61 research outputs found
Dimensional Effects in Micro- and Nanostructural Changes in Grain and Intragrained Structure of Steel 45 at Static-pulse Treatment
Conducted macro-, micro- and nanostructured materials were investigated by the influence of sample
sizes of steel 45 in the form of a parallelepiped, after intense static pulse processing in plastic deformation
as in the single (150 J), and pulsed (25 J) impact with a frequency of 23 Hz. When all modes of processing
bulk samples found structuring self-organized formation of dislocations. With a single exposure revealed as
filling pearlite grains periodic dislocations (200 nm), and the formation of dislocation-free regions. When a
periodic pulse treatment of the samples with transverse dimensions fold speed of propagation of elastic
waves and shock waves as well as the related transport velocity of dislocations turns shockwave
mechanism causing the formation of alternating strips of ferritic and pearlite walls (25 microns), wherein
the pearlite wall completely or partially filled with dislocations
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
Performance of a fine-sampling electromagnetic calorimeter prototype in the energy range from 1 to 19 GeV
The fine-sampling electromagnetic calorimeter prototype has been
experimentally tested using the 1-19 GeV/c tagged beams of negatively charged
particles at the U70 accelerator at IHEP, Protvino. The energy resolution
measured by electrons is Delta{E}/E=2.8%/\sqrt{E} + 1.3%. The position
resolution for electrons is Delta{x}=3.1 + 15.4/sqrt{E} mm in the center of the
cell. The lateral non-uniformity of the prototype energy response to electrons
and MIPs has turned out to be negligible. Obtained experimental results are in
a good agreement with Monte-Carlo simulations.Comment: Article is prepared for pdflatex using the class elsart. 13 pages, 9
figures in 11 PDF file
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
Correlation of Beam Electron and LED Signal Losses under Irradiation and Long-term Recovery of Lead Tungstate Crystals
Radiation damage in lead tungstate crystals reduces their transparency. The
calibration that relates the amount of light detected in such crystals to
incident energy of photons or electrons is of paramount importance to
maintaining the energy resolution the detection system. We report on tests of
lead tungstate crystals, read out by photomultiplier tubes, exposed to
irradiation by monoenergetic electron or pion beams. The beam electrons
themselves were used to measure the scintillation light output, and a blue
light emitting diode (LED) was used to track variations of crystals
transparency. We report on the correlation of the LED measurement with
radiation damage by the beams and also show that it can accurately monitor the
crystals recovery from such damage.Comment: 9 pages, 6 figures, LaTeX2
LED Monitoring System for the BTeV Lead Tungstate Crystal Calorimeter Prototype
We report on the performance of a monitoring system for a prototype
calorimeter for the BTeV experiment that uses Lead Tungstate crystals coupled
with photomultiplier tubes. The tests were carried out at the 70 GeV
accelerator complex at Protvino, Russia.Comment: 12 pages, 8 figures, LaTeX2e, revised versio
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
Deformations of quantum field theories on spacetimes with Killing vector fields
The recent construction and analysis of deformations of quantum field
theories by warped convolutions is extended to a class of curved spacetimes.
These spacetimes carry a family of wedge-like regions which share the essential
causal properties of the Poincare transforms of the Rindler wedge in Minkowski
space. In the setting of deformed quantum field theories, they play the role of
typical localization regions of quantum fields and observables. As a concrete
example of such a procedure, the deformation of the free Dirac field is
studied.Comment: 35 pages, 3 figure
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
Transverse momentum spectra of charged particles in proton-proton collisions at GeV with ALICE at the LHC
The inclusive charged particle transverse momentum distribution is measured
in proton-proton collisions at GeV at the LHC using the ALICE
detector. The measurement is performed in the central pseudorapidity region
over the transverse momentum range GeV/.
The correlation between transverse momentum and particle multiplicity is also
studied. Results are presented for inelastic (INEL) and non-single-diffractive
(NSD) events. The average transverse momentum for is (stat.) (syst.) GeV/ and
\left_{\rm NSD}=0.489\pm0.001 (stat.) (syst.)
GeV/, respectively. The data exhibit a slightly larger than measurements in wider pseudorapidity intervals. The results are
compared to simulations with the Monte Carlo event generators PYTHIA and
PHOJET.Comment: 20 pages, 8 figures, 2 tables, published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/390
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