Ring Imaging Cherenkov Research Articles

Readout electronics for a Hybrid Avalanche Photon Detector

This article presents the development of readout electronics for a Hybrid Avalanche Photon Detector (HAPD), the baseline photon sensor for the Belle II Ring Imaging Cherenkov Detector (RICH). The HAPD sensor with the readout electronics enable will enable position sensitive detection of single photons. An overview of the RICH readout system is given.

First observation of Cherenkov rings with a large area CsI-TGEM-based RICH prototype

We have built a RICH detector prototype consisting of a liquid C6F14 radiator and six triple Thick Gaseous Electron Multipliers (TGEMs), each of them having an active area of 10×10cm2. One triple TGEM has been placed behind the liquid radiator in order to detect the beam particles, whereas the other five have been positioned around the central one at a distance to collect the Cherenkov photons. The upstream electrode of each of the TGEM stacks has been coated with a 0.4μm thick CsI layer.In this paper, we will present the results from a series of laboratory tests performed with this prototype carried out using UV light, 6keV photons from 55Fe and electrons from 90Sr as well as recent results of tests with a beam of charged pions where for the first time Cherenkov Ring images have been successfully recorded with TGEM photodetectors. The achieved results prove the feasibility of building Cherenkov detector based on CsI coated TGEMs.

Simulation and reconstruction of the PANDA Barrel DIRC detector**Work supported by EU FP6 grant, contract number 515873, DIRAC secondary-beams and EU FP7 grant, contract number 227431, HadronPhysics2, HGS-Hire and HIC for FAIR.

The PANDA experiment at the future Facility for Antiproton and Ion Research (FAIR) at GSI, Darmstadt, aims at studying the strong interacting matter by precision spectroscopy. A detector system with excellent particle identification over a large range of solid angle and momentum is therefore mandatory. Charged hadron identification in the barrel region will be performed by a compact ring imaging Cherenkov detector based on the DIRC principle (Detection of Internally Reflected Cherenkov light), designed to separate pions from kaons with at least 3 standard deviations in the momentum range from 0.5 GeV/c to 3.5 GeV/c. We present details of the simulation of the PANDA Barrel DIRC and a study of the detector performance using a fast reconstruction algorithm to determine the single photon Cherenkov angle resolution and photon yield for several design options.

Georges Charpak

Georges Charpak

VHMPID detector for the ALICE experiment upgrade at LHC

Results from high energy nucleus-nucleus collisions at RHIC have shown the importance of particle identification in a very large momentum range, in particular for protons. The ALICE experiment has unique capabilities to identify particles; however its momentum coverage for track-by-track identification should be extended to meet new physics challenges at LHC. The Very High Momentum Charged Particle Identification (VHMPID) detector represents a possible upgrade of the ALICE experimental apparatus. It has been conceived to extend proton identification on a track-by-track basis up to p = 30 GeV/c . The VHMPID is a Ring Imaging Cherenkov with C4F10 gaseous radiator coupled to a CsI based photon detector. The focusing properties of a spherical mirror are exploited to focus Cherenkov photons on the photon detector. The detector layout and the expected performance will be discussed. First results from beam tests of a prototype of 60 × 40 cm 2 will be also presented.

First Results of the Ring Imaging Cherenkov Detectors of the LHCb Experiment

The LHCb experiment has commenced taking data from proton-proton interactions at the LHC with centre-of-mass energies of up to s = 7 TeV . Results are presented for the Ring Imaging Cherenkov Detectors during commissioning and with LHC beams, in particular on the performance of the photon detectors.

Analysis and correction of the magnetic field effects in the Hybrid Photo-Detectors of the RICH2 Ring Imaging Cherenkov detector of LHCb.

The Ring Imaging Cherenkov detectors of the LHCb experiment at the Large HadronCollider at CERN are equipped with Hybrid Photo-Detectors. These vacuumphoto-detectors are affected by the stray magnetic field of the LHCb magnet,which degrades their imagingproperties. This effect increasesthe error on the Cherenkov angle measurement and would reduce the particle identification capabilities of LHCb.A system has been developed for the RICH2 RingImaging Cherenkov detector to perform a detailed characterisation of the magneticdistortion effects. It is described, along with the methods implemented to correct for these effects,restoring the optimal resolution.

