4,218 research outputs found
The mass spectra and decay properties of dimesonic states, using the Hellmann potential
Mass spectra of the dimesonic (meson-antimeson) molecular states are computed
using the Hellmann potential in variational approach, which consists of
relativistic correction to kinetic energy term as well as to the potential
energy term. For the study of molecular bound state system, the Hellmann
potential of the form is
being used. The one pion exchange potential (OPEP) is also incorporated in the
mass calculation. The digamma decay width and decay width of the dimesonic
system are evaluated using the wave function. The experimental states such as
, , , , ,
,, , , ,
are compared with dimesonic states. Many of these states (masses
and their decay properties) are close to our theoretical predictions.Comment: 11 pages, 4 table
Growth, Characterization, Vortex Pinning and Vortex Flow Properties of Single Crystals of Iron Chalcogenide Superconductor FeCrSe
We report the growth and characterization of single crystals of iron
chalcogenide superconductor FeCrSe. There is an enhancement of the
superconducting transition temperature (T) as compared to the T of the single crystals of the parent compound FeSe by about 25%.
The superconducting parameters such as the critical fields, coherence length,
penetration depth and the Ginzburg-Landau parameter have been estimated for
these single crystals. Analysis of the critical current data suggests a
fluctuation in electronic mean free path induced () pinning mechanism
in this material. Thermally activated transport across the superconducting
transition in the presence of external magnetic fields suggests a crossover
from a single vortex pinning regime at low fields to a collective flux creep
regime at higher magnetic fields. The nature of charge carriers in the normal
state estimated from the Hall effect and thermal transport measurements could
provide crucial information on the mechanism of superconductivity in Fe-based
materials.Comment: 2 additional figures, additional discussion on nature of charge
carrier
Laser cooling and trapping of Yb from a thermal source
We have successfully loaded a magneto-optic trap for Yb atoms from a thermal
source without the use of a Zeeman slower. The source is placed close to the
trapping region so that it provides a large flux of atoms that can be cooled
and captured. The atoms are cooled on the
transition at 398.8 nm. We have loaded all seven stable isotopes of Yb into the
trap. For the most abundant isotope (Yb), we load more than
atoms into the trap within 1 s. For the rarest isotope (Yb) with a
natural abundance of only 0.13%, we still load about atoms into
the trap. We find that the trap population is maximized near a detuning of
and field gradient of 75 G/cm.Comment: 4 figures, 6 page
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