3,262 research outputs found
Pion-Nucleus Scattering at Medium Energies with Densities from Chiral Effective Field Theories
Recently developed chiral effective field theory models provide excellent
descriptions of the bulk characteristics of finite nuclei, but have not been
tested with other observables. In this work, densities from both relativistic
point-coupling models and mean-field meson models are used in the analysis of
meson-nucleus scattering at medium energies. Elastic scattering observables for
790
MeV/ on Pb are calculated in a relativistic impulse
approximation, using the Kemmer-Duffin-Petiau formalism to calculate the
nucleus optical potential.Comment: 9 page
Dimensional crossover of the exchange-correlation energy at the semilocal level
Commonly used semilocal density functional approximations for the
exchange-correlation energy fail badly when the true two dimensional limit is
approached. We show, using a quasi-two-dimensional uniform electron gas in the
infinite barrier model, that the semilocal level can correctly recover the
exchange-correlation energy of the two-dimensional uniform electron gas. We
derive new exact constraints at the semilocal level for the dimensional
crossover of the exchange-correlation energy and we propose a method to
incorporate them in any exchange-correlation density functional approximation.Comment: 6 pages, 5 figure
Data compression for the Cassini radio and plasma wave instrument
The Cassini Radio and Plasma Wave Science experiment will employ data compression to make effective use of the available data telemetry bandwidth. Some compression will be achieved by use of a lossless data compression chip and some by software in a dedicated 80C85 processor. A description of the instrument and data compression system are included in this report. Also, the selection of data compression systems and acceptability of data degradation is addressed
Scaling behaviour of the critical current in clean epitaxial Ba(Fe1-xCox)2As2 thin films
The angular-dependent critical current density, Jc(theta), and the upper
critical field, Hc2(theta), of epitaxial Ba(Fe1-xCox)2As2 thin films have been
investigated. No Jc(theta) peaks for H || c were observed regardless of
temperatures and magnetic fields. In contrast, Jc(theta) showed a broad maximum
at theta=90 degree, which arises from intrinsic pinning. All data except at
theta=90 degree can be scaled by the Blatter plot. Hc2(theta) near Tc follows
the anisotropic Ginzburg-Landau expression. The mass anisotropy increased from
1.5 to 2 with increasing temperature, which is an evidence for multi-band
superconductivity.Comment: Accepted in Physical Review B rapid communication
Highly anisotropic energy gap in superconducting Ba(FeCo)As from optical conductivity measurements
We have measured the complex dynamical conductivity, , of superconducting Ba(FeCo)As ( K) at terahertz frequencies and temperatures 2 - 30 K. In the frequency
dependence of below , we observe clear signatures of the
superconducting energy gap opening. The temperature dependence of
demonstrates a pronounced coherence peak at frequencies below 15 cm (1.8
meV). The temperature dependence of the penetration depth, calculated from
, shows power-law behavior at the lowest temperatures. Analysis of
the conductivity data with a two-gap model, gives the smaller isotropic s-wave
gap of meV, while the larger gap is highly anisotropic with
possible nodes and its rms amplitude is meV. Overall, our
results are consistent with a two-band superconductor with an gap
symmetry.Comment: 6 pages, 4 figures, discussion on pair-barking scattering and
possible lifting of the nodes is adde
- …