An 8 GeV linac as the Booster replacement in the Fermilab Power Upgrade

Increasing the Main Injector beam power above ∼ 1.2 MW requires replacement of the 8 GeV Booster by a higher intensity alternative. In this paper, we consider an 8 GeV linac Booster replacement that produces 8 GeV H^- beam for injection into the Recycler Ring or Main Injector. This upgrade will maximize the beam available for neutrino production for the long baseline DUNE experiment to greater than 2.5 MW and enable a next generation of intensity frontier experiments. The 8 GeV linac takes ∼ 1 GeV beam from the PIP-II Linac and accelerates it to ∼ 2 GeV in a 650 MHz superconducting RF linac, followed by a ∼ 2 to 8 GeV pulsed linac using 1300 MHz cryomodules. The linac components incorporate recent improvements in superconducting RF technology. The linac configuration and beam dynamics requirements are presented. Injection options are discussed, including use of an 8 GeV Accumulator Ring. Foil-based injection is the present standard but R&D toward implementing laser-assisted injection could enable a significant improvement. Research needed to implement the Booster replacement is described.