61 research outputs found
Test of the two TOTEM TripleGEM Chambers assembled at G&A Engineering
In this note we report the results of the tests performed at CERN on the two TOTEM TripleGEM chambers assembled by a private company
Fast Timing for High-Rate Environments with Micromegas
The current state of the art in fast timing resolution for existing
experiments is of the order of 100 ps on the time of arrival of both charged
particles and electromagnetic showers. Current R&D on charged particle timing
is approaching the level of 10 ps but is not primarily directed at sustained
performance at high rates and under high radiation (as would be needed for
HL-LHC pileup mitigation). We demonstrate a Micromegas based solution to reach
this level of performance. The Micromegas acts as a photomultiplier coupled to
a Cerenkov-radiator front window, which produces sufficient UV photons to
convert the ~100 ps single-photoelectron jitter into a timing response of the
order of 10-20 ps per incident charged particle. A prototype has been built in
order to demonstrate this performance. The first laboratory tests with a
pico-second laser have shown a time resolution of the order of 27 ps for ~50
primary photoelectrons, using a bulk Micromegas readout.Comment: MPGD2015 (4th Conference on Micro-Pattern Gaseous Detectors, Trieste,
Italy, 12 - 15 October, 2015). 5 pages, 8 figure
Beam Studies of the Segmented Resistive WELL: a Potential Thin Sampling Element for Digital Hadron Calorimetry
Thick Gas Electron Multipliers (THGEMs) have the potential of constituting
thin, robust sampling elements in Digital Hadron Calorimetry (DHCAL) in future
colliders. We report on recent beam studies of new single- and
double-THGEM-like structures; the multiplier is a Segmented Resistive WELL
(SRWELL) - a single-faced THGEM in contact with a segmented resistive layer
inductively coupled to readout pads. Several 1010 cm configurations
with a total thickness of 5-6 mm (excluding electronics) with 1 cm pads
coupled to APV-SRS readout were investigated with muons and pions. Detection
efficiencies in the 98 range were recorded with average pad-multiplicity of
1.1. The resistive anode resulted in efficient discharge damping, with
potential drops of a few volts; discharge probabilities were for
muons and for pions in the double-stage configuration, at rates
of a few kHz/cm. Further optimization work and research on larger detectors
are underway.Comment: Presented at the Vienna Conference on Instrumentation,
February 2013 and submitted to its proceeding
Evidence for non-exponential elastic proton-proton differential cross-section at low |t| and sqrt(s) = 8 TeV by TOTEM
The TOTEM experiment has made a precise measurement of the elastic
proton-proton differential cross-section at the centre-of-mass energy sqrt(s) =
8 TeV based on a high-statistics data sample obtained with the beta* = 90
optics. Both the statistical and systematic uncertainties remain below 1%,
except for the t-independent contribution from the overall normalisation. This
unprecedented precision allows to exclude a purely exponential differential
cross-section in the range of four-momentum transfer squared 0.027 < |t| < 0.2
GeV^2 with a significance greater than 7 sigma. Two extended parametrisations,
with quadratic and cubic polynomials in the exponent, are shown to be well
compatible with the data. Using them for the differential cross-section
extrapolation to t = 0, and further applying the optical theorem, yields total
cross-section estimates of (101.5 +- 2.1) mb and (101.9 +- 2.1) mb,
respectively, in agreement with previous TOTEM measurements.Comment: Final version published in Nuclear Physics
A large area 100 channel Picosec Micromegas detector with sub 20 ps time resolution
The PICOSEC Micromegas precise timing detector is based on a Cherenkov
radiator coupled to a semi-transparent photocathode and a Micromegas
amplification structure. The first proof of concept single-channel small area
prototype was able to achieve time resolution below 25 ps. One of the crucial
aspects in the development of the precise timing gaseous detectors applicable
in high-energy physics experiments is a modular design that enables large area
coverage. The first 19-channel multi-pad prototype with an active area of
approximately 10 cm suffered from degraded timing resolution due to the
non-uniformity of the preamplification gap. A new 100 cm detector module
with 100 channels based on a rigid hybrid ceramic/FR4 Micromegas board for
improved drift gap uniformity was developed. Initial measurements with 80 GeV/c
