1,788 research outputs found
Gain of a Single Gas Electron Multiplier
Gas Electron Multiplier (GEM) is a gaseous detector used in particle detection and is
known for its high rate capability. Ever since its invention in 1997, GEM was applied in
many areas and recently has been proposed to be installed in the CMS high η regions for
upgrade at LHC, CERN. A complete understanding of the working and gain behaviour does
not exist. GEM gain is influenced by charging up and this has been variedly interpreted
in literature lacking consensus. I have attempted in this work through simulations and
measurements to achieve a better understanding of single GEM gain and how it is affected by
various factors. Specific experimental methods which evolved with subsequent measurements
were employed to systematically study the charging up effect. Information from simulations
was applied to characterize measurements thereby enabling the development of a model for
charging up. Conductivity mechanism of the dielectric used in GEM was analyzed and the
resistivity measured. Gain free of charging up effects was measured and this is appropriate
for comparison with simulation
A dynamic method for charging-up calculations: the case of GEM
The simulation of Micro Pattern Gaseous Detectors (MPGDs) signal response is
an important and powerful tool for the design and optimization of such
detectors. However, several attempts to simulate exactly the effective charge
gain have not been completely successful. Namely, the gain stability over time
has not been fully understood. Charging-up of the insulator surfaces have been
pointed as one of the responsible for the difference between experimental and
Monte Carlo results. This work describes two iterative methods to simulate the
charging-up in one MPGD device, the Gas Electron Multiplier (GEM). The first
method uses a constant step for avalanches time evolution, very detailed, but
slower to compute. The second method uses a dynamic step that improves the
computing time. Good agreement between both methods was reached. Despite of
comparison with experimental results shows that charging-up plays an important
role in detectors operation, should not be the only responsible for the
difference between simulated and measured effective gain, but explains the time
evolution in the effective gain.Comment: Minor changes in grammatical statements and inclusion of some
important information about experimental setup at section "Comparison with
experimental results
Construction and Performance of Large-Area Triple-GEM Prototypes for Future Upgrades of the CMS Forward Muon System
At present, part of the forward RPC muon system of the CMS detector at the
CERN LHC remains uninstrumented in the high-\eta region. An international
collaboration is investigating the possibility of covering the 1.6 < |\eta| <
2.4 region of the muon endcaps with large-area triple-GEM detectors. Given
their good spatial resolution, high rate capability, and radiation hardness,
these micro-pattern gas detectors are an appealing option for simultaneously
enhancing muon tracking and triggering capabilities in a future upgrade of the
CMS detector. A general overview of this feasibility study will be presented.
The design and construction of small (10\times10 cm2) and full-size trapezoidal
(1\times0.5 m2) triple-GEM prototypes will be described. During detector
assembly, different techniques for stretching the GEM foils were tested.
Results from measurements with x-rays and from test beam campaigns at the CERN
SPS will be shown for the small and large prototypes. Preliminary simulation
studies on the expected muon reconstruction and trigger performances of this
proposed upgraded muon system will be reported.Comment: 7 pages, 25 figures, submitted for publication in conference record
of the 2011 IEEE Nuclear Science Symposium, Valencia, Spai
An overview of the design, construction and performance of large area triple-GEM prototypes for future upgrades of the CMS forward muon system
GEM detectors are used in high energy physics experiments given their good spatial resolution, high rate capability and radiation hardness. An international collaboration is investigating the possibility of covering the 1.6 < vertical bar eta vertical bar < 2.4 region of the CMS muon endcaps with large-area triple-GEM detectors. The CMS high-eta area is actually not fully instrumented, only Cathode Strip Chamber (CSC) are installed. The vacant area presents an opportunity for a detector technology able to to cope with the harsh radiation environment; these micropattern gas detectors are an appealing option to simultaneously enhance muon tracking and triggering capabilities in a future upgrade of the CMS detector. A general overview of this feasibility study is presented. Design and construction of small (10cm x 10cm) and full-size trapezoidal (1m x 0.5m) triple-GEM prototypes is described. Results from measurements with x-rays and from test beam campaigns at the CERN SPS is shown for the small and large prototypes. Preliminary simulation studies on the expected muon reconstruction and trigger performances of this proposed upgraded muon system are reported
