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Title: Predicting halo population and fractional loss in megawatt proton linacs
Plain: Simulations cannot yet predict the tiny fraction of protons that escape the core of an intense linac beam, which is what matters for radiation damage.
Precise: In MW-class proton and H- linacs (SNS, J-PARC, ESS, PIP-II) losses must stay below about 1e-6 to 1e-4 of the beam per unit length. Predict, blind and to within a factor 2, the halo population beyond 5 rms beam sizes from the measured initial distribution, lattice errors and space charge, and identify which mechanisms (envelope mismatch, particle-core resonances, intrabeam stripping of H- ions) dominate the measured loss pattern.
Settled by: Blind prediction of halo profiles measured with high-dynamic-range diagnostics in an operating MW linac.
Kind: phenomenon
Answer type: mechanism
References: (empty)
Literature status: open
Status note: (empty)
Posed since: (empty)