DIRC, the internally reflecting ring imaging Cerenkov detector for BABAR: Properties of the quartz radiators
- Stanford Linear Accelerator Center, Menlo Park, CA (United States)
A new type of detector for particle identification will be used in the BABAR experiment at the SLAC B Factory (PEP-II). This barrel region detector is called DIRC, an acronym for Detection of Internally Reflected Cerenkov (light). The DIRC is a Cerenkov ring imaging device which utilizes totally internally reflecting Cerenkov photons in the visible and near UV range. An extensive prototype program, demonstrated that the principles of operation are well understood, and that an excellent performance over the entire momentum range of the B factory is to be expected. The DIRC utilizes long, thin, flat quartz radiator bars (effective mean refractive index n{sub 1} = 1.474) with a rectangular cross section. In the present design the bars have transverse dimensions of 1.7 cm thick by 3.5 cm wide, and are about 4.90 m long. The length is achieved by gluing end-to-end four 1.225 m bars, that size being the longest high quality quartz bar currently available from industry. Several natural and synthetic fused silica candidate materials were tested for their optical properties and radiation hardness. In a Co{sup 60} source, samples were exposed to doses of up to 500 krad. While natural quartz materials showed significant absorption in the wavelength range of the Cerenkov photons after being exposed to only a few krad, the synthetic material proved to be sufficiently radiation hard. This led to the choice of Suprasil Standard and Spectrosil 2000 as bar material for the DIRC.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00515
- OSTI ID:
- 527518
- Report Number(s):
- SLAC-PUB-7602; CONF-9705154-1; ON: DE97008421; TRN: 97:016651
- Resource Relation:
- Conference: 7. ICFA school on instrumentation in elementary particle physics, Guanajuato (Mexico), 12-16 May 1997; Other Information: PBD: Jul 1997
- Country of Publication:
- United States
- Language:
- English
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