951 research outputs found
Latest Trends in Automotive Electronic Systems - Highway meets Off-Highway?
Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 9 (2007): Latest Trends in Automotive Electronic Systems - Highway meets Off-Highway?. Manuscript ATOE 07 012. Vol. IX. July, 2007
Polynomial Chaos Expansion method as a tool to evaluate and quantify field homogeneities of a novel waveguide RF Wien Filter
For the measurement of the electric dipole moment of protons and deuterons, a
novel waveguide RF Wien filter has been designed and will soon be integrated at
the COoler SYnchrotron at J\"ulich. The device operates at the harmonic
frequencies of the spin motion. It is based on a waveguide structure that is
capable of fulfilling the Wien filter condition ()
\textit{by design}. The full-wave calculations demonstrated that the waveguide
RF Wien filter is able to generate high-quality RF electric and magnetic
fields. In reality, mechanical tolerances and misalignments decrease the
simulated field quality, and it is therefore important to consider them in the
simulations. In particular, for the electric dipole moment measurement, it is
important to quantify the field errors systematically. Since Monte-Carlo
simulations are computationally very expensive, we discuss here an efficient
surrogate modeling scheme based on the Polynomial Chaos Expansion method to
compute the field quality in the presence of tolerances and misalignments and
subsequently to perform the sensitivity analysis at zero additional
computational cost.Comment: 12 pages, 19 figure
Beam Performance and Luminosity Limitations in the High-Energy Storage Ring (HESR)
The High-Energy Storage Ring (HESR) of the future International Facility for
Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an
antiproton synchrotron and storage ring in the momentum range from 1.5 to 15
GeV/c. An important feature of this new facility is the combination of phase
space cooled beams with dense internal targets (e.g. pellet targets), resulting
in demanding beam parameter of two operation modes: high luminosity mode with
peak luminosities up to 2*10^32 cm-2 s-1, and high resolution mode with a
momentum spread down to 10^-5, respectively. To reach these beam parameters
very powerful phase space cooling is needed, utilizing high-energy electron
cooling and high-bandwidth stochastic cooling. The effect of beam-target
scattering and intra-beam interaction is investigated in order to study beam
equilibria and beam losses for the two different operation modes.Comment: 8 pages, based on a talk presented at COULOMB'05, Accepted for
publication by Nuclear Instruments and Methods in Physics Research Section A:
Accelerators, Spectrometers, Detectors and Associated Equipmen
Hydrogen Spectroscopy with a Lamb-shift Polarimeter - An Alternative Approach Towards Anti-Hydrogen Spectroscopy Experiments
A Lamb-shift polarimeter, which has been built for a fast determination of
the polarization of protons and deuterons of an atomic-beam source and which is
frequently used in the ANKE experiment at COSY-J\"ulich, is shown to be an
excellent device for atomic-spectroscopy measurements of metastable hydrogen
isotopes. It is demonstrated that magnetic and electric dipole transitions in
hydrogen can be measured as a function of the external magnetic field, giving
access to the full Breit-Rabi diagram for the and the
states. This will allow the study of hyperfine structure, factors and the
classical Lamb shift. Although the data are not yet competitive with
state-of-the-art measurements, the potential of the method is enormous,
including a possible application to anti-hydrogen spectroscopy.Comment: 6 pages, 7 figures, accepted by European Physical Journal
Who Drives Climate-relevant Policies in Brazil?
In this report, the central question of our research is who drives/obstructs climate-relevant policies in Brazil, paying special attention to renewable energy policies, climate policies and politics. We aim to identify the actors (in government, the private sector and civil society) who drive, or obstruct, efforts to reduce the carbon intensity of Brazil’s energy mix. The hypothesis here is that the actors who drive climate policies in Brazil are not specifically concerned with global climate change itself, but with economic, social or even political issues, such as energy security, job creation, competitiveness, promoting national industries, and gaining political power domestically or internationally. In that sense, climate change mitigation can be regarded as a co-benefit of other policies (energy policies included) that may have very different objectives. To answer the above-mentioned question, this research assesses renewable energy policies in Brazil, identifying key actors from government, business and civil society and their explicit, or implicit, motivations.UK Department for International Developmen
A surprising method for polarising antiprotons
We propose a method for polarising antiprotons in a storage ring by means of
a polarised positron beam moving parallel to the antiprotons. If the relative
velocity is adjusted to the cross section for spin-flip is
as large as about barn as shown by new QED-calculations of
the triple spin-cross sections. Two possibilities for providing a positron
source with sufficient flux density are presented. A polarised positron beam
with a polarisation of 0.70 and a flux density of approximately /(mm s) appears to be feasible by means of a radioactive C
dc-source. A more involved proposal is the production of polarised positrons by
pair production with circularly polarised photons. It yields a polarisation of
0.76 and requires the injection into a small storage ring. Such polariser
sources can be used at low (100 MeV) as well as at high (1 GeV) energy storage
rings providing a time of about one hour for polarisation build-up of about
antiprotons to a polarisation of about 0.18. A comparison with other
proposals show a gain in the figure-of-merit by a factor of about ten.Comment: 13 pages, 8 figures; v2: minor language and signification corrections
v3: (14 pages, 12 figures) major error, nonapplicable polarisation transfer
cross sections replaced by the mandatory spin-flip cross section
Measurement of Partial-Wave Contributions in pp --> pp pi^0
We report a measurement of the spin-dependent total cross section ratios
delta_sigma_T/sigma_tot and delta_sigma_L/sigma_tot of the pp --> pp pi^0
reaction between 325 MeV and 400 MeV. The experiment was carried out with a
polarized internal target in a storage ring. Non-vertical beam polarization was
obtained by the use of solenoidal spin rotators. Near threshold, the knowledge
of both spin-dependent total cross sections is sufficient to deduce the
strength of certain participating partial waves, free of any model.Comment: 6 pages, 4 figure
Electromagnetic Simulation and Design of a Novel Waveguide RF Wien Filter for Electric Dipole Moment Measurements of Protons and Deuterons
The conventional Wien filter is a device with orthogonal static magnetic and
electric fields, often used for velocity separation of charged particles. Here
we describe the electromagnetic design calculations for a novel waveguide RF
Wien filter that will be employed to solely manipulate the spins of protons or
deuterons at frequencies of about 0.1 to 2 MHz at the COoler SYnchrotron COSY
at J\"ulich. The device will be used in a future experiment that aims at
measuring the proton and deuteron electric dipole moments, which are expected
to be very small. Their determination, however, would have a huge impact on our
understanding of the universe.Comment: 10 pages, 10 figures, 4 table
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