109 research outputs found
Potential for measurement of the tensor electric and magnetic polarizabilities of the deuteron in storage-ring experiments with polarized beams
Measurement of the tensor electric and magnetic polarizabilities of the
deuteron is of great interest, especially in connection with the possibilities
of COSY and GSI. These polarizabilities can be measured in storage rings by the
frozen spin method providing a disappearance of g-2 precession. This method
will be used in the planned deuteron electric-dipole-moment experiment in
storage rings. The tensor electric polarizability of the deuteron significantly
influences the buildup of the vertical polarization in the above experiment.
The spin interactions depending on the electric dipole moment, the tensor
electric polarizability, and main systematical errors caused by field
misalignments have very different symmetries. For the considered experimental
conditions, the sensitivity to the deuteron EDM of cm
corresponds to measuring the both of tensor polarizabilities with an accuracy
of cm. This
conservative estimate can be improved by excluding the systematical error
caused by the field instability which is negligible for the measurement of the
tensor polarizabilities. To find the tensor magnetic polarizability, the
horizontal components of the polarization vector should be measured.Comment: 11 pages, the extended version of the paper prepared for the
Proceedings of 19th International Spin Physics Symposium (September 27 -
October 2, 2010, Julich, Germany
Search for axions in streaming dark matter
A new search strategy for the detection of the elusive dark matter (DM) axion
is proposed. The idea is based on streaming DM axions, whose flux might get
temporally enormously enhanced due to gravitational lensing. This can happen if
the Sun or some planet (including the Moon) is found along the direction of a
DM stream propagating towards the Earth location. The experimental requirements
to the axion haloscope are a wide-band performance combined with a fast axion
rest mass scanning mode, which are feasible. Once both conditions have been
implemented in a haloscope, the axion search can continue parasitically almost
as before. Interestingly, some new DM axion detectors are operating wide-band
by default. In order not to miss the actually unpredictable timing of a
potential short duration signal, a network of co-ordinated axion antennae is
required, preferentially distributed world-wide. The reasoning presented here
for the axions applies to some degree also to any other DM candidates like the
WIMPs.Comment: 5 page
HNBR and its MWCNT reinforced nanocomposites : Crystalline morphology and electrical response
Morphology and electrical response of hydrogenated acrylonitrile butadiene rubber
(HNBR) and its multiwall carbon nanotube (MWCNT) reinforced nanocomposites
were studied by means of x-ray diffraction and broadband dielectric spectroscopy.
HNBR systems were found to be semi-crystalline, with their crystallinity to increase
with the addition of MWCNTs. In their dielectric spectra, four relaxation processes
were detected. Ascending in relaxation time, these were attributed to: (i) interfacial
polarization at the interface of crystalline and amorphous regions of HNBR and at the
interface between HNBR and MWCNTs, (ii) glass to rubber transition of the
amorphous part of HNBR, (iii) rearrangement of polar side groups, such as âCN, and
(iv) local motions of small segments of the main elastomer chain.
Electrical conductivity increases with MWCNT content and frequency increasing. The
effect of temperature, on the electrical response, is more pronounced at low frequencies. The temperature dependence of the electrical conductivity strongly deviates from a pure
Arrhenius behavior, signifying that the occurring conductance mechanisms do not
correspond to a single thermally activated process. Relaxation dynamics imply that
crystalline regions exert motion restrictions to large segments of the macromolecules
in the amorphous phase and to polar parts of the systems
aKWISP: investigating short-distance interactions at sub-micron scales
The sub-micron range in the field of short distance interactions has yet to
be opened to experimental investigation, and may well hold the key to
understanding al least part of the dark matter puzzle. The aKWISP
(advanced-KWISP) project introduces the novel Double Membrane Interaction
Monitor (DMIM), a combined source-sensing device where interaction distances
can be as short as 100 nm or even 10 nm, much below the 1-10 micron distance
which is the lower limit encountered by current experimental efforts. aKWISP
builds on the technology and the results obtained with the KWISP
opto-mechanical force sensor now searching at CAST for the direct coupling to
matter of solar chameleons. It will reach the ultimate quantum-limited
sensitivity by exploiting an array of technologies, including operation at
milli-Kelvin temperatures. Recent suggestions point at short-distance
interactions studies as intriguing possibilities for the detection of axions
and of new physical phenomena
Atmospheric Temperature anomalies as manifestation of the dark Universe
We are investigating the possible origin of small-scale anomalies, like the
annual stratospheric temperature anomalies. Unexpectedly within known physics,
their observed planetary "dependency", does not match concurrent solar
activity, whose impact on the atmosphere is unequivocal; this points at an
additional energy source of exo-solar origin. A viable concept behind such
observations is based on possible gravitational focusing by the Sun and its
planets towards the Earth of low-speed invisible streaming matter; its influx
towards the Earth gets temporally enhanced. Only a somehow "strongly"
interacting invisible streaming matter with the small upper atmospheric
screening can be behind the observed temperature excursions. Ordinary dark
matter (DM) candidates like axions or WIMPs, cannot have any noticeable impact.
The associated energy deposition is . The atmosphere has been
uninterruptedly monitored for decades. Therefore, the upper atmosphere can
serve as a novel (low-threshold) detector for the dark Universe, with built-in
spatiotemporal resolution while the solar system gravity acts temporally as a
signal amplifier. Interestingly, the anomalous ionosphere shows a relationship
with the inner earth activity like earthquakes. Similarly investigating the
transient sudden stratospheric warmings within the same reasoning, the nature
of the assumed "invisible streams" could be deciphered.Comment: 8 pages, 7 figures, Published in the proceedings of the "15th
International Conference on Meteorology, Climatology and Atmospheric Physics
(COMECAP 2021)" see
https://www.conferre.gr/allevents/comecap2020/Proceedings_Final.pd
Search for chameleons with CAST
In this work we present a search for (solar) chameleons with the CERN Axion
Solar Telescope (CAST). This novel experimental technique, in the field of dark
energy research, exploits both the chameleon coupling to matter () and to photons () via the Primakoff effect. By reducing
the X-ray detection energy threshold used for axions from 1keV to 400eV
CAST became sensitive to the converted solar chameleon spectrum which peaks
around 600eV. Even though we have not observed any excess above background,
we can provide a 95% C.L. limit for the coupling strength of chameleons to
photons of for .Comment: 8 pages, 12 figure
Guidebook of inclusion of best practices on suitable digital working environments
No abstract available.publishe
Perspectives on gender bias in recruitment
No abstract available.publishe
Axion Searches with Helioscopes and astrophysical signatures for axion(-like) particles
The first part reviews the working mechanisms, capabilities and performance
of axion helioscopes, including the achieved results so far. The 2nd part is
observationally driven. New simulation results obtained with the Geant4 code
reconstruct spectral shape of solar X-ray spectra, and their isotropic emission
and lateral size. The derived rst mass of the axion(-like) particles is ~10meV.
The axion interaction with magnetic field gradient is a generic theoretical
suggestion that could reconcile present limits with relevant solar X-ray
activity. A short outlook of the experimentally expanding solar axion field is
given.Comment: 31 pages, 18 figures. Aded 1 author, updated references. Accepted for
the special issue of NJP on dark matter (July 2009
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