Ring Imaging Cherenkov Research Articles

Modern trends in methods of charged particle identification at high energies

The survey is devoted to methods of charged particle identification at high energies that are based on measurements of the angle of Cherenkov radiation (ring imaging Cherenkov counters — RICH), of time of flight (TOF) and propagation (TOP), and of ionization energy loss (dE/dx). As an example, some operating spectrometers are considered (LHCb, ALICE, COMPASS, Belle, and BaBar) together with proposed ones (Belle-2 and PANDA) in which new achievements of recent years are introduced.

Electron reconstruction and identification capabilities of the CBM Experiment at FAIR

The Compressed Baryonic Matter (CBM) experiment at the future FAIR facility at Darmstadt will measure dileptons emitted from the hot and dense phase in heavy-ion collisions. In case of an electron measurement, a high purity of identified electrons is required in order to suppress the background. Electron identification in CBM will be performed by a Ring Imaging Cherenkov (RICH) detector and Transition Radiation Detectors (TRD). In this contribution, algorithms which were developed for the electron reconstruction and identification in RICH and TRD detectors are presented. A fast RICH ring recognition algorithm based on the Hough Transform method was implemented. An ellipse fitting algorithm was implemented since most of the RICH rings have elliptic shapes. An efficient algorithm based on the Artificial Neural Network is implemented for electron identification in RICH. In TRD track reconstruction algorithm which is based on track following and Kalman Filter methods was implemented. Several algorithms for electron identification in TRD were developed and investigated. The best-performed algorithm is based on the special transformation of energy losses measured in TRD and usage of the Boosted Decision Tree (BDT) method as classifier. Results and comparison of different methods of electron identification and pion suppression are presented.

A particle identification detector for the forward region of the SuperB experiment

The DIRC-like time-of-flight detector (FTOF) is a ring imaging Cherenkov counter designed to improve the charged particle identification on the forward side of SuperB. Here we review the main characteristics of this device, summarize the results of a prototype test done last year in the SLAC Cosmic Ray Telescope and present the future steps needed to build the FTOF.

Research and development of a Mini-RICH detector with a gas radiator as a first step towards a CBM-RICH prototype

The Compressed Baryonic Matter (CBM) Experiment is planned to be installed at a future accelerator facility, SIS 100/300 of FAIR (Facility for Antiproton and Ion Research), GSI (Gesellschaft fur SchwerIonenforschung) to study nuclear matter under extreme conditions with a high baryon density. A Ring Imaging Cherenkov (RICH) detector is now being developed for electron identification at pe < 8 GeV/c, well separated from pions. In order to optimize the physics performance of the CBM-RICH detector and to investigate different gas radiators, we developed a mini-RICH detector with a gas system as a first prototype and tested it with the pe ≃ 60 MeV/c electron beam at the Pohang Accelerator Laboratory (PAL).

Optical and Radiographical Characterization of Silica Aerogel for Cherenkov Radiator

We present optical and X-ray radiographical characterization of silica aerogels with refractive index from 1.05 to 1.07 for a Cherenkov radiator. A novel pin-drying method enables us to produce highly transparent hydrophobic aerogels with high refractive index by shrinking wet-gels. In order to investigate the uniformity in the density (i.e., refractive index) of an individual aerogel monolith, we use the laser Fraunhofer method, an X-ray absorption technique, and Cherenkov imaging by a ring-imaging Cherenkov detector in a beam test. We observed an increase in density at the edge of the aerogel tiles, produced by pin-drying.

X-ray radiographic technique for measuring density uniformity of silica aerogel

This paper proposes a new X-ray radiographic technique for measuring density uniformity of silica aerogels used as radiator in proximity-focusing ring-imaging Cherenkov detectors. To obtain high performance in a large-area detector, a key characteristic of radiator is the density (i.e. refractive index) uniformity of an individual aerogel monolith. At a refractive index of n=1.05, our requirement for the refractive index uniformity in the transverse plane direction of an aerogel tile is |δ(n−1)/(n−1)|<4% in a focusing dual layer radiator (with different refractive indices) scheme. We applied the radiographic technique to evaluate the density uniformity of our original aerogels from a trial production and that of Panasonic products (SP-50) as a reference, and to confirm they have sufficient density uniformity within ±1% along the transverse plane direction. The measurement results show that the proposed technique can quantitatively estimate the density uniformity of aerogels.

Development of a detector control system for a CBM-RICH prototype

For monitoring and controlling a complicated detector system in large-scale experiments, the CBM (compressed baryonic matter) experiment is now designing a detector control system using the EPICS (experimental physics and industrial control system). We successfully developed a mirror positioning control system with the TwinCAT program (the window control automation technology) and a HV (high-voltage) control system with SNMP (simple network management protocol) and integrated them into an all-in-one online DCS (detector control system) by using EPICS for the CBM RICH (ring imaging Cherenkov) detector prototype experiment at PS T9 in October 2011.

