Fine-pitch and thick-foil gas electron multipliers for cosmic x-ray polarimeters

Toru Tamagawa; Asami Hayato; Yorito Yamaguchi; Hideki Hamagaki; Shigehira Hashimoto; Masahide Inuzuka; Hiromasa Miyasaka; Ikuya Sakurai; Fuyuki Tokanai; Kazuo Makishima

doi:10.1117/12.671244

15 June 2006 Fine-pitch and thick-foil gas electron multipliers for cosmic x-ray polarimeters

Toru Tamagawa, Asami Hayato, Yorito Yamaguchi, Hideki Hamagaki, Shigehira Hashimoto, Masahide Inuzuka, Hiromasa Miyasaka, Ikuya Sakurai, Fuyuki Tokanai, Kazuo Makishima

Author Affiliations +

Proceedings Volume 6266, Space Telescopes and Instrumentation II: Ultraviolet to Gamma Ray; 62663W (2006) https://doi.org/10.1117/12.671244
Event: SPIE Astronomical Telescopes + Instrumentation, 2006, Orlando, Florida , United States

Abstract

We have produced various gas electron multiplier foils (GEMs) by using laser etching technique for cosmic X-ray polarimeters. The finest structure GEM we have fabricated has 30 μm-diameter holes on a 50 μm-pitch. The effective gain of the GEM reaches around 5000 at the voltage of 570 V between electrodes. The gain is slightly higher than that of the CERN standard GEM with 70 μm-diameter holes on a 140 μm-pitch. We have fabricated GEMs with thickness of 100 μm which has two times thicker than the standard GEM. The effective gain of the thick-foil GEM is 104 at the applied voltage of 350 V per 50 μm of thickness. The gain is about two orders higher than that of the standard GEM. The remarkable characteristic of the thick-foil GEM is that the effective gain at the beginning of micro-discharge is quite improved. For fabricating the thick-foil GEMs, we have employed new material, liquid crystal polymer (LCP) which has little moisture absorption rate, as an insulator layer instead of polyimide. One of the thick-foil GEM we have fabricated has 8 μm copper layer in the middle of the 100 μm-thick insulator layer. The metal layer in the middle of the foil works as a field-shaper in the multiplication channels, though it slightly decreases the effective gain.

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Toru Tamagawa, Asami Hayato, Yorito Yamaguchi, Hideki Hamagaki, Shigehira Hashimoto, Masahide Inuzuka, Hiromasa Miyasaka, Ikuya Sakurai, Fuyuki Tokanai, and Kazuo Makishima "Fine-pitch and thick-foil gas electron multipliers for cosmic x-ray polarimeters", Proc. SPIE 6266, Space Telescopes and Instrumentation II: Ultraviolet to Gamma Ray, 62663W (15 June 2006); https://doi.org/10.1117/12.671244

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