Discharge studies and prevention in the gas electron multiplier (GEM) Bachmann, S.; Bressan, A.; Capeáns, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2002, Letnik:
479, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The gas electron multiplier (GEM) used as single proportional counter or in a cascade of two or more elements, permits to attain high gains and to perform detection and localization of ionizing ...tracks at very high radiation rates. As in other micro-pattern detectors, however, the occasional occurrence of heavily ionizing trails may trigger a local breakdown, with possible harmful consequences on the device itself and on the readout electronics. This paper describes a systematic investigation of the discharge mechanisms in single and multiple GEM structures, and suggests various strategies to reduce both the energy and the probability of the discharges.
A wide range of gas mixtures is used for the operation of different gaseous detectors at the Large Hadron Collider (LHC) experiments. Nowadays some of these gases, as C2H2F4, CF4 and SF6, are ...indicated as greenhouse gases (GHG) and dominate the overall GHG emission from particle detectors at the LHC experiments. The release of GHG is an important subject for the design of future particle detectors as well as for the operation of the current experiments. Different strategies have been adopted at CERN for reducing the GHG emissions. The standard approach is the recirculation of the gas mixture with complex gas systems where system stability and the possible accumulation of impurities need to be attentively evaluated for the good operation and safety of the detectors. A second approach is based on the recuperation of the gas mixture exiting the detectors and the separation of its gas components for re-use. At long-term, the use of less invasive gases is being investigated, especially for the Resistive Plate Chamber (RPC) systems. Operation of RPC with environmentally friendly gas mixtures is demonstrated for streamer mode while avalanche mode operation needs more complex gas mixtures.
•Greenhouse gases (GHG) emission in the LHC experiments and detectors.•Strategies to reduce the GHG emissions: gas recirculation and recuperation systems.•GHG emission: achievements from LHC Run1 to Run2.•Resistive Plate Chambers operation with new environmentally friendly gases.
Further developments and beam tests of the gas electron multiplier (GEM) Benlloch, J.; Bressan, A.; Capeáns, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/1998, Letnik:
419, Številka:
2-3
Journal Article
Recenzirano
We describe the development and operation of the Gas Electron Multiplier (GEM), a thin insulating foil metal-clad on both sides and perforated by a regular pattern of small holes. The mesh can be ...incorporated into the gas volume of an active detector to provide a first amplification channel for electrons, or used as stand alone. We report on the basic properties of GEMs manufactured with different geometries and operated in several gas mixtures as well as on their long-term stability after accumulation of charge equivalent to several years of operation in high-luminosity experiments. Optimized GEMs reach gains close to 10 000 at safe operating voltages, permitting the detection of ionizing tracks, without other amplifying elements, on a simple Printed Circuit Board (PCB), opening new possibilities for detector design.
The Small Area Tracking system of the COMPASS experiment at CERN includes a set of 20 large area, fast position-sensitive Gas Electron Multiplier detectors, designed to reliably operate in the harsh ...radiation environment of the experiment. We describe in detail the design, choice of materials, assembly procedures and quality controls used to manufacture the devices. The test procedure in the laboratory, the performance in test beams and in the initial commissioning phase in the experiment are presented and discussed.
Aging and materials: lessons for detectors and gas systems Capeans, M.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2003, Letnik:
515, Številka:
1
Journal Article
Recenzirano
Aging of gaseous detectors is known as the degradation of their performance under the exposure to ionizing radiation. It is a complex phenomenon that depends on many parameters. Among others, aging ...depends on the gas mixture and may be enhanced by the presence of pollutants in the gas. The origin of the impurities is diverse and includes outgassing from assembly materials, contamination of the detector during the assembly process and the gas system itself. Systematic studies on this topic have been carried out. The methods used to ascertain the outgassing properties of materials are described and compared. Materials that might be used for assembling gaseous detectors and associated gas systems are catalogued according to their outgassing rate. Some factors affecting the aging rate of some fast gases are presented. Finally, a set of recommendations to build and operate gaseous detectors in high-luminosity experiments is given.
High-voltage pixel sensors for ATLAS upgrade Perić, I.; Kreidl, C.; Fischer, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2014, Letnik:
765
Journal Article
Recenzirano
Odprti dostop
The high-voltage (HV-) CMOS pixel sensors offer several good properties: a fast charge collection by drift, the possibility to implement relatively complex CMOS in-pixel electronics and the ...compatibility with commercial processes. The sensor element is a deep n-well diode in a p-type substrate. The n-well contains CMOS pixel electronics. The main charge collection mechanism is drift in a shallow, high field region, which leads to a fast charge collection and a high radiation tolerance. We are currently evaluating the use of the high-voltage detectors implemented in 180nm HV-CMOS technology for the high-luminosity ATLAS upgrade. Our approach is replacing the existing pixel and strip sensors with the CMOS sensors while keeping the presently used readout ASICs. By intelligence we mean the ability of the sensor to recognize a particle hit and generate the address information. In this way we could benefit from the advantages of the HV sensor technology such as lower cost, lower mass, lower operating voltage, smaller pitch, smaller clusters at high incidence angles. Additionally we expect to achieve a radiation hardness necessary for ATLAS upgrade. In order to test the concept, we have designed two HV-CMOS prototypes that can be readout in two ways: using pixel and strip readout chips. In the case of the pixel readout, the connection between HV-CMOS sensor and the readout ASIC can be established capacitively.
The gas electron multiplier (GEM) Bouclier, R.; Capeans, M.; Dominik, W. ...
IEEE transactions on nuclear science,
06/1997, Letnik:
44, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We describe operating principles and results obtained with a new detector element: the Gas Electron Multiplier (GEM). Consisting of a thin composite sheet with two metal layers separated by a thin ...insulator, and pierced by a regular matrix of open channels, the GEM electrode, inserted on the path of electrons in a gas detector, allows the transfer of charge with an amplification factor approaching ten. Uniform response and high rate capability are demonstrated. Coupled to another device, multiwire or micro-strip chamber, the GEM electrode permits higher gains or less critical operation; separation of the sensitive (conversion) volume and the detection volume have other advantages: a built-in delay (useful for triggering purposes), and the possibility of applying high fields on the photo-cathode of ring imaging detectors to improve efficiency. Multiple GEM grids in the same gas volume allow large amplification factors to be achieved in a succession of steps, leading to the realization of an effective gas-filled photomultiplier.
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