• J. Tang, J.F. Chen, Y. Zou
  IHEP Beijing, Beijing

Momentum collimation in a high intensity RCS is a very important issue. Based on the two-stage collimation principle, a combined momentum collimation method is proposed and studied here. The method makes use of the combination of secondary collimators in both the longitudinal and transverse planes. The primary collimator is placed at a high-dispersion location of an arc, and the transverse and longitudinal secondary collimators are in a dispersion-free long straight section and in an arc, respectively. The particles with a positive momentum deviation will be scattered by a carbon scraper and then cleaned by the transverse collimators, whereas the particles with a negative momentum deviation will be scattered by a Tantalum scraper and cleaned by the longitudinal secondary collimators. This is due that a carbon foil produces relatively more scattering than a Tantalum foil if the energy loss is kept the same. The relevant requirements on the lattice design are also discussed, especially for compact rings. The multi-particle simulations using both TURTLE and ORBIT codes are presented to show the physical images of the collimation method, with the input of the CSNS RCS ring.