294 research outputs found
Kinetics of grain refinemet in metallic materials during large strain deformation
The development of ultrafine grained microstructures in austenitic stainless steel and pure titanium subjected to large strain deformation was comparatively studied. The change in the volume fractions of newly developed ultrafine grains was used to quantify the progress in grain refinement during plastic deformatio
New experimental limits on neutron - mirror neutron oscillations in the presence of mirror magnetic field
Present probes do not exclude that the neutron () oscillation into mirror
neutron (), a sterile state exactly degenerate in mass with the neutron,
can be a very fast process, in fact faster than the neutron decay itself. This
process is sensitive to the magnetic field. Namely, if the mirror magnetic
field exists at the Earth, oscillation probability can be
suppressed or resonantly amplified by the applied magnetic field ,
depending on its strength and on the angle between and
. We present the results of ultra-cold neutron storage measurements
aiming to check the anomalies observed in previous experiments which could be a
signal for oscillation in the presence of mirror magnetic field ~G. Analyzing the experimental data on neutron loses, we obtain a new lower
limit on oscillation time s (95 % C.L.) for any
between 0.08 and 0.17 G, and s (95 % C.L.)
for any in the interval () G
Attosecond control of electron dynamics in carbon monoxide
Laser pulses with stable electric field waveforms establish the opportunity
to achieve coherent control on attosecond timescales. We present experimental
and theoretical results on the steering of electronic motion in a
multi-electron system. A very high degree of light-waveform control over the
directional emission of C+ and O+ fragments from the dissociative ionization of
CO was observed. Ab initio based model calculations reveal contributions to the
control related to the ionization and laser-induced population transfer between
excited electronic states of CO+ during dissociation
Sterile neutrino and dark matter
We consider the equation that describes the dynamics of the sterile neutrino
density in primeval plasma. The analysis of this equation results in the 5%
contribution of the sterile neutrino with mixing parameters and to the energy density of the
Universe. The considered parameters of the sterile neutrino correspond to the
warm dark matter.Comment: 7 pages, 11 figure
Microstructure evolution of commercial-purity titanium during cryorolling
Electron backscatter diffraction and transmission electron microscopy have been used to analyze the microstructural evolution of titanium during rolling at a cryogenic temperature (T = –196°C). It has been found that intensive twinning at the cryogenic deformation temperature accelerates the kinetics of micro structure refinement. The quantitative analysis of microstructure evolution in titanium upon cryorolling has shown that structure evolution is mainly related to mechanical twinning in the initial stages cryorolling is discusse
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