Impact of GEM foil hole geometry on GEM detector gain
Detailed 3D imaging of Gas Electron Multiplier (GEM) foil hole geometry was realized. Scanning White Light Interferometry was used to examine six topological parameters of GEM foil holes from both sides of the foil. To study the effect of the hole geometry on detector gain, the ANSYS and Garfield ++ software were employed to simulate the GEM detector gain on the basis of SWLI data. In particular, the effective gain in a GEM foil with equally shaped holes was studied. The real GEM foil holes exhibited a 4% lower effective gain and 6% more electrons produced near the exit electrode of the GEM foil than the design anticipated. Our results indicate that the GEM foil hole geometry affects the gain performance of GEM detectors.
GEM-based plasma radiation diagnostics development: design aspects affecting its performance
The advanced Soft X-ray (SXR) diagnostics setup devoted to studies of the SXR plasma emissivity focusing on the energy range of tungsten emission lines is at the moment a highly relevant and important for ITER/DEMO as W became a plasmafacing material and, therefore, plasma contamination by W and W transport in the plasma must be understood and monitored. The Gas Electron Multiplier (GEM) based SXR radiation detecting system under development by our group with a spatial and energy-resolved photon detecting chamber may become such a diagnostic setup; however, many physical, technical and technological aspects must be taken into consideration. This work presents the results of preliminary tests and simulations of the research into the optimal design of the detector’s internal chamber. The study of the influence of different GEM foils on the properties and distribution of the electron avalanche as well as the effect of the high rate photon flux on GEM foil performance was performed. Effect of electrodes alignment allowed choosing the gap distances which maximize electron transmission was also examined. Finally, the optimal readout structure design was identified suitable to collect a total formed charge effectively.
8.22 – Gas Electron Multiplier (GEM) Detectors: Principles of Operation and Applications
Introduced by the author in 1997, the gas electron multiplier (GEM) has been developed since by many research groups and used in a wide range of applications, from fast trackers in particle physics to detectors for astrophysics, medicine, and dosimetry. With high‐rate capability, sub-mm position accuracy, and flexibility in shape and design, GEM-based devices are a successful addition to the field of position-sensitive gaseous detectors. Manufacturing methods, operating principles, and basic measurements are illustrated, as well as recent development and applications of the technology.