19 research outputs found
Gravitomagnetism and spinor quantum mechanics
We give a systematic treatment of a spin 1/2 particle in a combined
electromagnetic field and a weak gravitational field that is produced by a
slowly moving matter source. This paper continues previous work on a spin zero
particle, but it is largely self-contained and may serve as an introduction to
spinors in a Riemann space. The analysis is based on the Dirac equation
expressed in generally covariant form and coupled minimally to the
electromagnetic field. The restriction to a slowly moving matter source, such
as the earth, allows us to describe the gravitational field by a
gravitoelectric (Newtonian) potential and a gravitomagnetic (frame-dragging)
vector potential, the existence of which has recently been experimentally
verified. Our main interest is the coupling of the orbital and spin angular
momenta of the particle to the gravitomagnetic field. Specifically we calculate
the gravitational gyromagnetic ratio as gsubg=1 ; this is to be compared with
the electromagnetic gyromagnetic ratio of gsube=2 for a Dirac electron.Comment: 12 pages, 1 figur
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Beam Dynamics Studies for the SPARC Project
The aim of the SPARC project, is to promote an R&D activity oriented to the development of a high brightness photoinjector to drive SASE-FEL experiments. We discuss in this paper the status of the beam dynamics simulation activities
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Bunch Length Measurements in SPEAR3
A series of bunch length measurements were made in SPEAR3 for two different machine optics. In the achromatic optics the bunch length increases from the low-current value of 16.6ps rms to about 30ps at 25ma/bunch yielding an inductive impedance of -0.17{Omega}. Reducing the momentum compaction factor by a factor of {approx}60 [1] yields a low-current bunch length of {approx}4ps rms. In this paper we review the experimental setup and results
Index Card: October 15, 1927
Note card unsigned. It is addressed to Thomas Evans in Eirie, PA. Purpose unclear, but lists cost and mentions cash
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Simulation of RF Cavity Dark Current in Presence of Helical Magnetic Field
In order to produce muon beam of high enough quality to be used for a Muon Collider, its large phase space must be cooled several orders of magnitude. This task can be accomplished by ionization cooling. Ionization cooling consists of passing a high-emittance muon beam alternately through regions of low Z material, such as liquid hydrogen, and very high accelerating RF cavities within a multi-Tesla solenoidal focusing channel. But first high power tests of RF cavity with beryllium windows in solenoidal magnetic field showed a dramatic drop in accelerating gradient due to RF breakdowns. It has been concluded that external magnetic fields parallel to RF electric field significantly modifies the performance of RF cavities. However, magnetic field in Helical Cooling Channel has a strong dipole component in addition to solenoidal one. The dipole component essentially changes electron motion in a cavity compare to pure solenoidal case, making dark current less focused at field emission sites. The simulation of dark current dynamic in HCC performed with CST Studio Suit is presented in this paper