[Paper Review] NOvA Proposal to Build a 30 Kiloton Off-Axis Detector to Study Neutrino Oscillations in the Fermilab NuMI Beamline

The NOvA Collaboration, D.S. Ayres|ArXiv.org|Mar 30, 2005

Neutrino Physics Research183 citations

TL;DR

This paper proposes the NOvA experiment, a 30-kiloton off-axis liquid scintillator detector designed to study neutrino oscillations in Fermilab's NuMI beamline. Utilizing wavelength-shifting fibers and avalanche photodiodes to detect charged particles, the detector aims to measure sin²(2θ₁₃) with improved sensitivity due to increased proton beam intensity expected after the Tevatron's shutdown.

ABSTRACT

This is an updated version of the NOvA proposal. The detector is a 30 kiloton tracking calorimeter, 15.7 m by 15.7 m by 132 m long, with alternating horizontal and vertical rectangular cells of liquid scintillator contained in PVC extrusion modules. Light from each 15.7 m long cell of liquid scintillator filled PVC is collected by a wavelength shifting fiber and routed to an avalanche photodiode pixel. The reach of NOvA for sin^2(2_theta_13) and related topics is increased relative to earlier versions of the proposal with the assumption of increased protons available from the Fermilab Main Injector following the end of Tevatron Collider operations in 2009.

Motivation & Objective

• To measure the neutrino mixing angle sin²(2θ₁₃) with high precision using a long-baseline neutrino oscillation experiment.
• To investigate the neutrino mass hierarchy by analyzing differences in oscillation patterns between neutrinos and antineutrinos.
• To improve sensitivity to CP violation in the neutrino sector by leveraging high-statistics data from the NuMI beamline.
• To exploit increased proton beam intensity expected after the Tevatron's decommissioning to enhance detector reach.
• To develop a large-scale, cost-effective liquid scintillator detector with high granularity and excellent particle identification capabilities.

Proposed method

• The detector is a 30-kiloton tracking calorimeter composed of alternating horizontal and vertical rectangular cells filled with liquid scintillator.
• Each 15.7 m long scintillator cell is instrumented with wavelength-shifting fibers that collect scintillation light and route it to avalanche photodiode (APD) pixels.
• The detector geometry is optimized for off-axis operation, focusing the neutrino beam to enhance the energy resolution and reduce background.
• The use of PVC extrusion modules enables scalable, modular construction of the large-volume detector.
• The readout system is designed for high timing resolution and low noise, enabling precise reconstruction of particle showers and tracks.
• The detector is positioned 810 km from the Fermilab NuMI beam source, enabling long-baseline neutrino oscillation measurements.

Experimental results

Research questions

• RQ1 What is the value of the neutrino mixing angle sin²(2θ₁₃), and can it be measured with high significance?
• RQ2 Can the neutrino mass hierarchy be determined using the NOvA detector's sensitivity to neutrino and antineutrino oscillations?
• RQ3 What is the potential for observing CP violation in the neutrino sector using this experimental setup?
• RQ4 How does increased proton beam intensity from the Fermilab Main Injector improve the sensitivity of the NOvA experiment?
• RQ5 Can the detector achieve the required energy resolution and particle identification performance for precise oscillation measurements?

Key findings

• The NOvA proposal demonstrates a significant increase in sensitivity to sin²(2θ₁₃) compared to earlier versions, due to anticipated higher proton beam intensity post-Tevatron.
• The detector design achieves a large fiducial volume of 30 kilotons, enabling high-statistics measurements of neutrino interactions.
• The use of wavelength-shifting fibers and avalanche photodiodes allows for efficient light collection with high dynamic range and low crosstalk.
• The off-axis geometry reduces beam divergence and improves energy resolution, enhancing the ability to distinguish oscillation patterns.
• The modular PVC extrusion design enables cost-effective construction of the large-scale detector with consistent performance across modules.
• The proposed detector is expected to achieve a sensitivity to sin²(2θ₁₃) at the level of 0.01–0.02, depending on the beam intensity and background conditions.