muons showed improvements in timing response over measured pads and a time
resolution below 25 ps. More recent measurements with a new thinner drift gap
detector module and newly developed RF pulse amplifiers show that the
resolution can be enhanced to a level of 17~ps. This work will present the
development of the detector from structural simulations, design, and beam test
commissioning with a focus on the timing performance of a thinner drift gap
detector module in combination with new electronics using an automated timing
scan method
Towards robust PICOSEC Micromegas precise timing detectors
The PICOSEC Micromegas (MM) detector is a precise timing gaseous detector
consisting of a Cherenkov radiator combined with a photocathode and a MM
amplifying structure. A 100-channel non-resistive PICOSEC MM prototype with
10x10 cm^2 active area equipped with a Cesium Iodide (CsI) photocathode
demonstrated a time resolution below 18 ps. The objective of this work is to
improve the PICOSEC MM detector robustness aspects; i.e. integration of
resistive MM and carbon-based photocathodes; while maintaining good time
resolution. The PICOSEC MM prototypes have been tested in laboratory conditions
and successfully characterised with 150 GeV/c muon beams at the CERN SPS H4
beam line. The excellent timing performance below 20 ps for an individual pad
obtained with the 10x10 cm^2 area resistive PICOSEC MM of 20 MOhm/sq showed no
significant time resolution degradation as a result of adding a resistive
layer. A single-pad prototype equipped with a 12 nm thick Boron Carbide (B4C)
photocathode presented a time resolution below 35 ps; opening up new
possibilities for detectors with robust photocathodes. The results made the
concept more suitable for the experiments in need of robust detectors with good
time resolution
The forward inelastic telescope T2 for the TOTEM experiment at the LHC
The TOTEM Experiment will measure the total pp cross-section with the luminosity-independent method and study elastic and diffractive scattering at the LHC. To achieve optimum forward coverage for charged particles emitted by the pp collisions in the interaction point IP5, two tracking telescopes, T1 and T2, will be installed on each side in the pseudorapidity region and Roman Pot stations will be placed at distances of 147 m and 220 m from the Interaction Point 5 (IP5). The triple Gas Electron Multiplier (GEM) technology has been chosen by the collaboration for its T2 telescope which will provide charged track reconstruction in the rapidity range and a fully inclusive trigger for diffractive events. Results from the preliminary tests on the prototypes of the TOTEM Triple GEM detectors up to the data taking during the first pp collisions at the LHC will be described in this thesis
Combined Optical and Electronic Readout For Event Reconstruction in a GEM-based TPC
Optically read out time projection chambers (TPCs) based on gaseous electron multipliers (GEMs) combine 3-D event reconstruction capabilities with high spatial resolution and charge amplification factors. The approach of reconstructing particle tracks from 2-D projections obtained with imaging sensors and depth information from photomultiplier tubes is limited to specific cases such as straight particle trajectories. A combination of optical and electronic readout realized by a semitransparent anode placed between a triple-GEM stack and a camera in an optically read out TPC has been realized and used to reconstruct more complex particle tracks. High spatial resolution 2-D projections combined with a low number of charge readout channels enable accurate 3-D event topology reconstruction. Straight alpha tracks as well as more complex cosmic events have been reconstructed with the presented readout concept. Relative depth information from electronically read out charge signals has been combined with drift time information between primary and secondary scintillation pulses to absolute alpha track reconstructions.Peer reviewe
Imaging Demonstration of a Glass Gas Electron Multiplier with Electronic Charge Readout
We have developed a Glass Gas Electron Multiplier (Glass GEM, G-GEM), which is composed of two copper electrodes separated by a photosensitive etchable glass substrate having holes arranged in a hexagonal pattern. In this paper, we report the result of imaging using a G-GEM combined with a 2D electronic charge readout. We used a crystallized photosensitive etchable glass as the G-GEM substrate. A precise X-ray image of a small mammal was successfully obtained with position resolutions of approximately 110 to 140 μm in RMS
- …