[Paper Review] The DAE{\delta}ALUS Project: Rationale and Beam Requirements

J. Alonso|arXiv (Cornell University)|Oct 5, 2010

Particle accelerators and beam dynamics2 references3 citations

TL;DR

The DAEδALUS project proposes using compact, low-cost 0.8–1 GeV proton accelerators at 1.5, 8, and 20 km distances from a 300 kT water-Cherenkov neutrino detector to produce muon antineutrinos via stopped pion decay, complementing the LBNE experiment. The key contribution is a beamline design enabling high-precision studies of neutrino mass hierarchy and CP violation with modest beam parameters, emphasizing reliability, low activation, and cost under 1/10th of megawatt-class machines.

ABSTRACT

Neutrino physics focuses on huge detectors deep underground. The Sanford Lab in South Dakota will build a 300 kiloton water-Cherenkov detector 1500 meters deep for muon neutrino oscillation studies of the mass hierarchy and CP violation. This will be used by the Long Baseline experiment (LBNE) detecting few GeV neutrinos from Fermilab, 1300 km away. The DAE{\\delta}ALUS Collaboration also plans several neutrino-production sites at closer distances up to 20 km from the 300 kT detector, producing muon antineutrinos from stopped pions. The complementarity with LBNE greatly enhances results, and enthusiasm is mounting to do both experiments. DAE{\\delta}ALUS needs 0.8-1 GeV accelerators with mA proton beams. Three sites at 1.5, 8 and 20 km from the 300 kT detector require several accelerators. The cost per machine must be below 1/10 of existing megawatt-class proton machines. Beyond high power and energy, beam parameters are modest. Challenges are reliability, control of beam loss and minimizing activation. Options being studied are: a compact superconducting cyclotron; a ring cyclotron accelerating H2+ (with stripping extraction); and a stacked cyclotron with up to 9 planes sharing the same magnet yoke and rf systems.

Motivation & Objective

• To enable high-precision neutrino oscillation measurements by producing muon antineutrinos from stopped pions at multiple short-baseline sites.
• To complement the Long Baseline Neutrino Experiment (LBNE) by providing additional data on neutrino mass hierarchy and CP violation.
• To design a cost-effective accelerator solution with beam power below 1/10th of existing megawatt-class proton machines.
• To ensure high reliability, minimize beam loss, and reduce activation in accelerator components.

Proposed method

• Utilize 0.8–1 GeV proton beams to produce pions in a target, followed by pion capture and decay to generate muon antineutrinos.
• Install three accelerator sites at 1.5 km, 8 km, and 20 km distances from the 300 kT water-Cherenkov detector to maximize baseline diversity.
• Explore three accelerator designs: compact superconducting cyclotron, ring cyclotron with H2+ stripping extraction, and stacked cyclotron with shared magnet yoke and RF systems.
• Optimize beam parameters for high reliability and low activation, focusing on beam loss control and radiation safety.
• Integrate beam delivery systems that maintain beam quality and stability over long distances to the detector.
• Leverage existing infrastructure at Sanford Lab, South Dakota, to reduce deployment costs and accelerate implementation.

Experimental results

Research questions

• RQ1 Can compact, low-cost accelerators produce sufficient muon antineutrino flux for high-precision oscillation measurements at short baselines?
• RQ2 How do multiple accelerator sites at varying distances (1.5–20 km) enhance sensitivity to neutrino mass hierarchy and CP violation compared to single-baseline experiments?
• RQ3 What accelerator design offers the best balance of performance, reliability, and cost under $100 million per machine?
• RQ4 How can beam loss and activation be minimized in high-intensity, low-energy proton beams for long-term operation?
• RQ5 To what extent can shared magnet yoke and RF systems in stacked cyclotrons reduce capital and operational costs?

Key findings

• The DAEδALUS project identifies three viable accelerator concepts—compact superconducting cyclotron, ring cyclotron with H2+ stripping, and stacked cyclotron—each capable of delivering 0.8–1 GeV proton beams with mA-level intensity.
• The beam requirements are modest in energy and power, enabling cost reduction to below 1/10th of existing megawatt-class proton accelerators.
• Three accelerator sites at 1.5 km, 8 km, and 20 km baselines provide optimal coverage for measuring neutrino mass hierarchy and CP violation with high statistical precision.
• Beam loss and activation are critical challenges, requiring advanced beam control and shielding strategies to ensure long-term reliability and safety.
• The stacked cyclotron design offers significant cost savings by sharing magnet yokes and RF systems across up to nine planes.
• The project demonstrates strong complementarity with LBNE, significantly enhancing the overall sensitivity to neutrino oscillation parameters.