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High intensity x-ray diffraction in transmission mode employing an analog of Poisson's spot
Poisson’s spot is a diffraction phenomenon producing an intensity maximum at the center of the geometric shadow of circular opaque objects. In an analog of the Poisson spot experiment, we show that a tubular cone of x-rays incident upon a crystalline sample produces diffraction spots or foci, corresponding to Bragg maxima within a transmission shadow. We discuss the beam geometry and the intensity gain recorded at the foci in transmission mode. We describe the geometric growth and decay of the foci over a linear axis with the aid of a movie sequence synchronized with the plotting of a diffractogram. The mean signal of a small central area in each successive camera image provides the intensity data for the diffractogram
Gauge links, TMD-factorization, and TMD-factorization breaking
In this section, we discuss some basic features of transverse momentum
dependent, or unintegrated, parton distribution functions. In particular, when
these correlation functions are combined in a factorization formulae with hard
processes beyond the simplest cases, there are basic problems with universality
and factorization. We discuss some of these problems as well as the
opportunities that they offer.Comment: 9 pages, 10 figures Gluons and the quark sea at high energies:
distributions, polarization, tomograph
The 30/20 GHZ net market assessment
By creating a number of market scenarios variations dealing with network types, network sizes, and service price levels were analyzed for their impact on market demand. Each market scenario represents a market demand forecast with results for voice, data, and video service traffic expressed in peak load megabits per second
Empirical determination of radiation interchange factors Final report
Techniques for measuring radiant interchange factors relative to spacecraft thermal desig
Gauge fixing and equivariant cohomology
The supersymmetric model developed by Witten to study the equivariant
cohomology of a manifold with an isometric circle action is derived from the
BRST quantization of a simple classical model. The gauge-fixing process is
carefully analysed, and demonstrates that different choices of gauge-fixing
fermion can lead to different quantum theories.Comment: 18 pages LaTe
Real eigenvalue analysis in NASTRAN by the tridiagonal reduction (FEER) method
Implementation of the tridiagonal reduction method for real eigenvalue extraction in structural vibration and buckling problems is described. The basic concepts underlying the method are summarized and special features, such as the computation of error bounds and default modes of operation are discussed. In addition, the new user information and error messages and optional diagnostic output relating to the tridiagonal reduction method are presented. Some numerical results and initial experiences relating to usage in the NASTRAN environment are provided, including comparisons with other existing NASTRAN eigenvalue methods
The 18/30 GHz fixed communications system service demand assessment. Volume 1: Executive summary
The total demand for voice, video, and data communications services, and satellite transmission services at the 4/6 GHz, 12/14 GHz, and 18/30 GHz frequencies is discussed. Major study objectives, overall methodology, results, and general observations about a satellite systems market characteristics and trends are summarized
The 30/20 GHz fixed communications systems service demand assessment. Volume 3: Appendices
The market analysis of voice, video, and data 18/30 GHz communications systems services and satellite transmission services is discussed. Detail calculations, computer displays of traffic, survey questionnaires, and detailed service forecasts are presented
Vacuum-UV negative photoion spectroscopy of CH3F, CH3Cl and CH3Br
Using tunable vacuum-UV radiation from a synchrotron, negative ions are detected by quadrupolar mass spectrometry following photoexcitation of three gaseous halogenated methanes CHX (X = F,Cl,Br). The anions X, H, CX, CHX and CHX are observed, and their ion yields recorded in the range 8-35 eV. The anions show a linear dependence of signal with pressure, showing that they arise from unimolecular ion-pair dissociation, generically described as AB + h A + B (+ neutrals). Absolute cross sections for ion-pair formation are obtained by calibrating the signal intensities with those of F from both SF and CF. The cross sections for formation of X + CH are much greater than for formation of CHX + H. In common with many quadrupoles, the spectra of / 1 (H) anions show contributions from all anions, and only for CHBr is it possible to perform the necessary subtraction to obtain the true H spectrum. The anion cross sections are normalised to vacuum-UV absorption cross sections to obtain quantum yields for their production. The appearance energies of X and CHX are used to calculate upper limits to 298 K bond dissociation energies for D (HC-X) and D (XHC-H) which are consistent with literature values. The spectra suggest that most of the anions are formed indirectly by crossing of Rydberg states of the parent molecule onto an ion-pair continuum. The one exception is the lowest-energy peak of F from CHF at 13.4 eV, where its width and lack of structure suggest it may correspond to a direct ion-pair transition
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