Since the last RICH Workshop held in 1998, a number of large RICH systems have been built and, some, already operated at different HEP experiments. The main features governing the operation and the ...performance of these systems are reviewed and discussed in view of possible improvements towards higher rates and ageing performance. As most of the new systems are based on CsI-photocathodes, a review is given on the progress done in the processing of efficient and reproducible large photocathodes. An alternative multi-GEM based photo-detector is discussed.
The VHMPID RICH upgrade project for ALICE at LHC Di Mauro, A.; Agocs, A.; Alfaro, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2011, Letnik:
639, Številka:
1
Journal Article
Recenzirano
RHIC results have shown the importance of high momentum particles as hard probes and the need for particle identification (PID) in a very large momentum range. A Very High Momentum PID (VHMPID) ...detector has been proposed as upgrade of ALICE to extend the track-by-track identification capabilities for charged hadrons from the present 5
GeV/c limit to the momentum range 10–30
GeV/c. The VHMPID detector is a focusing RICH using C
4F
10 gaseous radiator coupled to a CsI-based photon detector. Detector design studies, achievable Cherenkov angle resolution, expected performance and high momentum triggering will be discussed.
We report on studies of layout and performance of a new Ring Imaging Cherenkov detector using for the first time pressurized C4F8O radiator gas and a photon detector consisting of a MWPC equipped ...with a CsI photocathode. In particular, we present here the results of beam tests of a MWPC having an adjustable anode–cathode gap, aiming at the optimization of single photoelectron detection and Cherenkov angle resolution. This system was proposed as a Very High Momentum Particle Identification (VHMPID) upgrade for the ALICE experiment at LHC to provide charged hadron track-by-track identification in the momentum range 5–25GeV/c.
•The concept and design of a novel RICH counter operated with pressurized gaseous Cherenkov radiator have been validated.•We used for the first time C4F8O gaseous Cherenkov radiator pressurized up to 3.5atm in a RICH counter.•The refractive index of C4F8O in the UV range is similar to the per-mil level to that of C4F10.•A variable gap MWPC has been used to optimize the layout of the gaseous photon counter, based on CsI photocathodes and MWPC, for the detection of single photoelectrons.
Very high momentum particle identification in ALICE at the LHC Agocs, A.; Alfaro, R.; Barnafoldi, G.G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
We propose to construct and install a limited acceptance detector to identify hadrons (pions, K, p) up to 30
GeV/
c on a track-by-track basis in space available in ALICE. Details and PID performance ...simulation results will be presented for two possible options, including a high transverse momentum (
p
T
) trigger for this detector. The first option is a RICH design with a
C
4
F
10
gas UV-photon radiator, UV-mirror, quartz window and pad-readout. This design requires additional tracking detectors to enable high
p
T
triggering. A second option is a combination of three detectors: a RICH with
CF
4
gas both as a UV-photon radiator and as a gas amplification medium (a windowless approach); and a threshold Cherenkov detector (
C
4
F
10
) with a quartz window and pad readout. The response for minimum ionizing particles (MIP) and UV-photons in these detectors can be well separated. With an additional tracking detector this design will also provide high
p
T
triggering. The simulation includes UV-photon production due to
CF
4
scintillation.
We studied the ageing of large CsI photocathodes induced by ionizing particles (
90Sr) by correlating the integrated charge dose of the ionic avalanches hitting the photocathode to the local changes ...of the Quantum Efficiency (QE). The drop of the QE of the irradiated CsI spots is reported as a function of the charge dose. It was found that the ageing process continues even in absence of irradiation.
Aging of large-area CsI photocathodes for the ALICE HMPID prototypes Braem, A; Davenport, M; Di Mauro, A ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2003, Letnik:
515, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The ALICE High-Momentum Particle IDentification RICH detector is equipped with CsI photocathodes (PCs) in a MWPC for the detection of Cherenkov photons. The long-term operational experience with ...large-area CsI PCs is described. The RICH prototypes have shown a very high stability of operation and performance at a gain of 10
5 and with rates up to 2×10
4
cm
−2
s
−1. When exposure to air is avoided, no degradation of the CsI quantum efficiency has been observed on PCs periodically exposed to test beams over 7 years, corresponding to local integrated charge densities of ∼1
mC/cm
2. The results of limited exposures to oxygen and humidity are also presented.
The ALICE (A Large Ion Collider Experiment) high momentum particle identification (HMPID) detector, presently under construction, consists of seven identical proximity focusing ring imaging Cherenkov ...(RICH) counters exploiting large area CsI photocathodes for Cherenkov light imaging. With a total area of 11 m/sup 2/, it represents the largest CsI-RICH system ever used in High Energy Physics. The detector layout, assembly and quality checks will be presented, with particular emphasis on CsI photocathodes mass production. A validation procedure has been established combining the results of the photocathode response mapping obtained in a dedicated VUV scanner with test beam data. The long-term stability has also been studied by irradiation with a Sr-90 source of a final size CsI photocathode inside a detector prototype.
Quality evaluation of CsI photocathodes for the ALICE/HMPID detector Hoedlmoser, H.; Braem, A.; De Cataldo, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2005, Letnik:
553, Številka:
1
Journal Article
Recenzirano
The facility for the production of the large area
(
64
×
42
cm
2
)
CsI photocathodes for the ALICE/HMPID detector has been equipped with a photo-current scanner system for the in situ measurement of ...the CsI response over the full photosensitive area before transfer to the detector. The photo-current measured on a first batch of 17 PCs, out of the 42 needed to fully equip the seven HMPID modules, has been correlated with test beam measurements in order to define acceptance criteria. Furthermore the system's sensitivity to variations in quantum efficiency allows us to study various effects such as post-deposition heat enhancement or decreased quality due to ageing.
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