Overview of the LHC dynamic aperture studies

The dynamic aperture (D.A.) of the LHC is estimated by tracking a thin-lens model of the lattice over a real machine time of 9 seconds. This raw result is then processed to predict the D.A. over longer times and realistic conditions. We discuss the reliability and limits of the method, the phenomena limiting the D.A. and scaling laws used for fast estimates. The long-term dynamic aperture at injection is close to the requirements, with prospects of further improvements

Phenomena associated with the acceleration of polarized protons in circular accelerators

A series of machine studies has been done with the zero Gradient Synchrotron (ZGS) at Argonne National Laboratory in order to better understand the phenomena associated with the acceleration of polarized protons and to determine the feasibility of acceleration to energies higher than the 12 GeV/c available at the ZGS. We also investigated the question of how long polarized protons can remain in storage rings without losing excessive polarization.The three topics investigated were: 1. The adiabatic crossing of an intrinsic depolarizing resonance. 2. The depolarization due to imperfection resonances. 3. The survival time of polarization on a long flattop.This paper is a preliminary report of these three investigations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87334/2/396_1.pd