DIN ISO 15632-2015 Microbeam analysis - Selected instrumental performance parameters for the specification and checking of energy-dispersive X-ray spectrometers for use in electron.pdf

1、November 2015English price group 11No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 71.040.99!%GF:“2363523www.din.de

2、DIN ISO 15632Microbeam analysis Selected instrumental performance parameters for the specification and checking of energy-dispersive X-ray spectrometers for use in electron probe microanalysis (ISO 15632:2012),English translation of DIN ISO 15632:2015-11Mikrobereichsanalyse Ausgewhlte instrumentelle

3、 Performanceparameter zur Spezifizierung und berprfung engergiedispersiver Rntgenspektrometer fr die Anwendung in der Elektronenstrahl-Mikrobereichsanalyse (ISO 15632:2012),Englische bersetzung von DIN ISO 15632:2015-11Analyse par microfaisceaux Paramtres de performance instrumentale slectionns pour

4、 la spcification et le contrle desspectromtres X slection dnergie utiliss en microanalyse par sonde lectrons (ISO 15632:2012),Traduction anglaise de DIN ISO 15632:2015-11www.beuth.deDTranslation by DIN-Sprachendienst.In case of doubt, the German-language original shall be considered authoritative.Do

5、cument comprises 15 pages10.15 A comma is used as the decimal marker. Contents Page National foreword . 3 National Annex NA (informative) Bibliography . 3 Introduction 4 1 Scope . 5 2 Normative references . 5 3 Terms and definitions 5 4 Requirements 7 4.1 General description . 7 4.2 Energy resolutio

6、n . 7 4.3 Dead time. 7 4.4 Peak-to-background ratio . 8 4.5 Energy dependence of instrumental detection efficiency . 8 5 Check of further performance parameters . 8 5.1 General 8 5.2 Stability of the energy scale and resolution 8 5.3 Pile-up effects 8 5.4 Periodical check of spectrometer performance

7、 9 Annex A (normative) Measurement of line widths (FWHMs) to determine the energy resolution of the spectrometer 10 Annex B (normative) Determination of the L/K ratio as a measure for the energy dependence of the instrumental detection efficiency . 13 Bibliography . 15 2DIN ISO 15632:2015-11National

8、 foreword This document (ISO 15632:2012) has been prepared by Technical Committee ISO/TC 202 “Microbeam analysis” (Secretariat: SAC, China). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Working Committee NA 06

9、2-08-18 AA Elektronenmikroskopie und Mikrobereichsanalyse. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. DIN and/or DKE shall not be held responsible for identifying any or all such patent rights. The DIN Standards corresponding

10、 to the International Standards referred to in this document are as follows: ISO/IEC 17025 DIN EN ISO/IEC 17025 ISO 18115-1 DIN ISO 18115-1*ISO 22309 DIN ISO 22309 National Annex NA (informative) Bibliography DIN EN ISO/IEC 17025, General requirements for the competence of testing and calibration la

11、boratories DIN ISO 18115-1, Surface chemical analysis Vocabulary Part 1: General terms and terms used in spectroscopy DIN ISO 22309, Microbeam analysis Quantitative analysis using energy-dispersive spectrometry (EDS) for elements with an atomic number of 11 (Na) or above * in preparation 3DIN ISO 15

12、632:2015-11IntroductionRecent progress in energy-dispersive X-ray spectrometry (EDS) by means of improved manufacturing technologies for detector crystals and the application of advanced pulse-processing techniques have increased the general performance of spectrometers, in particular at high count

13、rates and at low energies (below 1 keV). A revision of this International Standard became necessary because silicon drift detector (SDD) technology was not included. SDDs provide performance comparable to Si-Li detectors, even at considerably higher count rates. In addition, a larger detector active

14、 area results in the capability of measuring even higher count rates. This International Standard has therefore been updated with criteria for the evaluation of the performance of such modern spectrometers.In the past, a spectrometer was commonly specified by its energy resolution at high energies d

15、efined as the full peak width at half maximum (FWHM) of the manganese K line. To specify the properties in the low energy range, values for the FWHM of carbon K, fluorine K or the zero peak are given by the manufacturers. Some manufacturers also specify a peak-to-background ratio, which may be defin

