168 research outputs found
Towards Space Solar Power - Examining Atmospheric Interactions of Power Beams with the HAARP Facility
In the most common space solar power (SSP) system architectures, solar energy
harvested by large satellites in geostationary orbit is transmitted to Earth
via microwave radiation. Currently, only limited information about the
interactions of microwave beams with energy densities of several tens to
hundreds of W/m with the different layers of the atmosphere is available.
Governmental bodies will likely require detailed investigations of safety and
atmospheric effects of microwave power beams before issuing launch licenses for
SSP satellite systems. This paper proposes to collect representative and
comprehensive data of the interaction of power beams with the atmosphere by
extending the infrastructure of the High Frequency Active Auroral Research
Program (HAARP) facility in Alaska, USA. Estimates of the transmission
infrastructure performance as well as measurement devices and scientific
capabilities of possible upgrade scenarios will be discussed. The proposed
upgrade of the HAARP facility is expected to deliver a wealth of data and
information which could serve as a decision base for governmental launch
licensing of SSP satellites, and which can be used in addition to deepen public
acceptance of SSP as a large-scale renewable energy source.
Copyright 2014 IEEE. Personal use of this material is permitted. Permission
from IEEE must be obtained for all other uses, in any current or future media,
including reprinting/republishing this material for advertising or promotional
purposes, creating new collective works, for resale or redistribution to
servers or lists, or reuse of any copyrighted component of this work in other
works.Comment: 7 pages, 3 figures; to be published in IEEE Xplore, in Proceedings to
IEEE Aerospace 2014 Conference, Mar 1 - 8, 2014, Big Sky, MT, US
Precise pion and kaon multiplicities at BELLE
Fragmentation functions (FFs) describe the formation of final state particles from a partonic initial state. Precise knowledge of these functions, especially
spin-average FFs, is a key ingredient in accessing quantities such as the nucleon spin structure in semi-inclusive deep inelastic scattering and proton-proton
collisions. However, fragmentation functions can currently not be determined from Quantum Chromodynamics first principles and have to be extracted from experimental data. The Belle experiment at KEK, Japan, provides a large data sample for high precision measurements of unpolarized and polarized fragmentation functions. Here, final extraction of the spin-independent FFs for identified pions and kaons will be presented
Helicity Parton Distributions at a Future Electron-Ion Collider: A Quantitative Appraisal
We present a quantitative assessment of the impact a future electron-ion
collider will have on determinations of helicity quark and gluon densities and
their contributions to the proton spin. Our results are obtained by performing
a series of global QCD analyses at next-to-leading order accuracy based on
realistic sets of pseudo-data for the inclusive and semi-inclusive
deep-inelastic scattering of longitudinally polarized electrons and protons at
different, conceivable center-of-mass system energies.Comment: 11 pages, 8 figure
Spin dependent fragmentation functions at Belle
The Belle detector at the KEKB e+e− collider provides large
amounts of statistics to study the fragmentation of light quarks into final state hadrons. In addition to unpolarized fragmentation functions also spin dependent fragmentation can be studied. Belle has successfully extracted asymmetries related to the Collins and interference fagmentation functions for charged pions
Precision measurement of charged pion and kaon differential cross sections in electron-positron annihilation at Q = 10.52 GeV
Measurements of inclusive differential cross sections for charged pion and
kaon production in electron-positron annihilation have been carried out at a
center-of-mass energy of Q = 10.52 GeV. The measurements were performed with
the Belle detector at the KEKB electron-positron collider using a data sample
containing 113 million e+e- -> qqbar events, where q={u,d,s,c}. We present
charge-integrated differential cross sections d\sigma_h+-/dz for h+- = pi+-,
K+- as a function of the relative hadron energy z = 2*E_h / sqrt{s} from 0.2 to
0.98. The combined statistical and systematic uncertainties for pi+- (K+-) are
4% (4%) at z ~ 0.6 and 15% (24%) at z ~ 0.9. The cross sections are the first
measurements of the z-dependence of pion and kaon production for z > 0.7 as
well as the first precision cross section measurements at a center-of-mass
energy far below the Z^0 resonance used by the experiments at LEP and SLC.Comment: 7 pages, 3 figures. Ancillary file including all cross section and
uncertainty values with 10 pages, 5 figure
Measurements of double-helicity asymmetries in inclusive production in longitudinally polarized collisions at GeV
We report the double helicity asymmetry, , in inclusive
production at forward rapidity as a function of transverse momentum
and rapidity . The data analyzed were taken during
GeV longitudinally polarized collisions at the Relativistic Heavy Ion
Collider (RHIC) in the 2013 run using the PHENIX detector. At this collision
energy, particles are predominantly produced through gluon-gluon
scatterings, thus is sensitive to the gluon polarization
inside the proton. We measured by detecting the decay
daughter muon pairs within the PHENIX muon spectrometers in the
rapidity range . In this kinematic range, we measured the
to be ~(stat)~~(syst). The
can be expressed to be proportional to the product of the
gluon polarization distributions at two distinct ranges of Bjorken : one at
moderate range where recent RHIC data of jet and
double helicity spin asymmetries have shown evidence for significant gluon
polarization, and the other one covering the poorly known small- region . Thus our new results could be used to further
constrain the gluon polarization for .Comment: 335 authors, 10 pages, 4 figures, 3 tables, 2013 data. Version
accepted for publication by Phys. Rev. D. Plain text data tables for the
points plotted in figures for this and previous PHENIX publications are (or
will be) publicly available at http://www.phenix.bnl.gov/papers.htm
J/psi suppression at forward rapidity in Au+Au collisions at sqrt(s_NN)=39 and 62.4 GeV
We present measurements of the J/psi invariant yields in sqrt(s_NN)=39 and
62.4 GeV Au+Au collisions at forward rapidity (1.2<|y|<2.2). Invariant yields
are presented as a function of both collision centrality and transverse
momentum. Nuclear modifications are obtained for central relative to peripheral
Au+Au collisions (R_CP) and for various centrality selections in Au+Au relative
to scaled p+p cross sections obtained from other measurements (R_AA). The
observed suppression patterns at 39 and 62.4 GeV are quite similar to those
previously measured at 200 GeV. This similar suppression presents a challenge
to theoretical models that contain various competing mechanisms with different
energy dependencies, some of which cause suppression and others enhancement.Comment: 365 authors, 10 pages, 11 figures, 4 tables. Submitted to Phys. Rev.
C. Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Cross Section and Transverse Single-Spin Asymmetry of Mesons in Collisions at GeV at Forward Rapidity
We present a measurement of the cross section and transverse single-spin
asymmetry () for mesons at large pseudorapidity from
~GeV collisions. The measured cross section for
~GeV/ and is well described by a
next-to-leading-order perturbative-quantum-chromodynamics calculation. The
asymmetries have been measured as a function of Feynman- () from
, as well as transverse momentum () from
~GeV/. The asymmetry averaged over positive is
. The results are consistent with prior
transverse single-spin measurements of forward and mesons at
various energies in overlapping ranges. Comparison of different particle
species can help to determine the origin of the large observed asymmetries in
collisions.Comment: 484 authors, 13 pages, 11 figures, 4 tables, 2008 data. v2 is version
accepted by Phys. Rev. D. Plain text data tables for the points plotted in
figures for this and previous PHENIX publications are (or will be)publicly
available at http://www.phenix.bnl.gov/papers.htm
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