[en] The LED system providing for monitoring the 1024-channel scintillation hodoscope operation, is described. It allows to check not only individual detection channel, but to check the operation of all electronics. 3 refs.; 6 figs

[en] A 1024 channel scintillation hodoscope design is described. It has 2 detection planes, which are completely identical structures. The hodoscope is of octagon shape, and its cross section is 4080x4080 mm, the fiducial area is 3584x3584 mm. The width of the element is 14 mm. 4 refs.; 4 figs.; 1 tab

[en] The manufacture of textiles with a structural effect is described. The structural effect is obtained by local irradiation with an electron beam whose intensity in the place of impingement is varied by means of an electric and/or magnetic field. This field may be produced by ferromagnetic coating or by applying onto the polymer textile pieces of magnetic and non-magnetic material or conductors through which electric current flows. The irradiated textile is then brought into contact with a 20% solution of acrylamide which is grafted on the irradiated portions of the textile material thus creating the structural effect. (J.P.)

[en] The main ratings of a 1024-channel scintillation hodoscope are presented and their measurement technique is described. The number of photoelectrons produced by the photomultiplier when a remote part of a scintillator is excited amounts to 4-7, the effective speed of light along the scintillator rod is 15cm/nsec, and the hodoscope efficiency is 98%. Delayed-coincidence curves are measured at different voltages of a high-voltage power supply

No abstract available

[en] The K_μ2 decay is the main source of particles in experiment with the beams of tagged neutrino at the Institute for High-Energy Physics. This decay cannot be used for tagging without reliable muon identification. This paper describes the muon identification scheme in the Tagged Neutrino Experiment and the apparatus designed for this purpose

[en] The optical properties of silica aerogel tiles with a refractive index of 1.03 and dimensions 11x11x1 cm³, 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

[en] 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, C₄F₁₀, 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

[en] Spin-polarized atomic hydrogen is used as a gaseous polarized-proton target in high-energy and nuclear-physics experiments operating with internal beams in storage rings. When such beams are intense and bunched, this type of target can be depolarized by a resonant interaction with the transient magnetic field generated by the beam bunches. This effect has been studied with the HERA positron beam in the HERMES experiment at DESY. Resonances have been observed and a simple analytic model has been used to explain their shape and position. Operating conditions for the experiment have been found where there is no significant target depolarization due to this effect. copyright 1999 The American Physical Society

[en] Exclusive incoherent electroproduction of the ρ⁰ number-sign< fence lpost='(' rpost=')' style='single'>770 meson from ¹H , number-sign< hspace space='-0.167'>²H , number-sign< hspace space='-0.167'>³He , and number-sign< hspace space='-0.167'>¹⁴N targets has been studied by the HERMES experiment at squared four-momentum transfer Q²>0.4 GeV² and positron energy loss ν from 9 to 20 GeV. The ratio of the number-sign< hspace space='-0.167'>¹⁴N to number-sign< hspace space='-0.167'>¹H cross sections per nucleon, known as the nuclear transparency, was found to decrease with increasing coherence length of quark-antiquark fluctuations of the virtual photon. The data provide clear evidence of the interaction of the quark-antiquark fluctuations with the nuclear medium. copyright 1999 The American Physical Society