16、ed as a peak-to-shelf ratio in a spectrum from an 55Fe source or as a peak-to-valley ratio in a boron spectrum. Differing definitions of the same quantity have sometimes been employed. The sensitivity of the spectrometer at low energies related to that at high energies depends strongly on the constr

17、uction of the detector crystal and the X-ray entrance window used. Although high sensitivity at low energies is important for the application of the spectrometer in the analysis of light-element compounds, normally the manufacturers do not specify an energy dependence for spectrometer efficiency.Thi

18、s International Standard was developed in response to a worldwide demand for minimum specifications of an energy-dispersive X-ray spectrometer. EDS is one of the most applied methods used to analyse the chemical composition of solids and thin films. This International Standard should permit comparis

19、on of the performance of different spectrometer designs on the basis of a uniform specification and help to find the optimum spectrometer for a particular task. In addition, this International Standard contributes to the equalization of performances in separate test laboratories. In accordance with

20、ISO/IEC 170251, such laboratories have to periodically check the calibration status of their equipment according to a defined procedure. This International Standard may serve as a guide for similar procedures in all relevant test laboratories.Microbeam analysis Selected instrumental performance para

21、meters for the specification and checking of energy-dispersive X-ray spectrometers for use in electron probe microanalysis 4DIN ISO 15632:2015-111 ScopeThis International Standard defines the most important quantities that characterize an energy-dispersive X-ray spectrometer consisting of a semicond

22、uctor detector, a pre-amplifier and a signal-processing unit as the essential parts. This International Standard is only applicable to spectrometers with semiconductor detectors operating on the principle of solid-state ionization. This International Standard specifies minimum requirements and how r

23、elevant 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 223092and ASTM E15083and is outside the scope of this Interna

24、tional Standard.2 Normative referencesThe 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, M

25、icrobeam analysis Electron probe microanalysis (EPMA) Vocabulary3 Terms and definitionsFor the purposes of this International Standard, the terms and definitions given in ISO 23833 and the following apply.NOTE With the exception of 3.1, 3.2, 3.2.1, 3.2.2, 3.11, 3.12 and 3.13, these definitions are g

26、iven in the same or analogous form in ISO 223092, ISO 18115-14and ISO 23833.3.1energy-dispersive X-ray spectrometerdevice for determining X-ray intensity as a function of the energy of the radiation by recording the whole X-ray spectrum simultaneouslyNOTE The spectrometer consists of a solid-state d

27、etector, a preamplifier, and a pulse processor. The detector converts X-ray photon energy into electrical current pulses which are amplified by the preamplifier. The pulse processor then sorts the pulses by amplitude so as to form a histogram distribution of X-ray intensity vs energy.3.2count ratenu

28、mber of X-ray photons per second3.2.1input count rateICRnumber of X-ray photons absorbed in the detector per second5DIN ISO 15632:2015-113.2.2output count rateOCRnumber of valid X-ray photon measurements per second that are output by the electronics and stored in memoryNOTE When the electronics meas

29、ures individual X-ray photon energies, there is some dead time 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”, OCR

30、) is less than the count rate of photons that cause signals in the detector (“input count rate”, ICR). OCR may be equal to ICR, e.g. at very low count rates and for very short measurements.3.3real timeduration in seconds of an acquisition as it would be measured with a conventional clockNOTE For X-r

31、ay acquisition, in every practical case the real time always exceeds the live time.3.4dead timetime during which the system is unable to record a photon measurement because it is busy processing a previous eventNOTE Dead-time fraction = 1 OCR/ICR.3.5live timeeffective duration of an acquisition, in

32、seconds, after accounting for the presence of dead-timeNOTE 1 Live time = real time for an analysis minus cumulative dead time.NOTE 2 Live-time fraction = 1 dead-time fraction.3.6spectral channeldiscrete interval of the measured energy for the histogram of recorded measurements with a width defined

33、by a regular energy increment3.7instrumental detection efficiencyratio of quantity of detected photons and quantity of the photons available for measurement3.8signal intensitystrength of the signal in counts per channel or counts per second per channel at the spectrometer output after pulse processi

