【经典外文翻译】-底土的土壤结构和饱和导水率毕业设计论文.doc

英文原文： Low-cost programmable pulse generator for particle telescope calibration Abstract In this paper we present a new calibration system for particle telescopes including multi pulse generator and digital controller. The calibration system generates synchronized pulses of variable height for every detector channel on the telescope. The control system is based on a commercial microcontroller linked to a personal computer through an RS-232 bidirectional line. The aim of the device is to perform laboratory calibration of multi-detector telescopes prior to calibration at accelerator. This task includes evaluation of linearity and resolution of each detector channel, as well as coincidence logic. The heights of the pulses sent to the detectors are obtained by Monte Carlo simulation of telescope response to a particle flux of any desired geometry and composition. Elsevier Science B.V. All rights reserved. To assure a correct interpretation of data obtained with scientific instruments onboard satellites, as well as to compare these data with those of similar instruments, a thorough pre-flight calibration is required. For solar and cosmic ray particle telescopes, this calibration is usually carried out in two steps: first, a calibration of each individual detector using radioactive sources and standard nuclear instrumentation (NIM or CAMAC modules),following by a final test of the whole telescope performed in a particle accelerator site. The success of calibration on accelerator requires that, prior to the experiences, all detectors and electronics parameter (polarization voltages, amplifier gains and shaping times, thresholds, etc.) have nearly definitive values. Here we propose a cheap and simple pre-calibration procedure based on a new system that we have called Programmable Pulse Generator (PPG). The PPG developed in our laboratory has been designed for a specific instrument, a four-detector cosmic ray telescope, but it can easily be modified for similar experiments. T