A spark-resistant bulk-micromegas chamber for high-rate applications Alexopoulos, T.; Burnens, J.; de Oliveira, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2011, Letnik:
640, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We report on the design and performance of a spark-resistant bulk-micromegas chamber. The principle of this design lends itself to the construction of large-area muon chambers for the upgrade of the ...detectors at the Large Hadron Collider at CERN for luminosities in excess of 10
34
cm
−2
s
−1 or other high-rate applications.
Neutron GEM-based detectors represent a new frontier of diagnostic devices in neutron-linked physics applications such as detectors for fusion experiments (Croci et al., 2012 1) and spallation ...sources (Murtas et al., 2012 2). Besides, detectors installed in HEP experiments (like LHC at CERN) are dip in a high flux neutron field. For example, the TOTEM T2 GEM telescope (Bagliesi et al., 2010 3) at LHC is currently installed very close to the beam pipe where a high intensity (>104ncm−2s−1) neutron background is present. In order to assess the capability (particularly related to discharge probability) of working in intense neutrons environment, a 10×10cm2 Triple GEM detector has been tested using a high flux (105ncm−2s−1) neutron beam. The neutron-induced discharge probability PDisch was measured to be 1.37×10−7 at an effective gain G=5×104. In addition, the different types of neutron interactions within the detector were fully explained through a GEANT4 simulation.
With the luminosity upgrade of the LHC machine (SLHC, Super-LHC), the Muon system of the ATLAS experiment at CERN will also need a detector upgrade in the highest rapidity region. MAMMA, Muon ATLAS ...Micromegas Activity, is an ongoing R&D activity with the aim to develop large detectors based on the bulk-Micromegas technology for use in the ATLAS Muon Spectrometer. Micromegas is a good potential candidate for the construction of large muon chambers that combine trigger and tracking capability and can sustain high particle rates expected at the SLHC. A medium size Micromegas prototype, in scale 1:10 of the final chambers, has been built and evaluated in the laboratory and in beam tests at CERN. Results from the analysis of test-beam data are presented. The results indicate that large size Micromegas is a viable candidate for ATLAS Muon upgrade
Detectors based on the micromegas principle have already been used in several atomic, nuclear and particle physics experiments. They have also been proposed as one of the options to upgrade the ATLAS ...muon spectrometer in the very forward/backward region. To meet this end, it is imperative to study their performance in a mixed (neutron and gamma) radiation field. The general-purpose Monte-Carlo code FLUKA has been employed in the present work in order to study the effect of 5.5MeV neutrons impinging on a prototype micromegas detector developed for sLHC. The response of the detector to the photons originating from the inevitable neutron inelastic scattering on the surrounding materials of the experimental facility was also studied, through comparisons with experimental data.
► We performed Monte-Carlo simulations of a prototype micromegas detector in a mixed neutron and gamma radiation field. ► We implemented the FLUKA code. ► We compared with experimental results using a VdG tandem accelerator.
Sampling calorimeters can be finely segmented and used to detect showers with high spatial resolution. This imaging power can be exploited at future linear collider experiments where the measurement ...of jet energy by a Particle flow method requires optimal use of tracking and calorimeter information. Gaseous detectors can achieve high granularity and a hadron sampling calorimeter using Micromegas chambers as active elements is considered in this paper. Compared to traditional detectors using wires or resistive plates, Micromegas is free of space charge effects and could therefore show superior calorimetric performance. To test this concept, a prototype of 1×1m2 equipped with 9216 readout pads of 1×1cm2 has been built. Its technical and basic operational characteristics are reported.
A measurement of the derivative (∂ lnF2/∂ lnx)Q2≡−λ(x,Q2) of the proton structure function F2 is presented in the low x domain of deeply inelastic positron–proton scattering. For 5×10−5⩽x⩽0.01 and ...Q2⩾1.5GeV2, λ(x,Q2) is found to be independent of x and to increase linearly with lnQ2.
With the tenfold luminosity increase envisaged at the HL-LHC, the background (i.e., photons, neutrons, \ldots ) and the event pileup probability are expected to highly increase in proportion in the ...different experiments, especially in the forward regions, for instance the muons chambers of the ATLAS detector. Detectors based on the Micromegas principle should be good alternatives for the detector upgrade in the HL-LHC framework because of its good spatial (< 100\mu{\hbox{m}}) and time (few ns) resolutions, high-rate capability, radiation hardness, good robustness, and the possibility to build large areas. The aim of this study is to demonstrate that it is possible to reduce the discharge probability and protect the electronics by using a resistive anode plane in a high-flux hadrons environment. Several prototypes of 10 \times 10~{\hbox{cm}}^{2} , with different pitches (0.5-2 mm) and different resistive layers have been tested at CERN (\pi^{+}@{\rm SPS}) . Several tests have been performed with a telescope at different voltages to assess the performance of the detectors in terms of position resolution and efficiency. The spark behavior in these conditions has also been evaluated. Resistive coating has been shown to be a successful method to reduce the effect of sparks on the efficiency of micromegas. A good spatial resolution (\sim 80\ \mu{\hbox{m}}) can be reached with a resistive strip coating detector of 1-mm pitch, and a high efficiency ( > 98\%) can be achieved with resistive-anode micromegas detector. An X-rays irradiation has also been performed, showing no ageing effect after more than 21 days exposure and an integrated charge of almost 1C.
Elastic J/ψ production at HERA Aktas, A.; Andreev, V.; Anthonis, T. ...
The European physical journal. C, Particles and fields,
06/2006, Letnik:
46, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Cross sections for elastic production of J/ψ mesons in photoproduction and electroproduction are measured in electron proton collisions at HERA using an integrated luminosity of 55 pb-1. Results are ...presented for photon virtualities Q2 up to 80 GeV2. The dependence on the photon-proton centre of mass energy Wγp is analysed in the range 40≤Wγp≤305 GeV in photoproduction and 40≤Wγp≤160 GeV in electroproduction. The Wγp dependences of the cross sections do not change significantly with Q2 and can be described by models based on perturbative QCD. Within such models, the data show a high sensitivity to the gluon density of the proton in the domain of low Bjorken x and low Q2. Differential cross sections dσ/dt, where t is the squared four-momentum transfer at the proton vertex, are measured in the range |t|<1.2 GeV2 as functions of Wγp and Q2. Effective Pomeron trajectories are determined for photoproduction and electroproduction. The J/ψ production and decay angular distributions are consistent with s-channel helicity conservation. The ratio of the cross sections for longitudinally and transversely polarised photons is measured as a function of Q2 and is found to be described by perturbative QCD based models.
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