34、ngNOTE This definition permits intensity to be expressed as either “counts” or “counts per second” (CPS). The distinction is not relevant to the procedures described in this standard so long as either one or the other is consistently employed.3.9peak intensitymaximum signal intensity of a spectral p

35、eak measured as height of the peak above a defined background3.10peak areanet peak areasum of signal intensities of a spectral peak after background removal6DIN ISO 15632:2015-113.11background signalcontinuous X-ray spectrumcontinuumnon-characteristic component of an X-ray spectrum arising from the

36、bremsstrahlung and other effectsNOTE Apart from the bremsstrahlung, degraded events occurring due to the operation of the spectrometer may contribute to the background. Extraneous signals arising from one or more parts of the spectrometer, microscope chamber or specimen itself (by X-ray scattering)

37、may also add to the background signal.3.12bremsstrahlungbraking radiationnon-characteristic X-ray spectrum created by electron deceleration in the coulombic field of an atom and having an energy distribution from 0 up to the incident beam energy3.13X-ray take-off angleTOAangle between the specimen s

38、urface and the direction where exiting X-rays will strike the center of the detectors sensorNOTE With increasing solid angle encompassed by the detector, TOA may vary significantly within a range around that TOA corresponding to the central position on the X-ray sensor.4 Requirements4.1 General desc

39、riptionThe manufacturer shall describe, using appropriate reference texts, the essential design elements of the spectrometer in order to permit the user to evaluate the performance of the spectrometer. Elements that are indispensable for the evaluation of the suitability of a spectrometer for a cert

40、ain field of application shall be given explicitly. These are to include the type of EDS (Si-Li EDS, HpGe EDS, SDD EDS, etc.), the thickness of the sensor, the net active sensor area (after collimation) and the type of the window (beryllium, thin film window or windowless). Parameters which may not

41、be encompassed by this International Standard, but that may influence detector performance, e.g. the construction principle of the cooling system, shall be explained in the reference text. Some detector systems are capable of very high count rates but at high count rates, other specifications like e

42、nergy resolution may alter and artifacts may appear in the spectrum. All specifications should therefore be accompanied by a statement of the count rate at which they are measured and it should not be assumed that the specification will be the same at other count rates.4.2 Energy resolutionThe energ

43、y resolution shall be specified as the FWHM of the manganese K peak and determined in accordance with Annex A. Spectrometers that claim detection of X-rays lower than 1 keV shall also be specified by the FWHM of the carbon K and the fluorine K-lines. The specified FWHM shall be an upper limit in tha

44、t the resolution determined in accordance with Annex A is guaranteed to be no greater than the specified value. The resolution value shall be accompanied by a statement of count rate for which the specification is valid. For most detector systems the best energy resolution is attained at an ICR 1 00

45、0 counts/s and the best energy resolution shall be specified. Where detector systems offer higher count rate capability, e.g. SDD EDS, the energy resolution shall also be specified at high ICR, e.g. 50 000 counts/s, 500 000 counts/s.4.3 Dead timeIn order to evaluate the process time of the EDS, comp

46、lementary to the energy resolution specified in 4.2, the corresponding dead-time fraction should be specified. The calculation of the dead-time fraction is given in 3.4.Dead time is a consequence of the electronics rejecting “bad” measurements in order to achieve high spectrum fidelity. In many syst

47、ems, the rejection criterion is designed to ensure that the measurement time for each 7DIN ISO 15632:2015-11photon is identical. However, it is possible to reduce the dead-time fraction by relaxing the criterion for pulse rejection and allowing the measurement time per photon to vary according to th

48、e arrival time of photons (“adaptive filtering”). In this case, the process time is not defined, the peak shape and resolution will change with count rate and this could cause analytical results to vary with count rate. Therefore, any specification of dead-time fraction should include a description

49、of the essential design elements of the electronics as per Subclause 4.1.4.4 Peak-to-background ratioThe peak-to-background ratio shall be derived at the point of manufacture of the spectrometer from an acquired spectrum of an 55Fe source as a characteristic spectrometer parameter. The ratio shall be given by the peak intensity of the manganese K line divided by the background. The background shall be calculated as the mean number of counts per channel w