Due to their construction simplicity and accuracy for reconstructing particle trajectories, Micromegas (mesh-GAseous Structure) and Gas Electron Multiplier (GEM) detectors are commonly used as ...readout systems in Time Projection Chambers (TPCs). The main limitation of these two types of detectors is the ion backflow, which may result in space charge in the TPC. We present a new Micro-Pattern Gaseous Detector (MPGD) structure, which combines a mesh and a set made of a GEM surmounted by a mesh at only a few hundreds μm above. We report the performance results of two prototypes using this new structure. We show that this new detector is capable of reducing the ion backflow to less than 0.2% for a total gain of around 2000.
Due to their simplicity and accuracy for reconstructing particle trajectories, Micromegas (Micro-MEsh-GAseous Structure) and Gas Electron Multiplier (GEM) detectors are commonly used as readout ...systems in Time Projection Chambers (TPCs). The main limitation of these two types of detectors is the ion backflow (IBF), which may result in space charge in a TPC. We present in this article a new Micro-Pattern Gaseous Detector (MPGD) structure, which combines a micro-mesh and a set made of a GEM surmounted by a micro-mesh at only a few hundreds μm above. We report the performance results of two prototypes using this new structure, and compare them to a single Micromegas and a hybrid detector composed of a Micromegas and a GEM with a few millimeters gap. Finally, we show that this new detector is capable of reducing the ion backflow to less than 0.2% for a total gain of around 2000.
The forward muon spectrometer of ALICE (A Large Ion Collider Experiment) is equipped with a trigger system made of four planes of Resistive Plate Chambers (RPC), arrangedin two stations with two ...planes each, for a total area of about 140 m super(2). The system provides singleand di-muon triggers with suitable transverse momentum selection, optimised for the physics ofquarkonia and open heavy flavour. In the first two years of data-taking at the Large Hadron Collider (2010 and 2011) the 72 RPCs were operated in highly saturated avalanche mode in both pp andPb-Pb collisions. The integrated charge was about 1.3 mC/cm super(2) on average and 3.5 mC/cm super(2) for themost exposed detectors. This paper describes two main results. The first result is the determinationof the RPC performance, with particular focus on the stability of the main detector parameters suchas efficiency, dark current, and dark rate. The second result is the measurement of the muon triggerperformance in Pb-Pb collisions at square root S sub(NN) = 2.76 TeV, in terms of the reliability and stability of thetrigger decision logic.
The CLAS12 software framework and event reconstruction Ziegler, V.; Baltzell, N.A.; Bossù, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
959, Številka:
C
Journal Article
Recenzirano
Odprti dostop
We describe offline event reconstruction for the CEBAF Large Acceptance Spectrometer at 12 GeV (CLAS12), including an overview of the offline reconstruction framework and software tools, a ...description of the algorithms developed for the individual detector subsystems, and the overall approach for charged and neutral particle identification. We also present the scheme for data processing and the code management procedures.
The CLAS12 Forward Tagger Acker, A.; Attié, D.; Aune, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
959, Številka:
C
Journal Article
Recenzirano
Odprti dostop
This document presents the technical layout and the performance of the CLAS12 Forward Tagger (FT). The FT, composed of an electromagnetic calorimeter based on PbWO4 crystals (FT-Cal), a scintillation ...hodoscope (FT-Hodo), and several layers of Micromegas trackers (FT-Trk), has been designed to detect electrons and photons scattered at polar angles from 2∘ to 5∘ and to meet the physics goals of the hadron spectroscopy program and other experiments running with the CLAS12 spectrometer in Hall B.
ALICE at the CERN LHC will investigate the physics of strongly interacting matter at extreme energy densities where the formation of the Quark Gluon Plasma is expected. Its properties can be studied ...from observations like the production of mesons with charm and beauty quarks. These signals have to be studied as a function of energy density, which is determined by the centrality of collisions. One of the physics observables that is closely related with the centrality of the collision is the number of spectator nucleons that can be measured by the Zero Degree Calorimeters (ZDC). Having a direct geometric interpretation allows to extract the impact parameter with minimal model assumptions. This paper describes the readout system of the ZDC. The ZDC readout consists of a VME system with a ZDC Readout Card, a VME Processor, Discriminators, a ZDC Trigger Card, scalers, QDCs and TDCs. The system was successfully tested during the 2009 ALICE data taking and is currently operational at the LHC.
ALICE at the CERN LHC will investigate the physics of strongly interacting matter at extreme energy densities where the formation of the Quark Gluon Plasma is expected. Its properties can be studied ...from observations like the production of mesons with charm and beauty quarks. These observations have to be studied as a function of energy density which is determined by the centrality of collisions. The energy carried by the spectator nucleons, related to the centrality, is measured by the Zero Degree Calorimeters (ZDC). The ZDC readout consists of a VME system with a ZDC Readout Card, a VME Processor, Discriminators, a ZDC Trigger Card, scalers, QDCs and TDCs. The system was successfully tested during the 2009 ALICE data taking and is currently operational at the LHC. This paper describes the ZDC Readout Card which forms an important part of the ZDC readout system.
A search for the rare two-body charmless baryonic decay $B^+ \to p \bar\Lambda$ is performed with $pp$ collision data, corresponding to an integrated luminosity of $3\mbox{\,fb}^{-1}$, collected by ...the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. An excess of $B^+ \to p \bar\Lambda$ candidates with respect to background expectations is seen with a statistical significance of 4.1 standard deviations, and constitutes the first evidence for this decay. The branching fraction, measured using the $B^+ \to K^0_{\mathrm S} \pi^+$ decay for normalisation, is \begin{eqnarray} \mathcal{B}(B^+ \to p \bar\Lambda) & = & ( 2.4 \,^{+1.0}_{-0.8} \pm 0.3 ) \times 10^{-7} \,, \nonumber \end{eqnarray} where the first uncertainty is statistical and the second systematic.
The $B_s^0\pi^\pm$ invariant mass distribution is investigated in order to search for possible exotic meson states. The analysis is based on a data sample recorded with the LHCb detector ...corresponding to $3$ fb$^{-1}$ of $pp$ collision data at $\sqrt{s} = 7$ and $8$ TeV. No significant excess is found, and upper limits are set on the production rate of the claimed $X(5568)$ state. Upper limits are also set as a function of the mass and width of a possible exotic meson decaying to the $B_s^0\pi^\pm$ final state.
Commissioning of the ALICE muon spectrometer trigger at LHC Ahn, S.; Arnaldi, R.; Baek, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2012, Letnik:
661
Journal Article
Recenzirano
ALICE (a large ion collider experiment) is the LHC experiment dedicated to the study of ultra-relativistic heavy ion collisions. The ALICE muon spectrometer covers a large range in pseudo-rapidity ...and is designed to study quarkonia and heavy flavours decaying into (di-)muons. The high particle multiplicities environment in such collisions require a specific, fast and efficient trigger system, the muon trigger. It consists of four planes of RPC detectors, covering an area of 36
m
2 each, 21k front-end channels and a fast-decision electronics. The muon trigger is designed to reconstruct (muon) tracks and deliver a trigger signal each 25
ns (40
MHz) with a total latency of 800
ns. The hit position on the RPC is measured in two orthogonal directions with an accuracy of about 1
cm. The performance measured with the first p–p collisions at
(
s
)
=
900
GeV
carried out in December 2009 is reported.
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