554 research outputs found
Simulations of the Interaction Region in a Photon-Photon Collider
The status and initial performance of a simulation program CAIN for
interaction region of linear colliders is described. The program is developed
to be applicable for e+e-, e-e-, e-gamma and gamma-gamma linear colliders. As
an example of an application, simulation of a gamma-gamma collider option of
NLC is reported.Comment: 16 pages, 6 eps figures, use epsf.st
Photoemission Quasi-Particle Spectra of SrRuO
Multi-band quasi-particle calculations based on perturbation theory and
dynamical mean field methods show that the creation of a photoemission hole
state in SrRuO is associated with a highly anisotropic self-energy.
Since the narrow Ru-derived bands are more strongly distorted by
Coulomb correlations than the wide band, charge is partially
transferred from to , thereby shifting the van
Hove singularity close to the Fermi level.Comment: 4 pages, to be published in PRB Rapid Com
Room temperature ferromagnetic behavior in the hollandite-type titanium oxide
A hollandite-type K(x)Ti(8)O(16) polycrystalline sample has been prepared and studied by magnetization, resistivity and x-ray photoelectron spectroscopy (XPS). Room temperature ferromagnetic behavior is observed in the magnetic hysteresis measurement. The sample shows a semiconductive temperature dependence in the resistivity measurement. Analysis of the Ti 2p(3/2) core-level XPS spectrum indicates that the titanium ions have a mixed valence of Ti(4+) and Ti(3+). In addition, the valence band spectrum reveals that the 3d electrons tend to localize on Ti(3+) ions in the hollandite-type TiO(2) lattice. Also, analysis of the valence band spectrum shows that the prepared sample is a wide-gap oxide with a band gap of 3.6 eV. These results indicate that the present hollandite-type K(x)Ti(8)O(16) sample can be classified as a TiO(2)-based wide-gap semiconductor with Curie temperature above room temperature. Room temperature ferromagnetism (RTFM) decreases in the sample prepared under a strong reducing gas atmosphere, accompanied with the decrease in the resistivity. The results imply that the localized 3d electrons are responsible for the RTFM of the K(x)Ti(8)O(16) sample
ILC Operating Scenarios
The ILC Technical Design Report documents the design for the construction of
a linear collider which can be operated at energies up to 500 GeV. This report
summarizes the outcome of a study of possible running scenarios, including a
realistic estimate of the real time accumulation of integrated luminosity based
on ramp-up and upgrade processes. The evolution of the physics outcomes is
emphasized, including running initially at 500 GeV, then at 350 GeV and 250
GeV. The running scenarios have been chosen to optimize the Higgs precision
measurements and top physics while searching for evidence for signals beyond
the standard model, including dark matter. In addition to the certain precision
physics on the Higgs and top that is the main focus of this study, there are
scientific motivations that indicate the possibility for discoveries of new
particles in the upcoming operations of the LHC or the early operation of the
ILC. Follow-up studies of such discoveries could alter the plan for the
centre-of-mass collision energy of the ILC and expand the scientific impact of
the ILC physics program. It is envisioned that a decision on a possible energy
upgrade would be taken near the end of the twenty year period considered in
this report
Metallic phase in stoichiometric CeOBiS 2 revealed by space-resolved ARPES
Recently CeOBiS2 system without any fluorine doping is found to show superconductivity posing question on its origin. Using space resolved ARPES we have found a metallic phase embedded in the morphological defects and at the sample edges of stoichiometric CeOBiS2. While bulk of the sample is semiconducting, the embedded metallic phase is characterized by the usual electron pocket at X point, similar to the Fermi surface of doped BiS2-based superconductors. Typical size of the observed metallic domain is larger than the superconducting correlation length of the system suggesting that the observed superconductivity in undoped CeOBiS2 might be due to this embedded metallic phase at the defects. The results also suggest a possible way to develop new systems by manipulation of the defects in these chalcogenides with structural instability
Superconductivity at 5.2 K in ZrTe3 polycrystals and the effect of Cu, Ag intercalation
We report the occurrence of superconductivity in polycrystalline samples of
ZrTe3 at 5.2 K temperature at ambient pressure. The superconducting state
coexists with the charge density wave (CDW) phase, which sets in at 63K. The
intercalation of Cu or Ag, does not have any bearing on the superconducting
transition temperature but suppresses the CDW state. The feature of CDW anomaly
in these compounds is clearly seen in the DC magnetization data. Resistivity
data is analysed to estimate the relative loss of carriers and reduction in the
nested Fermi surface area upon CDW formation in the ZrTe3 and the intercalated
compounds.Comment: 5 pages, 8 figure
Angle-resolved photoemission observation of the superconducting-gap minimum and its relation to the nesting vector in the phonon-mediated superconductor YNi<sub>2</sub>B<sub>2</sub>C
We have performed ultrahigh-resolution angle-resolved photoemission spectroscopy to directly study the large superconducting (SC) gap anisotropy of YNi2B2C. We succeed in measuring momentum (k) dependence of SC gap for individual Fermi surface (FS) sheets, which demonstrates complexity of SC gap in a phonon-mediated superconductor. Within measured k regions on FS sheets, we find a pointlike minimum of SC gap, whose k positions can be connected by the known nesting vector. This shows close correlation between the nesting vector and node formation
- …