105 research outputs found
A new type of resistive plate chamber: the multigap RPC
This paper describes the multigap resistive plate chamber (RPC). The goal is to obtain a much improved time resolution, keeping the advantages of the wide gap RPC in comparison with the conventional narrow gap RPC (smaller dynamic range and thus lower charge per avalanche which gives higher rate capability and lower power dissipation in the gas gap)
Design, development and performance study of six-gap glass MRPC detectors
The Multigap Resistive Plate Chambers (MRPCs) are gas ionization detectors
with multiple gas sub-gaps made of resistive electrodes. The high voltage (HV)
is applied on the outer surfaces of outermost resistive plates only, while the
interior plates are left electrically floating. The presence of multiple narrow
sub--gaps with high electric field results in faster signals on the outer
electrodes, thus improving the detector's time resolution. Due to their
excellent performance and relatively low cost, the MRPC detector has found
potential application in Time-of-Flight (TOF) systems. Here we present the
design, fabrication, optimization of the operating parameters such as the HV,
the gas mixture composition, and, performance of six--gap glass MRPC detectors
of area 27cm 27 cm, which are developed in order to find application
as trigger detectors, in TOF measurement etc. The design has been optimized
with unique spacers and blockers to ensure a proper gas flow through the narrow
sub-gaps, which are 250 m wide. The gas mixture consisting of R134A,
Isobutane and SF, and the fraction of each constituting gases has been
optimized after studying the MRPC performance for a set of different
concentrations. The counting efficiency of the MRPC is about 95% at kV.
At the same operating voltage, the time resolution, after correcting for the
walk effect, is found to be about ps.Comment: Revised version with 15 pages, 14 figures, 2 tables. Accepted for
publication in the European Physical Journal
TOFtracker: combination of time-of-flight and high-accuracy bidimensional tracking in a single gaseous detector
A 5-gap timing RPC equipped with patterned electrodes coupled to both charge-sensitive and
timing circuits yields a time accuracy of 77 ps along with a position accuracy of 38 ÎĽm. These
results were obtained by calculating the straight-line fit residuals to the positions provided by a
3-layer telescope made out of identical detectors, detecting almost perpendicular cosmic-ray
muons. The device may be useful for particle identification by time-of-flight, where
simultaneous measurements of trajectory and time are necessary
The MRPC-based ALICE Time-Of-Flight detector: status and performance
The large Time-Of-Flight (TOF) array is one of the main detectors devoted to
charged hadron identification in the mid-rapidity region of the ALICE
experiment at the LHC. It allows separation among pions, kaons and protons up
to a few GeV/c, covering the full azimuthal angle and -0.9 < eta < 0.9. The TOF
exploits the innovative MRPC technology capable of an intrinsic time resolution
better than 50 ps with an efficiency close to 100% and a large operational
plateau; the full array consists of 1593 MRPCs covering a cylindrical surface
of 141 m2. The TOF detector has been efficiently taking data since the first pp
collisions recorded in ALICE in December 2009. In this report, the status of
the TOF detector and the performance achieved for both pp and Pb--Pb collisions
are described.Comment: 4 pages, 6 figure
A new high-resolution TOF technology
In the framework of the ALICE collaboration we have recently studied the performance of multigap Resistive Plate Chambers operated in avalanche mode and at atmospheric pressure for time-of-flight measurements. The detector provided an overall (detector plus electronics) timing accuracy of 120 ps sigma at an efficiency of 98% for MIPs. The chambers had 4 gas gaps of 0.3 mm, each limited by a metallised ceramic plate and a glass plate, with an active dimension of 4'4cm2. The gas mixture contained C2H2F4+5%isobutane+10%SF6. A few percent of streamer discharges, each releasing about 20 pC, was tolerated without any noticeable inconvenience. This detector opens perspectives of affordable and reliable high granularity large area TOF detectors, with an efficiency and a time resolution comparable to existing scintillator-based TOF technology but with significantly, up to an order of magnitude, lower price per channel
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