3,190 research outputs found
Cosmogenic Mn-53 in meteorites
The distributions of the Mn-53 contents in 106 nonantarctic and 112 antarctic chondrites were analyzed. A correlation analysis of these distributions showed that the correlation coefficient is a maximum r sub max = 0.75 plus or minus 0.03) when the histogram for antarctic chondrites is displaced by 40 plus or minus 8 dpm kg-1Fe towards lower Mn-53 contents. The distribution of Mn-53 saturated contents in nonantarctic ordinary chondrites was investigated as a function of their radiation age (T). It is found that the Mn-53 average content is higher by (21 plus or minus 9)% in H-chondrites with radiation age T approximately 12 Myr than in thse with T 12 Myr. This effect can be attributed to the fact that a considerable proportion of H-chondrites with T 12 Myr originates from a comet or from the objects of Chiron like, with the orbits more inclined to the ecliptic plane and/or more extended, which caused their irradiation by cosmic rays of higher intensity
A generating functional approach to the Hubbard model
The method of generating functional is generalized to the case of strongly
correlated systems, and applied to the Hubbard model. For the electronic
Green's function constructed for Hubbard operators, an equation using
variational derivatives with respect to the fluctuating fields has been derived
and its multiplicative form has been determined. Corrections for the electronic
self-energy are calculated up to the second order with respect to the parameter
W/U (W width of the band), and a mean field type approximation was formulated,
including both charge and spin static fluctuations. The equations for the
Bose-like Green's functions have been derived, describing the collective modes:
the magnons and doublons. The properties of the poles of the doublon Green's
functions depend on electronic filling. The investigation of the special case
n=1 demonstrates that the doublon Green's function has a soft mode at the wave
vector Q=(pi,pi,...), indicating possible instability of the uniform
paramagnetic phase relatively to the two sublattices charge ordering. However
this instability should compete with an instability to antiferromagnetic
ordering.Comment: 31 pages, 7 figures, to be published in Eur. Phys. J.
On Possible Measurement of Gravitational Interaction Parameters on Board a Satellite
The recently suggested SEE (Satellite Energy Exchange) method of measuring
the gravitational constant , possible equivalence principle violation
(measured by the E\"{o}tv\"{o}s parameter ) and the hypothetic 5th force
parameters and on board a drag-free Earth's satellite is
discussed and further developed. Various particle trajectories near a heavy
ball are numerically simulated. Some basic sources of error are analysed. The
measurement procedure is modelled by noise insertion to a ``true''
trajectory. It is concluded that the present knowledge of (for
m) and can be improved by at least two orders of
magnitude.Comment: (only two misprints on title page) 7 page
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