We present a systematic investigation of the gain properties of a gas electron multiplier (GEM) foil in pure dimethyl ether (DME) at low pressures. The GEM is made from copper- clad liquid crystal polymer insulator (LCP-GEM) designed for space use, and is applied to a time projection chamber filled with low-pressure DME gas to observe the linear polarization of cosmic X-rays. We have measured gains of a 100 um-thick LCP-GEM as a function of the voltage between GEM electrodes at various gas pressures ranging from 10 to 190 Torr with 6.4 keV X-rays. The highest gain at 190 Torr is about 2x10^4, while that at 20 Torr is about 500. We find that the pressure and electric-field dependence of the GEM gain is described by the first Townsend coefficient. The energy scale from 4.5 to 8.0 keV is linear with non-linearity of less than 1.4% above 30 Torr.
@article{arxiv.1312.2343,
title = {Property of LCP-GEM in Pure Dimethyl Ether at Low Pressure},
author = {Y. Takeuchi and T. Tamagawa and T. Kitaguchi and S. Yamada and W. Iwakiri and F. Asami and A. Yoshikawa and K. Kaneko and T. Enoto and A. Hayato and T. Kohmura and the GEMS/XACT team},
journal= {arXiv preprint arXiv:1312.2343},
year = {2014}
}
Comments
3rd International Conference on Micro Pattern Gaseous Detectors (MPGD2013)