Test of the DIRC-like TOF prototype for the SuperB experiment

The DIRC-like TOFdetector is a ring imaging Cherenkov counter, designed for the SuperB experiment, which uses time-of-flight to identify charged particles. A prototype of this device was constructed and installed in the SLAC Cosmic Ray Telescope for timing measurement. A time resolution of about 70ps per photoelectron was obtained, in agreement with simulation. For this experiment we use the new 10ps 16-channel USB-WaveCatcher electronics developed by LAL (CNRS/IN2P3) and CEA/IRFU.

The Barrel DIRC of PANDA

Cooled antiproton beams of unprecedented intensities in the momentum range of 1.5-15 GeV/c will be used forthe PANDA experiment at FAIR to perform high precision experiments in the charmed quark sector. The PANDA detector will investigate antiprotonannihilations with beams in themomentum range of 1.5 GeV/c to 15 GeV/c on a fixed target.An almost 4π acceptance double spectrometer is divided in a forward spectrometer and a target spectrometer. The charged particle identification in the latter isperformed by ring imaging Cherenkov counters employing the DIRC principle.

Performance of the RICH Detectors of LHCb

Hadron identification, in particular the ability to distinguish charged kaons and pions, is crucial to many of LHCb core physics analyses. LHCb Ring Imaging CHerenkov (RICH) detector fulfils this role by providing charged particle identificationin the momentum range between1and 100 GeV/c. The calibration and monitoring of the RICH detectors is achieved using samples of D∗, KS0, Λ and φ events, which are plentiful in the data and can be cleanly isolated through their decay kinematics. The particle identification performance of the LHCb RICH detectors, measured in data taken during the 2010 and 2011 LHC runs, will be presented along with the strategy for aligning and calibrating the detector. Finally this performance will be placed in context by highlighting the impact of the RICH performance on some of LHCb benchmark analyses.

The Ring Imaging CHerenkov Detectors of the LHCb Experiment

Particle identification is a fundamental requirement of the LHCb experiment to fulfill its physics programme. Positive hadron identification is performed by two Ring Imaging CHerenkov (RICH) detectors. This system covers the full angular acceptance of the experiment and is equipped with three Cherenkov radiators to identify particles in a wide momentum range from1 GeV/ c up to 100 GeV/ c . The Hybrid Photon Detectors (HPDs) located outside the detector acceptance provide the photon detection with 500,000 channels. Specific read–out electronics has been developed to readout and process data from the HPDs including data transmission and power distribution. The operation and performanceoftheRICHsystemare ensuredbythe constant controland monitoringoflowandhighvoltage systems,of thegas qualityandenvironmental parameters,ofthe mirror alignment,and finallyofthe detector safety. The description of the LHCb RICH is given. The experience in operating the detector at the Large Hadron Collider is presented and discussed.

Development of Ring Imaging Cherenkov counter for Belle II experiment at super KEKB

For the Belle II experiment at the superKEKB, we have been developing a proximity focusing ring imaging Cherenkov detector using a silica aerogel as a radiator. A 144-channel Hybrid Avalanche Photo-Detector which is developed with Hamamatsu Photonics K.K. was adopted as the photon detector for the Aerogel RICH counter. We have conducted beam tests in order to evaluate the particle identification performance for the A-RICH system. One of our current concern for the system is a radiation hardness of the HAPD. In order to realize the neutron hardness for 10-year Belle II operation, we have tried to make APDs with a thinner P-layer which is expected to help in reducing the leakage current. As a result, we actually confirmed effects of the improved APD. In this paper, we would alike to report the status of the A-RICH development, especially about the improvement of the HAPD.

A RICH Detector for CLAS12 Spectrometer

Abstract The upgrade of the Jefferson Lab accelerator to 12 GeV electron beam energy, combined with that of the CEBAF Large Acceptance Spectrometer (CLAS12) located in Hall B, will provide the unique combination of wide kinematical coverage, high beam intensity (luminosity), high energy, high polarization, and advanced detection capabilities required to study Quantum Chromodynamics (QCD) in greater details. A Ring Imaging Cherenkov (RICH) will significantly enhance CLAS12 particle identification capabilities by providing clean separation between pions, kaons and protons over momenta from 2 to 8 GeV/c. A detailed simulation of a preliminary design of the RICH detector for CLAS12 using GEANT-4 Monte-Carlo will be presented. A reconstruction algorithm based on a likelihood approach will be discussed.

Verification of Focusing System for Time-of-Propagation Counter

Abstract The results of verifying focusing system for Time Of Propagation (TOP) counter is presented. The TOP counter have been developed as a new detector for particle identification at Belle-II experiment, which is a Ring Imaging Cherenkov counter with precise timing information. Performance of the TOP counter is directly depended on the time resolution for single photon detection. Propagated Cherenkov photons have group velocity related to wavelength. It generates fluctuation of propagation time approximately 53 ps/m. Chromatic dispersion provides serious deterioration of time resolution. Against this problem, the focusing mirror is planed to introduce. It focuses Cherenkov light to different channels of MCP-PMT by different wavelength, and so that the deterioration of time resolution is suppressed. We verified focusing mechanism using 120 GeV/ c π beam at CERN. Using a prototype TOP counter with the focusing mirror, we could confirm a work of focusing mechanism. The time resolution improved from 147 ps to 95 ps by using focusing mirror.

