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.
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 transition radiation tracker (TRT) is one of the three subsystems of the inner detector of the ATLAS experiment. It combines electron identification capability with charged-particle track ...reconstruction. A total of 420 000 electronic channels provide continuous tracking with many projective measurements per track. This paper gives details of some features of the TRT, from performance requirements to the consequences of its operation in the LHC environment. Some technical choices and operating conditions have been recently changed, the most significant one being the active gas. Presently, a large fraction of barrel and end-cap modules have been assembled in the United States and Russia, respectively. A strict quality assessment has been implemented at the assembly sites and at CERN upon arrival of the modules. The acceptance tests include dimensional surveys, wire-tension measurements, gas-tightness tests, high-voltage training, and gas-gain uniformity measurements along each individual straw. First estimates of the module quality are presented based on the analysis of these tests.
The gas systems for the LHC experiments Guida, R.; Capeans, M.; Hahn, F. ...
2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC),
10/2013
Conference Proceeding
Over the five experiments (ALICE, ATLAS, CMS, LHCb and TOTEM) taking data at the CERN Large Hadron Collider (LHC) more than 28 gas systems are delivering the proper gas mixture to the corresponding ...detectors. They are complex systems that extend over several hundred meters and have to ensure an extremely high reliability in terms of stability and quality of the gas mixture delivered to the detectors. In fact, the gas mixture is the sensitive medium and a correct and stable composition is basic requirements for good and safe long term operation. The present contribution describes the design philosophy focusing the attention on the main functional modules. The reliability over the past years is also discussed.
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