Gas selection for Xe-based LCP-GEM detectors onboard the CubeSat X-ray observatory NinjaSat

Abstract We present a gas selection for Xe-based electron multiplier (GEM) detectors, Gas Multiplier Counters (GMCs) onboard the CubeSat X-ray observatory NinjaSat. To achieve an energy bandpass of 2–50 keV, we decided to use mixture at pressure 1.2 atm that is sensitive high-energy X-rays. In addition, effective gain over 300 required single GEM so 2 keV signal can be sufficiently larger than electrical noise. At first, measured gains in nine mixtures (combinations Xe, Ar, CO , CH 4 and dimethyl ether; DME) 1.0 atm. The highest were obtained with Xe/Ar/DME mixtures, while relatively lower Xe/Ar/CO Xe/Ar/CH Xe+quencher mixtures. Based on these results, selected (75%/24%/1%) as sealed GMC. Then investigated dependence electric fields drift induction gaps ranging from 100–650 V cm -1 500–5000 respectively, mixture. weakly depended field it was almost linearly proportional field: 2.4 times higher 5000 1000 . With optimal fields, flight model GMC achieves 460 applied voltage 590 V.