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ISO 11843-6:2013 pdf free

ISO 11843-6:2013 pdf free.Capability of detection一Methodology for the determination of the critical value and the minimum detectable value in Poisson distributed measurements by normal approximations
The following restrictions should be observed if the minimum detectable value is to be determined reliably:
a) Both the signal and the background noise should follow the Poisson distributions. The signal is the mean value of the gross count.
b) The raw data should not receive any processing or treatment, such as smoothing.
c) Time interval: Measurement over a long period oftime is preferable to several shorter measurements.
A single measurement taken for over one second is better than 10 measurements over 100 ms each.The approximation of the Poisson distribution by the normal distribution is more reliable with higher mean values.
d) The number of measurements: Since only mean values are used in the approximations presented here, repeated measurements are needed to determine them. The power of test increases with the number of measurements.
e) Number of channels used by the detector: There should be no overlap of neighbouring peaks. The number of channels that are used to measure the background noise and the sample spectra should be identical (Annex D, Figure D.1).
f) Peak width: The full width at half maximum (FWHM) is the recommended coverage for monitoringa single peak. It is preferable to measurements based on the top and/or the bottom of a noisy peak. The appropriate FWHM should be assessed beforehand by measuring a standard sample. An identical value of the FWHM should be used for both the background noise and the sample measurements.
Additional factors are: the instrument should work correctly; the detector should be operating within its linear counting range; both the ordinate and the abscissa axes should be calibrated; there should be no signal that cannot be clearly identified as not being noise; degradation of the specimen during measurement should be negligibly small; at least one signal or peak belonging to the element under consideration should be observable.ISO 11843-6 pdf free download.

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