Other Means to Increase the SPS 25 ns Performance – Transverse Plane

Abstract

The LHC Injectors Upgrade (LIU) project aims at extending the brightness and intensity reach of the injector complex. After the implementation of all LIU upgrades, beam loading and longitudinal instabilities in the SPS will likely remain the main limitations for the achievable intensity of the 25 ns beam. The goal of this paper is to present options to circumvent this limitation and increase the intensity of the 25 ns beams out of the SPS. In particular, two aspects will be addressed: 1) Alternative SPS optics configurations with intermediate transition  energy between Q20 and Q26. Although the presently operational Q20 optics pushed the TMCI threshold from 1.6×10¹¹ p/b to 4×10¹¹ p/b, it might not be the optimal choice for  maximizing the intensity of the 25 ns beam due to the RF power limitations. Possible optics configurations with intermediate transition energy are investigated, aiming at a better  balance between TMCI threshold and RF power requirements. 2) Increase of the number of colliding bunches in the LHC by transferring a larger number of bunches between the PS and the SPS. In this context, schemes for transferring 80 or more bunches per PS batch and their operational implications are discussed, together with possible advantages for mitigating other limits in the SPS and LHC. Finally, machine development studies during Run 2 for evaluating the feasibility and potential of these schemes are addressed.