4,688 research outputs found

### Power Spectrum Analysis of LMSU (Lomonosov Moscow State University) Nuclear Decay-Rate Data: Further Indication of r-Mode Oscillations in an Inner Solar Tachocline

This article presents a power-spectrum analysis of 2,350 measurements of the
$^{90}$Sr/$^{90}$Y decay process acquired over the interval 4 August 2002 to 6
February 2009 at the Lomonosov Moscow State University (LMSU). As we have found
for other long sequences of decay measurements, the power spectrum is dominated
by a very strong annual oscillation. However, we also find a set of
low-frequency peaks, ranging from 0.26 year$^{-1}$ to 3.98 year$^{-1}$, which
are very similar to an array of peaks in a power spectrum formed from Mt Wilson
solar diameter measurements. The Mt Wilson measurements have been interpreted
in terms of r-mode oscillations in a region where the sidereal rotation
frequency is 12.08 year$^{-1}$. We find that the LMSU measurements may also be
attributed to the same type of r-mode oscillations in a solar region with the
same sidereal rotation frequency. We propose that these oscillations occur in
an inner tachocline that separates the radiative zone from a more slowly
rotating solar core.Comment: 5 pages, 8 figures. v2 corrects three typographical errors on page 3,
including the missing list of r-modes in sec. 3, para

### Comparative analysis of Gallex and GNO solar neutrino data

Since the GALLEX and GNO datasets were derived from closely related
experiments, there is a natural tendency to merge them. This is perhaps
appropriate for any analysis based on the hypothesis that the solar neutrino
flux is constant, but it is not necessarily appropriate for an analysis that
allows for possible variability, since the GALLEX and GNO experiments belong to
different solar cycles. Moreover, we find significant differences between the
GALLEX and GNO datasets. It appears, from inspection of the time series and
histograms, that GNO measurements are compatible with the assumption that the
solar neutrino flux is constant, but GALLEX measurements are not. Furthermore,
power-spectrum analysis yields evidence of rotational modulation in GALLEX data
but not in GNO data. We compare our results with those of Pandola, who claims
that GALLEX-GNO data show no evidence for variability.Comment: 20 pages plus 6 tables plus 11 figure

### Evidence for Solar Neutrino Flux Variability and its Implications

Althogh KamLAND apparently rules out Resonant-Spin-Flavor-Precession (RSFP)
as an explanation of the solar neutrino deficit, the solar neutrino fluxes in
the Cl and Ga experiments appear to vary with solar rotation. Added to this
evidence, summarized here, a power spectrum analysis of the Super-Kamiokande
data reveals significant variation in the flux matching a dominant rotation
rate observed in the solar magnetic field in the same time period. Three
frequency peaks, all related to this rotation rate, can be explained
quantitatively. A Super-Kamiokande paper reported no time variation of the
flux, but showed the same peaks, there interpreted as statistically
insignificant, due to an inappropriate analysis. This modulation is small (7%)
in the Super-Kamiokande energy region (and below the sensitivity of the
Super-Kamiokande analysis) and is consistent with RSFP as a subdominant
neutrino process in the convection zone. The data display effects that
correspond to solar-cycle changes in the magnetic field, typical of the
convection zone. This subdominant process requires new physics: a large
neutrino transition magnetic moment and a light sterile neutrino, since an
effect of this amplitude occurring in the convection zone cannot be achieved
with the three known neutrinos. It does, however, resolve current problems in
providing fits to all experimental estimates of the mean neutrino flux, and is
compatible with the extensive evidence for solar neutrino flux variability.Comment: 9 pages, 10 figures (5 in color); new figure, data added to another
figure, more clarification, especially on the origin of the effect and its
connection to sterile neutrinos; v3 is updated, especially using the results
of hep-ph/0402194; v4 is a further update, mainly of references, with a small
change to make the title more appropriate; v5 includes more clarification and
the result of now having hep-ph/0411148 and hep-ph/0501205 and so increases
the length; v6 has a small change in the title and some additional
information at the referee's request to correspond to the version to be
published in Astroparticle Physic

### False-alarm probability in relation to over-sampled power spectra, with application to Super-Kamiokande solar neutrino data

The term "false-alarm probability" denotes the probability that at least one
out of M independent power values in a prescribed search band of a power
spectrum computed from a white-noise time series is expected to be as large as
or larger than a given value. The usual formula is based on the assumption that
powers are distributed exponentially, as one expects for power measurements of
normally distributed random noise. However, in practice one typically examines
peaks in an over-sampled power spectrum. It is therefore more appropriate to
compare the strength of a particular peak with the distribution of peaks in
over-sampled power spectra derived from normally distributed random noise. We
show that this leads to a formula for the false-alarm probability that is more
conservative than the familiar formula. We also show how to combine these
results with a Bayesian method for estimating the probability of the null
hypothesis (that there is no oscillation in the time series), and we discuss as
an example the application of these procedures to Super-Kamiokande solar
neutrino data

### Analysis of Super-Kamiokande 5-day Measurements of the Solar Neutrino Flux

Data in 5-day bins, recently released by the Super-Kamiodande Consortium, has
been analyzed by a likelihood procedure that has certain advantages over the
Lomb-Scargle procedure used by the consortium. The two most prominent peaks in
the power spectrum of the 10-day data were at 9.42 y-1 and 26.57 y-1, and it
was clear that one was an alias of the other caused by the regularity of the
binning. There were reasons to believe that the 9.42 y-1 peak was an alias of
the 26.57 y-1 peak, but analysis of the 5-day data makes it clear that the
reverse is the case. In addition to a strong peak near 9.42 y-1, we find peaks
at 43.72 y-1and at 39.28 y-1. After comparing this analysis with a
power-spectrum analysis of magnetic-field data, we suggest that these three
peaks may be attributed to a harmonic of the solar rotation rate and to an
r-mode oscillation with spherical harmonic indices l = 2, m = 2.Comment: Accepted for publication in Astrophysical Journa

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