165 research outputs found
Studies and application of bent crystals for beam steering at 70-GeV IHEP accelerator
This report overviews studies accomplished in the U70 proton synchrotron of
IHEP-Protvino during the recent two decades. Major attention is paid to a
routine application of bent crystals for beam extraction from the machine. It
has been confirmed experimentally that efficiency of beam extraction with a
crystal deflector of around 85% is well feasible for a proton beam with
intensity up to 1012 protons per cycle. Another trend is to use bent crystals
for halo collimation in a high energy collider. New promising options emerge
for, say, LHC and ILC based on the "volume reflection" effect, which has been
discovered recently in machine study runs at U70 of IHEP (50 GeV) and SPS of
CERN (400 GeV).Comment: 12 pages, 14 figure
The measurement results of carbon ion beam structure extracted by bent crystal from U-70 accelerator
The carbon ion +6C beam with energy 25 GeV/nucleon was extracted by bent crystal from the U-70 ring. The bent angle of silicon crystal was 85 mrad. About 2*105 particles for 109 circulated ions in the ring were observed in beam line 4a after bent crystal. Geometrical parameters, time structure and ion beam structure were measure
Extraction of the carbon ion beam from the U-70 accelerator into beamline 4a using a bent single crystal
A beam of six-charged carbon ions with an energy of 24.8 GeV/nucleon is extracted from the U-70 synchrotron by means of a silicon crystal bent through 85 mrad. A total of 200000 particles are observed in beamline 4a upon forcing 109 circulating ions to the crysta
Light response of pure CsI calorimeter crystals painted with wavelength-shifting lacquer
We have measured scintillation properties of pure CsI crystals used in the
shower calorimeter built for a precise determination of the pi+ -> pi0 e+ nu
decay rate at the Paul Scherrer Institute (PSI). All 240 individual crystals
painted with a special wavelength-shifting solution were examined in a
custom-build detection apparatus (RASTA=radioactive source tomography
apparatus) that uses a 137Cs radioactive gamma source, cosmic muons and a light
emitting diode as complementary probes of the scintillator light response. We
have extracted the total light output, axial light collection nonuniformities
and timing responses of the individual CsI crystals. These results predict
improved performance of the 3 pi sr PIBETA calorimeter due to the painted
lateral surfaces of 240 CsI crystals. The wavelength-shifting paint treatment
did not affect appreciably the total light output and timing resolution of our
crystal sample. The predicted energy resolution for positrons and photons in
the energy range of 10-100 MeV was nevertheless improved due to the more
favorable axial light collection probability variation. We have compared
simulated calorimeter ADC spectra due to 70 MeV positrons and photons with a
Monte Carlo calculation of an ideal detector light response.Comment: Elsevier LaTeX, 35 pages in e-print format, 15 Postscript Figures and
4 Tables, also available at
http://pibeta.phys.virginia.edu/~pibeta/subprojects/csipro/tomo/rasta.p
An electromagnetic shashlik calorimeter with longitudinal segmentation
A novel technique for longitudinal segmentation of shashlik calorimeters has
been tested in the CERN West Area beam facility. A 25 tower very fine samplings
e.m. calorimeter has been built with vacuum photodiodes inserted in the first 8
radiation lengths to sample the initial development of the shower. Results
concerning energy resolution, impact point reconstruction and electron/pion
separation are reported.Comment: 13 pages, 12 figure
A lens-coupled scintillation counter in cryogenic environment
In this work we present an elegant solution for a scintillation counter to be
integrated into a cryogenic system. Its distinguishing feature is the absence
of a continuous light guide coupling the scintillation and the photodetector
parts, operating at cryogenic and room temperatures respectively. The prototype
detector consists of a plastic scintillator with glued-in wavelength-shifting
fiber located inside a cryostat, a Geiger-mode Avalanche Photodiode (G-APD)
outside the cryostat, and a lens system guiding the scintillation light
re-emitted by the fiber to the G-APD through optical windows in the cryostat
shields. With a 0.8mm diameter multiclad fiber and a 1mm active area G-APD the
coupling efficiency of the "lens light guide" is about 50%. A reliable
performance of the detector down to 3K is demonstrated.Comment: 14 pages, 11 figure
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