70 research outputs found
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
Rapid fluctuations in solar flares
Study of rapid fluctuations in the emission of radiation from solar flares provides a promising approach for probing the magneto-plasma structure and plasma processes that are responsible for a flare. It is proposed that elementary flare bursts in X-ray and microwave emission may be attributed to fine structure of the coronal magnetic field, related to the aggregation of photospheric magnetic field into magnetic knots. Fluctuations that occur on a subsecond time-scale may be due to magnetic islands that develop in current sheets during magnetic reconnection. The impulsive phase may sometimes represent the superposition of a large number of the elementary energy-release processes responsible for elementary flare bursts. If so, the challenge of trying to explain the properties of the impulsive phase in terms of the properties of the elementary processes must be faced. Magnetic field configurations that might produce solar flares are divided into a number of categories, depending on: whether or not there is a filament; whether there is no current sheet, a closed current sheet, or an open current sheet; and whether the filament erupts into the corona, or is ejected completely from the Sun's atmosphere. Analysis of the properties of these possible configurations is compared with different types of flares, and to Bai's subdivision of gamma-ray/proton events
Physics of solar activity
The aim of the research activity was to increase our understanding of solar activity through data analysis, theoretical analysis, and computer modeling. Because the research subjects were diverse and many researchers were supported by this grant, a select few key areas of research are described in detail. Areas of research include: (1) energy storage and force-free magnetic field; (2) energy release and particle acceleration; (3) radiation by nonthermal electrons; (4) coronal loops; (5) flare classification; (6) longitude distributions of flares; (7) periodicities detected in the solar activity; (8) coronal heating and related problems; and (9) plasma processes
Additional experimental evidence for a solar influence on nuclear decay rates
Additional experimental evidence is presented in support of the recent
hypothesis that a possible solar influence could explain fluctuations observed
in the measured decay rates of some isotopes. These data were obtained during
routine weekly calibrations of an instrument used for radiological safety at
The Ohio State University Research Reactor using Cl-36. The detector system
used was based on a Geiger-Mueller gas detector, which is a robust detector
system with very low susceptibility to environmental changes. A clear annual
variation is evident in the data, with a maximum relative count rate observed
in January/February, and a minimum relative count rate observed in July/August,
for seven successive years from July 2005 to June 2011. This annual variation
is not likely to have arisen from changes in the detector surroundings, as we
show here.Comment: 8 pages, 6 figure
Evidence for Solar Influences on Nuclear Decay Rates
Recent reports of periodic fluctuations in nuclear decay data of certain
isotopes have led to the suggestion that nuclear decay rates are being
influenced by the Sun, perhaps via neutrinos. Here we present evidence for the
existence of an additional periodicity that appears to be related to the Rieger
periodicity well known in solar physics.Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28-July 2, 201
- …