1,508 research outputs found
Nondestructive assessment of penetration of electron-beam welds
Empirical method correlates penetration of an electron-beam weld with external measurements of the weld. Empirical polygon accurately confirms full-penetration welds while a second, larger polygon provides for penetration of welds near the tip
QED \otimes QCD Threshold Corrections at the LHC
We use the theory of YFS resummation to compute the size of the expected
resummed soft radiative threshold effects in precision studies of heavy
particle production at the LHC, where accuracies of 1 percent are desired in
some processes. We find that the soft QED threshold effects are at the level of
0.3 percent whereas the soft QCD threshold effects enter at the level of 20
percent and hence both must be controlled to be on the conservative side to
achieve such goals.Comment: 8 pages, no figures; improved text; improved refs. and tex
The Virtual Correction to Bremsstrahlung in High-Energy e+ e- Annihilation: Comparison of Exact Results
We have compared the virtual corrections to single hard bremsstrahlung as
calculated by S. Jadach, M. Melles, B.F.L. Ward and S.A. Yost to several other
expressions. The most recent of these comparisons is to the leptonic tensor
calculated by J.H. Kuhn and G. Rodrigo for radiative return. Agreement is found
to within a part in 10^5 or better, as a fraction of the Born cross section,
for most of the range of photon energies. The massless limits have been shown
to agree analytically to NLL order.Comment: 7 pages, 2 figures. Presented by S.A. Yost at ICHEP 2004,
International Conference on High Energy Physics, Beijing, August 16-22, 200
X ray sensitive area detection device
A radiation sensitive area detection device is disclosed which comprises a phosphor-containing film capable of receiving and storing an image formed by a pattern of incoming x rays, UV, or other radiation falling on the film. The device is capable of fluorescing in response to stimulation by a light source in a manner directly proportional to the stored radiation pattern. The device includes: (1) a light source capable of projecting light or other appropriate electromagnetic wave on the film so as to cause it to fluoresce; (2) a means to focus the fluoresced light coming from the phosphor-containing film after light stimulation; and (3) at least one charged coupled detector or other detecting element capable of receiving and digitizing the pattern of fluoresced light coming from the phosphor-containing film. The device will be able to generate superior x ray images of high resolution from a crystal or other sample and will be particularly advantageous in that instantaneous near-real-time images of rapidly deteriorating samples can be obtained. Furthermore, the device can be made compact and sturdy, thus capable of carrying out x ray or other radiation imaging under a variety of conditions, including those experienced in space
New Results on Precision Studies of Heavy Vector Boson Physics
We present new results for two important heavy vector boson physics
processes: (1), virtual corrections to hard bremsstrahlung which are relevant
to precision predictions for the radiative return process in Z boson production
at and beyond LEP2 energies ; and, (2), electric charge screening effects in
single W production with finite p_T, multiple photon radiation in high energy
collider physics processes. In both cases we show that we improve the
respective precision tag significantly. Phenomenological implications are
discussed.Comment: 5 pages, 2 figures; to appear in Proc. DPF200
Comparison of Exact Results for the Virtual Corrections to Bremsstrahlung in Electron-Positron Annihilation at High Energies
We have compared the virtual corrections to electron-positron annihilation to
fermion pairs with single hard bremsstrahlung as calculated by S. Jadach, M.
Melles, B.F.L. Ward and S.A. Yost to several other expressions. The most recent
of these comparisons is to the leptonic tensor calculated by J.H. Kuhn and G.
Rodrigo for radiative return. Agreement is found to within or better,
as a fraction of the Born cross section.Comment: 5 pages, 2 figures. Presented at LCWS 2004, International Conference
on Linear Colliders, Paris, April 19-23, 200
Threshold Corrections in QED otimes QCD at the LHC
In some processes at the LHC, theoretical precisions of 1 percent are
desired. With an eye toward such precisions, we introduce the theory of the
simultaneous YFS resummation of QED and QCD to compute the size of the expected
resummed soft radiative threshold effects in precision studies of heavy
particle production at the LHC. Our results, that the soft QED threshold
effects are at the level of 0.3 percent whereas the soft QCD threshold effects
enter at the level of 20 percent, show that both must be controlled to be on
the conservative side to achieve such precision goals.Comment: 4 pages, no figures; presented by B.F.L. Ward at ICHEP0
Threshold Corrections in Precision LHC Physics: QED otimes QCD
With an eye toward LHC processes in which theoretical precisions of 1 percent
are desired, we introduce the theory of the simultaneous YFS resummation of QED
and QCD to compute the size of the expected resummed soft radiative threshold
effects in precision studies of heavy particle production at the LHC. Our
results show that both QED and QCD soft threshold effects must be controlled to
be on the conservative side to achieve such precision goals.Comment: 4 pages, no figures; presented by B.F.L. Ward in DPF200
Improvements to GOES Twilight Cloud Detection over the ARM SGP
The current ARM satellite cloud products derived from Geostationary Operational Environmental Satellite (GOES) data provide continuous coverage of many cloud properties over the ARM Southern Great Plains domain. However, discontinuities occur during daylight near the terminator, a time period referred to here as twilight. This poster presentation will demonstrate the improvements in cloud detection provided by the improved cloud mask algorithm as well as validation of retrieved cloud properties using surface observations from the Atmospheric Radiation Measurement Southern Great Plains (ARM SGP) site
XUV Frequency Combs via Femtosecond Enhancement Cavities
We review the current state of tabletop extreme ultraviolet (XUV) sources
based on high harmonic generation (HHG) in femtosecond enhancement cavities
(fsEC). Recent developments have enabled generation of high photon flux (1014
photons/sec) in the XUV, at high repetition rates (>50 MHz) and spanning the
spectral region from 40 nm - 120 nm. This level of performance has enabled
precision spectroscopy with XUV frequency combs and promises further
applications in XUV spectroscopic and photoemission studies. We discuss the
theory of operation and experimental details of the fsEC and XUV generation
based on HHG, including current technical challenges to increasing the photon
flux and maximum photon energy produced by this type of system. Current and
future applications for these sources are also discussed.Comment: invited review article, 38 page
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