New Shaving Scheme for Low-Intensity Beams in the CERN PS Booster and Feasibility at 160 MeV

The PS Booster is the first synchrotron in the CERN proton accelerator chain, serving all downstream machines. As part of the LHC Injector Upgrade Project, the PSB injection energy will increase from 50 MeV to 160 MeV and a new H⁻ charge-exchange injection scheme will be implemented. Beam losses are a concern due to the increased injection energy, and mitigation scenarios are under investigation. On the other hand it is desirable for low-intensity beams to have the possibility to precisely tailor sub-micron beam emittances through controlled scraping (transverse shaving process) towards a suitable aperture restriction. Challenges are the higher activation potential of the beam and the smaller transverse beam sizes around 160 MeV as compared to 63 MeV, at which the shaving is presently done. This paper describes the proposal of a new shaving scheme, more robust with respect to the steering errors and the choice of the working point, which localizes the scraping losses on the main PS Booster aperture restriction. The robustness of the new method, together with the results of simulations and measurements are discussed for the current (50 MeV) and future (160 MeV) situation.