Rapid-cycling synchrotron for multi-megawatt proton facility at Fermilab

Abstract

A: The Fermilab accelerator complex delivers intense high-energy proton beams to a variety of fixed-target scientific programs, including a flagship long-baseline neutrino program. With the advent of the Deep Underground Neutrino Experiment (DUNE) and Long Baseline Neutrino Facility (LBNF) program there is strong motivation for a 2.4 MW beam power upgrade of the Fermilab proton facility. We show the Fermilab proton facility can achieve 2.4 MW with a new rapid-cycling synchrotron (RCS) to replace the Fermilab Booster and we provide a comprehensive technical analysis of the RCS-based facility design. Past design efforts and operational experience at the Fermilab Booster, J-PARC RCS, and Oak Ridge SNS are leveraged to provide strong empirical precedent for the design. We provide a parametric study of slip-stacking accumulation, RCS extraction energy, space-charge limits, beampipe aperture, eddy current heating, injection foil heating, and lattice optics. The 2.4 MW benchmark for the long baseline neutrino program is achieved independently of a previously proposed multi-GeV linac program, but we assess the impact the linac upgrade would have on RCS performance.

Bifurcation analysis of nonlinear Hamiltonian dynamics in the Fermilab Integrable Optics Test Accelerator

“…The application of these methods to the IOTA ring reveals a rich diversity of accessible dynamical behavior that could be explored experimentally, subject to the limitations of the physical aperture. Understanding the dynamical dependence on the system parameters ðH; I; τÞ may also indicate new machine operating points and help to guide future accelerator designs [12] based on similar nonlinear magnetic elements. While we have not addressed the computation of characteristic orbital frequencies in this paper, we remark that this information may be obtained from the momentum mapping F , by evaluating a set of appropriately defined integrals over paths that lie within the level sets of F .…”

“…In addition, canonical transformations to such coordinates are difficult to obtain in explicit form in even the simplest systems. The techniques described here do not require the use of action-angle coordinates, and are sufficiently general to be applied to future machine designs [12] described by an autonomous Hamiltonian, in which a second invariant is analytically known. Related techniques have recently had a major impact in molecular spectroscopy [13][14][15], and have been applied to a number of systems of physical interest [16,17].…”

Novel Approaches to High-Power Proton Beams [Slides]

“…With present operational technology, protons would be accumulated in the Fermilab RCS via charge-stripping foil injection. The linear optics of the RCS [4] are heavily constrained by the foilheating limits (large-betas) and particle loss due to scattering off the injection foil (phase-advance into collimators). However, the combined us of use of high-power lasers and magnetic fields has an emerged as an alternative approach to stripping H − beams.…”

“…Nonlinear integrable optics is an innovation in acceleration design to provide immense nonlinear focusing without generating parametric resonances [12]. Strong nonlinear focusing could significantly enhance the performance of an RCS by mitigating halo formation and damping collective instabilities [4].…”

“…The Proton Improvement Plan II (PIP-II) [3] is a set of upgrades and improvements to the Fermilab accelerator complex to achieve 1.2 MW beam power at 120 GeV. A recent design study [4] proposes to enable 2.4 MW Main Injector (MI) beam power by replacing the Fermilab Booster with a new rapid-cycling synchrotron (RCS). The proposal is unique in that it envisions multi-MW slip-stacking, although alternative approaches are discussed.…”