Proximity Focusing RICH Research Articles

Silicon photomultiplier as a position sensitive detector of Cherenkov photons

A novel photon detector, silicon photomultiplier, whose main advantage over photomultiplier tubes for RICH applications is the operation in high magnetic field environments, has been tested in view of measuring Cherenkov photons in a RICH counter. Results of the measurements of single photo-electron pulse height and timing distributions and of uniformity of the response are presented. Feasibility of a proximity focusing RICH counter using this type of photon detector is discussed.

Study of a proximity focusing RICH with a silica aerogel radiator

A proximity focusing RICH based on a silica aerogel Cherenkov radiator has been developed for a new particle identification device in the upgraded Belle detector. To further improve the detector performance, a new concept for Cherenkov ring imaging has been introduced, where multiple aerogel layers with different indices are accumulated to increase the number of detected photons without making the Cherenkov photon angle resolution worse. By constructing a prototype counter, this idea was validated in a test beam experiment, and a 5.5 σ π / K separation at 4 GeV / c with more than nine photoelectrons was achieved. We will present new results from a beam test as well as recent improvements on aerogel radiators.

A study of proximity focusing RICH with aerogel radiator

Proximity focusing RICH based on an aerogel Cherenkov radiator has been developed for a new particle identifier in the Belle upgrade. To further improve the detector performance, a new concept for Cherenkov ring imaging has been introduced, where multiple aerogel layers with different indices are accumulated to increase observed photoelectrons without making the single photon resolution worse. By constructing a prototype counter, this idea was validated in a test beam experiment, and we achieved 5.5 σ π / K separation at 4 GeV / c . In addition, the potential of the time-of-flight capabilities to detect time information of Cherenkov photons, where a micro-channel plate PMT is employed as a photodetector, was examined in a beam test, and excellent performance of this technique was obtained.

Proximity focusing RICH with TOF capabilities

A proximity focusing RICH counter with a multi-channel micro-channel plate (MCP) PMT was tested as a time-of-flight counter. Cherenkov photons emitted in the radiator medium as well as in the entrance window of the PMT were used for the time-of-flight measurement, and an excellent performance of the counter could be demonstrated.

A novel type of proximity focusing RICH counter with multiple refractive index aerogel radiator

A proximity focusing ring imaging Cherenkov detector, with the radiator consisting of two or more aerogel layers of different refractive indices, has been tested in 1 – 4 GeV / c pion beams at KEK. Essentially, a multiple refractive index aerogel radiator allows for an increase in Cherenkov photon yield on account of the increase in overall radiator thickness, while avoiding the simultaneous degradation in single photon angular resolution associated with the increased uncertainty of the emission point. With the refractive index of consecutive layers suitably increasing in the downstream direction, one may achieve overlapping of the Cherenkov rings from a single charged particle. The impact of the observed improvement on the π / K separation at the upgraded Belle detector is discussed.

Study of a nonhomogeneous aerogel radiator in a proximity focusing RICH detector

The use of a nonhomogeneous aerogel radiator, i.e. one consisting of layers with different refractive indices, has been shown to improve the resolution of the Cherenkov angle measured with a proximity focusing RICH detector. In order to obtain further information on the performance of such a detector, a simple model has been used to calculate the resolution and search for optimal radiator parameters.

Focusing aerogel RICH (FARICH)

In this work we investigate a Ring Imaging Cherenkov detector based on “focusing” aerogel (FARICH). In the proximity focusing RICH, one of the main factors determining precision of ring radius measurements is a finite thickness of a radiator. FARICH development aims at the reduction of this effect by means of using multilayer aerogel. Two options have been considered. Single ring: refraction index and thickness of each layer are adjusted in such a way that Cherenkov rings from different layers are superimposed on each other. Multi-ring: refraction index and thickness of each layer are adjusted so that ring images from different layers have different radii and are clearly separated from each other. For the first time in the world we have developed a technique for production of multilayer aerogels (SAN-MULTI). A few samples consisting of four aerogel layers with indices from 1.022 to 1.030 have been produced. A GEANT4 based simulation program has been developed. Velocity resolution was investigated for different momenta and particle incidence angles. It was shown that velocity resolution of 5 × 10 - 4 is achievable. This permits us to have π / K separation at the level of more than 3 σ up to momentum 8.0 GeV / c , π / μ separation up to momentum 1.6 GeV / c .

