120 research outputs found
KWISP: an ultra-sensitive force sensor for the Dark Energy sector
An ultra-sensitive opto-mechanical force sensor has been built and tested in
the optics laboratory at INFN Trieste. Its application to experiments in the
Dark Energy sector, such as those for Chameleon-type WISPs, is particularly
attractive, as it enables a search for their direct coupling to matter. We
present here the main characteristics and the absolute force calibration of the
KWISP (Kinetic WISP detection) sensor. It is based on a thin Si3N4
micro-membrane placed inside a Fabry-Perot optical cavity. By monitoring the
cavity characteristic frequencies it is possible to detect the tiny membrane
displacements caused by an applied force. Far from the mechanical resonant
frequency of the membrane, the measured force sensitivity is 5.0e-14
N/sqrt(Hz), corresponding to a displacement sensitivity of 2.5e-15 m/sqrt(Hz),
while near resonance the sensitivity is 1.5e-14 N/sqrt(Hz), reaching the
estimated thermal limit, or, in terms of displacement, 7.5e-16 N/sqrt(Hz).
These displacement sensitivities are comparable to those that can be achieved
by large interferometric gravitational wave detectors.Comment: 9 pages, 8 figures in colo
The discrimination capabilities of Micromegas detectors at low energy
The latest generation of Micromegas detectors show a good energy resolution,
spatial resolution and low threshold, which make them idoneous in low energy
applications. Two micromegas detectors have been built for dark matter
experiments: CAST, which uses a dipole magnet to convert axion into detectable
x-ray photons, and MIMAC, which aims to reconstruct the tracks of low energy
nuclear recoils in a mixture of CF4 and CHF3. These readouts have been
respectively built with the microbulk and bulk techniques, which show different
gain, electron transmission and energy resolutions. The detectors and the
operation conditions will be described in detail as well as their
discrimination capabilities for low energy photons will be discussed.Comment: To be published in the proceedings of the TIPP2011 conference
(Physics Procedia
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
New concepts regarding micro/nanopharmaceutical polymer systems with applications in ophthalmology and neurosciences
Particulate systems like micro/nanoparticles have been used as a physical approach to modify the pharmacokinetic and pharmacodynamic properties of various types of drug molecules increasing this way the drug bioavailability and avoiding the toxic level. The major advantages of the particulate systems include the protection of the drug entity in the systemic circulation, restriction access of the drug to the chosen sites and delivery of the drug at a controlled and sustained rate to the site of action. Various materials have been used in the formulation of micro/nanoparticles for drug delivery research to increase therapeutic benefit, while minimizing side effects. Each class of materials (metals, lipids, polymers) presents advantages which make them suitable for different classes of applications. This paper focuses mainly on polymer particulate systems due to their large applicability area given by the diversity of the polymers properties. We review various aspects of micro/nanoparticle formulation including preparation, release mechanisms, effect of their characteristics and their applications in the field of ophthalmology and neurosciences. Some of the most interesting applications of polymer micro/nanoparticulates in glaucoma, retinal disorders and optical nerve disorders, respectivelly in neurology and neurosurgery are presented
CAST microbulk micromegas in the Canfranc Underground Laboratory
During the last taking data campaigns of the CAST experiment, the micromegas
detectors have achieved background levels of keVcms between 2 and 9 keV. This performance has
been possible thanks to the introduction of the microbulk technology, the
implementation of a shielding and the development of discrimination algorithms.
It has motivated new studies towards a deeper understanding of CAST detectors
background. One of the working lines includes the construction of a replica of
the set-up used in CAST by micromegas detectors and its installation in the
Canfranc Underground Laboratory. Thanks to the comparison between the
performance of the detectors underground and at surface, shielding upgrades,
etc, different contributions to the detectors background have been evaluated.
In particular, an upper limit keVcms
for the intrinsic background of the detector has been obtained. This work means
a first evaluation of the potential of the newest micromegas technology in an
underground laboratory, the most suitable environment for Rare Event Searches.Comment: 6 pages, 8 figures. To appear in the proceedings of the 2nd
International Conference on Technology and Instrumentation for Particle
Physics (TIPP 2011
X-ray detection with Micromegas with background levels below 10 keVcms
Micromegas detectors are an optimum technological choice for the detection of
low energy x-rays. The low background techniques applied to these detectors
yielded remarkable background reductions over the years, being the CAST
experiment beneficiary of these developments. In this document we report on the
latest upgrades towards further background reductions and better understanding
of the detectors' response. The upgrades encompass the readout electronics, a
new detector design and the implementation of a more efficient cosmic muon veto
system. Background levels below 10keVcms have been
obtained at sea level for the first time, demonstrating the feasibility of the
expectations posed by IAXO, the next generation axion helioscope. Some results
obtained with a set of measurements conducted in the x-ray beam of the CAST
Detector Laboratory will be also presented and discussed
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
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