1,021 research outputs found
A Validation Framework for the Long Term Preservation of High Energy Physics Data
The study group on data preservation in high energy physics, DPHEP, is moving
to a new collaboration structure, which will focus on the implementation of
preservation projects, such as those described in the group's large scale
report published in 2012. One such project is the development of a validation
framework, which checks the compatibility of evolving computing environments
and technologies with the experiments software for as long as possible, with
the aim of substantially extending the lifetime of the analysis software, and
hence of the usability of the data. The framework is designed to automatically
test and validate the software and data of an experiment against changes and
upgrades to the computing environment, as well as changes to the experiment
software itself. Technically, this is realised using a framework capable of
hosting a number of virtual machine images, built with different configurations
of operating systems and the relevant software, including any necessary
external dependencies.Comment: Proceedings of a poster presented at CHEP 2013, Amsterdam, October
14-18 201
Electronic mechanism of ion expulsion under UV nanosecond laser excitation of silicon: Experiment and modeling
We present experimental and modeling studies of UV nanosecond pulsed laser
desorption and ablation of (111) bulk silicon. The results involve a new
approach to the analysis of plume formation dynamics under high-energy photon
irradiation of the semiconductor surface. Non-thermal, photo-induced desorption
has been observed at low laser fluence, well below the melting threshold. Under
ablation conditions, the non-thermal ions have also a high concentration. The
origin of these ions is discussed on the basis of electronic excitation of Si
surface states associated with the Coulomb explosion mechanism. We present a
model describing dynamics of silicon target excitation, heating and
harge-carrier transport
Structure and properties of Ti/TiB metal-matrix composite after isothermal multiaxial forging
Microstructure and mechanical properties of a Ti/TiB metal-matrix composites after multiaxial forging at 850°C to the true strain " = 5:2 were studied. The composite with 17 vol.% of TiB was produced via spark plasma sintering at 1000°
Field-Induced Gap in a Quantum Spin-1/2 Chain in a Strong Magnetic Field
Magnetic excitations in copper pyrimidine dinitrate, a spin-1/2
antiferromagnetic chain with alternating -tensor and Dzyaloshinskii-Moriya
interactions that exhibits a field-induced spin gap, are probed by means of
pulsed-field electron spin resonance spectroscopy. In particular, we report on
a minimum of the gap in the vicinity of the saturation field T
associated with a transition from the sine-Gordon region (with soliton-breather
elementary excitations) to a spin-polarized state (with magnon excitations).
This interpretation is fully confirmed by the quantitative agreement over the
entire field range of the experimental data with the DMRG investigation of the
spin-1/2 Heisenberg chain with a staggered transverse field
ESR modes in a Strong-Leg Ladder in the Tomonaga-Luttinger Liquid Phase
Magnetic excitations in the strong-leg quantum spin ladder compound
(CHN)CuBr (known as DIMPY) in the field-induced
Tomonaga-Luttinger spin liquid phase are studied by means of high-field
electron spin resonance (ESR) spectroscopy. The presence of a gapped ESR mode
with unusual non-linear frequency-field dependence is revealed experimentally.
Using a combination of analytic and exact diagonalization methods, we compute
the dynamical structure factor and identify this mode with longitudinal
excitations in the antisymmetric channel. We argue that these excitations
constitute a fingerprint of the spin dynamics in a strong-leg spin-1/2
Heisenberg antiferromagnetic ladder and owe its ESR observability to the
uniform Dzyaloshinskii-Moriya interaction
Establishing the fundamental magnetic interactions in the chiral skyrmionic Mott insulator Cu2OSeO3 by terahertz electron spin resonance
The recent discovery of skyrmions in CuOSeO has established a new
platform to create and manipulate skyrmionic spin textures. We use high-field
electron spin resonance (ESR) spectroscopy combining a terahertz free electron
laser and pulsed magnetic fields up to 64 T to probe and quantify its
microscopic spin-spin interactions. Besides providing direct access to the
long-wavelength Goldstone mode, this technique probes also the high-energy part
of the excitation spectrum which is inaccessible by standard low-frequency ESR.
Fitting the behavior of the observed modes in magnetic field to a theoretical
framework establishes experimentally that the fundamental magnetic building
blocks of this skyrmionic magnet are rigid, highly entangled and weakly coupled
tetrahedra.Comment: 5 pages, 3 Figure
Magnetic excitations in the spin-1/2 triangular-lattice antiferromagnet CsCuBr
We report on high-field electron spin resonance (ESR) studies of magnetic
excitations in the spin-1/2 triangular-lattice antiferromagnet CsCuBr.
Frequency-field diagrams of ESR excitations are measured for different
orientations of magnetic fields up to 25 T. We show that the substantial
zero-field energy gap, K, observed in the low-temperature
excitation spectrum of CsCuBr [Zvyagin , Phys. Rev. Lett. 112,
077206 (2014)], is present well above . Noticeably, the transition into
the long-range magnetically ordered phase does not significantly affect the
size of the gap, suggesting that even below the high-energy spin dynamics
in CsCuBr is determined by short-range-order spin correlations. The
experimental data are compared with results of model spin-wave-theory
calculations for spin-1/2 triangle-lattice antiferromagnet.Comment: 6 pages, 9 figure
- …