LUT:A Lunar-based Ultraviolet Telescope

The Lunar-based Ultraviolet Telescope (LUT) is a funded lunar-based ultraviolet telescope dedicated to continuously monitoring variable stars for as long as dozens of days and performing low Galactic latitude sky surveys. The slow and smooth spin of the Moon makes its step by step pointing strategy possible. A flat mirror mounted on a gimbal mount is configured to enlarge the sky coverage of the LUT. A Ritchey-Chrétien telescope with a Nasmyth focus configuration is adopted to reduce the total length of the...     

A Compact,High Speed Ion Beam Chopper

Abstract

A simple, compact pulse circuit was designed for use as an ion beam chopper with both synchronous and asynchronous triggering. The rise and fall times of the beam-on pulse are 60 ns and 320 ns, respectively, with a beam suppression potential of 180 V. The beam chopper was interfaced to a spark-source mass spectrometer for which the precision of analyses can be improved by reducing effects of sample or spark inhomogeneities. Additionally, the synchronous mode of chopping provides a means for temporal analysis of the spark.     

Observation of disruptions in tokamak plasma under the influence of resonant helical magnetic fields

Summary Disruptive instabilities were investigated in the small-tokamak TBR-1 during the application of resonant helical magnetic fields created by external helical windings. Indications were found that the main triggering mechanism of the disruption was the rapid increase of them=2/n=1 mode which, apparently after reaching a certain amplitude, interacts with other resistive modes: the internal 1/1 mode in the case of a major disruption, or with higherm components, as the 3/1 or 4/1, in the case of minor disruptions. After the coupling, the growth of the associated islands would create a chaotic field line distribution in the region between the corresponding rational magnetic surfaces which caused the gross particle transport and, finally, destroyed the confinement. In addition, investigations on higherZ _eff discharges in which a mixture of helium and hydrogen was used resulted in much more unstable plasmas but apparently did not alter the basic characteristics of the disruptions. The authors of this paper have agreed to not receive the proofs for correction.     

The FIGARO II experiment: a general outline of the mission and the principal scientific results

Summary The FIGARO II (French Italian Gamma-Ray Observatory) experiment has been launched successfully three times: in July 1986 from Milo (Trapani), in November 1988 from Charleville (Australia) and in July 1990 again from Milo. In the first flight the observational program was limited to the Crab pulsar PSR0531+21 only because of a telemetry failure: the high sensitivity of FIGARO II allowed an accurate study of the pulse shape as well as a phase-resolved spectroscopy. It was also possible to evaluate the dispersion measure of the Crab pulsar at the flight date from the time delay between gamma-ray and radio pulses. The major results of the second flight were a stringent upper limit to the low-energy gamma-ray flux from PSR 0833-45 (Vela pulsar)—well below the detection claimed by the UCR group —and the observation of a strong emission in the 0.511 MeV annihilation line from the inner region of our Galaxy. The data acquired in the third flight are still under analysis, but preliminary results suggest changes in the shape of the pulse profile. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

Microcomputer control and data analysis for a far infrared Fourier spectrometer

A commercial general-purpose microcomputer is used to provide real-time experimental control, data acquisition and data analysis for a far infrared Fourier spectrometer. The interfacing and programming procedures are described. The microcomputer gives excellent performance at a low cost.     

Stellar X-ray polarimetry

Summary Stellar X-ray polarimetry has for a long time been indicated as a very powerful diagnostic tool. In spite of this widely recognised interest, positive results are limited to just one: the detection, in the now far 1978, of the polarisation of the X-ray emission from the Crab Nebula. Novel-generation experiments promise a wider and richer amount mess of results, at least for strong galactic sources. Polarimetry however, remains an unusually delicate technique that requires a very tight control of systematic effects (at the level of 1% or better) over the very long observing period (10⁵ seconds or more) needed for obtaining a reasonable sensitivity. Paper presented at the 6th Cosmic Physics National Conference, Palermo, 3–7 November 1992.     

PIXE microanalysis of human serum and amniotic fluid

Summary Twenty serum and amniotic-fluid samples, drawn from different pregnant womens at the end of their gestation period, have been analysed by proton-induced X-ray emission (PIXE) analysis. Sample preparation, as thin film, is treated in detail and method characteristics are discussed. Qualitative and quantitative results show a similarity between two biological liquids. All samples include Cl, K, Ca, Cr, Fe, Cu, Zn and Br in different concentrations from 7.6 mg/ml to 0.1 μg/ml.

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Riassunto Venti campioni di siero e di liquido amniotico, prelevati a differenti donne incinte alla fine del loro periodo di gestazione, sono stati analizzati tramite l'analisi PIXE (proton-induced X-ray emission). La preparazione dei campioni, come film sottili, è trattata in dettaglio e le caratteristiche del metodo sono discusse. I risultati qualitativi e quantitativi delle analisi mostrano una similitudine tra i due liquidi biologici. Tutti i campioni contengono Cl, K, Ca, Cr, Fe, Cu, Zn e Br in differenti concentrazioni comprese tra 7.6 mg/ml e 0.1 μg/ml.

     

The contribution of IFSI (Istituto di Fisica dello Spazio Interplanetario) to the ISO Project

Summary We describe the participation of the “Istituto di Fisica dello Spazio Interplanetario? in the Infrared Space Observatory (ISO) Project. We comtribute to the international consortium of Institutes to build the Long Wavelength Spectrometer (LWS): in particular we have responsability for the construction of the data processing unit,i.e. the on-board computer. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

Combination of a Gated Phtotomultiplier Tube and a Phase Sensitive Detector for Use in an Intensive Pulsed Background Light Situation

In order to detect a weak signal light that appears after an intensive pulsed background light, we constructed a light detection module that consisted of an internally-gated photomultiplier tube (PMT) and a phase sensitive detector (PSD). Plural even-numbered dynodes of a miniature PMT were controlled for the internal gate operation and the output signal from the PMT was fed into the PSD integration circuit (IC) that worked synchronously with the gated PMT. The module acts as a sort of lock-in light detection system. The combination of the gate-on PMT and the PSD IC detects the weak signal light while the gate-off PMT rejects the intensive pulsed background light. From fundamental performance tests, we found that a background rejection ratio (BGRR) of the gated PMT up to 10,000 could be obtained. We carried out an evaluation experiment using a multi-white light-emitting diode (LED) to demonstrate the pulsed-background-light rejection capability of the module.     

Very-high-speed liquid column chromatography the system and selected applications

Summary Instrumentation needed to achieve very high performance (plate/s) liquid chromatography is discussed. With recently available systems using relatively short (100–125 mm) columns of conventional internal diameter (4–6 mm) and packed with 3–5 m particles, analysis in very short times (usually 1–3 min) is possible. Coupling such columns in series provide very high performance in a time still significantly less than previously encountered. Performance of such liquid chromatographic systems is illustrated with a number of practical examples including analgesic tablets, cosmetics, soft drinks, antioxidants and polyaromatic hydrocarbons.Enlarged text of a paper presented at the 32nd Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, March 9–13, 1981, Atlantic City, New Jersey (Paper No. 462).