5,960 research outputs found
Synchro-Betatron Stop-Bands due to a Single Crab Cavity
We analyze the stop-band due to crab cavities for horizontal tunes that are
either close to integers or close to half integers. The latter case is relevant
for today's electron/positron colliders. We compare this stop-band to that
created by dispersion in an accelerating cavity and show that a single typical
crab cavity creates larger stop-bands than a typical dispersion at an
accelerating cavity.
We furthermore analyze whether it is beneficial to place the crab cavity at a
position where the dispersion and its slope vanish. We find that this choice is
worth while if the horizontal tune is close to a half integer, but not if it is
close to an integer. Furthermore we find that stop-bands can be avoided when
the horizontal tune is located at a favorable side of the integer or the half
integer.
While we are here concerned with the installation of a single crab cavity in
a storage ring, we show that the stop-bands can be weakened, although not
eliminated, significantly when two crab cavities per ring are chosen suitably.Comment: 7 pages, 9 figure
Wave scattering and splitting by magnetic metamaterials
We study experimentally propagation of electromagnetic waves
through a slab of uniaxial magnetic metamaterial. We observe a range of
novel phenomena including partial focusing and splitting into multiple
transmitted beams.We demonstrate that while some of these experimentally
observed effects can be described within the approximation of an effective
medium, a deeper understanding of the experimental results requires a
rigorous study of internal eigenmodes of the lattice of resonators
Recommended from our members
Tera-Hertz Coherent Radiation from Steady-State Microbunching in Storage Rings with X-band Radio-Frequency System
Multiplicity dependence of identical particle correlations in the quantum optical approach
Identical particle correlations at fixed multiplicity are consideres in the
presence of chaotic and coherent fields. The multiplicity distribution,
one-particle momentum density, and two-particle correlation function are
obtained based on the diagrammatic representation for cmulants in
semi-inclusive events. Our formulation is applied to the analysis of the
experimental data on the multiplicity dependence of correlation functions
reported by the UA1 and the OPAL Collaborations.Comment: 14 pages, 7 figure
A Crucial Test for Color-Octet Production Mechanism in Z^0 Decays
The direct production rates of -wave charmonia in the decays of is
evaluated. The color-octet production processes are shown to have distinctively large branching ratios, the same order
of magnitude as that of prodution, as compared with other -wave
charmonium production mechanisms. This may suggest a crucial channel to test
the color-octet mechanism as well as to observe the -wave charmonium states
in decays. In addition, a signal for the charmonium as strong as
or with large transverse momentum at the Tevatron should
also be observed.Comment: 14 pages in LaTex (3 figures in PS-file
Gamma photons from parametric resonance in neutron stars
Shock waves in cold nuclear matter, e.g. those induced by a collision of two
neutron stars, can generate a large number of gamma photons via parametric
resonance. We study the resonant production of gamma rays inside a shocked
neutron star and discuss the possible astrophysical consequences of this
phenomenon.Comment: 5 pages, ReVTeX, 5 figures inserted with epsf; replaced with a final
version (minor changes
Review of HBT or Bose-Einstein correlations in high energy heavy ion collisions
A brief review is given on the discovery and the first five decades of the
Hanbury Brown - Twiss effect and its generalized applications in high energy
nuclear and particle physics, that includes a meta-review. Interesting and
inspiring new directions are also highlighted, including for example source
imaging, lepton and photon interferometry, non-Gaussian shape analysis as well
as many other new directions. Existing models are compared to two-particle
correlation measurements and the so-called RHIC HBT puzzle is resolved.
Evidence for a (directional) Hubble flow is presented and the conclusion is
confirmed by a successful description of the pseudorapidity dependence of the
elliptic flow as measured in Au+Au collisions by the PHOBOS Collaboration.Comment: 14 pages, 1 figure, 8 sub-figures, invited plenary talk at the
ICPA-QGP 2005 conference in Kolkata, Indi
A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned Aerial Vehicles
In recent years, there has been a dramatic increase in the use of unmanned
aerial vehicles (UAVs), particularly for small UAVs, due to their affordable
prices, ease of availability, and ease of operability. Existing and future
applications of UAVs include remote surveillance and monitoring, relief
operations, package delivery, and communication backhaul infrastructure.
Additionally, UAVs are envisioned as an important component of 5G wireless
technology and beyond. The unique application scenarios for UAVs necessitate
accurate air-to-ground (AG) propagation channel models for designing and
evaluating UAV communication links for control/non-payload as well as payload
data transmissions. These AG propagation models have not been investigated in
detail when compared to terrestrial propagation models. In this paper, a
comprehensive survey is provided on available AG channel measurement campaigns,
large and small scale fading channel models, their limitations, and future
research directions for UAV communication scenarios
Scaling violations: Connections between elastic and inelastic hadron scattering in a geometrical approach
Starting from a short range expansion of the inelastic overlap function,
capable of describing quite well the elastic pp and scattering data,
we obtain extensions to the inelastic channel, through unitarity and an impact
parameter approach. Based on geometrical arguments we infer some
characteristics of the elementary hadronic process and this allows an excellent
description of the inclusive multiplicity distributions in and
collisions. With this approach we quantitatively correlate the violations of
both geometrical and KNO scaling in an analytical way. The physical picture
from both channels is that the geometrical evolution of the hadronic
constituents is principally reponsible for the energy dependence of the
physical quantities rather than the dynamical (elementary) interaction itself.Comment: 16 pages, aps-revtex, 11 figure
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