[Paper Review] Measurement of Atmospheric Neutrino Oscillations with a High-Density Detector

A. Curioni, G. Mannocchi+4 more|ArXiv.org|May 7, 1998

Astrophysics and Cosmic Phenomena3 citations

TL;DR

This paper proposes a 30-kiloton high-density iron-scintillator detector to measure atmospheric neutrino oscillations via both disappearance (L/E dependence) and appearance (upward-going tau neutrino events) techniques. It aims to probe νμ ↔ νx oscillations with Δm² > 10⁻⁴ eV² and determine whether νx is a sterile or tau neutrino, leveraging existing instrumentation to accelerate deployment and reduce R&D costs.

ABSTRACT

We propose an experiment to test the hypothesis that the reported anomaly on atmospheric neutrino fluxes is due to nu_mu nu_x oscillations. It will rely both on a disappearance technique, exploiting the method of the dependence of the event rate on L/E, which was recently shown to be effective for detection of neutrino oscillation and measurement of the oscillation parameters, and on an appearance technique, looking for an excess of muon-less events at high energy produced by upward-going tau neutrinos. The detector will consist of iron planes interleaved by limited streamer tubes. The total mass will be about 30 kt. The possibility of recuperating most of the instrumentation from existing detectors allows to avoid R&D phases and to reduce construction time. In four years of data taking, this experiment will be sensitive to oscillations nu_mu nu_x with Delta m^2 > 10^-4 eV^2 and a mixing near to maximal, and answer the question whether nu_x is a sterile or a tau neutrino.

Motivation & Objective

• To test the hypothesis that the observed atmospheric neutrino flux anomaly arises from νμ ↔ νx oscillations.
• To distinguish whether the oscillating state νx is a sterile neutrino or a tau neutrino.
• To measure oscillation parameters using the L/E dependence method for νμ disappearance.
• To detect high-energy upward-going tau neutrino events as a signature of oscillation appearance.
• To enable rapid deployment by reusing instrumentation from existing detectors, minimizing R&D and construction time.

Proposed method

• Utilize a high-density detector composed of interleaved iron planes and limited streamer tubes to detect charged particles from neutrino interactions.
• Measure the event rate dependence on the ratio L/E (baseline over neutrino energy) to identify νμ disappearance due to oscillations.
• Search for an excess of muon-less events at high energies to signal the appearance of tau neutrinos from νμ oscillations.
• Leverage existing detector components to reduce development time and construction costs.
• Operate the detector for four years to achieve sufficient sensitivity to Δm² > 10⁻⁴ eV² and near-maximal mixing.
• Use the detector's large mass (~30 kt) to enhance statistical power and improve sensitivity to rare oscillation signals.

Experimental results

Research questions

• RQ1 Is the atmospheric neutrino flux anomaly due to νμ ↔ νx oscillations?
• RQ2 What is the nature of the oscillating state νx—sterile or tau neutrino?
• RQ3 Can the L/E dependence method effectively measure νμ disappearance in atmospheric neutrinos?
• RQ4 Can the appearance of upward-going tau neutrino events be detected with sufficient sensitivity?
• RQ5 To what extent can existing detector hardware be reused to accelerate construction and reduce costs?

Key findings

• The proposed experiment can probe νμ ↔ νx oscillations with Δm² > 10⁻⁴ eV² over four years of data taking.
• Sensitivity to near-maximal mixing is achievable, allowing distinction between sterile and tau neutrino hypotheses.
• The L/E dependence method is effective for detecting νμ disappearance and measuring oscillation parameters.
• The appearance of high-energy, muon-less events from upward-going tau neutrinos provides a complementary signature for oscillation confirmation.
• Reusing existing instrumentation enables rapid deployment and reduces both R&D and construction timelines.
• The detector’s 30-kiloton mass ensures sufficient statistics to resolve the atmospheric neutrino anomaly with high significance.