ISO 15632:2021 pdf – Microbeam analysis — Selected instrumental performance parameters for the specification and checking of energy-dispersive X-ray spectrometers (EDS) for use with a scanning electron microscope (SEM) or an electron probe microanalyser (EPMA).
1 Scope This document defines the most important quantities that characterize an energy-dispersive X-ray spectrometer consisting of a semiconductor detector, a pre-amplifier and a signal-processing unit as the essential parts. This document is only applicable to spectrometers with semiconductor detectors operating on the principle of solid-state ionization. This document specifies minimum requirements and how relevant instrumental performance parameters are to be checked for such spectrometers attached to a scanning electron microscope (SEM) or an electron probe microanalyser (EPMA). The procedure used for the actual analysis is outlined in ISO 22309  and ASTM E1508  and is outside the scope of this document. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 23833, Microbeam analysis — Electron probe microanalysis (EPMA) — Vocabulary ISO 22493, Microbeam analysis — Scanning electron microscopy — Vocabulary 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 23833, ISO 22493 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https:// www .iso .org/ obp — IEC Electropedia: available at http:// www .electropedia .org/ NOTE With the exception of 3.1, 3.2, 3.2.1, 3.2.2, 3.9, 3.11, 3.12, 3.13 and 3.14, these definitions are given in the same or analogous form in ISO 22309  , ISO 18115-1  and ISO 23833. 3.1 energy-dispersive X-ray spectrometer device for determining X-ray signal intensity as a function of the energy of the radiation by recording the whole X-ray spectrum simultaneously Note 1 to entry: The spectrometer consists of a solid-state detector, a preamplifier, and a pulse processor.
3.2 count rate number of X-ray photons per second 3.2.1 input count rate ICR number of X-ray photons absorbed in the active detector area per second that are input to the electronics 3.2.2 output count rate OCR number of valid X-ray photon measurements per second that are output by the electronics and stored in memory, including sum peaks Note 1 to entry: When the electronics measures individual X-ray photon energies, there is some dead time (3.4) associated with each individual measurement. Consequently, the number of successful measurements is less than the number of incident photons in every practical case. Thus, the accumulation rate into the spectrum (output count rate (3.2.2)) is less than the count rate of photons that cause signals in the detector (input count rate (3.2.1)). Output count rate (3.2.2) may be equal to input count rate (3.2.1), e.g. at very low count rates and for very short measurements. 3.3 real time duration in seconds of an acquisition as it would be measured with a conventional clock Note 1 to entry: For X-ray acquisition, in every practical case the real time (3.3) always exceeds the live time (3.5). 3.4 dead time time during which the system is unable to record a photon measurement because it is busy processing a previous event (frequently expressed as a percentage of the real time (3.3)) Note 1 to entry: Dead time = real time – live time. Note 2 to entry: Dead-time fraction = 1 − OCR/ICR. 3.5 live time effective duration of an acquisition, in seconds, after accounting for the presence of dead time (3.4) Note 1 to entry: Live time = real time for an analysis minus cumulative dead time. Note 2 to entry: Live-time fraction = 1 − dead-time fraction. 3.6 spectral channel discrete interval of the measured energy for the histogram of recorded measurements with a width defined by a regular energy increment