1,080 research outputs found
Notes from the 3rd Axion Strategy Meeting
In this note we briefly summarize the main future targets and strategies for
axion and general low energy particle physics identified in the "3rd axion
strategy meeting" held during the AXIONS 2010 workshop. This summary follows a
wide discussion with contributions from many of the workshop attendees.Comment: 5 pages, 1 figur
Frequency locking to a high-finesse Fabry-Perot cavity of a Frequency doubled Nd:YAG laser used as the optical phase modulator
We report on the frequency locking of a frequency doubled Nd:YAG laser to a
45 000 finesse, 87-cm-long, Fabry-Perot cavity using a modified form of the
Pound-Drever-Hall technique. Necessary signals, such as light phase modulation
and frequency correction feedback, are fed direcly to the infrared pump laser.
This is sufficient to achieve a stable locking of the 532 nm visible beam to
the cavity, also showing that the doubling process does not degrade laser
performances.Comment: submitted to Review of Scientific Instrument
Polarization measurements and their perspectives: PVLAS Phase II
We sketch the proposal for a "PVLAS-Phase II" experiment. The main physics
goal is to achieve the first direct observation of non-linear effects in
electromagnetism predicted by QED and the measurement of the photon-photon
scattering cross section at low energies (1-2 eV). Physical processes such as
ALP and MCP production in a magnetic field could also be accessible if
sensitive enough operation is reached. The short term experimental strategy is
to compact as much as possible the dimensions of the apparatus in order to
bring noise sources under control and to attain a sufficient sensitivity. We
will also briefly mention future pespectives, such as a scheme to implement the
resonant regeneration principle for the detection of ALPs.Comment: Paper submitted to the proceedings of the "4th Patras Workshop on
Axions, WIMPs and WISPs", DESY, Hamburg Site /Germany, 18-21 June 200
Optical production and detection of dark matter candidates
The PVLAS collaboration is at present running, at the Laboratori Nazionali di
Legnaro of I.N.F.N., Padova, Italy, a very sensitive optical ellipsometer
capable of measuring the small rotations or ellipticities which can be acquired
by a linearly polarized laser beam propagating in vacuum through a transverse
magnetic feld (vacuum magnetic birefringence). The apparatus will also be able
to set new limits on mass and coupling constant of light scalar/pseudoscalar
particles coupling to two photons by both producing and detecting the
hypothetical particles. The axion, introduced to explain parity conservation in
strong interactions, is an example of this class of particles, all of which are
considered possible dark matter candidates. The PVLAS apparatus consists of a
very high finesse (> 140000), 6.4 m long, Fabry-Perot cavity immersed in an
intense dipolar magnetic field (~6.5 T). A linearly polarized laser beam is
frequency locked to the cavity and analysed, using a heterodyne technique, for
rotation and/or ellipticity acquired within the magnetic field.Comment: presented at "Frontier Detectors for Frontier Physics - 8th Pisa
Meeting on Advanced Detectors - May 21-27, 2000" to appear in: Nucl.Instr.
and Meth.
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
Detecting solar chameleons through radiation pressure
Light scalar fields can drive the accelerated expansion of the universe.
Hence, they are obvious dark energy candidates. To make such models compatible
with tests of General Relativity in the solar system and "fifth force" searches
on Earth, one needs to screen them. One possibility is the so-called
"chameleon" mechanism, which renders an effective mass depending on the local
matter density. If chameleon particles exist, they can be produced in the sun
and detected on Earth exploiting the equivalent of a radiation pressure. Since
their effective mass scales with the local matter density, chameleons can be
reflected by a dense medium if their effective mass becomes greater than their
total energy. Thus, under appropriate conditions, a flux of solar chameleons
may be sensed by detecting the total instantaneous momentum transferred to a
suitable opto-mechanical force/pressure sensor. We calculate the solar
chameleon spectrum and the reach in the chameleon parameter space of an
experiment using the preliminary results from a force/pressure sensor,
currently under development at INFN Trieste, to be mounted in the focal plane
of one of the X-Ray telescopes of the CAST experiment at CERN. We show, that
such an experiment signifies a pioneering effort probing uncharted chameleon
parameter space.Comment: revised versio
Experimental observation of optical rotation generated in vacuum by a magnetic field
We report the experimental observation of a light polarization rotation in
vacuum in the presence of a transverse magnetic field. Assuming that data
distribution is Gaussian, the average measured rotation is (3.9+/-0.5)e-12
rad/pass, at 5 T with 44000 passes through a 1m long magnet, with lambda = 1064
nm. The relevance of this result in terms of the existence of a light, neutral,
spin-zero particle is discussed.Comment: 11 pages, 4 figures, submitted to Physical Review Letters Comment to
version 2: minor changes to abstract and final discussion. Added 2 references
Comment to version 3: corrected minor typographical errors, eliminated the
distinction between scalar and pseudoscalar in the particle interpretation of
the resul
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