iTeh StandardsiTeh Standards
EURUSD
Your shopping cart is empty.
ASTM

ASTM E2426-05

(Practice)

Standard Practice for Pulse Counting System Dead Time Determination by Measuring Isotopic Ratios with SIMS

Standard Practice for Pulse Counting System Dead Time Determination by Measuring Isotopic Ratios with SIMS

SIGNIFICANCE AND USE
Electron multipliers are commonly used in pulse-counting mode to detect ions from magnetic sector mass spectrometers. The electronics used to amplify, detect and count pulses from the electron multipliers always have a characteristic time after the detection of a pulse after which no other pulses can be counted. This characteristic time is known as the “dead time.” The dead time has the effect of reducing the measured count rate compared with the “true” count rate.
In order to measure count rates accurately over the entire dynamic range of a pulse counting detector, such as an electron multiplier, the dead time of the entire pulse counting system must be well known. Accurate count rate measurement forms the basis of isotopic ratio measurements as well as elemental abundance determinations.
The procedure described herein has been successfully used to determine the dead time of counting systems on SIMS instruments.5 The accurate determination of the dead time by this method has been a key component of precision isotopic ratio measurements made by SIMS.
SCOPE
1.1 This practice provides the Secondary Ion Mass Spectrometry (SIMS) analyst with a method for determining the dead time of the pulse-counting detection systems on the instrument. This practice also allows the analyst to determine whether the apparent dead time is independent of count rate.
1.2 This practice is applicable to most types of mass spectrometers that have pulse-counting detectors.
1.3 This practice does not describe methods for precise or accurate isotopic ratio measurements, or both.
1.4 This practice does not describe methods for the proper operation of pulse counting systems and detectors for mass spectrometry.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

Status
Historical
Publication Date
31-Oct-2005
ICS
71.040.50 - Physicochemical methods of analysis
Technical Committee
E42 - Surface Analysis
Drafting Committee
E42.06 - SIMS
Current Stage
Ref Project

Relations

Replaced By
ASTM E2426-10 - Standard Practice for Pulse Counting System Dead Time Determination by Measuring Isotopic Ratios with SIMS
Effective Date
01-Jun-2010

Buy Standard

ASTM E2426-05 - Standard Practice for Pulse Counting System Dead Time Determination by Measuring Isotopic Ratios with SIMSASTM E2426-05 - Standard Practice for Pulse Counting System Dead Time Determination by Measuring Isotopic Ratios with SIMS
PreviousNext
Standard
ASTM E2426-05 - Standard Practice for Pulse Counting System Dead Time Determination by Measuring Isotopic Ratios with SIMS
English language
3 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (Sample)


NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:E2426–05
Standard Practice for
Pulse Counting System Dead Time Determination by
Measuring Isotopic Ratios with SIMS
This standard is issued under the fixed designation E2426; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.2 See Terminology ISO 21270 for definitions of terms
related to counting system measurements.
1.1 This practice provides the Secondary Ion Mass Spec-
m2 m1
3.1.3 isotopic ratio, n—written as X/ X, for an element
trometry (SIMS) analyst with a method for determining the
X with isotopes m1 and m2, refers to the ratios of their atomic
dead time of the pulse-counting detection systems on the
abundances. When it is a value measured in a mass spectrom-
instrument. This practice also allows the analyst to determine
eter it refers to the ratio of the signal intensities for the two
whether the apparent dead time is independent of count rate.
species.
1.2 This practice is applicable to most types of mass
m2 m2
3.1.3.1 Discussion—The notation D X or d X refers to
spectrometers that have pulse-counting detectors.
the fractional deviation of the measured isotopic ratio from the
1.3 This practice does not describe methods for precise or
m2
standard ratio or reference. In this guide, D X will refer to the
accurate isotopic ratio measurements, or both.
fractional deviation of the measured ratio, uncorrected for
1.4 This practice does not describe methods for the proper
m2
mass-fractionation (see 3.1.4) and d X will refer to the
operation of pulse counting systems and detectors for mass
fractional deviation of the measured ratio that has been
spectrometry.
corrected for mass-fractionation. An example for Mg is:
1.5 This standard does not purport to address all of the
25 24
safety concerns, if any, associated with its use. It is the
~ Mg/ Mg!
Meas
D Mg 5 – 1 (1)
25 24
responsibility of the user of this standard to establish appro-
~ Mg/ Mg!
Ref
priate safety and health practices and determine the applica-
where:
bility of regulatory limitations prior to use.
25 24 4
( Mg/ Mg) = 0.12663 .
Ref
2. Referenced Documents
3.1.4 mass-fractionation, n—sometimes called “ mass-
bias,”referstothetotalmass-dependent,intra-isotopevariation
2.1 ASTM Standards:
E673 Terminology Relating to Surface Analysis in ion intensity observed in the measured isotopic ratios for a
given element compared with the reference ratios. It can be
2.2 ISO Standard:
ISO 21270 Surface chemical analysis — X-ray photoelec- expressed as the fractional deviation per unit mass.
3.1.4.1 Discussion—The mass of an isotope i of element X
tron and Auger electron spectrometers — Linearity of
mi
intensity scale; and references 1, 2, 10, 13 and 14 therein. ( X) shall be represented by the notation m, where “i”isan
i
integer.
3. Terminology
4. Summary of Practice
3.1 Definitions:
4.1 This practice describes a method whereby the overall
3.1.1 SeeTerminology E673 for definitions of terms used in
effective dead time of a pulse counting system can be deter-
SIMS.
mined by measuring isotopic ratios of an element having at
least 3 isotopes. One of the isotopes should be approximately
This practice is under the jurisdiction of ASTM Committee E42 on Surface
afactorof10moreabundantthantheotherssothatafirstorder
Analysis and is the direct responsibility of Subcommittee E42.06 on SIMS.
estimate of the dead time can be calculated that will be close to
Current edition approved Nov. 1, 2005. Published January 2006. DOI: 10.1520/
the true value. The efficacy of the method is increased if the
E2426-05.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or sample is flat and uniform, such as a Si wafer or a polished
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. Catanzaro E. J., Murphy T. J., Garner E. L., and Shields W. R., “Absolute
Available from International Organization for Standardization (ISO), 1 rue de Isotopic Abundance Ratios and Atomic Weight of Magnesium,” J. Res. Nat. Bur.
Varembé, Case postale 56, CH-1211, Geneva 20, Switzerland. Stand., 70a, 1966, pp. 453-458.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2426–05
metal block so that the count rate of the isotopes varies
minimally during the individual measurements.
5. Significance and Use
5.1 Electron multipliers are commonly used in pulse-
counting mode to detect ions from magnetic sector mass
spectrometers. The electronics used to amplify, detect and
count pulses from the electron multipliers always have a
characteristic time after the detection of a pulse after which no
other pulses can be counted. This characteristic time is known
asthe“deadtime.”Thedeadtimehastheeffectofreducingthe
measured count rate compared with the “true” count rate.
5.2 In order to measure count rates accurately over the
entire dynamic range of a pulse counting detector, such as an
electron multiplier, the dead time of the entire pulse counting
system must be well known.Accurate count rate measurement
forms the basis of isotopic ratio measurements as well as
elemental abundance determinations.
5.3 The procedure described herein has been successfully FIG. 1 Representation of the Effects of Dead Time and Mass
Fractionation on Measured Isotopic Ratios Expressed as
used to determine the dead time of counting systems on SIMS
Fractional Deviations
instruments. The accurate determination of the dead time by
this method has b
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.

