• B.D.S. Hall, G. Burt, C. Lingwood
  Cockcroft Institute, Lancaster University, Lancaster
• R.A. Rimmer, H. Wang
  JLAB, Newport News, Virginia

The planned lu­mi­nos­i­ty up­grade to LHC is like­ly to ne­ces­si­tate a large cross­ing angle and a local crab cross­ing scheme. For this scheme crab cav­i­ties align bunch­es prior to col­li­sion. The scheme re­quires at least four such cav­i­ties, a pair on each beam line ei­ther side of the in­ter­ac­tion point (IP). Up­stream cav­i­ties ini­ti­ate ro­ta­tion and down­stream cav­i­ties can­cel ro­ta­tion. Can­cel­la­tion is usu­al­ly done at a lo­ca­tion where the op­tics has re-aligned the bunch. The beam line sep­a­ra­tion near the IP ne­ces­si­tates a more com­pact de­sign than is pos­si­ble with el­lip­ti­cal cav­i­ties such as those used at KEK. The re­duc­tion in size must be achieved with­out an in­crease in the op­er­a­tional fre­quen­cy to main­tain com­pat­i­bil­i­ty with the long bunch length of the LHC. This paper pro­pos­es a suit­able su­per­con­duct­ing vari­ant of a four rod coax­i­al de­flect­ing cav­i­ty (to be phased as a crab cav­i­ty), and pre­sents an­a­lyt­i­cal mod­els and sim­u­la­tions of suit­able de­signs.