2,133 research outputs found
A method for detecting gravitational waves coincident with gamma ray bursts
The mechanism for gamma ray bursters and the detection of gravitational waves
(GWs) are two outstanding problems facing modern physics. Many models of gamma
ray bursters predict copious GW emission, so the assumption of an association
between GWs and GRBs may be testable with existing bar GW detector data. We
consider Weber bar data streams in the vicinity of known GRB times and present
calculations of the expected signal after co-addition of 1000 GW/GRBs that have
been shifted to a common zero time. Our calculations are based on assumptions
concerning the GW spectrum and the redshift distribution of GW/GRB sources
which are consistent with current GW/GRB models. We discuss further
possibilities of GW detection associated with GRBs in light of future bar
detector improvements and suggest that co-addition of data from several
improved bar detectors may result in detection of GWs (if the GW/GRB assumption
is correct) on a time scale comparable with the LIGO projects.Comment: Accepted by MNRAS. 9 pages, 6 ps figures, MNRAS style. Proof
corrections made, accepted versio
Addressing a single NV spin with a macroscopic dielectric microwave cavity
We present a technique for addressing single NV center spins in diamond
over macroscopic distances using a tunable dielectric microwave cavity. We
demonstrate optically detected magnetic resonance (ODMR) for a single NV
center in a nanodiamond (ND) located directly under the macroscopic microwave
cavity. By moving the cavity relative to the ND, we record the ODMR signal as a
function of position, mapping out the distribution of the cavity magnetic field
along one axis. In addition, we argue that our system could be used to
determine the orientation of the NV major axis in a straightforward
manner
Fabrication and Properties of an Anisotropic TiO 2 Dielectric Composite
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65849/1/j.1551-2916.2006.01134.x.pd
Tests of relativity using a microwave resonator
The frequencies of a cryogenic sapphire oscillator and a hydrogen maser are
compared to set new constraints on a possible violation of Lorentz invariance.
We determine the variation of the oscillator frequency as a function of its
orientation (Michelson-Morley test) and of its velocity (Kennedy-Thorndike
test) with respect to a preferred frame candidate. We constrain the
corresponding parameters of the Mansouri and Sexl test theory to and which is equivalent to the best previous result for the
former and represents a 30 fold improvement for the latter.Comment: 8 pages, 2 figures, submitted to Physical Review Letters (October 3,
2002
On the Detection of a Scalar Stochastic Background of Gravitational Waves
In the near future we will witness the coming to a full operational regime of
laser interferometers and resonant mass detectors of spherical shape. In this
work we study the sensitivity of pairs of such gravitational wave detectors to
a scalar stochastic background of gravitational waves. Our computations are
carried out both for minimal and non minimal coupling of the scalar fields.Comment: 25 pages, 3 figure
Determination of scattering lengths from measurement of atom lifetime
The DIRAC experiment at CERN has achieved a sizeable production of
atoms and has significantly improved the precision on its lifetime
determination. From a sample of 21227 atomic pairs, a 4% measurement of the
S-wave scattering length difference
has been attained, providing an important test of Chiral Perturbation Theory.Comment: 6 pages, 6 figure
Detectability of gravitational wave events by spherical resonant-mass antennas
We have calculated signal-to-noise ratios for eight spherical resonant-mass
antennas interacting with gravitational radiation from inspiralling and
coalescing binary neutron stars and from the dynamical and secular bar-mode
instability of a rapidly rotating star. We find that by using technology that
could be available in the next several years, spherical antennas can detect
neutron star inspiral and coalescence at a distance of 15 Mpc and the dynamical
bar-mode instability at a distance of 2 Mpc.Comment: 39 pages, 4 EPS Figures, some additional SNRs for secular
instabilities, some changes to LIGO SNRs, Appendix added on the asymptotic
expansion of energy sensitivity, corrected supernova rates. Results available
at http://www.physics.umd.edu/rgroups/gen_rel_exp/snr.html Submitted to Phys.
Rev.
Cold atom Clocks and Applications
This paper describes advances in microwave frequency standards using
laser-cooled atoms at BNM-SYRTE. First, recent improvements of the Cs
and Rb atomic fountains are described. Thanks to the routine use of a
cryogenic sapphire oscillator as an ultra-stable local frequency reference, a
fountain frequency instability of where
is the measurement time in seconds is measured. The second advance is a
powerful method to control the frequency shift due to cold collisions. These
two advances lead to a frequency stability of at 7\times 10^{-16}^{87}^{133}$Cs fountains.
Finally we give an update on the cold atom space clock PHARAO developed in
collaboration with CNES. This clock is one of the main instruments of the
ACES/ESA mission which is scheduled to fly on board the International Space
Station in 2008, enabling a new generation of relativity tests.Comment: 30 pages, 11 figure
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