BS ISO 15632-2012 Microbeam analysis Selected instrumental performance parameters for the specification and checking of energy-dispersive X-ray spectrometers for use in electron pr.pdf

1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 15632:2012Microbeam analysis Selected instrumentalperformance parameters forthe specification and checkingof energy-dispersive X-rayspectrometers for use inelectron probe

2、microanalysisBS ISO 15632:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 15632:2012. It supersedes BS ISO 15632:2002, which is withdrawn.The UK participation in its preparation was entrusted to T e c h n i c a l C o m m i t t e e C I I / 9 , M i c r o b e

3、 a m a n a l y s i s .A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2012Pu

4、blished by BSI Standards Limited 2012ISBN 978 0 580 66881 4 ICS 19.100 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 August 2012.Amendments issued since pub

5、licationDate T e x t a f f e c t e dBS ISO 15632:2012 ISO 2012Microbeam analysis Selected instrumental performance parameters for the specification and checking of energy-dispersive X-ray spectrometers for use in electron probe microanalysisAnalyse par microfaisceaux Paramtres de performance instrum

6、entale slectionns pour la spcification et le contrle des spectromtres X slection dnergie utiliss en microanalyse par sonde lectronsINTERNATIONAL STANDARDISO15632Second edition2012-08-01Reference numberISO 15632:2012(E)BS ISO 15632:2012ISO 15632:2012(E)ii ISO 2012 All rights reservedCOPYRIGHT PROTECT

7、ED DOCUMENT ISO 2012All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs membe

8、r body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 15632:2012ISO 15632:2012(E) ISO 2012 All rights reserved iiiContents PageForeword ivIntroduction

9、 v1 Scope 12 Normative references . 13 Terms and definitions . 14 Requirements . 34.1 General description 34.2 Energy resolution 34.3 Dead time . 34.4 Peak-to-background ratio . 44.5 Energy dependence of instrumental detection efficiency . 45 Check of further performance parameters . 45.1 General .

10、45.2 Stability of the energy scale and resolution 45.3 Pile-up effects . 45.4 Periodical check of spectrometer performance 5Annex A (normative) Measurement of line widths (FWHMs) to determine the energy resolution of the spectrometer . 6Annex B (normative) Determination of the L/K ratio as a measure

11、 for the energy dependence of the instrumental detection efficiency . 9Bibliography . 11BS ISO 15632:2012ISO 15632:2012(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International S

12、tandards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, als

13、o take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees

14、 is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibil

15、ity that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 15632 was prepared by Technical Committee ISO/TC 202, Microbeam analysis.This second edition cancels and replaces the first edition

16、(ISO 15632:2002), which has been technically revised (see the Introduction, first paragraph, for details).iv ISO 2012 All rights reservedBS ISO 15632:2012ISO 15632:2012(E)IntroductionRecent progress in energy-dispersive X-ray spectrometry (EDS) by means of improved manufacturing technologies for det

17、ector crystals and the application of advanced pulse-processing techniques have increased the general performance of spectrometers, in particular at high count rates and at low energies (below 1 keV). A revision of this International Standard became necessary because silicon drift detector (SDD) tec

18、hnology was not included. SDDs provide performance comparable to Si-Li detectors, even at considerably higher count rates. In addition, a larger detector active area results in the capability of measuring even higher count rates. This International Standard has therefore been updated with criteria f

19、or the evaluation of the performance of such modern spectrometers.In the past, a spectrometer was commonly specified by its energy resolution at high energies defined 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

20、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 defined 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

21、 same quantity have sometimes been employed. The sensitivity of the spectrometer at low energies related to that at high energies depends strongly on the construction of the detector crystal and the X-ray entrance window used. Although high sensitivity at low energies is important for the applicatio

22、n of the spectrometer in the analysis of light-element compounds, normally the manufacturers do not specify an energy dependence for spectrometer efficiency.This International Standard was developed in response to a worldwide demand for minimum specifications of an energy-dispersive X-ray spectromet

23、er. EDS is one of the most applied methods used to analyse the chemical composition of solids and thin films. This International Standard should permit comparison of the performance of different spectrometer designs on the basis of a uniform specification and help to find the optimum spectrometer fo

24、r a particular task. In addition, this International Standard contributes to the equalization of performances in separate test laboratories. In accordance with ISO/IEC 170251, such laboratories have to periodically check the calibration status of their equipment according to a defined procedure. Thi

25、s International Standard may serve as a guide for similar procedures in all relevant test laboratories. ISO 2012 All rights reserved vBS ISO 15632:2012BS ISO 15632:2012Microbeam analysis Selected instrumental performance parameters for the specification and checking of energy-dispersive X-ray spectr

26、ometers for use in electron probe microanalysis1 ScopeThis International Standard 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 Internat

27、ional 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 relevant instrumental performance parameters are to be checked for such spectrometers attached to a

28、 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 International Standard.2 Normative referencesThe following referenced documents are indispensable for the

29、 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) Vocabulary3 Terms and definitionsFor the pur

30、poses 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 given in the same or analogous form in ISO 223092, ISO 18115-14and ISO 23833.3.1energy-dispersive X

31、-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 detector, a preamplifier, and a pulse processor. The detector converts X-ray photon energy into ele

32、ctrical 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 ratenumber of X-ray photons per second3.2.1input count rateICRnumber of X-ray photons absorbed in the de

33、tector per secondINTERNATIONAL STANDARD ISO 15632:2012(E) ISO 2012 All rights reserved 1BS ISO 15632:2012ISO 15632:2012(E)3.2.2output count rateOCRnumber of valid X-ray photon measurements per second that are output by the electronics and stored in memoryNOTE When the electronics measures individual

34、 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) is less than

35、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-ray acquisition,

36、 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 seconds, after

37、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 by a regular en

38、ergy 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 processingNOTE This def

39、inition 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 peak measured as

40、 height of the peak above a defined background3.10peak areanet peak areasum of signal intensities of a spectral peak after background removal2 ISO 2012 All rights reservedBS ISO 15632:2012ISO 15632:2012(E)3.11background signalcontinuous X-ray spectrumcontinuumnon-characteristic component of an X-ray

41、 spectrum arising from the 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 it

42、self (by X-ray scattering) 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 angleTOAa

43、ngle between the specimen surface 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 R

44、equirements4.1 General descriptionThe 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 o

45、f a spectrometer for a certain 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)

46、. Parameters which may not 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,

47、other specifications like energy 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

48、 Energy resolutionThe energy 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 sha

49、ll be an upper limit in that 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 1 000 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. 5