Multimegawatt DAE$\delta$ALUS Cyclotrons for Neutrino Physics

TL;DR

This paper discusses the design and challenges of high-power multimegawatt cyclotrons for neutrino experiments, focusing on subsystem design, beam dynamics, and halo mitigation for future CP violation studies.

Contribution

It presents a detailed analysis of the design considerations and challenges for megawatt-class cyclotrons used in neutrino physics, including beam dynamics and subsystem optimization.

Findings

Successful beam dynamics simulations including space charge effects.

Identification of beam halo as a key limiting factor.

Design insights for ion source, injection, and RF systems.

Abstract

DAE$\delta$ALUS (Decay-At-rest Experiment for $\delta_{CP}$ studies At the Laboratory for Underground Science) provides a new approach to the search for CP violation in the neutrino sector. High-power continuous-wave proton cyclotrons efficiently provide the necessary proton beams with an energy of up to 800 MeV to create neutrinos from pion and muon decay-at-rest. The experiment searches for $\bar{\nu}_{\mu} \rightarrow \bar{\nu}_e$ at short baselines corresponding to the atmospheric $\Delta m^2$ region. The $\bar{\nu}_e$ will be detected via inverse beta decay. Thus, the cyclotrons will be employed at a future ultra-large gadolinium-doped water or scintillator detector. In this paper we address the most challenging questions regarding a cyclotron-based high-power proton driver in the megawatt range with a kinetic energy of 800 MeV. Aspects of important subsystems like the ion source and injection chain, the magnet design and radio frequency system will be addressed. Precise beam dynamics simulations, including space charge and the $\text{H}_2^+$ stripping process, are the base for the characterization and quantification of the beam halo -- one of the most limiting processes in high-power particle accelerators.