476 research outputs found
Photoproduction of electron-positron pairs in bent single crystals
The process of photoproduction of electron-positron pairs in bent single
crystals is considered in this paper. In particular, it is shown that the
probability of the process for gamma-quanta with energies from 100 GeV on is
significantly higher than the one in an amorphous medium.
A possible scenario for the experimental validation of the process is
discussed and the positive features of the photoproduction in bent crystals
compared to straight ones are underlined from the point of view of possible
applications.Comment: 13 pages, 6 figure
BAT According to Climatic Neutrality of Production of Steel Products
The purpose of this article is to estimate the best available technologies for values of the following technological numbers: fuel, ecological, depreciation, greenhouse and their sums. All these numbers have power dimension: t of conditional fuel/unit of production that allows to put them. The fuel technological number characterizes power consumption of production. The technological ecological number transfers a payment of the enterprise for environmental pollution to power units. The technological depreciation number transfers depreciation charges from rubles to power units. The technological greenhouse number translates a payment of the enterprise for emissions of greenhouse gases in power units. Technological numbers have through character – from extraction of raw materials before receiving finished goods. The best available technologies are characterized by the smallest sum of all technological numbers.
Keywords: through power-ecological analysis, power ecological capacity of production of steel products, technological fuel ecological greenhouse number, best available technologies, climatic neutralit
Towards a combined analysis of inclusive/exclusive electroproduction
In view of the major advances achieved by the CLAS experiments in studying
the N* electroexcitation amplitudes, as well as further extension of these
studies in the experiments with CLAS12, we present an approach for the
evaluation of the resonant contributions to inclusive electron scattering off
protons. For the first time, the resonant contributions are determined from the
experimental results on N* electrocouplings available from the data analyses of
exclusive meson electroproduction off protons. This is a useful benchmark for
future endeavours on understanding the transition region between low and
high-energy regions, strongly related to tests on quark-hadron duality.Comment: NSTAR2019 conference proceeding
Nucleon resonance contributions to unpolarised inclusive electron scattering
The first CLAS12 experiments will provide high-precision data on inclusive
electron scattering observables at a photon virtuality ranging from 0.05
GeV to 12 GeV and center-of-mass energies up to 4 GeV. In view of
this endeavour, we present the modeling of the resonant contributions to the
inclusive electron scattering observables. As input, we use the existing CLAS
electrocoupling results obtained from exclusive meson electroproduction data
off protons, and evaluate for the first time the resonant contributions based
on the experimental results on the nucleon resonance electroexcitation. The
uncertainties are given by the data and duly propagated through a Monte Carlo
approach. In this way, we obtain estimates for the resonant contributions,
important for insight into the nucleon parton distributions in the resonance
region and for the studies of quark-hadron duality
Application of bent crystals at IHEP 70-GeV accelerator to enhance the efficiency of its usage
Bent crystal was extracting 70-GeV protons with average intensity 4*10^11 (as
measured in external beamline) per spill of 1.6 s duration, in parallel to the
simultaneous work of two internal targets in the accelerator ring. An
additional crystal, placed in the external beamline, was deflecting a small
part of the extracted beam with intensity 10^7 protons toward another physics
experiment. Crystal-extracted beam had a typical size of 4 mm by 4 mm fwhm at
the end of the external beamline. Measurements for the extraction efficiency
and other characteristics at the simultaneous work of four experimental set-ups
are presented. With crystal working in the above-said regime during one month,
no degradation of channeling was observed. The studies of extraction efficiency
have been continued with new crystals.Comment: 6pp. Presented at EPAC 200
Crystal experiments on efficient beam extraction
Silicon crystal was channeling and extracting 70-GeV protons from the U-70
accelerator with efficiency of 85.3+-2.8% as measured for a beam of 10^12
protons directed towards crystals of 2 mm length in spills of 1-2 s duration.
The experimental data follow very well the prediction of Monte Carlo
simulations. This success is important to devise a more efficient use of the
U-70 accelerator in Protvino and provides a crucial support for implementation
of crystal-assisted collimation of gold ion beam in RHIC and slow extraction
from AGS onto E952, now in preparation at Brookhaven Nat'l Lab. Future
applications, spanning in the energy from sub-GeV (medical) to order of 1 GeV
(scraping in the SNS, extraction from COSY) to order of 1 TeV and beyond
(scraping in the Tevatron, LHC, VLHC), can benefit from these studies.Comment: 12pp. Presented at 19-th Intern. Conference on Atomic Collisions in
Solids (ICACS-19: Paris, July 29 - August 3, 2001
Progress in crystal extraction and collimation
Recent IHEP Protvino experiments show efficiencies of crystal-assisted slow
extraction and collimation of 85.3+-2.8%, at the intensities of the channeled
beam on the order of 10^12 proton per spill of 2 s duration. The obtained
experimental data well follows the theory predictions. We compare the
measurements against theory and outline the theoretical potential for further
improvement in the efficiency of the technique. This success is important for
the efficient use of IHEP accelerator and for implementation of
crystal-assisted collimation at RHIC and slow extraction from AGS onto E952,
now in preparation. Future applications, spanning in the energy from order of 1
GeV (scraping in SNS, slow extraction from COSY and medical accelerators) to
order of 1 TeV and beyond (scraping in Tevatron, LHC, VLHC), can benefit from
these studies.Comment: 7pp. Presented at HEACC 2001 (Tsukuba, March 25-30
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