Spin Observables for Polarizing Antiprotons

The PAX project at GSI Darmstadt plans to polarize an antiproton beam by repeated interaction with a hydrogen target in a storage ring. Many of the beam particles are required to remain within the ring after interaction with the target, so small scattering angles are important. Hence we concentrate on low momentum transfer (small t), a region where electromagnetic effects dominate the hadronic effects. A colliding beam of polarized electrons with energy sufficient to provide scattering of antiprotons beyond ring acceptance may polarize an antiproton beam by spin filtering. Expressions for spin observables are provided and are used to estimate the rate of buildup of polarization of an antiproton beam.Comment: 4 pages, 2 figures, to be published in the Proceedings of the 17th International Spin Physics Symposium (SPIN 2006), Kyoto, Japan; October 2-7, 200

Dynamics of polarization buildup by spin filtering

There has been much recent research into polarizing an antiproton beam, instigated by the recent proposal from the PAX (Polarized Antiproton eXperiment) project at GSI Darmstadt. It plans to polarize an antiproton beam by repeated interaction with a polarized internal target in a storage ring. The method of polarization by spin filtering requires many of the beam particles to remain within the ring after scattering off the polarized internal target via electromagnetic and hadronic interactions. We present and solve sets of differential equations which describe the buildup of polarization by spin filtering in many different scenarios of interest to projects planning to produce high intensity polarized beams. These scenarios are: 1) spin filtering of a fully stored beam, 2) spin filtering while the beam is being accumulated, i.e. unpolarized particles are continuously being fed into the beam, 3) the particle input rate is equal to the rate at which particles are being lost due to scattering beyond ring acceptance angle, the beam intensity remaining constant, 4) increasing the initial polarization of a stored beam by spin filtering, 5) the input of particles into the beam is stopped after a certain amount of time, but spin filtering continues. The rate of depolarization of a stored polarized beam on passing through an electron cooler is also shown to be negligible.Comment: 15 pages, references added, introduction elaborated on, some variables defined in more detail. Submitted to Eur. Phys. J.

Cultural Capital: Arts Graduates, Spatial Inequality, and London’s Impact on Cultural Labor Markets

This article looks at the degree to which spatial inequalities reinforce other forms of social inequality in cultural labor markets. It does so using the example of London, an acknowledged hub for the creative and cultural industries. Using pooled data from 2013 to 2015 quarters of the United Kingdom’s. Labour Force Survey, we consider the social makeup of London’s cultural labor force, and reveal the extent to which, rather than acting as an “engine room” of social mobility, London’s dominance in fact reenforces social class disparities in cultural employment