The Ring Imaging Cherenkov Detectors for LHCb

The success of the LHCb experiment depends heavily on particle identification over the momentum 2-100 GeV/c. To meet this challenge, LHCb uses a Ring Imaging Cherenkov (RICH) system composed of two detectors with three radiators. RICH1 has both aerogel and gas (C$_4$F$_{10}$) radiators, while RICH2 has only a gas (CF$_4$) radiator. The design of RICH1 is almost complete, whereas RICH2 has been constructed and installed (Nov 2005). Novel Hybrid Photon Detectors (HPDs) have been developed in collaboration with industry to detect the Cherenkov photons. A silicon pixel detector bump-bonded to a readout chip is encapsulated in a vacuum tube. A bi-alkali photocathode is deposited on the inside of the quartz entrance window to convert photons in the range 200-600 nm. The pixel chip is manufactured in 0.25 $\mu$m deep-submicron radiation-tolerant technology and consists of 1024 logical pixels, each pixel having an area of 0.5 mm x 05. Mm. Photo-electrons are accelerated by a 20kV potential, resulting in a signal of typically 5000 electrons that is amplified and digitized at the LHC speed of 40 MHz. The HPDs are enclosed in iron shielding and Mumetal cylinders surround the individual detectors to protect them from magnetic fields within the external shielding of up to 50 mT. The mass production of a total of 484 HPDs required for the two RICH detectors has already commenced. The design and current status of the LHCb RICH system will be reviewed. Results obtained using prototype HPDs to detect Cherenkov light in particle test beams using the full LHCb readout chain will be presented. Finally, the expected performance of the LHCb RICH system, obtained from realistic simulation, will be shown

LHCb Upgraded RICH 1 Engineering Design Review Report

During the Long Shutdown 2 of the LHC, the LHCb collaboration will replace the upstream Ring Imaging Cherenkov detector (RICH 1). The magnetic shield of the current RICH 1 will be modified, new spherical and plane mirrors will be installed and a new gas enclosure will be manufactured. New photon detectors (multianode photomultiplier tubes) will be used and these, together with their readout electronics, require a new mechanical support system. This document describes the new optical arrangement of RICH 1, its engineering design, installation and alignment. A summary of the project schedule and institute responsibilities is provided

LHCb Upgraded RICH 1 Engineering Design Review Report

During the Long Shutdown 2 of the LHC, the LHCb collaboration will replace the upstream Ring Imaging Cherenkov detector (RICH 1). The magnetic shield of the current RICH 1 will be modified, new spherical and plane mirrors will be installed and a new gas enclosure will be manufactured. New photon detectors (multianode photomultiplier tubes) will be used and these, together with their readout electronics, require a new mechanical support system. This document describes the new optical arrangement of RICH 1, its engineering design, installation and alignment. A summary of the project schedule and institute responsibilities is provided

The calibration and alignment of the LHCb RICH system

Hadron identification in the LHCb experiment is performed by two Ring Imaging Cherenkov (RICH) detectors, comprising three radiators and 484 Hybrid Photon Detectors (HPDs). A well calibrated and aligned RICH system is essential for providing the particle identification performance necessary for realising the physics goals. The total number of mirrors in the two RICH detectors is 116 and they must be aligned to an accuracy of 0.1 mrad in order not to degrade the performance of the system. The refractive indices $n$ of the two gas radiators, namely C$_4$F$_{10}$ and CF$_4$, are expected to change with atmospheric pressure, and the refractivity ($n$ - 1) will be monitored to an accuracy of 0.1% from physics data. The Cherenkov angle resolutions and photon yields will be calibrated using saturated Cherenkov rings and particles of known type. Both RICH detectors operate in the fringe field of the LHCb dipole magnet, which produces image distortions of the HPDs. Solutions to correct for these distortions are in the implementation phase. Finally, the overall performance of the RICH system for hadron identification will be evaluated using samples of pions and kaons identified from D$^*$ decays, which can be isolated with high purity independently of the RICH itself

Simulation of LHCb RICH detectors using GEANT4

LHCb is one of the experiments at the Large Hadron Collider at CERN. It aims to make precision measurements of CP violation in the B-meson decays. The detector simulation of LHCb was developed using the GEANT4 software toolkit interfaced to the LHCb software framework named GAUDI. This is now being used for a large production run of 210 million events. An important feature of the LHCb experiment is the use of ring imaging Cherenkov counters (RICH) for particle identification. The Cherenkov photons created in this detector are focused onto an array of photodetectors made of Hybrid Photodiodes. A brief overview of the GEANT4 based LHCb simulation program named GAUSS will be given with the main emphasis on RICH simulation and its verification

Proposal for a CERN Virtual Visit Service

This note proposes the development of a CERN-wide Virtual Visit Service. Such a service would build upon the experience of the LHC Experiments, CERN DG EDU and DG COM, and the expertise of CERN IT CIS, to develop a world-leading communication and educational programme designed to serve the entire community in an effective and economical manner. Administration and Operation of the service would be modelled on the highly successful CERN Visits and Collaboration Services, and would extend the reach of Education, Outreach, and Communication to audiences around the globe, many of who might not have the opportunity to visit the laboratory in person