Performance and results of the RICH detector for kaon physics in Hall A at Jefferson Lab

A proximity focusing RICH detector has been constructed for the hadron High Resolution Spectrometer (HRS) of Jefferson Lab Experimental Hall-A. This detector is intended to provide excellent hadron identification up to a momentum of 2.5 GeV / c . The RICH uses a 15 mm thick liquid perfluorohexane radiator in proximity focusing geometry to produce Cherenkov photons traversing a 100 mm thick proximity gap filled with pure methane and converted into electrons by a thin film of CsI deposited on the cathode plane of a MWPC. The detector has been successfully employed in the fixed target, high luminosity and high resolution hypernuclear spectroscopy experiment. With its use as a kaon identifier in the 2 GeV / c region, the very large contribution from pions and protons to the hypernuclear spectrum was reduced to a negligible level. The basic parameters and the resulting performance obtained during the experiment are reported in this paper.

Proximity focusing RICH with flat panel PMT as photon detector and aerogel as radiator

Using aerogel as radiator and 64-channel flat panel multi-anode PMTs (Hamamatsu H8500) for photon detection, a proximity focusing Cherenkov ring imaging detector has been constructed and tested in the KEK π 2 beam. The single photon resolution obtained in the tests (typically around 14 mrad) is well approximated by estimates of contributions from pixel size and emission point uncertainty. The number of detected photons per Cherenkov ring, typically about 6 for a 2 cm thick aerogel radiator tile, is in good agreement with estimates based on aerogel and detector characteristics. The detector allows a very efficient separation of kaons and pions at 4 GeV / c .

A novel type of proximity focusing RICH counter with multiple refractive index aerogel radiator

A proximity focusing ring imaging Cherenkov detector, with the radiator consisting of two or more aerogel layers of different refractive indices, has been tested in 1– 4 GeV / c pion beams at KEK. Essentially, a multiple refractive index aerogel radiator allows for an increase in Cherenkov photon yield on account of the increase in overall radiator thickness, while avoiding the simultaneous degradation in single photon angular resolution associated with the increased uncertainty of the emission point. With the refractive index of consecutive layers suitably increasing in the downstream direction, one may achieve overlapping of the Cherenkov rings from a single charged particle. In the opposite case of decreasing refractive index, one may obtain well separated rings. In the former combination an approximately 40% increase in photon yield is accompanied with just a minor degradation in single photon angular resolution. The impact of this improvement on the π / K separation at the upgraded Belle detector is discussed.

Proximity focusing RICH with flat panel PMT (Hamamatsu H8500) as photon detector and aerogel radiator

Using aerogel as radiator and 64-channel flat panel multi-anode PMTs (Hamamatsu H8500) for photon detection, a proximity focusing Cherenkov ring imaging detector has been constructed and tested in the KEK π2 beam. The single photon resolution obtained in the tests (typically around 11 mrad ) is well approximated by estimates of contributions from pixel size and emission point uncertainty. The number of detected photons per Cherenkov ring, typically about 6 for a 2 cm thick aerogel radiator tile, is in good agreement with estimates based on aerogel and detector characteristics. The detector allows a very efficient separation of kaons and pions at 4 GeV/c .

Studies of a proximity focusing RICH with aerogel radiator

A proximity focusing ring imaging Cherenkov detector using aerogel as the radiator is studied for the upgrade of the Belle detector at KEK-B-factory. The second beam test of the detector was carried out using the recently introduced flat-panel PMTs (Hamamatsu H8500) and newly developed aerogel samples having better transmission length. We observe Cherenkov rings with a single photon resolution of about 14 mrad , and typically on average 6 detected photons per ring. The results show that such a detector is a promising step in R&D for upgrading the Belle spectrometer.

Studies of proximity focusing RICH with an aerogel radiator using flat-panel multi-anode PMTs (Hamamatsu H8500)

A proximity focusing ring imaging Cherenkov detector using aerogel as the radiator has been studied for upgrading the Belle detector at the KEK-B-factory. We constructed a prototype Cherenkov counter using a 4×4 array of 64-channel flat-panel multi-anode PMTs (Hamamatsu H8500) with a large effective area. The aerogel samples were made with a new technique to obtain a higher transmission length at a high refractive index ( n=1.05). Multi-channel PMTs are read-out with analog memory chips. The detector was tested at the KEK-PS π2 beam line in November, 2002. To evaluate systematically the performance of the detector, tests were carried out with various aerogel samples using pion beams with momenta between 0.5 and 4 GeV/c . The typical angular resolution was around 14 mrad , and the average number of detected photoelectrons was around 6. We expect that pions and kaons can be separated at a 4 σ level at 4 GeV/c .

