The series of upgrades to the Large Hadron Collider, culminating in the High Luminosity Large Hadron Collider, will enable a significant expansion of the physics program of the CMS experiment. ...However, the accelerator upgrades will also make the experimental conditions more challenging, with implications for detector operations, triggering, and data analysis. The luminosity of the proton-proton collisions is expected to exceed \(2-3\times10^{34}\)~cm\(^{-2}\)s\(^{-1}\) for Run 3 (starting in 2022), and it will be at least \(5\times10^{34}\)~cm\(^{-2}\)s\(^{-1}\) when the High Luminosity Large Hadron Collider is completed for Run 4. These conditions will affect muon triggering, identification, and measurement, which are critical capabilities of the experiment. To address these challenges, additional muon detectors are being installed in the CMS endcaps, based on Gas Electron Multiplier technology. For this purpose, 161 large triple-Gas Electron Multiplier detectors have been constructed and tested. Installation of these devices began in 2019 with the GE1/1 station and will be followed by two additional stations, GE2/1 and ME0, to be installed in 2023 and 2026, respectively. The assembly and quality control of the GE1/1 detectors were distributed across several production sites around the world. We motivate and discuss the quality control procedures that were developed to standardize the performance of the detectors, and we present the final results of the production. Out of 161 detectors produced, 156 detectors passed all tests, and 144 detectors are now installed in the CMS experiment. The various visual inspections, gas tightness tests, intrinsic noise rate characterizations, and effective gas gain and response uniformity tests allowed the project to achieve this high success rate.
After the Phase-2 high-luminosity upgrade to the Large Hadron Collider (LHC),
the collision rate and therefore the background rate will significantly
increase, particularly in the high $\eta$ region. ...To improve both the tracking
and triggering of muons, the Compact Muon Solenoid (CMS) Collaboration plans to
install triple-layer Gas Electron Multiplier (GEM) detectors in the CMS muon
endcaps. Demonstrator GEM detectors were installed in CMS during 2017 to gain
operational experience and perform a preliminary investigation of detector
performance. We present the results of triple-GEM detector performance studies
performed in situ during normal CMS and LHC operations in 2018. The
distribution of cluster size and the efficiency to reconstruct high $p_T$ muons
in proton--proton collisions are presented as well as the measurement of the
environmental background rate to produce hits in the GEM detector.
An estimate of environmental background hit rate on triple-GEM chambers is performed using Monte Carlo (MC) simulation and compared to data taken by test chambers installed in the CMS experiment ...(GE1/1) during Run-2 at the Large Hadron Collider (LHC). The hit rate is measured using data collected with proton-proton collisions at 13 TeV and a luminosity of 1.5\(\times10^{34}\) cm\(^{-2}\) s\(^{-1}\). The simulation framework uses a combination of the FLUKA and Geant4 packages to obtain the hit rate. FLUKA provides the radiation environment around the GE1/1 chambers, which is comprised of the particle flux with momentum direction and energy spectra ranging from \(10^{-11}\) to \(10^{4}\) MeV for neutrons, \(10^{-3}\) to \(10^{4}\) MeV for \(\gamma\)'s, \(10^{-2}\) to \(10^{4}\) MeV for \(e^{\pm}\), and \(10^{-1}\) to \(10^{4}\) MeV for charged hadrons. Geant4 provides an estimate of detector response (sensitivity) based on an accurate description of detector geometry, material composition and interaction of particles with the various detector layers. The MC simulated hit rate is estimated as a function of the perpendicular distance from the beam line and agrees with data within the assigned uncertainties of 10-14.5%. This simulation framework can be used to obtain a reliable estimate of background rates expected at the High Luminosity LHC.
We present analytical calculations, Finite Element Analysis modeling, and physical measurements of the interstrip capacitances for different potential strip geometries and dimensions of the readout ...boards for the GE2/1 triple-Gas Electron Multiplier detector in the CMS muon system upgrade. The main goal of the study is to find configurations that minimize the interstrip capacitances and consequently maximize the signal-to-noise ratio for the detector. We find agreement at the 1.5--4.8% level between the two methods of calculations and on the average at the 17% level between calculations and measurements. A configuration with halved strip lengths and doubled strip widths results in a measured 27--29% reduction over the original configuration while leaving the total number of strips unchanged. We have now adopted this design modification for all eight module types of the GE2/1 detector and will produce the final detector with this new strip design.
After the Phase-2 high-luminosity upgrade to the Large Hadron Collider (LHC), the collision rate and therefore the background rate will significantly increase, particularly in the high \(\eta\) ...region. To improve both the tracking and triggering of muons, the Compact Muon Solenoid (CMS) Collaboration plans to install triple-layer Gas Electron Multiplier (GEM) detectors in the CMS muon endcaps. Demonstrator GEM detectors were installed in CMS during 2017 to gain operational experience and perform a preliminary investigation of detector performance. We present the results of triple-GEM detector performance studies performed in situ during normal CMS and LHC operations in 2018. The distribution of cluster size and the efficiency to reconstruct high \(p_T\) muons in proton--proton collisions are presented as well as the measurement of the environmental background rate to produce hits in the GEM detector.
Materials for sustainable energy Dusastre, Vincent; Martiradonna, Luigi
Nature materials,
12/2016, Letnik:
16, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Available and affordable energy has so far led to spectacular industrialization and development, but with growth accelerating in developing countries, demands on non-renewable energy sources are ...reaching their limits. Moreover, the recent conrmation that global warming is due to the increase of greenhouse gases in the atmosphere, together with the uneven global distribution of energy sources, urgently requires drastic changes in the way we generate and supply energy.
The electrical properties of grapheneare highly sensitive to the perturbationof carrier concentration that is inducedby the physisorption of molecules on its surface. Now, Manoharan Muruganathan and ...colleagues show that the van der Waals interactions between graphene and CO2 molecules adsorbed onto it can be tunedby applying an external electric field. By means of first-principle calculations and transport measurements, they demonstrate that the molecules behave as weak electron acceptors when no voltage is applied to the substrate, and that such electron transfer increases under the effect of a positive voltage. In contrast, a negative voltage reverses the charge-transfer direction, causing the CO2 molecules to behaveas donors. This is because the external electric field alters the internal dipole created in the grapheneCO2 complex together with the bonding distance andthe OCO angle in the molecule. The researchers suggest that such effectsmay be useful for the realization of graphene-based gas sensors with improved molecule-recognitioncapabilities. LM
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