60 research outputs found
A Large TPC Prototype with MPGD Readout: Status and Plans
The use of a TPC in future collider experiments needs significant research
and development. Within the EUDET program an infrastructure has been designed
and built to allow the efficient testing of TPC prototypes under realistic
conditions. The infrastructure consists of a test beam facility, located at
DESY Hamburg, and a multi-purpose TPC field cage.Comment: Conference LCES 2008, Chicag
A Lightweight Field Cage for a Large TPC Prototype for the ILC
We have developed and constructed the field cage of a prototype Time
Projection Chamber for research and development studies for a detector at the
International Linear Collider. This prototype has an inner diameter of 72 cm
and a length of 61 cm. The design of the field cage wall was optimized for a
low material budget of 1.21 % of a radiation length and a drift field
homogeneity of Delta(E)/(E) less or equal 10^-4. Since November 2008 the
prototype has been part of a comprehensive test beam setup at DESY and used as
a test chamber for the development of Micro Pattern Gas Detector based readout
devices.Comment: 16 pages, 13 figures, 3 table
Design and Performance of the Alignment System for the CMS Muon Endcaps
The alignment system for the CMS Muon Endcap detector employs several hundred sensors such as optical 1-D CCD sensors illuminated by lasers and analog distance- and tilt-sensors to monitor the positions of one sixth of 468 large Cathode Strip Chambers. The chambers mounted on the endcap yoke disks undergo substantial deformation on the order of centimeters when the 4T field is switched on and off. The Muon Endcap alignment system is required to monitor chamber positions with \mbox{75-200 m} accuracy in the R plane, 400 m in the radial direction, and 1 mm in the z-direction along the beam axis. The complete alignment hardware for one of the two endcaps has been installed at CERN. A major system test was performed when the 4T solenoid magnet was ramped up to full field for the first time in August 2006. We present the overall system design and first results on disk deformations, which indicate that the measurements agree with expectations
A Time Projection Chamber with GEM-Based Readout
For the International Large Detector concept at the planned International
Linear Collider, the use of time projection chambers (TPC) with micro-pattern
gas detector readout as the main tracking detector is investigated. In this
paper, results from a prototype TPC, placed in a 1 T solenoidal field and read
out with three independent GEM-based readout modules, are reported. The TPC was
exposed to a 6 GeV electron beam at the DESY II synchrotron. The efficiency for
reconstructing hits, the measurement of the drift velocity, the space point
resolution and the control of field inhomogeneities are presented.Comment: 22 pages, 19 figure
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Design and performance of the alignment system for the CMS muon endcaps
The alignment system for the CMS Muon Endcap detector employs several hundred sensors such as optical 1-D CCD sensors illuminated by lasers and analog distance- and tilt-sensors to monitor the positions of one sixth of 468 large Cathode Strip Chambers. The chambers mounted on the endcap yoke disks undergo substantial deformation on the order of centimeters when the 4T field is switched on and off. The Muon Endcap alignment system is required to monitor chamber positions with 75-200 {micro}m accuracy in the R? plane, {approx}400 {micro}m in the radial direction, and {approx}1 mm in the z-direction along the beam axis. The complete alignment hardware for one of the two endcaps has been installed at CERN. A major system test was performed when the 4T solenoid magnet was ramped up to full field for the first time in August 2006. We present the overall system design and first results on disk deformations, which indicate that the measurements agree with expectations
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
Study of Spin and Decay-Plane Correlations of W Bosons in the e+e- -> W+W- Process at LEP
Data collected at LEP at centre-of-mass energies \sqrt(s) = 189 - 209 GeV are
used to study correlations of the spin of W bosons using e+e- -> W+W- -> lnqq~
events. Spin correlations are favoured by data, and found to agree with the
Standard Model predictions. In addition, correlations between the W-boson decay
planes are studied in e+e- -> W+W- -> lnqq~ and e+e- -> W+W- -> qq~qq~ events.
Decay-plane correlations, consistent with zero and with the Standard Model
predictions, are measured
Ultrarelativistic sources in nonlinear electrodynamics
The fields of rapidly moving sources are studied within nonlinear
electrodynamics by boosting the fields of sources at rest. As a consequence of
the ultrarelativistic limit the delta-like electromagnetic shock waves are
found. The character of the field within the shock depends on the theory of
nonlinear electrodynamics considered. In particular, we obtain the field of an
ultrarelativistic charge in the Born-Infeld theory.Comment: 10 pages, 3 figure
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