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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
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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.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
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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Cited by 10 scholarly publications.
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KEYWORDS
Copper

Gas lasers

X-rays

Electrodes

Carbon monoxide

Polarimetry

Etching

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