Development of a 400 MHz Superconducting RF Crabbing Cavity

The Large Hadron Collider (LHC), which is scheduled to be fully operational in 2009, will be at the energy frontier in high energy physics for many years to come. Even before being operational, plans have been under discussion for an upgrade, particularly with respect to an increase in luminosity. One avenue that has been under discussion is the introduction of a bunch crabbing scheme to restore the luminosity lost due the finite crossing angle. Because LHC bunches are fairly long, the curvature introduced by the RF field must be kept to a minimum, in order to gain the maximum benefit from crabbing the bunches. This requirement implies low RF frequency, 400 MHz or less. Unfortunately, all conventional designs for RF crabbing cavities at that frequency are larger than space allows. This project will develop a 400 MHz superconducting crabbing cavity that is about half the size of the conventional design and, at the same time, has other attractive properties. Phase I will develop the crabbing structure and cryomodule design, based on systems efficiency, beam dynamics simulations, and higher order mode (HOM) analysis. Phase II will prototype critical aspects of the system, such as the SRF cavities, power coupler, HOM spectrum, and frequency tuners. Commercial Applications and other Benefits as described by the awardee: A cavity that will satisfy the requirements of the Large Hadron Collider luminosity upgrade would be marketed internationally to existing and planned facilities.