7 research outputs found
First study of radiation hardness of lead tungstate crystals at low temperatures
The electromagnetic calorimeter of PANDA at the FAIR facility will rely on an
operation of lead tungstate (PWO) scintillation crystals at temperatures near
-25 deg.C to provide sufficient resolution for photons in the energy range from
8 GeV down to 10 MeV. Radiation hardness of PWO crystals was studied at the
IHEP (Protvino) irradiation facility in the temperature range from room
temperature down to -25 deg.C. These studies have indicated a significantly
different behaviour in the time evolution of the damaging processes well below
room temperature. Different signal loss levels at the same dose rate, but at
different temperatures were observed. The effect of a deep suppression of the
crystal recovery process at temperatures below
0 deg.C has been seen.Comment: 10 pages 7 figure
Development of a Momentum Determined Electron Beam in the 1 -45 GeV Range
A beam line for electrons with energies in the range of 1 to 45 GeV, low
contamination of hadrons and muons and high intensity up to 10^6 per
accelerator spill at 27 GeV was setup at U70 accelerator in Protvino, Russia. A
beam tagging system based on drift chambers with 160 micron resolution was able
to measure relative electron beam momentum precisely. The resolution sigma_p p
was 0.13% at 45 GeV where multiple scattering is negligible. This test beam
setup provided the possibility to study properties of lead tungstate crystals
(PbWO_4) for the BTeV experiment at Fermilab.Comment: 12 pages, 8 figures; work done by the BTeV Electromagnetic
Calorimeter grou
Comparison of Radiation Damage in Lead Tungstate Crystals under Pion and Gamma Irradiation
Studies of the radiation hardness of lead tungstate crystals produced by the
Bogoroditsk Techno-Chemical Plant in Russia and the Shanghai Institute of
Ceramics in China have been carried out at IHEP, Protvino. The crystals were
irradiated by a 40-GeV pion beam. After full recovery, the same crystals were
irradiated using a -ray source. The dose rate profiles along
the crystal length were observed to be quite similar. We compare the effects of
the two types of radiation on the crystals light output.Comment: 10 pages, 8 figures, Latex 2e, 28.04.04 - minor grammatical change
Design and performance of LED calibration system prototype for the lead tungstate crystal calorimeter
A highly stable monitoring system based on blue and red light emitting diodes
coupled to a distribution network comprised of optical fibers has been
developed for an electromagnetic calorimeter that uses lead tungstate crystals
readout with photomultiplier tubes. We report of the system prototype design
and on the results of laboratory tests. Stability better than 0.1% (r.m.s.) has
been achieved during one week of prototype operation.Comment: 10 pages, 6 figures, LaTeX2
Study of Radiation Damage in Lead Tungstate Crystals Using Intense High Energy Beams
We report on the effects of radiation on the light output of lead tungstate
crystals. The crystals were irradiated by pure, intense high energy electron
and hadron beams as well as by a mixture of hadrons, neutrons and gammas. The
crystals were manufactured in Bogoroditsk, Apatity (both Russia), and Shanghai
(China). These studies were carried out at the 70-GeV proton accelerator in
Protvino
Evaluation of Mandelbrot-Zipf rank distribution parameters
Получены оценки параметра распределения Ципфа-Мандельброта методом моментов и методом максимума правдоподобия.Одержані оцінки параметра розподілу Ціпфа-Манедельброта методом моментів та методом максимуму правдоподібності.Evaluations of Zipf-Mandelbrot distribution parameter were obtained by method of moments and method of maximum likelihood