at several irradiation rates.