138 research outputs found
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
THE 18O + 12C FUSION-EVAPORATION REACTION
No abstract availabl
Accurate mass measurements of Ne, Na, Mg performed with the {\sc Mistral} spectrometer
The minuteness of the nuclear binding energy requires that mass measurements
be highly precise and accurate. Here we report on new measurements Mg
and Na performed with the {\sc Mistral} mass spectrometer at {\sc
Cern}'s {\sc Isolde} facility. Since mass measurements are prone to systematic
errors, considerable effort has been devoted to their evaluation and
elimination in order to achieve accuracy and not only precision. We have
therefore conducted a campaign of measurements for calibration and error
evaluation. As a result, we now have a satisfactory description of the {\sc
Mistral} calibration laws and error budget. We have applied our new
understanding to previous measurements of Ne, Na and
Mg for which re-evaluated values are reported.Comment: submitted to Nuclear Physics
Gamma-Ray Spectroscopy of O and N Hypernuclei via the O reaction
he bound-state level structures of the O and
N hypernuclei were studied by -ray spectroscopy using
a germanium detector array (Hyperball) via the O ()
reaction. A level scheme for O was determined from the
observation of three -ray transitions from the doublet of states
(,) at MeV to the ground-state doublet (,). The
N hypernuclei were produced via proton emission from unbound
states in O . Three -rays were observed and the
lifetime of the state in N was measured by the
Doppler shift attenuation method. By comparing the experimental results with
shell-model calculations, the spin-dependence of the interaction is
discussed. In particular, the measured O ground-state doublet
spacing of 26.4 1.6 0.5 keV determines a small but nonzero strength
of the tensor interaction.Comment: 22 pages, 17 figure
Up-Down Quark Mass Difference Effect in Nuclear Many-Body Systems
A charge-symmetry-breaking nucleon-nucleon force due to the up-down quark
mass difference is evaluated in the quark cluster model. It is applied to the
shell-model calculation for the isovector mass shifts of isospin multiplets and
the isospin-mixing matrix elements in 1s0d-shell nuclei. We find that the
contribution of the quark mass difference effect is large and agrees with
experiment. This contribution may explain the Okamoto-Nolen-Schiffer anomaly,
alternatively to the meson-mixing contribution, which is recently predicted to
be reduced by the large off-shell correction
Power Spectrum Analysis of Physikalisch-Technische Bundesanstalt Decay-Rate Data: Evidence for Solar Rotational Modulation
Evidence for an anomalous annual periodicity in certain nuclear decay data
has led to speculation concerning a possible solar influence on nuclear
processes. We have recently analyzed data concerning the decay rates of Cl-36
and Si-32, acquired at the Brookhaven National Laboratory (BNL), to search for
evidence that might be indicative of a process involving solar rotation.
Smoothing of the power spectrum by weighted-running-mean analysis leads to a
significant peak at frequency 11.18/yr, which is lower than the equatorial
synodic rotation rates of the convection and radiative zones. This article
concerns measurements of the decay rates of Ra-226 acquired at the
Physikalisch-Technische Bundesanstalt (PTB) in Germany. We find that a similar
(but not identical) analysis yields a significant peak in the PTB dataset at
frequency 11.21/yr, and a peak in the BNL dataset at 11.25/yr. The change in
the BNL result is not significant since the uncertainties in the BNL and PTB
analyses are estimated to be 0.13/yr and 0.07/yr, respectively. Combining the
two running means by forming the joint power statistic leads to a highly
significant peak at frequency 11.23/yr. We comment briefly on the possible
implications of these results for solar physics and for particle physics.Comment: 15 pages, 13 figure
Standard Neutrino Spectrum from B-8 Decay
We present a systematic evaluation of the shape of the neutrino energy
spectrum produced by beta-decay of B. We place special emphasis on
determining the range of uncertainties permitted by existing laboratory data
and theoretical ingredients (such as forbidden and radiative corrections). We
review and compare the available experimental data on the
BBe decay chain. We analyze the theoretical and
experimental uncertainties quantitatively. We give a numerical representation
of the best-fit (standard-model) neutrino spectrum, as well as two extreme
deviations from the standard spectrum that represent the total (experimental
and theoretical) effective deviations. Solar neutrino experiments
that are currently being developed will be able to measure the shape of the
B neutrino spectrum above about 5 MeV. An observed distortion of the B
solar neutrino spectrum outside the range given in the present work could be
considered as evidence, at an effective significance level greater than three
standard deviations, for physics beyond the standard electroweak model. We use
the most recent available experimental data on the Gamow--Teller strengths in
the system to calculate the B neutrino absorption cross section on
chlorine: ~cm (
errors). The chlorine cross section is also given as a function of the neutrino
energy. The B neutrino absorption cross section in gallium is cm ( errors).Comment: Revised version, to appear in Phys. Rev.
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Survey of results from Brookhaven Experiment 802 at the AGS
Brookhaven Experiment 802 (E-802) is a magnetic spectrometer experiment which is directed toward the measurement of particle momentum spectra and particle-particle correlations following reactions with 14.5 GeV/u O and Si ions. In addition to the spectrometer there are detectors to measure the transverse energy flow, longitudinal energy flow, and the multiplicity. These detectors can be used to characterize the particle spectra or correlated between themselves. Particle spectra have been obtained for protons, pions, and kaons using targets of gold, copper, and aluminum although the data are not entirely analyzed as yet. A first result that is of interest is the K/sup +//..pi../sup +/ ratio for Si + Au reactions which is larger than expected on the basis of the known p + p data. 4 refs., 11 figs
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