Accuracy of Measurement for Counting and Intensity-Correlation Experiments

A quantum-mechanical analysis is made of the experimental accuracy to be expected for particle-counting and intensity-correlation experiments. The mean-square fluctuation for an ensemble, consisting of a large number of experiments each conducted over a time interval T, is calculated

Doppler Shift in Frequency in the Transport of Electromagnetic Waves through an Underdense Plasma

In an earlier publication, the validity of the radiation transport theory was studied for the calculation of multiple scattering of electromagnetic waves by a turbulent plasma. In the present paper, we extend the transport theory to include a description of the Doppler shift in frequency caused by electron motion

Eikonal Approximation for Coupled Equations for Multichannel Scattering

It is well known that the Glauber approximation for scattering amplitudes is obtained by applying the eikonal approximation to the Fourier transform of the transition operator. The eikonal approximation can also be applied to the coupled equations of scattering obtained by the expansion of the state function in terms of a suitable set of functions. The scattering amplitude can thus be obtained by solving the set of eikonal coupled equations. The latter approach is analyzed for a special class of channel-coupling potentials. The first-order approximation to the derived eikonal coupled equations is the eikonal Born approximation. Numerical illustrations in this approximation are given for the 1s-2s and 1s-2p excitations of hydrogen atoms by electron and positron impact. The results are compared with those obtained in the Glauber eikonal approximation and with experimental measurements

Concerning the notion of "time interval" in S-matrix theory

The notion of time duration is considered within the framework of S-matrix theory. It is shown that Wigner's definition of the time delay, -ih[(dlnS/dE)], for a scattering process permits one to define time duration in a "coarse-grained" sense

Measurement of time correlations for quantum-mechanical systems

Measurements that are of limited accuracy, are incomplete, or require a finite time to make do not generally permit one to construct a wave function for describing a physical system. The use of such partial information to predict the results of subsequent measurements is studied here. There are several practical applications of this problem, including the use of the autocorrelation function for a particle counter in a scattering experiment

SeaTrack: Ground station orbit prediction and planning software for sea-viewing satellites

An orbit prediction software package (Sea Track) was designed to assist High Resolution Picture Transmission (HRPT) stations in the acquisition of direct broadcast data from sea-viewing spacecraft. Such spacecraft will be common in the near future, with the launch of the Sea viewing Wide Field-of-view Sensor (SeaWiFS) in 1994, along with the continued Advanced Very High Resolution Radiometer (AVHRR) series on NOAA platforms. The Brouwer-Lyddane model was chosen for orbit prediction because it meets the needs of HRPT tracking accuracies, provided orbital elements can be obtained frequently (up to within 1 week). Sea Track requires elements from the U.S. Space Command (NORAD Two-Line Elements) for the satellite's initial position. Updated Two-Line Elements are routinely available from many electronic sources (some are listed in the Appendix). Sea Track is a menu-driven program that allows users to alter input and output formats. The propagation period is entered by a start date and end date with times in either Greenwich Mean Time (GMT) or local time. Antenna pointing information is provided in tabular form and includes azimuth/elevation pointing angles, sub-satellite longitude/latitude, acquisition of signal (AOS), loss of signal (LOS), pass orbit number, and other pertinent pointing information. One version of Sea Track (non-graphical) allows operation under DOS (for IBM-compatible personal computers) and UNIX (for Sun and Silicon Graphics workstations). A second, graphical, version displays orbit tracks, and azimuth-elevation for IBM-compatible PC's, but requires a VGA card and Microsoft FORTRAN

Synthetic approaches to coronafacic acid, coronamic acid, and coronatine

The phytotoxin coronatine (COR) is a functional mimic of the active plant hormone (+)-7-iso-jasmonoyl-l-isoleucine (JA-IIe), which regulates stress responses. Structurally, COR is composed of a core unit, coronafacic acid (CFA), which is connected to coronamic acid (CMA), via an amide linkage. COR has been found to induce a range of biological activity in plants and based on its biological profile, COR, as well as CFA, and CMA are attractive starting points for agrochemical discovery, resulting in numerous total synthesis efforts. This review will discuss the synthetic approaches towards CFA, CMA and, ultimately COR, to date

Use of intensity correlations to determine the phase of a scattering amplitude

A new technique is described for observing scattered particles in a scattering experiment. This involves a measurement of the correlated counting rates of two detectors and is based on an idea proposed by Hanbury-Brown and Twiss for astronomical observations. With this technique it is possible, for example, to explicitly measure the phase of a scattering amplitude