108 research outputs found
Measurement of the analyzing power in pp elastic scattering in the peak CNI region at RHIC
We report the first measurements of the A_N absolute value and shape in the
-t range from 0.0015 to 0.010GeV/c^2 with a precision better than 0.005 for
each A_N data point using a polarized atomic hydrogen gas jet target and the
100 GeV RHIC proton beam.Comment: 4 pages, 5 figure
Optical properties and Raman scattering of vanadium ladder compounds
We investigate electronic and optical properties of the V-based ladder
compounds NaV2O5, the iso-structural CaV2O5, as well as MgV2O5, which differs
from NaV2O5 and CaV2O5 in the c axis stacking. We calculate ab initio the A_g
phonon modes in these compounds as a basis for the investigation of the
electron-phonon and spin-phonon coupling. The phonon modes together with the
dielectric tensors as a function of the corresponding ion displacements are the
starting point for the calculation of the A_g Raman scattering.Comment: 4 pages, 5 figures, .bbl file with references included. Accepted for
publication in Physica Script
Fractional Power-Law Spectral Response of CaCu3Ti4O12 Dielectric: Many-Body Effects
Spectral character of dielectric response in CaCu3Ti4O12 across 0.5Hz-4MHz
over 45-200K corresponding to neither the Debyean nor the KWW relaxation
patterns rather indicates a random-walk like diffusive dynamics of moments.
Non-linear relaxation here is due to the many body dipole-interactions, as
confirmed by spectral-fits of our measured permittivity to the Dissado-Hill
behaviour. Fractional power-laws observed in {\epsilon}*({\omega})
macroscopically reflect the fractal microscopic configurations. Below ~100K,
the power-law exponent m (n) steeply decreases (increases), indicating finite
length-scale collective response of moment-bearing entities. At higher
temperatures, m gradually approaches 1 and n falls to low values, reflecting
tendency towards the single-particle/Debyean relaxation.Comment: 10 pages, 3 figures, 22 reference
The GDH sum rule for the deuteron
As first topic, the GDH sume rule is discussed in the context of a more
general class of sum rules associated with the various contributions to the
total photoabsorption cross section for target and beam polarization. Then I
address the question of whether the GDH sum rule for the neutron can be
determined from the one for the deuteron. It appears that this will not be
possible in a simple manner. The spin response of the deuteron is calculated
including contributions from the photodisintegration channel and from coherent
and incoherent single pion production as well, and the GDH integral is
evaluated up to a photon energy of 550 MeV. The photodisintegration channel
converges fast enough and gives a large negative contribution, essentially from
the state near threshold and its absolute size is about the same than
the sum of proton and neutron GDH values. It is only partially cancelled by the
single pion production contribution. But the incoherent channel has not reached
convergence at 550 MeV.Comment: talk at GDH-2000 Symposium, Mainz, 14.-17.6.2000 12 pages latex
including 3 figures, needs world scientific style (ws-p8-50x6-00.cls
Modification of the standard model for the lanthanides
We show that incorporation of strong electron correlations into the Kohn-Sham
scheme of band structure calculations leads to a modification of the standard
model of the lanthanides and that this procedure removes the existing
discrepancy between theory and experiment concerning the ground state
properties. Within the picture suggested, part of the upper Hubbard -band is
occupied due to conduction band--mixing interaction (that is renormalized
due to correlations) and this contributes to the cohesive energy of the
crystal. The lower Hubbard band has zero width and describes fermionic
excitations in the shell of localized -s. Fully self-consistent calculations
(with respect to both charge density and many-electron population numbers of
the -shell) of the equilibrium volume and the bulk modulus of selected
lanthanides have been performed and a good agreement is obtained.Comment: 1 fi
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