The Use of a Passive Scatterer for SPS Slow Extraction Beam Loss Reduction

A significant reduction in the fraction of protons lost on the SPS electrostatic septum ES during resonant slow extraction is highly desirable for present Fixed-Target beam operation, and will become mandatory for the proposed SHiP experiment, which is now being studied in the framework of CERN's Physics Beyond Colliders program. In this paper the possible use of a passive scattering device (diffuser) is investigated. The physics processes underlying the use of a diffuser are described, and the dependence on the diffuser geometry, material and location of the potential loss reduction on the electrostatic septum (ES) wires is investigated with a semi-analytical approach. Numerical simulations to quantify the expected performance gain for the optimum configuration are presented, and the results discussed in view of the feasibility of a potential realisation in the SPS.