This May Also Interest You

ASTM
ASTM E2735-14(2020)(Guide)
Standard Guide for Selection of Calibrations Needed for X-ray Photoelectron Spectroscopy (XPS) Experiments

SIGNIFICANCE AND USE
4.1 The purpose of this guide is assist users and analysts in selecting the standardization procedures relevant to a defined XPS experiment. These experiments may be based, for example, upon material failure analysis, the determination of surface chemistry of a solid, or the composition profile of a thin film or coating. A series of options will be summarized giving the standards that are related to specific information requirements. ISO 15470 and ISO 10810 also aid XPS users in experiment design for typical samples. ASTM Committee E42 and ISO TC201 are in a continuous process of updating and adding standards and guides. It is recommended to refer to the ASTM and ISO websites for a current list of standards.
SCOPE
1.1 This guide describes an approach to enable users and analysts to determine the calibrations and standards useful to obtain meaningful surface chemistry data with X-ray photoelectron spectroscopy (XPS) and to optimize the instrument for specific analysis objectives and data collection time.  
1.2 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This guide cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide will be applicable in all circumstances.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project’s many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

  • Guide
    6 pages
    English language
    sale 15% off
ASTM
ASTM E984-12(2020)(Guide)
Standard Guide for Identifying Chemical Effects and Matrix Effects in Auger Electron Spectroscopy

SIGNIFICANCE AND USE
4.1 Auger electron spectroscopy is often capable of yielding information concerning the chemical and physical environment of atoms in the near-surface region of a solid as well as giving elemental and quantitative information. This information is manifested as changes in the observed Auger electron spectrum for a particular element in the specimen under study compared to the Auger spectrum produced by the same element when it is in some reference form. The differences in the two spectra are said to be due to a chemical effect or a matrix effect. Despite sometimes making elemental identification and quantitative measurements more difficult, these effects in the Auger spectrum are considered valuable tools for characterizing the environment of the near-surface atoms in a solid.
SCOPE
1.1 This guide outlines the types of chemical effects and matrix effects which are observed in Auger electron spectroscopy.  
1.2 Guidelines are given for the reporting of chemical and matrix effects in Auger spectra.  
1.3 Guidelines are given for utilizing Auger chemical effects for identification or characterization.  
1.4 This guide is applicable to both electron excited and X-ray excited Auger electron spectroscopy.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

  • Guide
    5 pages
    English language
    sale 15% off
ASTM
ASTM E1829-14(2020)(Guide)
Standard Guide for Handling Specimens Prior to Surface Analysis

SIGNIFICANCE AND USE
4.1 Proper handling and preparation of specimens is particularly critical for analysis. Improper handling of specimens can result in alteration of the surface composition and unreliable data. Specimens should be handled carefully so as to avoid the introduction of spurious contaminants. The goal must be to preserve the state of the surface so that analysis remains representative of the original subject.  
4.2 AES, XPS, and SIMS are sensitive to surface layers that are typically a few nanometres thick. Such thin layers can be subject to severe perturbations from improper specimen handling  (1).4  
4.3 This guide describes methods to minimize the effects of specimen handling on the results obtained using surface-sensitive analytical techniques. It is intended for the specimen owner or the purchaser of surface analytical services and the surface analyst. Because of the wide range of types of specimens and desired information, only broad guidelines and general examples are presented here. The optimum handling procedures will be dependent on the particular specimen and the needed information. It is recommended that the specimen supplier consult the surface analyst as soon as possible with regard to specimen history, the specific problem to be solved or information needed, and the particular specimen preparation or handling procedures required. The surface analyst also is referred to Guide E1078 that discusses additional procedures for preparing, mounting, and analysis of specimens.
SCOPE
1.1 This guide covers specimen handling and preparation prior to surface analysis and applies to the following surface analysis disciplines:  
1.1.1 Auger electron spectroscopy (AES),  
1.1.2 X-ray photoelectron spectroscopy (XPS or ESCA), and  
1.1.3 Secondary ion mass spectrometry (SIMS).  
1.1.4 Although primarily written for AES, XPS, and SIMS, these methods may also apply to many surface-sensitive analysis methods, such as ion scattering spectrometry, low-energy electron diffraction, and electron energy loss spectroscopy, where specimen handling can influence surface-sensitive measurements.  
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

