1,045 research outputs found
Magnescope: Applications in nondestructive evaluation
This paper describes recent results obtained with the Magnescope, which has been used on location in industrial environments and has successfully detected impending fatigue failure, creep damage, applied stress, and microstructural differences. It is concluded that the device provides a useful nondestructive method for evaluating the mechanical properties of materials through the measurement of their structure sensitive magnetic properties
Coherent photon bremsstrahlung and dynamics of heavy-ion collisions: comparison of different models
Differential spectra of coherent photon bremsstrahlung in relativistic heavy
ion collisions are calculated within various schematic models of the
projectile-target stopping. Two versions of the degradation length model, based
on a phenomenological deceleration law, are considered. The simple shock wave
model is studied analytically. The predictions of these models agree in the
soft photon limit, where the spectrum is determined only by the final velocity
distribution of charged particles. The results of these models in the case of
central Au+Au collisions at various bombarding energies are compared with the
predictions of the microscopic transport model UrQMD. It is shown that at the
AGS energy the coherent photon bremsstrahlung exceeds the photon yield from
-decays at photon energies \omega\loo 50 MeV.Comment: 23 pages RevTeX, 9 eps Figure
The electromagnetic interaction of ultrarelativistic heavy ions
The validity of a delta-function approximation for the electromagnetic
interaction of relativistic heavy ions is investigated. The production of e+e-
pairs, with electron capture, is used as a test of the approximation.Comment: 11 pages, 3 figure
Multipole Expansion of Bremsstrahlung in Intermediate Energy Heavy Ion Collisions
Using a multipole expansion of the radiated field generated by a classical
electric current, we present a way to interprete the bremsstrahlung spectra of
low energy heavy ion collisions. We perform the calculation explicitely for the
system ^{12}C+ ^{12}C at 84AMeV and compare the result with the experimental
data of E. Grosse et al. Using simple model assumptions for the electromagnetic
source current we are able to describe the measured data in terms of coherent
photon emission. In this context, the information contained in the measured
data is discussed.Comment: LaTex, 4 Figure
Survey of J=0,1 mesons in a Bethe-Salpeter approach
The Bethe-Salpeter equation is used to comprehensively study mesons with
J=0,1 and equal-mass constituents for quark masses from the chiral limit to the
b-quark mass. The survey contains masses of the ground states in all
corresponding J^{PC} channels including those with "exotic" quantum numbers.
The emphasis is put on each particular state's sensitivity to the low- and
intermediate-momentum, i.e., long-range part of the strong interaction.Comment: 8 pages, 4 figure
Generation of short-pulse VUV and XUV radiation
Starting from intense short-pulse KrF (248 nm, 25 mJ, 400 fs), ArF (193 nm, 10 mJ, sim1 ps), and Ti:sapphire (810 nm, 100 mJ, 150 fs) laser systems, schemes for the generation of fixed-frequency and tunable VUV and XUV radiation by nonlinear optical techniques are investigated. With the KrF system, a four-wave mixing process in xenon yields tunable radiation in the range of 130–200 nm with output energies of, so far, 100 mgrJ in less than 1 ps. For the XUV spectral range below 100 nm, nonperturbative high-order harmonic generation and frequency mixing processes in noble gas jets are considered. To achieve tunability, the intense fixed-frequency pump laser radiation is mixed with less intense but broadly tunable radiation from short-pulse dye lasers or optical parametric generator-amplifier systems. In this way, tunability down to wavelengths of less than 40 nm has been demonstrated
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