Single spin asymmetries for identified hadrons at COMPASS

COMPASS is a fixed target experiment at CERN SPS, dedicated to the study of the nucleon spin structure and hadron spectroscopy. The transverse spin structure of the nucleon is investigated by measuring semi-inclusive deep inelastic scattering (SIDIS) of a 160 GeV/c longitudinally polarized muon beam off transversely polarised targets. Particle Identification (PID) is performed with a Ring Imaging CHerenkov detector (RICH) that has been upgraded in 2005. COMPASS took data using transversely polarised 6LiD target from 2002 to 2004 and with a transversely polarised NH3 target in 2007.In this talk the Collins and Sivers asymmetries on polarised proton for charged pions and kaons will be shown for the first time and compared with the same results on polarised deuteron for COMPASS.

Readout electronics for an HAPD detector

We describe the design, construction and performance of electronics for the readout of a hybrid avalanche photodiode (HAPD). The HAPDs are being studied as possible candidates for the detection of Cherenkov rings in a proximity focusing ring imaging Cherenkov (RICH) detector, which is foreseen for the upgrade of the Belle spectrometer at the KEKB collider.

The DIRC-Like FTOF: A Time-of-Flight Cherenkov Detector for Particle Identification at SUPERB;PACS numbers: 29.40.Ka, 29.85.Ca, 29.85.Fj

The DIRC-like FTOF detector is a ring imaging Cherenkov counter which uses Time-of-Flight to identify charged particles. A prototype of such device was constructed and installed in the SLAC Cosmic Ray Telescope for timing measurement. A time resolution of about 90 ps/channel was obtained, in agreement with simulation. To estimate the different contributions to the single channel time resolution, a precise simulation of the whole system (detector + MCP-PMT) was written. For this experiment we use the new 10 ps 16-channel USB wave catcher electronics developed by LAL (CNRS/IN2P3) and CEA/IRFU. In this paper, preliminary results of the test ongoing at SLAC are presented. This work is done in collaboration with N. Arnaud, D. Breton, J. Maalmi, V. Puill, A. Stocchi from LAL and D. Aston, J. Va'vra from SLAC. (author)

Very high momentum particle identification at the LHC

The anomalies observed at RHIC for the baryon — meson ratios have prompted a number of theoretical works on the nature of the hadrochemistry in the hadronisation stage of the pp collisions and in the evolution of the dense system formed in heavy ion collisions. Although the predictions differ in the theoretical approach, generally a substantial increase in the baryon production is predicted in the range 10–30 GeV/c. We will present the possibilities of a gas ring imaging Cherenkov detector of limited acceptance which would be able to identify track-by-track protons until 24 GeV/c for the ALICE experiment.

Operating the Hybrid Photon Detectors in the LHCb RICH counters

Results are presented on the commissioning and operation of Hybrid Photon Detectors used in the Ring Imaging Cherenkov detectors of LHCb. Cherenkov photons from proton–proton interactions at a centre-of-mass energy of 7 TeV have been recorded. An explanation is given of the steps that have been taken to achieve these results.

Status and perspectives of solid state photon detectors

Recent years have seen a considerable progress in the development of solid state photon detectors. In particular it is the Geiger mode avalanche photodiode, also known as the silicon photomultiplier (SiPM), which is much investigated for its single photon sensitivity as well as its other appealing properties. In the present paper we discuss the recent advances of such photon detectors as well as possibilities for their application, mainly in ring imaging Cherenkov detectors.

A RICH detector for hadron identification at JLab

The "standard" Hall A apparatus at Jefferson Lab (TOF and aerogel threshold Cherenkov detectors) does not provide complete identification for proton, kaon and pion. To this aim, a proximity focusing C(6)F(14)/CsI RICH (Ring Image CHerenkov) detector has been designed, built, tested and operated to separate kaons from pions with a pion contamination of a few percent up to 2.4GeV/c. Two quite different experimental investigations have benefitted of the RICH identification: on one side, the high-resolution hypernuclear spectroscopy series of experiments on carbon, beryllium and oxygen, devoted to the study of the lambda-nucleon potential. On the other side, the measurements of the single spin asymmetries of pion and kaon on a transversely polarized (3)He target are of utmost interest in understanding QCD dynamics in the nucleon. We present the technical features of such a RICH detector and comment on the presently achieved performance in hadron identification.

Particle identification for the [formula omitted] detector

Cooled antiproton beams of unprecedented intensities in the momentum range of 1.5–15 GeV/ c will be used for the P ¯ ANDA experiment at FAIR to perform high precision experiments in the charmed quark sector. The proposed P ¯ ANDA detector is a 4 π internal target spectrometer at the HESR allowing the detection and identification of neutral and charged particles generated within the total energy range of the antiproton annihilation products. The detector is divided in a forward spectrometer and a target spectrometer. The charged particle identification in the latter is performed by ring imaging Cherenkov counters employing the DIRC principle.