  • Guide
    5 pages
    English language
    sale 15% off
ASTM
ASTM E1078-14(2020)(Guide)
Standard Guide for Specimen Preparation and Mounting in Surface Analysis

SIGNIFICANCE AND USE
4.1 Proper preparation and mounting of specimens is particularly critical for surface analysis. Improper preparation of specimens can result in alteration of the surface composition and unreliable data. Specimens should be handled carefully so as to avoid the introduction of spurious contaminants in the preparation and mounting process. The goal must be to preserve the state of the surface so that the analysis remains representative of the original.  
4.2 AES, XPS or ESCA, and SIMS are sensitive to surface layers that are typically a few nanometres thick. Such thin layers can be subject to severe perturbations caused by specimen handling (1)4 or surface treatments that may be necessary prior to introduction into the analytical chamber. In addition, specimen mounting techniques have the potential to affect the intended analysis.  
4.3 This guide describes methods that the surface analyst may need to minimize the effects of specimen preparation when using any surface-sensitive analytical technique. Also described are methods to mount specimens so as to ensure that the desired information is not compromised.  
4.4 Guide E1829 describes the handling of surface sensitive specimens and, as such, complements this guide.
SCOPE
1.1 This guide covers specimen preparation and mounting prior to, during, and following surface analysis and applies to the following surface analysis disciplines:  
1.1.1 Auger electron spectroscopy (AES),  
1.1.2 X-ray photoelectron spectroscopy (XPS and ESCA), and  
1.1.3 Secondary ion mass spectrometry (SIMS).  
1.1.4 Although primarily written for AES, XPS, and SIMS, these methods will also apply to many surface sensitive analysis methods, such as ion scattering spectrometry, low energy electron diffraction, and electron energy loss spectroscopy, where specimen handling can influence surface sensitive measurements.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

  • Guide
    10 pages
    English language
    sale 15% off
ASTM
ASTM E1504-11(2019)(Practice)
Standard Practice for Reporting Mass Spectral Data in Secondary Ion Mass Spectrometry (SIMS)

SIGNIFICANCE AND USE
5.1 This practice is intended for use in reporting the experimental and data reduction procedures described in other publications.
SCOPE
1.1 This practice provides the minimum information necessary to describe the instrumental, experimental, and data reduction procedures used in acquiring and reporting secondary ion mass spectrometry (SIMS) mass spectral data.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

  • Standard
    2 pages
    English language
    sale 15% off
ASTM
ASTM E1635-06(2019)(Practice)
Standard Practice for Reporting Imaging Data in Secondary Ion Mass Spectrometry (SIMS)

SIGNIFICANCE AND USE
5.1 This practice is to be used for reporting the experimental and data reduction procedures to be described with the publication of the data.
SCOPE
1.1 This practice lists the minimum information necessary to describe the instrumental, experimental, and data reduction procedures used in acquiring and reporting images generated by secondary ion mass spectrometry (SIMS).  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

  • Standard
    3 pages
    English language
    sale 15% off
ASTM
ASTM E1217-11(2019)(Practice)
Standard Practice for Determination of the Specimen Area Contributing to the Detected Signal in Auger Electron Spectrometers and Some X-Ray Photoelectron Spectrometers

