Special Coverage

Home

Spill-Resistant Alkali-Metal-Vapor Dispenser

This dispenser can be used in a gravitational or non-gravitational environment.  A spill-resistant vessel has been developed for dispensing an alkali-metal vapor. Vapors of alkali metals (most commonly, cesium or rubidium, both of which melt at temperatures slightly above room temperature) are needed for atomic frequency standards, experiments in spectroscopy, and experiments in laser cooling. Although the present spill-resistant alkali-metal dispenser was originally intended for use in the low-gravity environment of outer space, it can also be used in normal Earth gravitation: indeed, its utility as a vapor source was confirmed by use of cesium in a ground apparatus.

Posted in: Physical Sciences, Briefs, TSP

Read More >>

Improved Compression of Wavelet-Transformed Images

Code parameters are selected adaptively to achieve high compression performance.  A recently developed data-compression method is an adaptive technique for coding quantized wavelet-transformed data, nominally as part of a complete image-data compressor. Unlike some other approaches, this method admits a simple implementation and does not rely on the use of large code tables.

Posted in: Physical Sciences, Briefs

Read More >>

Flexible Heater Provides Thermal Solution for Fast Temperature-Cycling Environments

Uniformity and tight dimensional tolerances provide flexibility for smaller, more robust heating components. Thermal components for military, aerospace, and medical applications are continually getting smaller, more accurate, and more robust. To match these technological advancements, heating systems are being custom-designed to provide critical edgeto- edge uniformity, tight dimensional tolerances, and integrated sensors and flex leads to create complete thermal solutions.

Posted in: Physical Sciences, Briefs

Read More >>

Digital Equivalent Data System for XRF Labeling of Objects

Conventions for XRF labels and converting XRF spectra to alphanumeric data leads to new identification method.

Posted in: Physical Sciences, Briefs

Read More >>

Identifying Objects via Encased X-Ray- Fluorescent Materials — the Bar Code Inside

XRF spectra would be used as labels, similarly to bar codes, inside a product.

Posted in: Physical Sciences, Briefs

Read More >>

The THz Hot-Electron Photon Counter Concept

Abstract¡ªWe discuss an implementation of a hot-electron transition-edge sensor   (TES) capable of counting THz photons. The main need for such a THz calorimeter   is spectroscopy on future space telescopes with a background limited NEP ~ 10-20   W/Hz1/2. The micromachined bolometers will unlikely reach such sensitivity at   temperatures above 10 mK. The hot-electron TES with sufficient sensitivity will   still have a time constant ~ 0.1-1.0 ms that is too short for integrating a   flux of THz background photons arriving at a rate of < 100 s-1. The Hot-Electron   Photon Counter based on a submicron-size superconducting Ti bridge with Nb Andreev   contacts will be able to detect individual photons above 170 GHz due to its   very low heat capacity. A discrimination of the low energy fluctuations with   a threshold device would allow for realization of an NEP ~ 10-20 W/Hz1/2 at   ¡Ý 1 THz while operating at 300 mK. With the sensor time constant of a few microseconds,   the dynamic range is ~ 30-40 dB. A compact array of the antenna-coupled counters   can be fabricated on a silicon wafer without membranes. Index Terms¡ªradiation   detectors, submillimeter wave detectors, bolometers, superconducting devices.   I. INTRODUCTION Several new advanced space submillimeter (SMM) astronomy missions   (Single-Aperture FIR Observatory ¨C SAFIR [1,2], Submillimeter Probe of the   Evolution of Cosmic Structure ¨C SPECS [3], Space Infrared Telescope for Cosmology   and Astrophysics ¨C SPICA [4]) have been recently proposed. They are expected   to make a dramatic impact on the attainable sensitivity in the moderate resolution   mode  where direct   detectors are typically used. This will be achieved by active cooling of telescope   mirrors to 4-5 K. For all existing platforms, the radiation of the atmosphere   and/or the temperature of the telescope set the sensitivity limit. Deep cooling   of a telescope mirror to ~4K would almost completely eliminate the effect of   the telescope emissivity. Then the limiting noise equivalent power (NEP) would   be set by the background fluctuation at the level of  in the most of the SMM range (see Fig. 1).

Posted in: Physical Sciences, Briefs, TSP

Read More >>

Vacuum Attachment for XRF Scanner

A greater range of elements could be analyzed.

Posted in: Physical Sciences, Briefs

Read More >>