5,451 research outputs found
Non-invasive single-bunch matching and emittance monitor
On-line monitoring of beam quality for high brightness beams is only possible
using non-invasive instruments. For matching measurements, very few such
instruments are available. One candidate is a quadrupole pick-up. Therefore, a
new type of quadrupole pick-up has been developed for the 26 GeV Proton
Synchrotron (PS) at CERN, and a measurement system consisting of two such
pick-ups is now installed in this accelerator. Using the information from these
pick-ups, it is possible to determine both injection matching and emittance in
the horizontal and vertical planes, for each bunch separately. This paper
presents the measurement method and some of the results from the first year of
use, as well as comparisons with other measurement methods.Comment: 10 pages, 10 figures; added figure, minor textual additions; To be
resubmitted to Phys. Rev. ST-A
Mechanical behavior of a continuous fiber reinforced aluminum matrix composite subjected to transverse and thermal loading
The transverse properties of an aluminum alloy metal matrix composite reinforced by continuous alumina fibers were investigated. The composite is subjected to both mechanical and cyclic thermal loading. The results of an experimental program indicate that the shakedown concept of structural mechanics provides a means of describing the material behavior. When the loading conditions are within the shakedown region, the material finally responds in an elastic manner after initial plastic response, and for loading conditions outside the shakedown region, the material exhibits a rapid incremental plastic strain accumulation. The failure strain varies by an order of magnitude according to the operating conditions. Hence, for high mechanical and low thermal loading, the failure strains is small; for low mechanical and high thermal loading, the failure strain is large
Reduction of thermal stresses in continuous fiber reinforced metal matrix composites with interface layers
The potential of using an interface layer to reduce thermal stresses in the matrix of composites with a mismatch in coefficients of thermal expansion of fiber and matrix was investigated. It was found that compliant layers, with properties of readily available materials, do not have the potential to reduce thermal stresses significantly. However, interface layers with high coefficient of thermal expansion can compensate for the mismatch and reduce thermal stresses in the matrix significantly
Tomographic reconstruction of transverse phase space from turn-by-turn profile data
Tomographic methods have the potential for useful application in beam diagnostics. The tomographic reconstruction of transverse phase space density from turn-by-turn profile data has been studied with particular attention to the effects of dispersion and chromaticity. It is shown that the modified Algebraic Reconstruction Technique (ART) that deals successfully with the problem of non-linear motion in the longitudinal plane cannot, in general, be extended to cover the transverse case. Instead, an approach is proposed in which the effect of dispersion is deconvoluted from the measured profiles before the phase space picture is reconstructed using either the modified ART algorithm or the inverse Radon Transform. This requires an accurate knowledge of the momentum distribution of the beam and the modified ART reconstruction of longitudinal phase space density yields just such information. The method has been tested extensively with simulated data
Ion counting efficiencies at the IGISOL facility
At the IGISOL-JYFLTRAP facility, fission mass yields can be studied at high
precision. Fission fragments from a U target are passing through a Ni foil and
entering a gas filled chamber. The collected fragments are guided through a
mass separator to a Penning trap where their masses are identified. This
simulation work focuses on how different fission fragment properties (mass,
charge and energy) affect the stopping efficiency in the gas cell. In addition,
different experimental parameters are varied (e. g. U and Ni thickness and He
gas pressure) to study their impact on the stopping efficiency. The simulations
were performed using the Geant4 package and the SRIM code. The main results
suggest a small variation in the stopping efficiency as a function of mass,
charge and kinetic energy. It is predicted that heavy fragments are stopped
about 9% less efficiently than the light fragments. However it was found that
the properties of the U, Ni and the He gas influences this behavior. Hence it
could be possible to optimize the efficiency.Comment: 52 pages, 44 figure
Beam instrumentation for the Tevatron Collider
The Tevatron in Collider Run II (2001-present) is operating with six times
more bunches and many times higher beam intensities and luminosities than in
Run I (1992-1995). Beam diagnostics were crucial for the machine start-up and
the never-ending luminosity upgrade campaign. We present the overall picture of
the Tevatron diagnostics development for Run II, outline machine needs for new
instrumentation, present several notable examples that led to Tevatron
performance improvements, and discuss the lessons for future colliders
Considerations for an Ac Dipole for the LHC
Following successful experience at the BNL AGS, FNAL Tevatron, and CERN SPS,
an AC Dipole will be adopted at the LHC for rapid measurements of ring optics.
This paper describes some of the parameters of the AC dipole for the LHC,
scaling from performance of the FNAL and BNL devices.Comment: proceedings of the 2007 Particle Accelerator Conferenc
- …