338 research outputs found
The QUAX proposal: a search of galactic axion with magnetic materials
Aim of the QUAX (QUaerere AXion) proposal is to exploit the interaction of
cosmological axions with the spin of electrons in a magnetized sample. Their
effect is equivalent to the application of an oscillating rf field with
frequency and amplitude which are fixed by axion mass and coupling constant,
respectively. The rf receiver module of the QUAX detector consists of
magnetized samples with the Larmor resonance frequency tuned to the axion mass
by a polarizing static magnetic field. The interaction of electrons with the
axion-equivalent rf field produces oscillations in the total magnetization of
the samples. To amplify such a tiny field, a pump field at the same frequency
is applied in a direction orthogonal to the polarizing field. The induced
oscillatory magnetization along the polarizing field is measured by a SQUID
amplifier operated at its quantum noise level.Comment: 5 pages, Contribution for the proceedings of the TAUP2015,
International Conference on Topics in Astroparticle and Underground Physics,
7-11 September 2015, Torino, Ital
The influence of time varying magnetic fields on the determinations of Newton’s constant at the Bureau International des Poids et Mesures
Electrostatic Patch Effect in Cylindrical Geometry. III. Torques
We continue to study the effect of uneven voltage distribution on two close
cylindrical conductors with parallel axes started in our papers [1] and [2],
now to find the electrostatic torques. We calculate the electrostatic potential
and energy to lowest order in the gap to cylinder radius ratio for an arbitrary
relative rotation of the cylinders about their symmetry axis. By energy
conservation, the axial torque, independent of the uniform voltage difference,
is found as a derivative of the energy in the rotation angle. We also derive
both the axial and slanting torques by the surface integration method: the
torque vector is the integral over the cylinder surface of the cross product of
the electrostatic force on a surface element and its position vector. The
slanting torque consists of two parts: one coming from the interaction between
the patch and the uniform voltages, and the other due to the patch interaction.
General properties of the torques are described. A convenient model of a
localized patch suggested in [2] is used to calculate the torques explicitly in
terms of elementary functions. Based on this, we analyze in detail patch
interaction for one pair of patches, namely, the torque dependence on the patch
parameters (width and strength) and their mutual positions. The effect of the
axial torque is then studied for the experimental conditions of the STEP
mission.Comment: 28 pages, 6 Figures. Submitted to Classical Quantum Gravit
Searching for galactic axions through magnetized media: QUAX status report
The current status of the QUAX R\&D program is presented. QUAX is a
feasibility study for a detection of axion as dark matter based on the coupling
to the electrons. The relevant signal is a magnetization change of a magnetic
material placed inside a resonant microwave cavity and polarized with a static
magnetic field.Comment: Contributed to the 13th Patras Workshop on Axions, WIMPs and WISPs,
Thessaloniki, May 15 to 19, 201
A Measurement of Newton's Gravitational Constant
A precision measurement of the gravitational constant has been made using
a beam balance. Special attention has been given to determining the
calibration, the effect of a possible nonlinearity of the balance and the
zero-point variation of the balance. The equipment, the measurements and the
analysis are described in detail. The value obtained for G is 6.674252(109)(54)
10^{-11} m3 kg-1 s-2. The relative statistical and systematic uncertainties of
this result are 16.3 10^{-6} and 8.1 10^{-6}, respectively.Comment: 26 pages, 20 figures, Accepted for publication by Phys. Rev.
Meta-analysis of the effect of perioperative intravenous lidocaine on return of gastrointestinal function after colorectal surgery
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