2,812 research outputs found
Special treatment reduces helium permeation of glass in vacuum systems
Internal surfaces of the glass component of a vacuum system are exposed to cesium in gaseous form to reduce helium permeation. The cesium gas is derived from decomposition of cesium nitrate through heating. Several minutes of exposure of the internal surfaces of the glass vessel are sufficient to complete the treatment
Extreme vacuum technology including cryosorption, diffusion pump and pressure calibration studies Summary technical report, 1 Feb. 1965 - 1 Mar. 1966
Cryosorption, diffusion pump, and pressure calibration studies in extreme vacuum science and technology application progra
Extreme vacuum technology including cryosorption, diffusion pump and pressure calibration studies Quarterly status report no. 8, 1 May - 1 Aug. 1965
Cryosorption, diffusion pump, and low pressure calibration studies on Penning gauge and cold cathode magnetro
Study of low pressure application of the orbitron
Evaluation of low pressure performance of orbitron ionization gaug
From Feynman Proof of Maxwell Equations to Noncommutative Quantum Mechanics
In 1990, Dyson published a proof due to Feynman of the Maxwell equations
assuming only the commutation relations between position and velocity. With
this minimal assumption, Feynman never supposed the existence of Hamiltonian or
Lagrangian formalism. In the present communication, we review the study of a
relativistic particle using ``Feynman brackets.'' We show that Poincar\'e's
magnetic angular momentum and Dirac magnetic monopole are the consequences of
the structure of the Lorentz Lie algebra defined by the Feynman's brackets.
Then, we extend these ideas to the dual momentum space by considering
noncommutative quantum mechanics. In this context, we show that the
noncommutativity of the coordinates is responsible for a new effect called the
spin Hall effect. We also show its relation with the Berry phase notion. As a
practical application, we found an unusual spin-orbit contribution of a
nonrelativistic particle that could be experimentally tested. Another practical
application is the Berry phase effect on the propagation of light in
inhomogeneous media.Comment: Presented at the 3rd Feynman Festival (Collage Park, Maryland,
U.S.A., August 2006
Pose, posture, formation and contortion in kinematic systems
The concepts of pose, posture, formation and contortion are defined for serial, parallel and hybrid kinematic systems. Workspace and jointspace structure is examined in terms of these concepts. The inter-relationships of pose, posture, formation and contortion are explored for a range of robot workspace and jointspace types
Spin Hall effect of Photons in a Static Gravitational Field
Starting from a Hamiltonian description of the photon within the set of
Bargmann-Wigner equations we derive new semiclassical equations of motion for
the photon propagating in static gravitational field. These equations which are
obtained in the representation diagonalizing the Hamiltonian at the order
, present the first order corrections to the geometrical optics. The
photon Hamiltonian shows a new kind of helicity-magnetotorsion coupling.
However, even for a torsionless space-time, photons do not follow the usual
null geodesic as a consequence of an anomalous velocity term. This term is
responsible for the gravitational birefringence phenomenon: photons with
distinct helicity follow different geodesics in a static gravitational field.Comment: 6 page
Extreme vacuum technology including cryopump, getter-ion pump, diffusion pump and pressure standardization studies Summary technical report, 16 Jun. 1966 - 16 Jun. 1967
Ultrahigh vacuum technology including cryopump, getter ion pump, diffusion pump, and pressure standardization studie
Appearance of Gauge Fields and Forces beyond the adiabatic approximation
We investigate the origin of quantum geometric phases, gauge fields and
forces beyond the adiabatic regime. In particular, we extend the notions of
geometric magnetic and electric forces discovered in studies of the
Born-Oppenheimer approximation to arbitrary quantum systems described by matrix
valued quantum Hamiltonians. The results are illustrated by several physical
relevant examples
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