[Paper Review] The Future of Neutrino Mass Measurements: Terrestrial, Astrophysical, and Cosmological Measurements in the Next Decade. Highlights of the NuMass 2013 Workshop. Milano, Italy, February 4 - 7, 2013

A. Nucciotti, F. Terranova+20 more|arXiv (Cornell University)|Sep 30, 2013

Astrophysics and Cosmic Phenomena3 citations

TL;DR

This paper summarizes key insights from the NuMass 2013 workshop on future neutrino mass measurements, focusing on terrestrial, astrophysical, and cosmological approaches. It evaluates experimental strategies for determining the absolute neutrino mass, mass hierarchy, and Majorana/Dirac nature using next-generation experiments like KATRIN, CUORE, and Project 8, with particular emphasis on supernova neutrino detection via coherent scattering in cryogenic bolometers, achieving a discovery potential for galactic supernovae within 5.5 kpc with high statistical significance.

ABSTRACT

The third Workshop of the NuMass series ("The Future of Neutrino Mass Measurements: Terrestrial, Astrophysical, and Cosmological Measurements in the Next Decade: NuMass 2013") was held at Dipartimento di Fisica "G. Occhialini, University of Milano-Bicocca in Milano, Italy, on 4-7 February 2013. The goal of this international workshop was to review the status and future of direct and indirect neutrino mass measurements in the laboratory as well as from astrophysical and cosmological observations. This paper collects most of the contributions presented during the Workshop.

Motivation & Objective

• To assess the future experimental landscape for measuring the absolute neutrino mass and determining its Majorana/Dirac nature.
• To evaluate the potential of terrestrial experiments (e.g., KATRIN, CUORE, Project 8) to probe the neutrino mass scale and hierarchy.
• To explore the feasibility of detecting supernova neutrinos via coherent neutrino-nucleus scattering in cryogenic bolometer arrays.
• To investigate the role of cosmological and astrophysical observations in constraining neutrino properties.
• To examine the implications of sterile neutrino anomalies and their impact on future experimental design.

Proposed method

• Utilizes data and projections from major neutrino experiments, including KATRIN’s tritium beta decay spectrometry, CUORE’s tellurium-130 bolometric decay detection, and Project 8’s electron cyclotron radiation detection.
• Applies maximum likelihood fitting to time-resolved event data to trigger supernova neutrino burst detection in CUORE, modeling signal as an exponentially decaying component over 3.5 seconds.
• Simulates Monte Carlo data with varying signal amplitudes and background rates to test trigger efficiency and false positive rates.
• Evaluates statistical significance of signal detection as a function of energy threshold and supernova distance, using a 3 keV threshold for optimal sensitivity.
• Models neutrino fluxes from proto-neutron stars with varying average energies (T_e) to predict event yields and assess sensitivity to supernova cooling physics.
• Analyzes the impact of background reduction (e.g., 10× lower in CUORE vs. CCVR2) on detection efficiency and discovery potential.

Experimental results

Research questions

• RQ1 Can CUORE detect a galactic supernova via coherent neutrino-nucleus scattering with high statistical significance?
• RQ2 What is the minimum supernova distance at which CUORE can reliably detect a neutrino burst without prior timing information?
• RQ3 How does the average energy of the electron neutrino flux affect the number of detectable events in a bolometric detector?
• RQ4 To what extent can the trigger algorithm distinguish a true supernova burst from background fluctuations?
• RQ5 What improvements in background suppression are needed to achieve a weekly false positive rate below one?

Key findings

• CUORE can detect a galactic supernova at a distance of 5.5 kpc with a statistical significance exceeding 5σ using a 3 keV energy threshold.
• The trigger algorithm achieves a discovery efficiency of ~80% for supernovae within 5.5 kpc, assuming a 10× reduction in low-energy background compared to CCVR2.
• The number of detectable events above 3 keV varies by a factor of ~2 across different supernova cooling models, depending on the average energy of the ν_e flux (T_e), enabling discrimination between models.
• The false positive trigger rate is kept below one per week by setting a threshold on the signal amplitude reconstruction, based on zero-signal Monte Carlo simulations.
• The statistical significance of detection increases with lower energy thresholds and closer supernova distances, peaking at ~10σ for a 3 keV threshold and 4.5 kpc distance.
• Coherent scattering detection in CUORE would not only confirm a key neutrino interaction but also provide constraints on proto-neutron star temperature and cooling dynamics.