726 research outputs found
Beam-Material Interaction
Th is paper is motivated by the growing importance of better understanding of
the phenomena and consequences of high- intensity energetic particle beam
interactions with accelerator, generic target , and detector components. It
reviews the principal physical processes of fast-particle interactions with
matter, effects in materials under irradiation, materials response, related to
component lifetime and performance, simulation techniques, and methods of
mitigating the impact of radiation on the components and envir onment in
challenging current and future applicationComment: 28 pages, contribution to the 2014 Joint International Accelerator
School: Beam Loss and Accelerator Protection, Newport Beach, CA, USA , 5-14
Nov 201
Intrinsic defects in silicon carbide LED as a perspective room temperature single photon source in near infrared
Generation of single photons has been demonstrated in several systems.
However, none of them satisfies all the conditions, e.g. room temperature
functionality, telecom wavelength operation, high efficiency, as required for
practical applications. Here, we report the fabrication of light emitting
diodes (LEDs) based on intrinsic defects in silicon carbide (SiC). To fabricate
our devices we used a standard semiconductor manufacturing technology in
combination with high-energy electron irradiation. The room temperature
electroluminescence (EL) of our LEDs reveals two strong emission bands in
visible and near infrared (NIR), associated with two different intrinsic
defects. As these defects can potentially be generated at a low or even single
defect level, our approach can be used to realize electrically driven single
photon source for quantum telecommunication and information processing
Energy deposition studies for the High-Luminosity Large Hadron Collider inner triplet magnets
A detailed model of the High Luminosity LHC inner triplet region with new
large-aperture Nb3Sn magnets, field maps, corrector packages, and segmented
tungsten inner absorbers was built and implemented into the FLUKA and MARS15
codes. In the optimized configuration, the peak power density averaged over the
magnet inner cable width is safely below the quench limit. For the integrated
luminosity of 3000 fb-1, the peak dose in the innermost magnet insulator ranges
from 20 to 35 MGy. Dynamic heat loads to the triplet magnet cold mass are
calculated to evaluate the cryogenic capability. In general, FLUKA and MARS
results are in a very good agreement.Comment: 24 p
Energy Deposition Studies for the Hi-Lumi LHC Inner Triplet Magnets
A detailed model of the High Luminosity LHC inner triplet region with new
large-aperture Nb3Sn magnets, field maps, corrector packages, and segmented
tungsten inner absorbers was built and implemented into the FLUKA and MARS15
codes. In the optimized configuration, the peak power density averaged over the
magnet inner cable width is safely below the quench limit. For the integrated
luminosity of 3000 fb -1, the peak dose in the innermost magnet insulator
ranges from 20 to 35 MGy. Dynamic heat loads to the triplet magnet cold mass
are calculated to evaluate the cryogenic capability. In general, FLUKA and MARS
results are in a very good agreement.Comment: 4 pp. Presented paper at the 5th International Particle Accelerator
Conference, June 15 -20, 2014, Dresden, German
Room-temperature near-infrared silicon carbide nanocrystalline emitters based on optically aligned spin defects
Bulk silicon carbide (SiC) is a very promising material system for
bio-applications and quantum sensing. However, its optical activity lies beyond
the near infrared spectral window for in-vivo imaging and fiber communications
due to a large forbidden energy gap. Here, we report the fabrication of SiC
nanocrystals and isolation of different nanocrystal fractions ranged from 600
nm down to 60 nm in size. The structural analysis reveals further fragmentation
of the smallest nanocrystals into ca. 10-nm-size clusters of high crystalline
quality, separated by amorphization areas. We use neutron irradiation to create
silicon vacancies, demonstrating near infrared photoluminescence. Finally, we
detect, for the first time, room-temperature spin resonances of these silicon
vacancies hosted in SiC nanocrystals. This opens intriguing perspectives to use
them not only as in-vivo luminescent markers, but also as magnetic field and
temperature sensors, allowing for monitoring various physical, chemical and
biological processes.Comment: 5 pages, 4 figure
Energy Deposited in the High Luminosity Inner Triplets of the LHC by Collision Debris
The 14 TeV center of mass proton-proton collisions in the LHC produce not only debris interesting for physics but also showers of particles ending up in the accelerator equipment, in particular in the superconducting magnet coils. Evaluations of this contribution to the heat, that has to be transported by the cryogenic system, have been made to guarantee that the energy deposition in the superconducting magnets does not exceed limits for magnet quenching and the capacity of the cryogenic system. The models of the LHC base-line are detailed and include description of, for energy deposition, essential elements like beam-pipes and corrector magnets. The evaluations made using the Monte-Carlo code FLUKA are compared to previous studies using MARS. For the comparison and consolidation of the calculations, a dedicated study of code comparison for a reduced setup was made
Hamiltonian structure of real Monge-Amp\`ere equations
The real homogeneous Monge-Amp\`{e}re equation in one space and one time
dimensions admits infinitely many Hamiltonian operators and is completely
integrable by Magri's theorem. This remarkable property holds in arbitrary
number of dimensions as well, so that among all integrable nonlinear evolution
equations the real homogeneous Monge-Amp\`{e}re equation is distinguished as
one that retains its character as an integrable system in multi-dimensions.
This property can be traced back to the appearance of arbitrary functions in
the Lagrangian formulation of the real homogeneous Monge-Amp\`ere equation
which is degenerate and requires use of Dirac's theory of constraints for its
Hamiltonian formulation. As in the case of most completely integrable systems
the constraints are second class and Dirac brackets directly yield the
Hamiltonian operators. The simplest Hamiltonian operator results in the
Kac-Moody algebra of vector fields and functions on the unit circle.Comment: published in J. Phys. A 29 (1996) 325
Applications of Temperley-Lieb algebras to Lorentz lattice gases
Motived by the study of motion in a random environment we introduce and
investigate a variant of the Temperley-Lieb algebra. This algebra is very rich,
providing us three classes of solutions of the Yang-Baxter equation. This
allows us to establish a theoretical framework to study the diffusive behaviour
of a Lorentz Lattice gas. Exact results for the geometrical scaling behaviour
of closed paths are also presented.Comment: 10 pages, latex file, one figure(by request
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