The HERMES dual-radiator ring imaging Cherenkov detector Akopov, N; Aschenauer, E.C; Bailey, K ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2002, Letnik:
479, Številka:
2
Journal Article
Recenzirano
The construction and use of a dual radiator Ring Imaging Cherenkov (RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasises measurements of ...semi-inclusive deep-inelastic scattering. It provides particle identification for pions, kaons, and protons in the momentum range from 2 to
15
GeV
, which is essential to these studies. The instrument uses two radiators, C
4F
10, a heavy fluorocarbon gas, and a wall of silica aerogel tiles. The use of aerogel in a RICH detector has only recently become possible with the development of clear, large, homogeneous and hydrophobic aerogel. A lightweight mirror was constructed using a newly perfected technique to make resin-coated carbon-fiber surfaces of optical quality. The photon detector consists of 1934 photomultiplier tubes (PMT) for each detector half, held in a soft steel matrix to provide shielding against the residual field of the main spectrometer magnet.
The optical properties of silica aerogel tiles with a refractive index of 1.03 and dimensions
11×11×1
cm
3
, produced by the Matsushita Electric Works (Japan), have been measured in the wavelength ...range from 200 to 900 nm. The tiles are used as one of the two radiators of the ring imaging Cherenkov counter of the HERMES experiment at DESY-HERA. The transmittance of light has been measured on 200 tiles by means of a double beam spectrophotometer. The light transflectance and reflectance have been measured on one tile by means of a single-beam spectrophotometer and an integrating reflecting sphere. Typical values of the measured transmittances at a wavelength
λ=400 nm are around 0.67. The measured transflectance increases almost linearly from 0.4 to 0.96 in the interval 200–300 nm, and remains nearly constant at the value 0.95 in the complementary
λ-range. The measured reflectance, mostly confined below 400 nm, is completely interpretable as backscattering from inside the aerogel, revealing an absence of light reflection at the aerogel surfaces. The transmittance data have been fitted with the Hunt formula, whose parameters have been used to evaluate the number of unscattered and scattered Cherenkov photons produced by aerogel. For stacks of 5 tiles and quantum efficiencies of phototubes with bialkali photocathodes, rings with up to 19 photoelectrons/event can be expected for
β=1 particles.
Quality Test of Aerogel for RICH ZHANG, L.F; KANESAKA, J.; SAKEMI, Y. ...
Meeting Abstracts of the Physical Society of Japan,
1998/03/10
Journal Article
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