Fast Timing Bi-Directional Charge Coupled Devices for Use in Gamma -Ray Astronomy.

A Charge Coupled Device (CCD) coupled with a pixellated inorganic scintillator (such as segmented CsI) can provide high position resolution (∼300 mum). However, standard CCDs are integrating devices typically operating no faster than video rates. For a balloon-borne gamma-ray telescope capable of measuring the energy of individual photons, the CCD must have a time resolution better than the average time interval between cosmic ray events on the veto shield (∼10 kHz). A Fast Timing Bi-Directional CCD has better than 10 mus time resolution and 50 mum position resolution. We describe the CCD readout architecture, the ASIC readout design, the present status of the development, and the application to a gamma-ray astronomy telescope suitable for a 100-day Ultra Long Duration Balloon mission

Luminosity Measurement in the L3 Detector at LEP

One of the limiting factors in the determination of the electroweak parameters from cross section measurements of e+e- annihilation close to the Z pole is the precision of the luminosity measurement. The luminosity monitor of the L3 detector at LEP and the analysis of its data are described. Using a combination of a BGO calorimeter and a 3-layer silicon tracker, the absolute luminosity has been measured with an experimental precision of 0.08% in 1993 and 0.05% in 1994. The measurement relies on a detailed understanding of small-angle elastic e+e-(Bhabha) scattering from the experimental and theoretical point of view, as well as an excellent knowledge of the detector geometry

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences