[Paper Review] Megaton Modular Multi-Purpose Neutrino Detector for a Program of Physics in the Homestake DUSEL

M. Diwan, Hahn, R. L.+8 more|ArXiv.org|Jun 26, 2003

Neutrino Physics Research1 references3 citations

TL;DR

This paper proposes a megaton-scale, modular, multi-purpose neutrino detector (3M) at the Homestake Underground Science Laboratory in South Dakota, designed to study neutrino oscillations, proton decay, ultra-high-energy neutrinos, and CP violation in the lepton sector using long-baseline accelerator beams. The detector, composed of multiple 100-kiloton chambers with liquid-scintillator or water-Cherenkov technology, enables high-precision measurements of neutrino mixing parameters and offers a path to discovering CP violation in the neutrino sector with a projected cost of ~$52–54M per chamber and a 10-year program timeline.

ABSTRACT

This is a preliminary version of a formal proposal by the 3M collaboration to construct a megaton, modular, multipurpose (3M) neutrino detector for a program of experiments in neutrino physics. The detector components will be located in chambers approximately 7000 ft below the Earth's surface in the Homestake Mine at Lead, South Dakota, to carry out experiments on neutrino oscillations directed toward the principal experimental goal of the program, viz., the issue of CP-invariance violation in the lepton sector of elementary particles, an issue that has been the subject of study in the quark sector for several decades. The principal physics goal of this program also requires a moderately intense neutrino beam from an accelerator located a long distance from the detector array, such as the 2540 km distance of BNL from Homestake. The construction plan for that neutrino beam is at http://nwg.phy.bnl.gov/. Other experimental searches that do not require the accelerator-generated beam can be carried out with the 3M detector independently of and at the same time as the neutrino oscillation and CP-invariance violation measurements are in progress. They are searches for Proton Decay, UHE Neutrinos, and Supernovae Neutrinos.

Motivation & Objective

• To construct a megaton-scale, modular, multi-purpose neutrino detector at the Homestake DUSEL facility to enable a comprehensive program in neutrino physics.
• To measure neutrino oscillation parameters with high precision, particularly Δm²₁₂ and Δm²₂₃, using long-baseline accelerator beams.
• To search for CP-invariance violation in the lepton sector by observing differences in oscillation probabilities between neutrinos and antineutrinos.
• To study proton decay, supernova neutrinos, and ultra-high-energy cosmic neutrinos using a large-volume detector in a deep underground environment.
• To establish a long-term, multi-phase experimental program that supports early physics data collection and scientific outreach.

Proposed method

• The detector consists of multiple 100-kiloton chambers excavated at ~7000 ft depth in the Homestake Mine, using modular design for phased construction and operation.
• Each chamber houses a Cherenkov or scintillator-based detector with photomultiplier tubes (PMTs), reflectors, mechanical structures, and data acquisition systems for particle detection.
• Neutrino beams from Brookhaven National Laboratory (2540 km away) are used to probe oscillation parameters over a long baseline, enabling sensitivity to Δm²₂₃ and νₑ appearance.
• The design includes water purification, cooling systems, calibration systems, and PMT cabling to ensure detector stability and signal fidelity.
• The project employs a phased construction approach, starting with a single chamber and expanding to five chambers, with annual costs projected at ~$60 million.
• The detector leverages the low cosmic ray background at 6950 ft depth (0.4 muons/m²/day) to reduce background noise for rare processes.

Experimental results

Research questions

• RQ1 Can the 3M detector achieve sufficient sensitivity to observe CP violation in the lepton sector through long-baseline neutrino oscillation measurements?
• RQ2 What is the sensitivity of the detector to the solar neutrino parameter Δm²₁₂, and can it confirm or constrain its value with a modest event sample?
• RQ3 Can the detector observe the disappearance of νμ at the n=2 and n=3 oscillation nulls for Δm²₂₃ = 2×10⁻³ eV² using the AGS neutrino beam spectrum?
• RQ4 What is the feasibility of detecting ultra-high-energy neutrinos from astrophysical sources, and how does Earth's matter affect their propagation?
• RQ5 How can a modular, multi-chamber design enable early physics data collection while maintaining cost and schedule control?

Key findings

• The 3M detector is projected to cost approximately $52–54 million per 100-kiloton chamber, including underground excavation and contingency, with a total program cost of ~$60 million per year over 10 years.
• The detector can observe the n=2 and n=3 nulls in νμ disappearance at Eν = 1.37 GeV and 0.85 GeV, respectively, which lie within the natural energy spectrum of the AGS neutrino beam.
• For Δm²₁₂ = 6×10⁻⁵ eV², the detector can directly probe the solar neutrino parameter with a modest statistical sample, enabling a conclusive test of the MSW effect.
• The detector's low background environment at 6950 ft depth (0.4 muons/m²/day) supports high-sensitivity searches for rare processes like proton decay and CP violation.
• The five-module array is not required for meaningful physics; a single chamber can already provide significant constraints on oscillation parameters and early data on extra-terrestrial neutrinos.
• The project is designed to be scalable and modular, allowing early operation of the first chamber within five years of approval, enabling early physics and detector R&D.