Test Spectra

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Gaining confidence in your spectrum analysis

Whether the algorithms enshrined in your software perform satisfactorily depends to some extent on how they are coded into the program. One cannot assume that the same algorithm implemented in different programs, or even different versions of the same program, will give precisely the same result. The reasons are connected with the detail of the program coding, the compiler used and the computer on which the program is run. The implication is that the computer program should be evaluated to check that consistent and accurate results are obtained.

The ANSI N42 standard recommends a number of tests for:

  • Automatic peak finding
  • Independence of peak-area from peak-height-to-baseline ratio
  • Doublet peak finding and fitting
In Chapter 15, I discuss the use of test spectra for assessing the performance of one's spectrum analysis software. In this section are links to all the usable test spectra I am aware of. All are easily available, although not all can be downloaded from the Internet. The list below is chronological, no necessarily in order of usefulness - although SpecMaker is highly regarded!

  • 1977 IAEA G1 Intercomparison Spectra
    These spectra were originally provided by the UKAEA as part of a blind intercomparison exercise. They can now be downloaded from this site. The spectra allow the peak area measurement algoriths to be checked.

  • Sanderson Test Spectra
    These test spectra, used for the re-evaluation a number of spectrum analysis programs examined some years before. Spectra were devised to test peak search, doublet resolution with equal and asymmetric peak ratios and an efficiency test. A spectrum of an environmental, post Chernobyl, air filter sample was included as a test of a 'real life' situation.

  • 1995 IAEA Intercomparison Spectra
    These spectra, created by Menno Blaauw, allow a peak area measurement test. Blaauw maintains that the target peak areas are known absolutely and traceable.

  • 1999 NPL Intercomparison Spectra
    This again was a blind intercomparison exercise. Nowadays the spectra can be obtained from the NPL on CD-ROM together with 'the answers' in a sealed envelope.

    I am hoping to be allowed to have these spectra available on this site.

  • 2002 Intercomparison Spectra
    These spectra, again created by Menno Blaauw, are a test of the whole measurement process. This is a very comprensive set of spectra and the only one available that includes the calibration spectra necessary to allow true coincidence summming corrections to be performed.

  • SpecMaker
    This is a program created by the author of Practical Gamma-Ray Spectrometry - Second Edition that allows the user to create his/her own test spectra. Up to 50 gaussian peaks can be superimposed on a mathematical background or onto an actual background spectrum. A spreadsheet is available to assess the spectrum analysis results. This program is no longer available for download. Anyone interested in trying it out should contact Gordon Gilmore directly.

Appendices Data Example Spectra Links Spreadsheets Test Spectra

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