Tests of a proximity focusing RICH with aerogel as radiator

Using aerogel as radiator and multianode PMTs for photon detection, a proximity focusing Cherenkov ring imaging detector has been constructed and tested in the KEK $\pi$2 beam. The aim is to experimentally study the basic parameters such as resolution of the single photon Cherenkov angle and number of detected photons per ring. The resolution obtained is well approximated by estimates of contributions from pixel size and emission point uncertainty. The number of detected photons per Cherenkov ring is in good agreement with estimates based on aerogel and detector characteristics. The values obtained turn out to be rather low, mainly due to Rayleigh scattering and to the relatively large dead space between the photocathodes. A light collection system or a higher fraction of the photomultiplier active area, together with better quality aerogels are expected to improve the situation. The reduction of Cherenkov yield, for charged particle impact in the vicinity of the aerogel tile side wall, has also been measured.

Lens-based collection system for a proximity focusing RICH

The performance of a proximity focusing RICH with aerogel as radiator and PMTs for detection of Cherenkov rings has been studied. The rather large insensitive area in the photon detector plane could be reduced by various optical systems. The present work describes measurements carried out with two such systems: a system of lenses and a system of light guides. The results are in favour of the lens system, which has been tested also with Cherenkov photons.

Tests of a proximity focusing RICH with aerogel as radiator

Using aerogel as radiator and multi-anodephotomultiplier tubes (PMTs) for photon detection, a proximity focusing Cherenkov ring imaging detector has been constructed and tested with beams containing pions, muons, and electrons. The aim is to experimentally study the basic parameters such as resolution of the single photon Cherenkov angle and number of detected photons per ring. The resolution obtained is well approximated by estimates of contributions from pixel size and emission point uncertainty. The number of detected photons per Cherenkov ring is in good agreement with estimates based on aerogel and detector characteristics. The values obtained turn out to be rather low, mainly due to Rayleigh scattering and to the relatively large dead space between the photocathodes. A light collection system or a higher fraction of the photomultiplier active area, together with better quality aerogels are expected to improve the situation. The reduction of Cherenkov yield, for charged particle impact in the vicinity of the aerogel tile side wall, has also been measured.

The CSI-based RICH detector array for the identification of high momentum particles in ALICE

Abstract After ten years of R&D activities, an array of seven proximity focusing RICH modules is being built to identify π - K in the range 1 p c and K-p in the range 1.5 p 2 , represents the largest scale application of MWPCs with high Quantum Efficiency (QE) CsI segmented photo-cathodes for the Cherenkov photon conversion. An overview of the RICH layout, the technique of photocathode production, the front-end (FE) and readout (R/O) electronics and finally the detector control system (DCS), are presented.

A proximity focusing RICH detector for kaon physics at Jefferson lab hall A

Important information on the LN interaction can be obtained from High Resolution Hypenuclear Spectroscopy experiments with electromagnetic probes. A challenging experiment on electroproduction of hypernuclei is scheduled for 2003 in Hall A at Jefferson Lab. One of the challenges is the high performance particle identification system needed. The signal is expected to be rare compared to the very high pion and proton backgrounds due to the small electron and kaon detection angles. The ‘‘standard’’ Hall A PID apparatus (TOF and two aerogel threshold Cherenkov detectors) does not provide sufficient suppression of the background. Simulations and calculations have shown that a RICH detector would solve the problem. A proximity focusing fluorocarbon/CsI detector similar to the ALICE RICH detector has been designed, built, tested and commissioned. The results show that the detector performs as expected. r 2003 Published by Elsevier Science B.V. PACS: 29.40.Ka; 85.60.Gz

The CLEO III upgrade

The electron storage ring CESR at Cornell University is presently undergoing a major upgrade together with its B-physics detector CLEO. Improved focusing and superconducting cavities will increase the luminosity of the collider to more than 2×10 33 cm 2 s −1 . To accommodate the necessary accelerator elements the tracking region of CLEO has to be rebuilt. The new tracking system consists of a four-layer silicon vertex detector and a large volume drift chamber, which also provides d E/d x particle identification information. The CLEO III upgrade also includes a new particle identification system which allows full exploitation of the possibilities provided by the upgraded accelerator. This PID system is a proximity focusing RICH with lithium fluoride radiators and multi-wire chambers filled with a methane/triethylamine mixture to detect UV Cherenkov photons. Installation of the new detector elements in the CLEO detector is taking place during summer 1999.

Prototype study of a Proximity Focusing RICH for the AMS experiment

A study prototype of a Proximity Focusing Ring Imaging Cherenkov detector (PFRICH) has been developed and built at the ISN Grenoble. The detector has been tested with cosmic-ray particles, 12C beams and fragmentation ions at different energies at GSI-Darmstadt.