排序方式: 共有1条查询结果,搜索用时 15 毫秒
1
1.
Dean A.J. Bird A.J. Diallo N. Ferguson C. Lockley J.J. Shaw S.E. Westmore M.J. Willis D.R. 《Space Science Reviews》2003,105(1-2):285-376
Gamma ray photons interact with matter through a wide variety of complex physical mechanisms, which can be readily imitated
by other particle processes. Unfortunately since γ-ray telescopes are obliged to function in a hostile radiation environment
above the earth's atmosphere the net result is low signal to noise observations and a corresponding loss in sensitivity. Consequently,
understanding the generation of the systematic background noise is crucial if the full performance of a γ-ray instrument is
to be realised. In the past it was not possible to reliably estimate the background levels in a fully quantitative manner;
semi-empirical methods were employed. Although the basic underlying sources of the background noise were reasonably well understood,
and the spectral intensities of the associated particles were reasonably well known, it was not possible to associate resultant
noise components with the input source of that noise with any real degree of accuracy. The advent of sophisticated and accurate
computer programmes capable of dependably representing the requisite particle physics processes and interactions coupled with
the advances made in the context of high power/low cost computers has revolutionised the situation. The so-called ‘mass modelling’
technique is a truly physics-based approach, which takes the input particle spectra of the local radiation environment together
with a computer representation of the mechanical structure and chemical composition of the instrumentation and associated
spacecraft to trace the trajectories and interactions of all the incident particles throughout the system. All energy deposits
from the various interactions and likewise those from the prompt and delayed secondary products are also accurately recorded.
Subsequent energy discriminators and time coincidences can be applied to the event arrays with additional software to simulate
on-board electronics systems. Internal spectral counting rates may be readily derived and analysed in terms of a wide variety
of desired purposes. The impact of an accurate physics-based mass modelling technique has been to expand application of the
procedure to effectively all the main aspects of a space γ-ray astronomy mission: instrument design; internal counting rates
and spectral sensitivity estimates; optimisation of the design of the on-board processing electronics; operational planning
and mission optimisation; estimation of radiation damage and its limitation; calibration planning and interpretation; the
production of accurate instrumental response matrices; data analysis software; normalisation of astronomical results across
instrument and instrumental degradation boundaries; and data archiving.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
1