Readout ASICs and Electronics for the 144-channel HAPDs for the Aerogel RICH at Belle II

Abstract The particle identification (PID) device in the endcap of the Belle detector will be upgraded to a ring imaging Cherenkov counter (RICH) using aerogel as a radiator at the Belle II experiment. We develop the electronics to read out the 70,000 channels of hit information from the 144-channel hybrid avalanche photodetectors (HAPD), of the aerogel RICH detector. A readout ASIC is developed to digitize the HAPD signals, and was used in a beam test with the prototype detector. The performance and plan of the ASIC is reported in this study. We have also designed the readout electronics for the aerogel RICH, which consist of front-end boards with the ASICs merger boards to collect data from the front-end boards. A front-end board that fits in the actual available space for the aerogel RICH electronics was produced.

Research and development of a CBM-RICH prototype

We have developed a gaseous Ring Imaging CHerenkov detector prototype (PNU-RICH2) of the CBM-RICH detector. This prototype has the same radiator length as the planned CBM-RICH detector. The PNU-RICH2 includes a spherical concave mirror and 2 types of Multi-anode PMTs. The PNU-RICH2 detector has tested at the PAL-TEST LINAC with 60MeV electron beam. A detector performance from the beam test will be presented and discussed in comparison with simulation results.

Photon Detection Systems for Modern Cherenkov Detectors

Abstract Modern experiments in hadronic physics require detector systems capable of identifying and reconstructing all final–state particle and their momentum vectors. The ANDA experiment at FAIR and the CLAS 12 experiment and Jefferson Laboratory both plan to use imaging Cherenkov counters for particle identification. CLAS 12 will feature a Ring Imaging CHerenkov counter (RICH), while ANDA plans to construct Cherenkov counters relying on the Detections of Internally Reflected Cherenkov light (DIRC). These detectors require high–rate, single–photon capable light detection systems with sufficient granularity and position resolution. Several candidate systems are available, ranging from multi–anode photomultiplier tubes to micro–channel plate systems to silicon photomultipliers. Each of these detection solutions has particular advantages and disadvantages. Detailed studies of the rate dependence, cross–talk, time–resolution and position resolution fro a range of commercially available photon detection solutions are presented and evaluated on their applicability to the ANDA and CLAS12 Cherenkov counters.

Development of novel designs of spark-protected micropattern gaseous detectors with resistive electrodes

In the last few years many efforts have been made by various groups to develop spark-protected micropattern gaseous detectors equipped with resistive electrodes instead of metallic ones. Great success has recently been achieved with resistive gas electron multipliers (GEMs), resistive micromesh gaseous structures and resistive Well/compteur a trou detectors. In this paper, we will focus on the development of a new family of spark-protected micropattern detectors: the 2D sensitive resistive microstrip counter and the resistive microhole and strip plate, which combines in one design a resistive GEM with a microstrip detector. These innovative detectors are manufactured on standard printed circuit boards by using a simple technology thus reducing the production cost. These novel detectors have several important advantages over other micropattern detectors and are unique for applications like the readout detectors for dual phase noble liquid time projection chambers and ring imaging Cherenkov detectors.

Development of THGEM-based Photon Detectors for COMPASS RICH-1

Abstract An R&D project is presented, aimed to develop a high performance gaseous detector of single photons, for the upgrade of the Ring Imaging Cherenkov Counter RICH-1 of the COMPASS Experiment at CERN SPS. The detector has to stably operate at high gain and high rate, to provide good time resolution and insensitivity to magnetic field, and to offer the possibility to cover very large areas at affordable cost. The proposed solution is based on the use of a novel and robust electron multiplier, the Thick GEM (THGEM), arranged in a multilayer architecture, where the first layer is coated with a photosensitive CsI film. A systematic study of the response of THGEMs with various geometrical and production parameters and in different conditions was performed, leading to the choice of a set of optimal parameters. Prototypes of THGEM-based photon detectors able to efficiently detect Cherenkov photons have been built, tested in laboratory and operated in test beam exercises with typical gain of 10 5 and time resolution better than 10 ns. The engineering aspects of building large area (600×600 mm 2 ) THGEM-based photon detectors are presently being investigated.

MCP-PMT development for Belle-II TOP counter

Abstract We have developed a multiple-anode square-shape MCP-PMT for the Belle-II Time-Of-Propagation (TOP) counter. This detector is a hybrid cherenkov ring imaging and timing detector for particle identification in the barrel region of the upgraded detector. The Belle-II experiment will operate at high event rates and needs to withstand the correspondingly high background environment. MCP-PMT's have demonstrated excellent single photon timing resolution. However, the lifetime of photocathode is a known issue. Recently, we successfully improved the lifetime of a square-shape MCP-PMT by a factor of about 10, which is adequate for estimates of the nominal Belle-II background rates in the TOP counter. We have also developed a new MCP-PMT with Hamamatsu photonics, that adopts a super bialkali photocathode. Currently a peak quantum effciency of 28% for 400 nm photons has been achieved.