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تسجيل مستخدم جديدOptical Properties of the DIRC Fused Silica Cherenkov Radiator
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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 DIRCs 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.
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This paper reports the successful fabrication of silica aerogel Cherenkov radiators produced in the first batches from a 96-tile mass production performed using pin-drying technique in our laboratory. The aerogels are to be used in a ring-imaging Che
renkov detector in the spectrometer of a planned balloon-borne cosmic-ray observation program, HELIX (High Energy Light Isotope eXperiment). A total of 36 transparent, hydrophobic aerogel tiles with a high refractive index of 1.16 and dimensions of 10 cm $times $ 10 cm $times $ 1 cm will be chosen as the flight radiators. Thus far, 40 out of the 48 tiles fabricated were confirmed as having no tile cracking. In the first screening, 8 out of the first 16 tiles were accepted as flight-qualified candidates, based on basic optical measurement results. To fit the aerogel tiles into a radiator support structure, the trimming of previously manufactured prototype tiles using a water-jet cutting device was successful.
We have evaluated the performance of a Ce-doped fused-silica fiber as wavelength shifter coupled to a CeF$_{3}$ crystal using electron beams at CERN. The pulse shape and collection efficiency were measured using irradiated (100 kGy) and un-irradiated
fibers. In addition, we evaluated the light yield of various Ce-doped fibers and explored the possibility of using them in the future, including for precision timing applications in a high-luminosity collider environment.
We report on the effects of an electrical charge on mechanical loss of a fused silica disk. A degradation of Q was seen that correlated with charge on the surface of the sample. We examine a number of models for charge damping, including eddy current
damping and loss due to polarization. We conclude that rubbing friction between the sample and a piece of dust attracted by the charged sample is the most likely explanation for the observed loss.
Using aerogel as radiator and multianode PMTs for photon detection, a proximity focusing Cherenkov ring imaging detector has been constructed and tested in the KEK $pi$2 beam. The aim is to experimentally study the basic parameters such as resolution
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Current interferometric gravitational wave detectors (IGWDs) are operated at room temperature with test masses made from fused silica. Fused silica shows very low absorption at the laser wavelength of 1064 nm. It is also well suited to realize low th
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