D. Nelson

The silicon tracker readout electronics of the Gamma-ray Large Area Space Telescope

A unique electronics system has been built and tested for reading signals from the silicon-strip detectors of the Gamma-ray Large Area Space Telescope mission. The system amplifies and processes signals from 884 736 36-cm strips using only 160 W of power, and it achieves close to 100% detection efficiency with noise occupancy sufficiently low to allow it to self trigger. The design of the readout system is described, and results are presented from ground-based testing of the completed detector system.

The Analog Processing System for the Liquid Argon Calorimeter for SLD at SLAC

The analog processing system for the Liquid Argon Calorimeter for the SLD project at SLAC is described. Amplification, storage of the analog information, and multiplexing is realized on specially developed hybrids, which will be mounted directly on the detector. This leads to a substantial reduction of the cable plant. Test results for the amplifier and for the sampling and multiplexing hybrid (CDU hybrid) are presented. The latter hybrid contains a custom monolithic device, the Calorimeter Data Unit (CDU).

Electronics for the BaBar central drift chamber

The central drift chamber for the BaBar detector at the SLAC B-factory is based on a hexagonal cell design with 7104 cells arranged in 40 layers and drift gas helium:isobutane (80%:20%). Performance optimization and integration requirements led to an electronics design that mounts the amplifier-discriminator and digitizing circuitry directly on the endplate. High channel density is achieved using a 4-channel custom amplifier-discriminator IC and an 8-channel custom CMOS TDC/FADC IC on a single circuit board. Data read from the front ends are multiplexed on 4 fiber optic links, and prompt trigger data are sent out continuously on 24 links. Analysis of cosmic ray data demonstrates that the electronics design meets the performance goals for the BaBar drift chamber. The final electronics were installed on the drift chamber in July, 1998. Installation of BaBar on beamline is scheduled for March, 1999.

Fabrication of the GLAST Silicon Tracker Readout Electronics

A unique electronics system has been built and tested for reading signals from the silicon-strip detectors of the Gamma-ray Large Area Space Telescope mission. The system amplifies and processes signals from 884 736 36-cm long silicon strips in a 4times4 array of tower modules. An aggressive mechanical design fits the readout electronics in narrow spaces between the tower modules, to minimize dead area. This design and the resulting departures from conventional electronics packaging led to several fabrication challenges and lessons learned. This paper describes the fabrication processes and how the problems peculiar to this design were overcome

Development of a Temporally Modulated Fuel Injector With Controlled Spray Dynamics

It is now well established that combustion instability in liquid-fueled gas turbines can be controlled through the use of active fuel modulation. What is less clear is the mechanism by which this is achieved. This results from the fact that in most fuel modulation strategies not only is the instantaneous mass flow rate of fuel affected but so too are the parameters which define the post-atomization spray that takes part in the combustion. Specifically, experience with piezoelectric modulated sprays has shown that drop size, velocity, cone angle, and patternation are all affected by the modulation process. This inability to decouple changes in the fueling rate from changes in the spray distribution makes understanding of the mechanism of instability control problematic. This paper presents the results of an effort to develop an injector which can provide temporal modulation of the fuel flow rate but without concomitant changes in spray dynamics. This is achieved using an atomization strategy which is insensitive to both fuel flow rate and combustor acoustics (an over-pressured spill-return nozzle) coupled with an actuator with flat frequency response (a low-mass voice coil). The design and development of the actuator (and its control system) are described, and a combination of phase-Doppler interferometry and imaging are used to establish its performance. Results show that the system is capable of producing sprays which have little variation in cone angle or spray distribution function despite variations in mass flow rate (number density) of greater than 50% over a range of frequencies of interest for control of combustion instability (10 Hz to I kHz).

Design and fabrication of advanced hybrid circuits for high energy physics

Current design and fabrication techniques of hybrid devices as applied to the Stanford Linear Collider Large Detector (SLD) are discussed. Methods of developing layouts ranging from hand-cut templates to advanced designs utilizing CAD tools with special hybrid design software were applied. Physical and electrical design rules for good yield and performance are discussed. Fabrication and assembly of of a variety of SLD hybrids using different construction methods are described. >

SLD Liquid Argon Calorimeter Prototype Test Results

The results of the SLD test beam program for the selection of a calorimeter radiator composition within a liquid argon system are described, with emphasis on the study of the use of uranium to obtain equalization of pion and electron responses.

The BaBaR drift chamber project

The BaBar Drift Chamber is now under construction. We review its design, the progress in the construction of the components, the plan for assembly and stringing and we present test results obtained with a prototype exposed at SLAC to cosmic rays. We also report on projected dE/dx performance from beam tests done with a chamber with a different cell design.

A Bipolar front end integrated circuit for the BaBar helium drift chamber

Abstract A Bipolar chip consisting of 4 channels, each with a digital, and an analog output has been developed for use with the BaBar drift chamber. The full design is described and results from the prototype are presented.

Universal File Processing Program for Field Programmable Integrated Circuits

A computer program is presented that translates logic equations into promburner files (or the reverse) for programmable logic devices of various kinds, namely PROMs FPLAs, FPLSs and PALs. The program achieves flexibility through the use of a database containing detailed information about the devices to be programmed. New devices can thus be accommodated through simple extensions of the database. When writing logic equations, the user can define logic combinations of signals as new logic variables for use in subsequent equations. This procedure yields compact and transparent expressions for logic operations, thus reducing the chances for error. A logic simulation program is also provided so that an independent check of the design can be performed at the software level.