DIRC, a New Type of Particle Identification System for BABAR

The DIRC, a new type of Cherenkov imaging device, has been selected as the primary particle identification system for the BABAR detector at the asymmetric B-factory, PEP-II. It is based on total internal reflection and uses long, rectangular bars made from synthetic fused silica as Cherenkov radiators and light guides. In this paper, the principles of the DIRC ring imaging Cherenkov technique are explained and results from the prototype program are presented. The studies of the optical properties and radiation hardness of the quartz radiators are described, followed by a discussion of the detector design.Comment: Invited talk given at the 5th international workshop on B-Physics at hadron machines (Beauty'97), Santa Monica, California, USA, Oct 13-17, 1997. (16pp

Construction and performance of the BABAR-DIRC

The new type of ring-imaging Cherenkov detector technology called DIRC (an acronym for Detection of Internally Reflected Cherenkov (Light)) has been used successfully for hadronic particle identification in the BABAR experiment at the B Factory (PEP-II) located at the SLAC National Accelerator Laboratory. This paper describes the R&D for and the construction of the DIRC radiator bars and the performance of the DIRC during more than eight years of B Factory operation

Optical Properties of the DIRC Fused Silica Cherenkov Radiator

The DIRC is a new type of Cherenkov detector that is successfully operating as the hadronic particle identification system for the BABAR experiment at SLAC. The fused silica bars that serve as the DIRC's Cherenkov radiators must transmit the light over long optical pathlengths with a large number of internal reflections. This imposes a number of stringent and novel requirements on the bar properties. This note summarizes a large amount of R&D that was performed both to develop specifications and production methods and to determine whether commercially produced bars could meet the requirements. One of the major outcomes of this R&D work is an understanding of methods to select radiation hard and optically uniform fused silica material. Others include measurement of the wavelength dependency of the internal reflection coefficient, and its sensitivity to surface contaminants, development of radiator support methods, and selection of good optical glue.Comment: 36 pages, submitted to Nuclear Instruments and Methods

The GlueX DIRC Project

The GlueX experiment was designed to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions at a new tagged photon beam facility in Hall D at Jefferson Laboratory. The particle identification capabilities of the GlueX experiment will be enhanced by constructing a DIRC (Detection of Internally Reflected Cherenkov light) detector, utilizing components of the decommissioned BaBar DIRC. The DIRC will allow systematic studies of kaon final states that are essential for inferring the quark flavor content of both hybrid and conventional mesons. The design for the GlueX DIRC is presented, including the new expansion volumes that are currently under development.Comment: 8 pages, 6 figure