Fermilab, Batavia, Illinois, USA
FRIB, East Lansing, Michigan, USA
The new PIP-II superconducting linac will deliver a 2 mA average H- beam to the existing Booster synchrotron. The injected beam is accumulated by charge exchange over approximately 300 turns; phase space painting is used to mitigate space charge effects. To limit the power load on the internal waste beam absorber from the transverse tails of the H− distribution missing the foil, the beam will be collimated in both planes in the linac to Booster transfer line using compact collimators of a novel design. Both the number of parasitic hits and the fraction of the beam missing the foil are sensitive functions of the H− beam centroid position with respect to the edge of the foil. The positioning of the collimation is constrained by the availability of suitable space in the transfer line lattice, by specifics of the collimator design, by the phase space orientation at the collimator, and by the betatron phase advance to the foil needed to achieve proper orientation of the spatial distribution at the injection point. In this contribution, we describe the procedure by which collimator positions were optimized. We then discuss the expected performance of the overall system.
Uppsala University, Uppsala, Sweden
The ESSnuSB, a neutrino facility based on the European Spallation Source, aims at measuring, with precision, the charge-parity (CP) violating lepton phase at the 2nd oscillation maximum. The ESS linac will have to be upgraded to provide an additional 5 MW beam for the ESSnuSB to produce an unprecedented high-intensity neutrino beam. An accumulator ring is employed to compress the 2.86 ms long pulse from the linac to around 1.5 µs in order to satisfy the target requirements and improve the physics performance. In the operation of a high-intensity proton accumulator, the most important issue is to minimize the uncontrolled beam loss to reduce component activation to make hands-on maintenance possible. For this purpose, a two-stage collimation system is designed, which consists of a thin scraper to scatter halo particles and secondary collimators to absorb those scattered particles. Phase advances between scraper and secondary collimators, together with the material, the thickness of collimators, have been detailed studied and numerical simulations have been performed to evaluate the performance of the collimation system. This paper presents the design of the collimation system.
