Signal shape and charge sharing between electrodes of GEM in dimethyl ether

• Published in: Journal of instrumentation Vol. 7; no. 3; pp. 1 - 12
• Main Authors: Takeuchi, Y, Tamagawa, T, Asami, F, Yoshikawa, A, Iwahashi, T, Konami, S, Iwakiri, W
• Format: Journal Article
• Language: English
• Published: 01.03.2012
• Subjects: Charge; Dimethyl ether; Electrodes; Foils; Gain; Instrumentation; Insulators; Parallel plates
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/7/03/C03042

We have performed a systematic investigation of the gain properties of the GEM foil made from copper-clad liquid crystal polymer insulator (LCP-GEM), which will be used for a satellite mission. We have measured the gain curve of LCP-GEM in pure DME at 190 Torr, and achieved a gain of 3 x 10 super(4) at an applied high voltage of 605 V between the LCP-GEM electrodes with a thickness of 100 mu m. The charge sharing between the GEM electrodes and readout pad were measured as a function of drift (E sub(d)) or induction (E sub(i)) field. We found that the parallel plate multiplication occurred between the bottom electrode of LCP-GEM and the readout pad above E sub(i) = 6 kV/cm, and the amount of charge collected in each electrode was almost constant with E sub(d). We investigated the signal shape obtained in each electrode and found that the rise time of signals was explained as induced charge by moving ions and electrons.