Building blocks of a multi-layer PET with time sequence photon interaction discrimination and double Compton camera
[EN] Current PET detectors have a very low sensitivity, of the order of a few percent. One of the reasons is the fact that Compton interactions are rejected. If an event involves multiple Compton scattering and the total deposited energy lays within the photoelectric peak, then an energy-weighted centroid is the given output for the coordinates of the reconstructed interaction point. This introduces distortion in the final reconstructed image. The aim of our work is to prove that Compton events are a very rich source of additional information as one can improve the resolution of the detector and implicitly the final reconstructed image. This could be a real breakthrough for PET detector technology as one should be able to obtain better results with less patient radiation. Using a PET as a double Compton camera, by means of Compton cone matching i.e., Compton cones coming from the same event should be compatible, is applied to discard randoms, patient scattered events and also, to perform a correct matching among events with multiple coincidences. In order to fully benefit experimentally from Compton events using monolithic scintillators a multi-layer configuration is needed and a good time-of-flight resolution.This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 695536). This work was supported in part by the Spanish Government Grants TEC2016-79884-C2 and RTC-2016-5186-1.Ilisie, V.; Giménez-Alventosa, V.; Moliner Martínez, L.; Sánchez, F.; González Martínez, AJ.; Rodríguez-Álvarez, M.; Benlloch Baviera, JM. (2018). Building blocks of a multi-layer PET with time sequence photon interaction discrimination and double Compton camera. Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment. 895:74-83. https://doi.org/10.1016/j.nima.2018.03.076S748389
Test beam results of the GE1/1 prototype for a future upgrade of the CMS high-η muon system
Gas Electron Multipliers (GEM) are an interesting technology under consideration for the future upgrade of the forward region of the CMS muon system, specifically in the 1.6 < vertical bar eta vertical bar < 2.4 endcap region. With a sufficiently fine segmentation GEMs can provide precision tracking as well as fast trigger information. The main objective is to contribute to the improvement of the CMS muon trigger. The construction of large-area GEM detectors is challenging both from the technological and production aspects. In view of the CMS upgrade we have designed and built the largest full-size Triple-GEM muon detector, which is able to meet the stringent requirements given the hostile environment at the high-luminosity LHC. Measurements were performed during several test beam campaigns at the CERN SPS in 2010 and 2011. The main issues under study are efficiency, spatial resolution and timing performance with different inter-electrode gap configurations and gas mixtures. In this paper results of the performance of the prototypes at the beam tests will be discussed
Test beam results of the GE1/1 prototype for a future upgrade of the CMS high- muon system
Gas Electron Multipliers (GEM) are an interesting technology under
consideration for the future upgrade of the forward region of the CMS muon
system, specifically in the endcap region. With a
sufficiently fine segmentation GEMs can provide precision tracking as well as
fast trigger information. The main objective is to contribute to the
improvement of the CMS muon trigger. The construction of large-area GEM
detectors is challenging both from the technological and production aspects. In
view of the CMS upgrade we have designed and built the largest full-size
Triple-GEM muon detector, which is able to meet the stringent requirements
given the hostile environment at the high-luminosity LHC. Measurements were
performed during several test beam campaigns at the CERN SPS in 2010 and 2011.
The main issues under study are efficiency, spatial resolution and timing
performance with different inter-electrode gap configurations and gas mixtures.
In this paper results of the performance of the prototypes at the beam tests
will be discussed
Search for narrow resonances in dilepton mass spectra in proton-proton collisions at root s=13 TeV and combination with 8 TeV data
Peer reviewe
Search for top squark pair production in pp collisions at root s=13 TeV using single lepton events
Peer reviewe
Search for new physics with dijet angular distributions in proton-proton collisions at root S = 13 TeV
Peer reviewe
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