The key parameters for a long-term operation of GEM-based detectors in the harsh environment of high-rate experiments are radiation hardness, ageing resistance and stability against electrical discharges. Therefore, a comprehensive understanding of the discharge mechanism is mandatory to assure a stable operation of the detector.
We report on discharge probability studies in single- and...
Two resistive bulk-micromegas chambers were installed in May 2015 at the CERN Gamma Irradiation Facility exposed to an intense gamma irradiation with the aim to study the detector behavior under high irradiation and the long-term aging.
The chambers have an active area of 10 x 10 cm2, strip pitch of 400 μm, amplification gap of 128 μm and drift gap of 5 mm.
The desired accumulated charge of...
We present a study of the performance of a resistive Micromegas detector with elongated pillars. The purpose of this study was to certify that these pillars do not deteriorate the resolution and detection efficiency while adding safety in the detector fabrication. It was motivated by the fact that in large-size Micromegas boards produced in industry missing or weakly attached pillars have been...
The behaviour of two resistive-strip bulk micromegas detectors has been studied up to a temperature of approximately 50°C. A strong increase of the dark current is observed at temperatures in excess of 40 degrees. Measurements, keeping the the gas or detector temperature constant and varying the other, show that the increase of the dark current is primarily related to the temperature of the...
The VMM is a System on Chip (SoC) custom Application Specific Integrated Circuit (ASIC). It is intended to be used in the front end readout electronics of both Micromegas and sTGC detectors of the ATLAS Muon New Small Wheels upgrade. Due to its highly configurable parameters it can be used in a variety of tracking detectors. It is fabricated in the 130nm Global Foundries 8RF-DM process. The...
The Level-1 Data Driver Card (L1DDC) was designed for the needs of the future upgrades of the innermost stations of the ATLAS end-cap muon spectrometer, the New Small Wheel project, based on Micromegas and sTGC technologies. The L1DDC is a high speed aggregator board capable of communicating with multiple front-end electronic boards. It collects the Level-1 data along with monitoring data and...
We report on pulse counting imaging with glass GEM (G-GEM) combined with a newly developed electronic readout based on the dynamic time-over-threshold (dynamic ToT) pulse processing method.
The ToT is a pulse processing method to convert an analog pulse to a digital pulse whose width is proportional to the original analog pulse height, measuring the time while the analog pulse is over the...
We have improved the self-stretching GEM assembling technique that was initially developed at CERN for the CMS GEM upgrade project. With this improved technique, we can build GEM detectors at a scale of > 1m that still preserve very good gain uniformity. The stretching of GEM foils is of high quality and gas tightness is well ensured in GEM detectors built with the technique. This report...
Tracking detectors based on GEM foils are widely used in ongoing experiments and are the choice for numerous upgrades in the near future. An example is ALICE at the LHC of CERN, where the use of GEM foils will allow the TPC to be employed in a high-rate environment.
In order to optimize and predict the performance of GEM detectors in terms of gain, energy resolution and ion backflow, a good...
Presently, neutrinos are one of the most mysterious and interesting particles in physics, they seem to be the ones that can explain different processes of high energy physics, antimatter, conservation of energy and momentum in radioactive decay, and contribute with important data for cosmology and astrophysics. To better understand their different properties such as mass, parity, oscillations,...
One challenge of gaseous tracking detectors, such as the Time Projection Chamber (TPC), is the calibration of the electric field inside the radiation sensitive volume. This is crucial since deviations from a perfectly homogeneous drift field have direct impact on the spatial resolution. Reasons for these deviations are static imperfections of the detector structure, on the one hand, and...
Gas Electron Multipliers have undergone a very consistent development since their invention in 1997. Their production procedures have been tuned in such a way that nowadays it is possible to produce foils with areas of the order of the square meter that can operate at a reasonable gain with a very good stability. For the 3rd run of LHC, they will be included in the CMS and ALICE experiments...
We report the performance stability of the gas electron multiplier (GEM) against frequent high voltage on and off switching.
We have been developing a GEM, which is included in the X-ray polarimeter by utilizing a micropattern time projection chamber. Our GEMs are adopted by some coming satellite missions (e.g., Imaging X-ray Polarimetry Explore, IXPE) which have a low Earth orbit with a high...
