74 research outputs found
Angular analysis of bremsstrahlung in alpha decay
A new quantum electrodynamical method of calculations of bremsstrahlung
spectra in the -decay of heavy nuclei taking into account the angle
between the directions of -particle motion (or its tunneling) and
photon emission is presented. The angular bremsstrahlung spectra for
have been obtained for the first time. According to calculations,
the bremsstrahlung in the -decay of this nucleus depends extremely
weakly on the angle. Taking into account nuclear forces, such dependence is not
changed visibly. An analytical formula of the angular dependence of the
bremsstrahlung spectra is proposed and gives its harmonic behavior. The
extremal values of the angle, at which the bremsstrahlung has maximal and
minimal values, has been found.Comment: 15 pages, 1 file of figure in EPS format, LaTeX v.2e with EPJ style.
In the new variant of the paper: 1) more attention is given to a convergence
problem of computer calculations of the bremsstrahlung spectra; 2) a new
section with inclusion of Woods-Saxon component in construction of the total
realistic -nucleus potential into our model (with our first
brermsstrahlung spectra for at such potential) is included into
the paper; 3) possible ways of further improvement of the quantum-mechanical
models are pointed ou
Radiative corrections to low energy neutrino reactions
We show that the radiative corrections to charged current (CC) nuclear
reactions with an electron(positron) in the final state are described by a
universal function. The consistency of our treatment of the radiative
corrections with the procedure used to extract the value of the axial coupling
constant is discussed. To illustrate we apply our results to
(anti)neutrino deuterium disintegration and to fusion in the sun. The
limit of vanishing electron mass is considered, and a simple formula valid for
E_{obs}\gsim 1 MeV is obtained. The size of the nuclear structure-dependent
effects is also discussed. Finally, we consider CC transitions with an
electron(positron) in the initial state and discuss some applications to
electron capture reactions.Comment: 23 pages, 5 figure
Bremsstrahlung emission during -decay of
We obtained the spectrum of probability of the bremsstrahlung emission
accompanying the -decay of (E=4.8 MeV) by
measuring the - coincidences and using the model presented in
our previous study on the decay of (E=7.7
MeV). We compare the experimental data with the quantum mechanical calculation
and find a good agreement between theory and experiment. We discuss the
differences between the photon spectra connected with the -decay of the
and nuclei. For the two mentioned nuclei we
analyze the bremsstrahlung emission contributions from the tunneling and
external regions of the nucleus barrier into the total spectrum, and we find
the destructive interference between these contributions. We also find that the
emission of photons during tunneling of the -particle gives an
important contribution to the bremsstrahlung spectrum in the whole E
energy range of the studied Ra nucleus
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.
Multipolar model of bremsstrahlung accompanying proton-decay of nuclei
Emission of bremsstrahlung photons accompanying proton decay of nuclei is
studied. The new improved multipolar model describing such a process is
presented. The angular formalism of calculations of the matrix elements is
stated in details. The bremsstrahlung probabilities for the ,
, and nuclei decaying from
the state, the and nuclei decaying from the state, the and nuclei decaying from the
state are predicted. Such spectra have orders of values similar to the
experimental data for the bremsstrahlung photons emitted during the
-decay. This indicates on real possibility to study bremsstrahlung
photons during proton decay experimentally and perform further measurements.Comment: 14 pages, 6 figure
Electromagnetic fields: biological and clinical aspects.
Our entire biosphere is immersed in a sea of man-made electromagnetic fields (EMF). Occupational and public health data suggest that these fields may be a health hazard, possibly involving cancer and fetal loss. This paper reviews the history and pertinent physics of electromagnetic fields and presents evidence from the authors' work, and that of others, of biological interaction with living systems. Epidemiological data suggesting EMF hazards are reviewed including a discussion of possible risks associated with Hawaii's Lualualei transmitter site, TV and FM antennas in high-density population areas, fields surrounding electric power transmission and computer terminals, and the plan to route a major highway through the near-field of an operating Omega signal-source. In the face of current public fear and controversial research reports about long-term EMF exposure, suggestions are presented for public policy about these local sources of concern, as well as for the EMF risks common to any similarly developed areas
- …