Recent progress in GEM manufacturing and operation.

The Gas Electron Multiplier (GEM) is a robust and ubiquitous device for the proportional amplification of electrons released in a gas by radiation, and can be used as a pre-amplification stage in a cascade of detectors. Using single and double GEM detectors with simple segmented printed circuits for signal read-out, we have achieved full efficiency of detection for minimum ionizing particles. With suitably configured readout electrodes, fast, two-dimensional localization and imaging of radiation has been demonstrated. Extended discharge studies confirm that multiple devices including a GEM amplifier can perform reliably in the harsh operating conditions expected at high luminosity colliders. Applications and developments of GEM detectors for the imaging of single photoelectrons are also briefly discussed.