A MODIFIED HALBACH QUADRUPOLE FOR NUCLEAR PHYSICS APPLICATIONS

摘要

The proposed eRHIC accelerator will collide 20 GeV polarized electrons with 250 GeV polarized protons or 100 GeV/n polarized ~3He ions or other unpolarized heavy ions. The electron accelerator of the eRHIC will be based on a 1.665 GeV Energy Recovery Linac (ERL) placed in the RHIC tunnel with two recirculating rings placed alongside the RHIC accelerator. The recirculating rings are based on the Fixed Field Alternating Gradient (FFAG) principle and are made of FODO cells with two quadrupoles per cell. A modified Halbach type quadrupole has been designed to be used as a focusing or defocusing quad in the FFAG cell of the recirculating rings. This paper is a study of the 2D and 3D electromagnetic design of the quadrupoles. The experimentally measured multipoles of the modified Halbach quadrupoles are also compared with those calculated using the OPERA computer code. The beam optics of one of the FFAG cells will also be presented.