352 research outputs found
A polarisation modulation scheme for measuring vacuum magnetic birefringence with static fields
A novel polarisation modulation scheme for polarimeters based on Fabry-Perot
cavities is presented. The application to the proposed HERA-X experiment aiming
to measuring the magnetic birefringence of vacuum with the HERA superconducting
magnets is discussed
Upper limits on the amplitude of ultra-high-frequency gravitational waves from graviton to photon conversion
In this work, we present the first experimental upper limits on the presence of stochastic gravitational waves in a frequency band with frequencies above 1 THz. We exclude gravitational waves in the frequency bands from (2.7 - 14) × 10 14 Hz and (5 - 12) × 10 18 Hz down to a characteristic amplitude of hcmin≈6×10-26 and hcmin≈5×10-28 at 95% confidence level, respectively. To obtain these results, we used data from existing facilities that have been constructed and operated with the aim of detecting weakly interacting slim particles, pointing out that these facilities are also sensitive to gravitational waves by graviton to photon conversion in the presence of a magnetic field. The principle applies to all experiments of this kind, with prospects of constraining (or detecting), for example, gravitational waves from light primordial black-hole evaporation in the early universe
Upper limits on the amplitude of ultra-high-frequency gravitational waves from graviton to photon conversion
In this work, we present the first experimental upper limits on the presence of stochastic gravitational waves in a frequency band with frequencies above 1 THz. We exclude gravitational waves in the frequency bands from
(2.7−14)×
10
14
(2.7−14)×1014
Hz and
(5−12)×
10
18
(5−12)×1018
Hz down to a characteristic amplitude of
h
min
c
≈6×
10
−26
hcmin≈6×10−26
and
h
min
c
≈5×
10
−28
hcmin≈5×10−28
at 95% confidence level, respectively. To obtain these results, we used data from existing facilities that have been constructed and operated with the aim of detecting weakly interacting slim particles, pointing out that these facilities are also sensitive to gravitational waves by graviton to photon conversion in the presence of a magnetic field. The principle applies to all experiments of this kind, with prospects of constraining (or detecting), for example, gravitational waves from light primordial black-hole evaporation in the early universe
Measurement of the Cotton Mouton effect of water vapour
In this paper we report on a measurement of the Cotton Mouton effect of water
vapour. Measurement performed at room temperature ( K) with a wavelength
of 1064 nm gave the value for the
unit magnetic birefringence (1 T magnetic field and atmospheric pressure)
The PVLAS experiment: measuring vacuum magnetic birefringence and dichroism with a birefringent Fabry-Perot cavity
Vacuum magnetic birefringence was predicted long time ago and is still
lacking a direct experimental confirmation. Several experimental efforts are
striving to reach this goal, and the sequence of results promises a success in
the next few years. This measurement generally is accompanied by the search for
hypothetical light particles that couple to two photons. The PVLAS experiment
employs a sensitive polarimeter based on a high finesse Fabry-Perot cavity. In
this paper we report on the latest experimental results of this experiment. The
data are analysed taking into account the intrinsic birefringence of the
dielectric mirrors of the cavity. Besides the limit on the vacuum magnetic
birefringence, the measurements also allow the model-independent exclusion of
new regions in the parameter space of axion-like and milli-charged particles.
In particular, these last limits hold also for all types of neutrinos,
resulting in a laboratory limit on their charge
New PVLAS model independent limit for the axion coupling to for axion masses above 1meV
During 2014 the PVLAS experiment has started data taking with a new apparatus
installed at the INFN Section of Ferrara, Italy. The main target of the
experiment is the observation of magnetic birefringence of vacuum. According to
QED, the ellipticity generated by the magnetic birefringence of vacuum in the
experimental apparatus is expected to be . No ellipticity signal is present so far with a noise floor
after 210 hours of data taking.
The resulting ellipticity limit provides the best model independent upper limit
on the coupling of axions to for axion masses above eV
Erratum to: A polarisation modulation scheme for measuring vacuum magnetic birefringence with static fields
In the original article unfortunately we missed two typos in the equation for at the top of the fourth page of the article
First results from the new PVLAS apparatus: a new limit on vacuum magnetic birefringence
Several groups are carrying out experiments to observe and measure vacuum
magnetic birefringence, predicted by Quantum Electrodynamics (QED). We have
started running the new PVLAS apparatus installed in Ferrara, Italy, and have
measured a noise floor value for the unitary field magnetic birefringence of
vacuum T (the error
represents a 1 deviation). This measurement is compatible with zero and
hence represents a new limit on vacuum magnetic birefringence deriving from non
linear electrodynamics. This result reduces to a factor 50 the gap to be
overcome to measure for the first time the value of predicted by QED:
~T. These birefringence measurements also yield improved
model-independent bounds on the coupling constant of axion-like particles to
two photons, for masses greater than 1 meV, along with a factor two improvement
of the fractional charge limit on millicharged particles (fermions and
scalars), including neutrinos
Relic gravitational waves from light primordial black holes
The energy density of relic gravitational waves (GWs) emitted by primordial
black holes (PBHs) is calculated. We estimate the intensity of GWs produced at
quantum and classical scattering of PBHs, the classical graviton emission from
the PBH binaries in the early Universe, and the graviton emission due to PBH
evaporation. If nonrelativistic PBHs dominated the cosmological energy density
prior to their evaporation, the probability of formation of dense clusters of
PBHs and their binaries in such clusters would be significant and the energy
density of the generated gravitational waves in the present day universe could
exceed that produced by other known mechanisms. The intensity of these
gravitational waves would be maximal in the GHz frequency band of the spectrum
or higher and makes their observation very difficult by present detectors but
also gives a rather good possibility to investigate it by present and future
high frequency gravitational waves electromagnetic detectors. However, the low
frequency part of the spectrum in the range Hz may be detectable
by the planned space interferometers DECIGO/BBO. For sufficiently long duration
of the PBH matter dominated stage the cosmological energy fraction of GWs from
inflation would be noticeably diluted.Comment: 32 pages, 4 figures; according to the referee comments some
inaccurate statements are corrected and high frequency detectors of
gravitational waves are briefly discusse
- …