405 research outputs found
A high efficiency, low background detector for measuring pair-decay branches in nuclear decay
We describe a high efficiency detector for measuring electron-positron pair
transitions in nuclei. The device was built to be insensitive to gamma rays and
to accommodate high overall event rates. The design was optimized for total
pair kinetic energies up to about 7 MeV.Comment: Accepted for publication by Nucl. Inst. & Meth. in Phys. Res. A (NIM
A
Digital Computer Analysis of the Kinetic Response of a Thermal Pressurized Water Reactor Power Plant
A digital computer model has been developed to simulate the kinetic response of a thermal pressurized water reactor power plant. The program is capable of predicting core power and plant temperature variations which result from disturbances due to routine demand changes, control rod movement, and fission product poison transients as well as from transients during plausible accident situations. The development of the differential equations describing the influence of various primary plant components on the dynamics of the reactor have been heretofore documented in the literature. Finite difference equations facilitating the employment of a digital computer solution are fully derived. Confidence in program validity is supported by the simulation of previously studied accidents and comparison with the safety analyses of a licensed nuclear power generating plant. A source listing of the computer program is provided in the Appendix
Analysis of Gamma Radiation from a Radon Source: Indications of a Solar Influence
This article presents an analysis of about 29,000 measurements of gamma
radiation associated with the decay of radon in a sealed container at the
Geological Survey of Israel (GSI) Laboratory in Jerusalem between 28 January
2007 and 10 May 2010. These measurements exhibit strong variations in time of
year and time of day, which may be due in part to environmental influences.
However, time-series analysis reveals a number of periodicities, including two
at approximately 11.2 year and 12.5 year. We have previously
found these oscillations in nuclear-decay data acquired at the Brookhaven
National Laboratory (BNL) and at the Physikalisch-Technische Bundesanstalt
(PTB), and we have suggested that these oscillations are attributable to some
form of solar radiation that has its origin in the deep solar interior. A
curious property of the GSI data is that the annual oscillation is much
stronger in daytime data than in nighttime data, but the opposite is true for
all other oscillations. This may be a systematic effect but, if it is not, this
property should help narrow the theoretical options for the mechanism
responsible for decay-rate variability.Comment: 9 pages, 21 figure
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
Sr/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 to 3.98 year, 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. 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
Study of the dependence of 198Au half-life on source geometry
We report the results of an experiment to determine whether the half-life of
\Au{198} depends on the shape of the source. This study was motivated by recent
suggestions that nuclear decay rates may be affected by solar activity, perhaps
arising from solar neutrinos. If this were the case then the -decay
rates, or half-lives, of a thin foil sample and a spherical sample of gold of
the same mass and activity could be different. We find for \Au{198},
, where
is the mean half-life. The maximum neutrino flux at the sample in our
experiments was several times greater than the flux of solar neutrinos at the
surface of the Earth. We show that this increase in flux leads to a significant
improvement in the limits that can be inferred on a possible solar contribution
to nuclear decays.Comment: 5 pages, 1 figur
Analysis of environmental influences in nuclear half-life measurements exhibiting time-dependent decay rates
In a recent series of papers evidence has been presented for correlations
between solar activity and nuclear decay rates. This includes an apparent
correlation between Earth-Sun distance and data taken at Brookhaven National
Laboratory (BNL), and at the Physikalisch-Technische Bundesanstalt (PTB).
Although these correlations could arise from a direct interaction between the
decaying nuclei and some particles or fields emanating from the Sun, they could
also represent an "environmental" effect arising from a seasonal variation of
the sensitivities of the BNL and PTB detectors due to changes in temperature,
relative humidity, background radiation, etc. In this paper, we present a
detailed analysis of the responses of the detectors actually used in the BNL
and PTB experiments, and show that sensitivities to seasonal variations in the
respective detectors are likely too small to produce the observed fluctuations
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