An overview of data acquisition, signal coding and data analysis techniques for MST radars

An overview is given of the data acquisition, signal processing, and data analysis techniques that are currently in use with high power MST/ST (mesosphere stratosphere troposphere/stratosphere troposphere) radars. This review supplements the works of Rastogi (1983) and Farley (1984) presented at previous MAP workshops. A general description is given of data acquisition and signal processing operations and they are characterized on the basis of their disparate time scales. Then signal coding, a brief description of frequently used codes, and their limitations are discussed, and finally, several aspects of statistical data processing such as signal statistics, power spectrum and autocovariance analysis, outlier removal techniques are discussed

Comparison of scatter storage techniques using an analysis of variance model

An analysis of variance model is developed to determine if a significant difference exists between various scatter storage techniques. The model is a two-factor hierarchical mixed design with each combination of transformation and search method considered as a treatment. The data used in the analysis is obtained from a computer program which provides statistics on the number of probes needed to load the (k+l)st item into a table for the different treatments. An ANOVA table was then computed for various load factors. A significant difference among the treatments was detected for load factors above .4. Comparison of individual treatments using Tukey\u27s multiple range test shows that although some treatments are significantly inferior, most treatments are not significantly different in terms of the average number of probes needed to load an item --Abstract, page ii

Scientific Opportunities with an X-ray Free-Electron Laser Oscillator

An X-ray free-electron laser oscillator (XFELO) is a new type of hard X-ray source that would produce fully coherent pulses with meV bandwidth and stable intensity. The XFELO complements existing sources based on self-amplified spontaneous emission (SASE) from high-gain X-ray free-electron lasers (XFEL) that produce ultra-short pulses with broad-band chaotic spectra. This report is based on discussions of scientific opportunities enabled by an XFELO during a workshop held at SLAC on June 29 - July 1, 2016Comment: 21 pages, 12 figure

Sub-nanosecond, time-resolved, broadband infrared spectroscopy using synchrotron radiation

A facility for sub-nanosecond time-resolved (pump-probe) infrared spectroscopy has been developed at the National Synchrotron Light Source of Brookhaven National Laboratory. A mode-locked Ti:sapphire laser produces 2 ps duration, tunable near-IR pump pulses synchronized to probe pulses from a synchrotron storage ring. The facility is unique on account of the broadband infrared from the synchrotron, which allows the entire spectral range from 2 cm-1 (0.25 meV) to 20,000 cm-1 (2.5 eV) to be probed. A temporal resolution of 200 ps, limited by the infrared synchrotron-pulse duration, is achieved. A maximum time delay of 170 ns is available without gating the infrared detector. To illustrate the performance of the facility, a measurement of electron-hole recombination dynamics for an HgCdTe semiconductor film in the far- and mid infrared range is presented.Comment: 11 pages with 9 figures include

Structure and Magnetism of well-defined cobalt nanoparticles embedded in a niobium matrix

Our recent studies on Co-clusters embedded in various matrices reveal that the co-deposition technique (simultaneous deposition of two beams : one for the pre-formed clusters and one for the matrix atoms) is a powerful tool to prepare magnetic nanostructures with any couple of materials even though they are miscible. We study, both sharply related, structure and magnetism of the Co/Nb system. Because such a heterogeneous system needs to be described at different scales, we used microscopic and macroscopic techniques but also local selective absorption ones. We conclude that our clusters are 3 nm diameter f.c.c truncated octahedrons with a pure cobalt core and a solid solution between Co and Nb located at the interface which could be responsible for the magnetically inactive monolayers we found. The use of a very diluted Co/Nb film, further lithographed, would allow us to achieve a pattern of microsquid devices in view to study the magnetic dynamics of a single-Co cluster.Comment: 7 TeX pages, 9 Postscript figures, detailed heading adde

Real-time phase-selective data acquisition system for measurement of wave phenomena in pulsed plasma discharges

A novel data acquisition system and methodology have been developed for the study of wave phenomena in pulsed plasma discharges. The method effectively reduces experimental uncertainty due to shot-to-shot fluctuations in high repetition rate experiments. Real-time analysis of each wave form allows classification of discharges by wave amplitude, phase, or other features. Measurements can then be constructed from subsets of discharges having similar wave properties. The method clarifies the trade-offs between experimental uncertainty reduction and increased demand for data storage capacity and acquisition time. Finally, this data acquisition system is simple to implement and requires relatively little equipment: only a wave form digitizer and a moderately fast computer

Wavelength-scale stationary-wave integrated Fourier-transform spectrometry

Spectrometry is a general physical-analysis approach for investigating light-matter interactions. However, the complex designs of existing spectrometers render them resistant to simplification and miniaturization, both of which are vital for applications in micro- and nanotechnology and which are now undergoing intensive research. Stationary-wave integrated Fourier-transform spectrometry (SWIFTS)-an approach based on direct intensity detection of a standing wave resulting from either reflection (as in the principle of colour photography by Gabriel Lippmann) or counterpropagative interference phenomenon-is expected to be able to overcome this drawback. Here, we present a SWIFTS-based spectrometer relying on an original optical near-field detection method in which optical nanoprobes are used to sample directly the evanescent standing wave in the waveguide. Combined with integrated optics, we report a way of reducing the volume of the spectrometer to a few hundreds of cubic wavelengths. This is the first attempt, using SWIFTS, to produce a very small integrated one-dimensional spectrometer suitable for applications where microspectrometers are essential