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The Unified Data System (UDS) group at JPL is attempting to reduce total mission costs by designing a spacecraft data system which takes advantage of the natural and historical partitioning of a spacecraft into subsystems. Each subsystem is assigned a microprocessor which needs just enough capability to control the sensors and actuators of that subsystem, collect its data and maintain time synchronization with the rest of the spacecraft. The resulting distributed system avoids many of the overhead costs of a single centralized multi-processing system. To minimize complexity and therefore minimize total mission costs, a variety of standards and restrictions are imposed on the design of hardware, software, and communications. Articulation of these standards and restrictions is a major benefit deriving from the UDS program.
The paper describes software techniques developed for the Unified Data System (UDS), a distributed processor network for control and data handling onboard a planetary spacecraft. These techniques include a structured language for specifying the programs contained in each module, and a small executive program in each module which performs scheduling and implements the module task.
The CMS Electromagnetic Calorimeter will be composed of nearly 80,000 lead tungstate crystals. Owing to the high-energy resolution aimed at it and to the hostile Large Hadron Collider (LHC) radiation environment, a rigorous quality control of the crystals is performed on several parameters such as light yield, uniformity of the light collection or radiation hardness. The results of this quality control for the first 15,000 crystals delivered and characterized at the CERN Regional Centre by Bogoroditsk Techno-Chemical Plant are presented here. In addition, an overview of the construction status is given.
The distribution of about 5000 mass-produced PWO crystals by their light yield and radiation hardness is analysed. The correlation between results of radiation hardness measurements at low and saturating dose rates is refined. A method for the evaluation of the energy resolution of the electromagnetic calorimeter accounting for a distribution of individual PWO crystal characteristics is proposed. A preliminary analysis of the PWO crystal recovery kinetics is also performed.
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