Physics & Astronomy ETDs

Publication Date



A detailed description of a space qualified linear energy transfer (LET) spectrometer is presented. The Cellular Absorbed Dose Spectrometer (CADS) is a prototype instrument which was launched on March 17, 1969 into an elliptical orbit. Its purpose was to obtain the first successful LET measurements in space; and, thereby provide additional data to assess the biological hazards of the near earth space environment, especially during periods of in­creased solar activity.

The physical processes that take place in the CADS in­strument are discussed, and a definition of linear energy transfer is given, as well as its relation to dE/dx. The performance of the CADS throughout the satellite lifetime is presented, in addition to a discussion of some of the problems that arose during the flight. The data reduction techniques used to convert the satellite digital information into physical data are also discussed. Results are presented in the form of LET channel response curves for a typical orbit of data, and LET channel count-rates are plotted in terms of the McIlwain B and L parameters. The CADS performance during the April 11, 1969 solar flare proton event is discussed, as well as the effects of protons trapped in the earth's radiation belts.

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Level of Degree


Department Name

Physics & Astronomy

First Committee Member (Chair)

Christopher Pratt Leavitt

Second Committee Member

David S. King

Third Committee Member

Alan Winston Peterson



Document Type