272 research outputs found
Recent Advances in Electron and Positron Sources
Recent advances in electron and positron sources have resulted in new
capabilities driven in most cases by the increasing demands of advanced
accelerating systems. Electron sources for brighter beams and for high
average-current beams are described. The status and remaining challenges for
polarized electron beams are also discussed. For positron sources, recent
activity in the development of polarized positron beams for future colliders is
reviewed. Finally, a new proposal for combining laser cooling with beam
polarization is presented.Comment: 9 pages, 3 figures, contributed to the AAC 2000 Worksho
Recommended from our members
Summary of Polarized e-/e+ Source Presentations
The development of polarized electron sources in the 1970s capable of generating beams for injection into electron accelerators has been a major enabling factor for spin physics with electrons during the past quarter century. These sources continue to be refined for higher polarization and better operability. Recent developments were presented at this workshop in both plenary sessions and in 2 separate parallel sessions. The ILC plans to utilize not only a polarized electron source but also a polarized positron source. The current state of two types of positron sources were presented. This paper is a brief summary of all of these presentations
The SLAC Polarized Electron Source
The SLAC PES, developed in the early 1990s for the SLC, has been in
continuous use since 1992, during which time it has undergone numerous
upgrades. The upgrades include improved cathodes with their matching laser
systems, modified activation techniques and better diagnostics. The source
itself and its performance with these upgrades will be described with special
attention given to recent high-intensity long-pulse operation for the E-158
fixed-target parity-violating experiment.Comment: 6 pages, 4 figures, Workshop on Polarized Electron Sources and
Polarimeters (PESP 2002), September 4-6, 2002, Danvers, M
Compendium of scientific linacs
This compendium comprises 176 scientific linacs distributed over 3 continents
Atomic Hydrogen Cleaning of Polarized GaAs Photocathodes
Atomic hydrogen cleaning followed by heat cleaning at 450C was used
to prepare negative-electron-affinity GaAs photocathodes. When hydrogen ions
were eliminated, quantum efficiencies of 15% were obtained for bulk GaAs
cathodes, higher than the results obtained using conventional 600C heat
cleaning. The low-temperature cleaning technique was successfully applied to
thin, strained GaAs cathodes used for producing highly polarized electrons. No
depolarization was observed even when the optimum cleaning time of about 30
seconds was extended by a factor of 100
Strain-Compensated AlInGaAs-GaAsP Superlattices for Highly-Polarized Electron Emission
Spin-polarized electron emission from the first superlattice photocathodes
developed with strain compensation is investigated. An opposite strain in the
quantum well and barrier layers is complished using an InAlGaAs/GaAsP
superlattice structure. The measured values of maximum polarization and quantum
yield for the structure with a 0.18 um-thick working layer are close to the
best results reported for any strained superlattice photocathode structure,
demonstrating the high potential of strain compensation for future photocathode
applications. An analysis of the photoemission spectra is used to estimate the
parameters responsible for the polarization losses.Comment: 10 pages, 2 figure
Electron (positron) beam polarization by Compton scattering on circularly polarized laser photons
In a number of papers an attractive method of laser polarization of electrons
(positrons) at storage rings or linear colliders has been proposed. We show
that these suggestions are incorrect and based on errors in simulation of
multiple Compton scattering and in calculation of the Compton spin-flip cross
sections. We argue that the equilibrium polarization in this method is zero.Comment: 11 pages, LaTeX, talk at 9-th Intern. Workshop on Linear Colliders
(LC02), Feb. 4-8, 2002, SLAC, Stanford, US
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