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Gas electron multipliers with a liquid crystal polymer insulator (LCP-GEMs) can be employed as X-ray polarimeters in several satellite missions in low-earth orbit. To evaluate their resistance to radiation, LCP-GEMs were exposed to Fe ion and proton beams from the heavy-ion accelerator facility HIMAC, and the gas gain was monitored. The LCP-GEMs survived 14.4-year-equivalent irradiation by fully stripped Fe ions with an energy of 500 MeV\ nuc^-1, which simulated galactic cosmic-ray ions. We also studied the degradation of the insulator layer of the LCP-GEMs by irradiation with 160 MeV protons to simulate geomagnetically trapped protons. After irradiation with protons for 31.6 years equivalent, no significant change in gain was observed. [ABSTRACT FROM AUTHOR]

Abstract: We have produced thick-foil and fine-pitch gas electron multipliers (GEMs) using a laser etching technique. To improve production yield we have employed a new material, liquid crystal polymer, instead of polyimide as an insulator layer. The effective gain of the thick-foil GEM with a hole pitch of , a hole diameter of , and a thickness of reached a value of at an applied voltage of 720V. The measured effective gain of the thick-foil and fine-pitch GEM ( pitch, diameter, and thick) was similar to that of the thick-foil GEM. The gain stability was measured for the thick-foil and fine-pitch GEM, showing no significant increase or decrease as a function of elapsed time from applying the high voltage. The gain stability over 3h of operation was about 0.5%. Gain mapping across the GEM showed a good uniformity with a standard deviation of about 4%. The distribution of hole diameters across the GEM was homogeneous with a standard deviation of about 3%. There was no clear correlation between the gain and hole diameter maps. [Copyright &y& Elsevier]