301 research outputs found
Constraints on Exotic Heavily Ionizing Particles from the Geological Abundance of Fullerenes
The C_{60} molecule exhibits a remarkable stability and inertness that leads
to its survival in ancient carbonaceous rocks initially subject to the high
temperatures requisite for its formation. Elementary particles having very high
electronic stopping powers can similarly form C_{60} and higher fullerenes in
their wake. Combined, these two features point at the possibility of using the
C_{60} presence (or absence) in selected bulk geological samples as a new type
of solid-state nuclear track detector, with applications in astro-particle
physics.Comment: Final version (few modifications). Phys. Rev. Lett. (in press). 4
pages LaTeX, 1 eps figure embedde
Solar X-rays as Signature for New Particles
Massive axions of the Kaluza-Klein type, created inside the solar core, can
be gravitationally trapped by the Sun itself in orbits inside/outside the Sun,
where they accumulate over cosmic times. Their radiative decay can give rise to
various solar phenomena, like the celebrated solar coronal heating, which lacks
a conventional explanation since its first observation in 1939. Such and other
recent observations favour the existence of a halo of exotic particles near the
Sun. X-ray telescopes can provide novel and important information. The
underlying solar axion scenario is presented in details in ref.'s [4,15]Comment: 6 pages, TeX file, Proc. Results and Perspectives in Particle
Physics, La Thuile (2004
Running CAST 2008-2010
This document contains additional information to complement the request for additional running time 2008-2010 (CERN-SPSC-2007-012
A Critique of Drexler Dark Matter
Drexler dark matter is an alternate approach to dark matter that assumes that
highly relativistic protons trapped in the halo of the galaxies could account
for the missing mass. We look at various energetics involved in such a scenario
such as the energy required to produce such particles and the corresponding
lifetimes. Also we look at the energy losses from synchrotron and inverse
Compton scattering and their signatures. The Coulomb repulsive instability due
to the excess charge around the galaxies is also calculated. The above results
lead us to conclude that such a model for DM is unfeasible.Comment: 4 pages, 10 equation
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
Guidelines for axion identification in astrophysical observations
The origin of various celestial phenomena have remained mysterious for
conventional astrophysics. Therefore, alternative solutions should be
considered, taking into account the involvement of unstable dark-matter
particle candidates, such as the celebrated axions or other as yet unforeseen
axion-like particles. Their spontaneous and induced decay by the ubiquitous
solar magnetic fields can be at the origin of persisting enigmatic X-ray
emission, giving rise to a steady and a transient/local solar activity,
respectively. The (coherent) conversion of photons into axion(-like) particles
in intrinsic magnetic fields may modify the solar axion spectrum. The reversed
process can be behind transient (solar) luminosity deficits in the visible.
Then, the Sun might be also a strong source of ~eV-axions. Thus, enigmatic
observations might be the as yet missing direct signature for axion(-like)
particles in earth-bound detectors.Comment: 6 pages, to be submitted to JCA
Photon Production From The Scattering of Axions Out of a Solenoidal Magnetic Field
We calculate the total cross section for the production of photons from the
scattering of axions by a strong inhomogeneous magnetic field in the form of a
2D delta-function, a cylindrical step function and a 2D Gaussian distribution,
which can be approximately produced by a solenoidal current. The theoretical
result is used to estimate the axion-photon conversion probability which could
be expected in a reasonable experimental situation. The calculated conversion
probabilities for QCD inspired axions are bigger by a factor of 2.67 (for the
cylindrical step function case) than those derived by applying the celebrated
1D calculation of the (inverse) coherent Primakoff effect. We also consider
scattering at a resonance , which corresponds to the
scattering from a delta-function and gives the most enhanced results. Finally,
we analyze the results of this work in the astrophysical extension to suggest a
way in which they may be directed to a solution to some basic solar physics
problems and, in particular, the coronal heating problem.Comment: 19 pages, 1 figure, added analysis of our results in the
astrophysical extensio
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