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Title: Reactor neutrino spectral distortions play little role in mass hierarchy experiments

Abstract

The Coulomb enhancement of low energy electrons in nuclear beta decay generates sharp cutoffs in the accompanying antineutrino spectrum at the beta decay endpoint energies. It has been conjectured that these features will interfere with measuring the effect of a neutrino mass hierarchy on an oscillated nuclear reactor antineutrino spectrum. These sawtoothlike features will appear in detailed reactor antineutrino spectra, with characteristic energy scales similar to the oscillation period critical to neutrino mass hierarchy determination near a 53 km baseline. However, these sawtoothlike distortions are found to contribute at a magnitude of only a few percent relative to the mass hierarchy-dependent oscillation pattern in Fourier space. In the Fourier cosine and sine transforms, the features that encode a neutrino mass hierarchy dominate by over sixteen (thirty-three) times in prominence to the maximal contribution of the sawtoothlike distortions from the detailed energy spectrum, given 3.2 % / √ E vis/MeV (perfect) detector energy resolution. The effect of these distortions is shown to be negligible even when the uncertainties in the reactor spectrum, oscillation parameters, and counting statistics are considered. This result is shown to hold even when the opposite hierarchy oscillation patterns are nearly degenerate in energy space, if energy responsemore » nonlinearities are controlled to below 0.5%. Therefore with accurate knowledge of detector energy response, the sawtoothlike features in reactor antineutrino spectra will not significantly impede neutrino mass hierarchy measurements using reactor antineutrinos.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [3]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of California, Davis, CA (United States). Dept. of Physics
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Washington, Seattle, WA (United States). Dept. of Physics
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1495152
Report Number(s):
LA-UR-18-23776
Journal ID: ISSN 2470-0010; PRVDAQ
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 99; Journal Issue: 3; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Atomic, Nuclear and Particle Physics; Beta decay; Neutrino oscillations; Neutrinos; Ab initio calculations; Neutrino detectors

Citation Formats

Danielson, Daine Lee, Hayes-Sterbenz, Anna Catherine, and Garvey, Gerald Thomas. Reactor neutrino spectral distortions play little role in mass hierarchy experiments. United States: N. p., 2019. Web. doi:10.1103/PhysRevD.99.036001.
Danielson, Daine Lee, Hayes-Sterbenz, Anna Catherine, & Garvey, Gerald Thomas. Reactor neutrino spectral distortions play little role in mass hierarchy experiments. United States. doi:10.1103/PhysRevD.99.036001.
Danielson, Daine Lee, Hayes-Sterbenz, Anna Catherine, and Garvey, Gerald Thomas. Tue . "Reactor neutrino spectral distortions play little role in mass hierarchy experiments". United States. doi:10.1103/PhysRevD.99.036001. https://www.osti.gov/servlets/purl/1495152.
@article{osti_1495152,
title = {Reactor neutrino spectral distortions play little role in mass hierarchy experiments},
author = {Danielson, Daine Lee and Hayes-Sterbenz, Anna Catherine and Garvey, Gerald Thomas},
abstractNote = {The Coulomb enhancement of low energy electrons in nuclear beta decay generates sharp cutoffs in the accompanying antineutrino spectrum at the beta decay endpoint energies. It has been conjectured that these features will interfere with measuring the effect of a neutrino mass hierarchy on an oscillated nuclear reactor antineutrino spectrum. These sawtoothlike features will appear in detailed reactor antineutrino spectra, with characteristic energy scales similar to the oscillation period critical to neutrino mass hierarchy determination near a 53 km baseline. However, these sawtoothlike distortions are found to contribute at a magnitude of only a few percent relative to the mass hierarchy-dependent oscillation pattern in Fourier space. In the Fourier cosine and sine transforms, the features that encode a neutrino mass hierarchy dominate by over sixteen (thirty-three) times in prominence to the maximal contribution of the sawtoothlike distortions from the detailed energy spectrum, given 3.2 % / √ Evis/MeV (perfect) detector energy resolution. The effect of these distortions is shown to be negligible even when the uncertainties in the reactor spectrum, oscillation parameters, and counting statistics are considered. This result is shown to hold even when the opposite hierarchy oscillation patterns are nearly degenerate in energy space, if energy response nonlinearities are controlled to below 0.5%. Therefore with accurate knowledge of detector energy response, the sawtoothlike features in reactor antineutrino spectra will not significantly impede neutrino mass hierarchy measurements using reactor antineutrinos.},
doi = {10.1103/PhysRevD.99.036001},
journal = {Physical Review D},
issn = {2470-0010},
number = 3,
volume = 99,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
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