603 research outputs found
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
Electrostatic accelerators
The principle of electrostatic accelerators is presented. We consider Cockcroft Walton, Van de Graaff and Tandem Van de Graaff accelerators. We resume high voltage generators such as cascade generators, Van de Graaff band generators, Pelletron generators, Laddertron generators and Dynamitron generators. The speci c features of accelerating tubes, ion optics and methods of voltage stabilization are described. We discuss the characteristic beam properties and the variety of possible beams. We sketch possible applications and the progress in the development of electrostatic accelerators
Ion optics with electrostatic lenses
Ion optics with electrostatic lenses is presented using the standard matrix formalism of magnetic ion optics. We introduce the paraxial ray equation which is appropriate to systems with rotational symmetry. The rst-order solutions of the paraxial ray equation are derived. The resulting transport matrices can be used to study systems with acceleration tube lenses, aperture lenses, einzel lenses and dc accelerators. The analogy with geometrical optics is discussed. Beam transport and phase ellipses are described using the so-called matrices. The equations of the longitudinal transport matrix are derived. Besides rotational symmetric elements, electrostatic quadrupoles and electrostatic de- ectors are also presented. The effect of space charge forces is discussed
Study of the Interaction Close to the and Thresholds
The interaction close to the threshold is considered.
Specifically, the pronounced structure seen in production reactions like and around the threshold
is analyzed. Modern interaction models of the coupled
systems generate such a structure either due to the presence of a
(deuteron-like) unstable bound state or of an inelastic virtual state. % A
determination of the position of the prominent peak as observed in various
experiments for the two aforementioned reactions leads to values that agree
quite well with each other. Furthermore, the deduced mean value of MeV for the peak position coincides practically with the threshold energy
of the channel. This supports the interpretation of the structure
as a genuine cusp, signaling an inelastic virtual state in the
partial wave of the isospin 1/2 channel. % There is also evidence
for a second peak (or shoulder) in the data sets considered which appears at
roughly 10-15 MeV above the threshold. However, its concrete
position varies significantly from data set to data set and, thus, a
theoretical interpretation is difficult.Comment: accepted for publication Nucl. Phys.
Experimental study of isospin mixing in ¹²C + n-->¹³C(T=3/2) and ¹⁶O + n-->¹⁷O(T=3/2)resonances
Study of the and reactions close to threshold
Two--kaon production in proton--deuteron collisions has been studied at three
energies close to threshold using a calibrated magnetic spectrograph to measure
the final He and a vertex detector to measure the pair.
Differential and total cross sections are presented for the production of
--mesons, decaying through , as well as for prompt
production. The prompt production seems to follow phase space in both
its differential distributions and in its energy dependence. The amplitude for
the {He} reaction varies little for excess energies below 22
MeV and the value is consistent with that obtained from a threshold
measurement. The angular distribution of the decay pair shows that
near threshold the --mesons are dominantly produced with polarization
along the initial proton direction. No conclusive evidence for
production is found in the data.Comment: 13 figure
Cross section of the reaction close to threshold
We have measured inclusive data on -meson production in collisions
at COSY J\"ulich close to the hyperon production threshold and determined the
hyperon-nucleon invariant mass spectra. The spectra were decomposed into three
parts: , and . The cross section for the
channel was found to be much smaller than a previous measurement in
that excess energy region. The data together with previous results at higher
energies are compatible with a phase space dependence.Comment: accepted by Phys. lett. B some typos correcte
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