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Title: Periodogram and likelihood periodicity search in the SNO solar neutrino data

Abstract

In this work a detailed spectral analysis for the periodicity search of the time series of the {sup 8}B solar neutrino flux released by the SNO Collaboration is presented. The data have been publicly released with truncation of the event times to the unit of day (1 day binning); they are thus suited to undergo the traditional Lomb-Scargle analysis for periodicity investigation, as well as an extension of such a method based on a likelihood approach. The results of the analysis presented here confirm the absence of modulation signatures in the SNO data. For completeness, a more refined ''1 day binned'' likelihood is also illustrated, which approximates the unbinned likelihood methodology, based upon the availability of the full time information, adopted by the SNO collaboration. Finally, this work is completed with two different joint analyses of the SNO and Super-Kamiokande data, respectively, over the common and the entire data taking periods. While both analyses reinforce the case of the constancy of the neutrino flux, the latter in addition provides evidence of the detection at the 99.7% confidence level of the annual modulation spectral line due to the Earth's orbit eccentricity around the Sun.

Authors:
;  [1]
  1. Istituto Nazionale di Fisica Nucleare, Via Celoria 16, 20133 Milan (Italy)
Publication Date:
OSTI Identifier:
20935187
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevD.75.013010; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; BORON 8; PERIODICITY; RADIATION DETECTION; SOLAR NEUTRINOS; TIME-SERIES ANALYSIS

Citation Formats

Ranucci, Gioacchino, and Rovere, Marco. Periodogram and likelihood periodicity search in the SNO solar neutrino data. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.013010.
Ranucci, Gioacchino, & Rovere, Marco. Periodogram and likelihood periodicity search in the SNO solar neutrino data. United States. doi:10.1103/PHYSREVD.75.013010.
Ranucci, Gioacchino, and Rovere, Marco. Mon . "Periodogram and likelihood periodicity search in the SNO solar neutrino data". United States. doi:10.1103/PHYSREVD.75.013010.
@article{osti_20935187,
title = {Periodogram and likelihood periodicity search in the SNO solar neutrino data},
author = {Ranucci, Gioacchino and Rovere, Marco},
abstractNote = {In this work a detailed spectral analysis for the periodicity search of the time series of the {sup 8}B solar neutrino flux released by the SNO Collaboration is presented. The data have been publicly released with truncation of the event times to the unit of day (1 day binning); they are thus suited to undergo the traditional Lomb-Scargle analysis for periodicity investigation, as well as an extension of such a method based on a likelihood approach. The results of the analysis presented here confirm the absence of modulation signatures in the SNO data. For completeness, a more refined ''1 day binned'' likelihood is also illustrated, which approximates the unbinned likelihood methodology, based upon the availability of the full time information, adopted by the SNO collaboration. Finally, this work is completed with two different joint analyses of the SNO and Super-Kamiokande data, respectively, over the common and the entire data taking periods. While both analyses reinforce the case of the constancy of the neutrino flux, the latter in addition provides evidence of the detection at the 99.7% confidence level of the annual modulation spectral line due to the Earth's orbit eccentricity around the Sun.},
doi = {10.1103/PHYSREVD.75.013010},
journal = {Physical Review. D, Particles Fields},
number = 1,
volume = 75,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The Ottawa 2.8 GHz burst record from 1955 January to 1990 February has been examined for evidence of a periodicity near 154 days in the occurrence rate of solar flares. This periodicity is found to be statistically significant, at the 1-percent level, only for the years from 1978 to 1983, corresponding to the activity maximum of solar cycle 21. Through 1990 February, the Ottawa data show no evidence for a 154 day period in the current 22d solar cycle that began in 1986 September. A spectral peak near 51 days is found in solar cycle 19 (1955-1964), as had beenmore » previously reported based on an examination of CFI data, but its significance is low, at the 33-percent level. It is concluded that, other than for the period in cycle 21 in which it was first discovered, the evidence for the 154 day periodicity from flare-related data sets is contradictory and not compelling. Stronger evidence for the occurrence of the 154 day periodicity outside cycle 21 can be found in recent studies that examine parameters such as sunspot counts and areas that characterize solar active regions. 29 refs.« less
  • Recent studies of solar UV spectra and various indices of solar activity indicate a strong period at about 5 months. In the 10.7 cm solar radio flux (F10.7), a conventional index for the solar EUV and UV variabilities, the spectral power of the 5 month period is comparable to the well known 27 day solar period. However, in the solar UV flux at 205 nm, directly measured from the Nimbus-7 SBUV spectrometer, the (spectral) power of the 5 month period is about half that of the 27 day period. This paper examines the possible impact of the 5 month solarmore » period on ozone and temperature at various pressure levels in the stratosphere and discusses the implications of differences in solar forcing at the 27 day and 5 month periods. It is shown that ozone, both in the lower and upper stratosphere, has a measurable response to solar UV forcing 27 days. Such a solar response is not observed at 5 month period because of a relatively weaker 5 month solar UV component in the solar signal and a strong interference from dynamical signals associated with planetary wave activity.« less
  • The time series of the {sup 8}B solar neutrino measurements released by the Super- Kamiokande and SNO Collaborations have been recently investigated by several groups for possible modulation signatures through standard Fourier-based techniques. In this work we present an alternative analysis of the same data sets based on the wavelet approach, whose key advantage with respect to the traditional methodologies is the ability to capture and follow the time evolution of transient modulation features as well. Moreover, we show the results of the wavelet analysis applied to the mean solar magnetic field and flare index data recorded in the samemore » data-taking period of the two experiments, with the goal of carrying out a direct check of the concurrent presence (if any) of evidence for corresponding time variations in the solar data and in the solar neutrino series. The main outcomes of this investigation are, on one hand, the clear identification of the expected annual modulation variation due to the eccentricity of the Earth's orbit, and on the other, the demonstration that no further reliable time variation signals can be unraveled, within the current experimental sensitivity, in the measured solar neutrino flux.« less
  • Evidence for a periodicity about 155 +- 5 days in the production of energetic solar flares was reported in 1984 by Rieger et al. and Kiplinger et al. The data on which these analyses were based are restricted to the years 1980 through early 1984. To see whether this periodicity is a persistent phenomenon, we have examined the occurrences of flares inferred from microwave data, which are available for most of the present and previous solar cycles. We find strong confirmation of a 152 day periodicity in the time interval previously studied, demonstrating that these flares are a useful indicatormore » for the observed periodicity. We find evidence for persistence of the periodicity in the previous cycle (cycle 20). In cycle 20 the periodic modulation of the flare occurrence rate was weaker than in cycle 21, but the phase has apparently remained coherent through both cycles.« less
  • No abstract prepared.