Magnetic distortion calibration for LHCb RICH detectors

The LHCb experiment will search for new physics in CP violation and rare decays from heavy flavour production at the LHC. Particle identification is provided by two Ring Imaging Cherenkov (RICH) detectors, which incorporate a total of 484 Hybrid Photon Detectors (HPDs). The RICH detectors are located in the fringe field of the LHCb dipole magnet and fields as large as 2.5 mT have been measured in some regions occupied by the RICH 1 photodetectors. It is necessary to make corrections for the distortion of the ring-images measured by the HPDs. RICH 1 incorporates a magnetic calibration system comprising a series of collimated LEDs mounted on x– y stages which scan over the front-faces of the HPD arrays. A similar system based on commercial projectors is used on RICH 2. The calibration is performed in dedicated runs with dipole field on and off. The calibration parameters are then stored in the Conditions Database and applied to the LHC collision data reconstruction. This report will present the improvement in Cherenkov angular resolutions with the magnetic calibration.

The ALICE-HMPID Detector Control System: Its evolution towards an expert and adaptive system

The High Momentum Particle IDentification (HMPID) detector is a proximity focusing Ring Imaging Cherenkov (RICH) for charged hadron identification. The HMPID is based on liquid C 6F 14 as the radiator medium and on a 10 m 2 CsI coated, pad segmented photocathode of MWPCs for UV Cherenkov photon detection. To ensure full remote control, the HMPID is equipped with a detector control system (DCS) responding to industrial standards for robustness and reliability. It has been implemented using PVSS as Slow Control And Data Acquisition (SCADA) environment, Programmable Logic Controller as control devices and Finite State Machines for modular and automatic command execution. In the perspective of reducing human presence at the experiment site, this paper focuses on DCS evolution towards an expert and adaptive control system, providing, respectively, automatic error recovery and stable detector performance. HAL9000, the first prototype of the HMPID expert system, is then presented. Finally an analysis of the possible application of the adaptive features is provided.

Prototype tests for a DIRC detector for the WASA-at-COSY experiment

The WASA-at-COSY experiment allows the study of production and decay of η and η ′ mesons in proton–proton reactions. At the moment the Forward Range Hodoscope (FRH) in the forward angle spectrometer region determines the identity of the particles by measuring the energy loss Δ E − E . Simulations concerning the estimated background have shown that an additional ring imaging Cherenkov detector in front of the FRH would significantly improve the particle identification and the energy resolution as well. Due to the very limited space available at the intended detector position, the development of a DIRC (Detection of Internally Reflected Cherenkov light) detection system based on Plexiglas (PMMA) radiators is under discussion. In order to show the feasibility, two different prototypes, consisting of a square PMMA radiator bar and a PMMA focusing element were tested using the COSY proton beam. One focusing element is based on an internal reflecting polynomial shape surface, the other is based on a mirrored circular shape surface. The photon readout in the focal plane is done by Hamamatsu H8500C 64 channel multianode photomultipliertubes (MAPMT). In addition, new MAPMTs with higher quantum efficiency were studied in order to increase the number of detected photons.

VHMPID detector for the ALICE upgrade at the LHC: Simulation results on mirror segmentation

The Very High Momentum Charged Particle Identification (VHMPID) detector represents a possible upgrade for the ALICE experimental apparatus. It has been conceived to extend protons identification on a track-by-track basis up to p=30 GeV/ c. The VHMPID is a ring imaging Cherenkov with C 4F 10 gaseous radiator coupled to CsI-based photon detector. The focusing properties of a spherical mirror are exploited to focus Cherenkov photons on the photon detector. Mirror segmentation is a critical parameter for the ring pattern recognition performance and for the capability to identify tracks close in phase space. This feature is crucial for the contribution of VHMPID to the ALICE jets physics program. We will present the results of simulation studies that have been carried out in order to optimize the mirror segmentation.

The barrel DIRC detector for the P¯ ANDA experiment at FAIR

The P ¯ ANDA experiment at FAIR will perform high precision experiments in the charmed quark sector using cooled antiproton beams of unprecedented intensities of L=2×10 32 cm −2 s −1 in the momentum range of 1–15 GeV/ c. The charged particle identification in the barrel region needs a thin detector operating in a strong magnetic field. A ring imaging Cherenkov detector using the DIRC principle is an excellent match to those requirements. This article describes aspects of the design and R&D for the P ¯ ANDA barrel DIRC detector. The availability of highly pixelated fast photon detectors allows several key improvements compared to the successful BaBar-DIRC detector, some of which were tested in a proton beam at GSI. The optical properties of the radiator bars, made from synthetic fused silica, are critical to the success of the DIRC. Measurements of the attenuation length and reflection coefficient allow the determination of the surface roughness of prototype radiator bars.