SIGNIFICANCE AND USE
5.1 Auger electron spectroscopy and X-ray photoelectron spectroscopy are used extensively for the surface analysis of materials. This practice summarizes methods for determining the specimen area contributing to the detected signal (a) for instruments in which a focused electron beam can be scanned over a region with dimensions greater than the dimensions of the specimen area viewed by the analyzer, and (b) by employing a sample with a sharp edge.  
5.2 This practice is intended as a means for determining the observed specimen area for selected conditions of operation of the electron energy analyzer. The observed specimen area depends on whether or not the electrons are retarded before energy analysis, the analyzer pass energy or retarding ratio if the electrons are retarded before energy analysis, the size of selected slits or apertures, and the value of the electron energy to be measured. The observed specimen area depends on these selected conditions of operation and also can depend on the adequacy of alignment of the specimen with respect to the electron energy analyzer.  
5.3 Any changes in the observed specimen area as a function of measurement conditions, for example, electron energy or analyzer pass energy, may need to be known if the specimen materials in regular use have lateral inhomogeneities with dimensions comparable to the dimensions of the specimen area viewed by the analyzer.  
5.4 This practice can give useful information on the imaging properties of the electron energy analyzer for particular conditions of operation. This information can be helpful in comparing analyzer performance with manufacturer's specifications.  
5.5 Information about the shape and size of the area viewed by the analyzer can also be employed to predict the signal intensity in XPS experiments when the sample is rotated and to assess the axis of rotation of the sample manipulator.  
5.6 Examples of the application of the methods described in this practice have been publis...
SCOPE
1.1 This practice describes methods for determining the specimen area contributing to the detected signal in Auger electron spectrometers and some types of X-ray photoelectron spectrometers (spectrometer analysis area) when this area is defined by the electron collection lens and aperture system of the electron energy analyzer. The practice is applicable only to those X-ray photoelectron spectrometers in which the specimen area excited by the incident X-ray beam is larger than the specimen area viewed by the analyzer, in which the photoelectrons travel in a field-free region from the specimen to the analyzer entrance. Some of the methods described here require an auxiliary electron gun mounted to produce an electron beam of variable energy on the specimen (“electron-gun method”). Other experiments require a sample with a sharp edge, such as a wafer covered with a uniform clean layer (for example, gold (Au) or silver (Ag)) and cleaved to obtain a long side (“sharp-edge method”).  
1.2 This practice is recommended as a useful means for determining the specimen area viewed by the analyzer for different conditions of spectrometer operation, for verifying adequate specimen and beam alignment, and for characterizing the imaging properties of the electron energy analyzer.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recomm...

  • Standard
    9 pages
    English language
    sale 15% off
ASTM
ASTM E1634-11(2019)(Guide)
Standard Guide for Performing Sputter Crater Depth Measurements

SIGNIFICANCE AND USE
4.1 Sputter crater depth measurements are performed in order to determine a sputter rate (depth/time) for each matrix sputtered during a sputter depth profile or similar in-depth type analyses. From sputter rate values, a linear depth scale can be calculated and displayed for the sputter depth profile.  
4.2 Data obtained from surface profilometry are useful in monitoring instrumental parameters (for example, raster size, shape, and any irregularities in topography of the sputtered crater) used for depth profiles.
SCOPE
1.1 This guide covers the preferred procedure for acquiring and post-processing of sputter crater depth measurements. This guide is limited to stylus-type surface profilometers equipped with a stage, stylus, associated scan and sensing electronics, video system for sample and scan alignment, and computerized system.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

  • Guide
    3 pages
    English language
    sale 15% off
ASTM
ASTM E1162-11(2019)(Practice)
Standard Practice for Reporting Sputter Depth Profile Data in Secondary Ion Mass Spectrometry (SIMS)

SIGNIFICANCE AND USE
5.1 This practice is used for reporting the experimental conditions as specified in Section 6 in the “Methods” or “Experimental” sections of other publications (subject to editorial restrictions).  
5.2 The report would include specific conditions for each data set, particularly, if any parameters are changed for different sputter depth profile data sets in a publication. For example, footnotes of tables or figure captions would be used to specify differing conditions.
SCOPE
1.1 This practice covers the information needed to describe and report instrumentation, specimen parameters, experimental conditions, and data reduction procedures. SIMS sputter depth profiles can be obtained using a wide variety of primary beam excitation conditions, mass analysis, data acquisition, and processing techniques (1-4).2  
1.2 Limitations—This practice is limited to conventional sputter depth profiles in which information is averaged over the analyzed area in the plane of the specimen. Ion microprobe or microscope techniques permitting lateral spatial resolution of secondary ions within the analyzed area, for example, image depth profiling, are excluded.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

  • Standard
    3 pages
    English language
    sale 15% off
ASTM
ASTM E2426-10(2019)(Practice)
Standard Practice for Pulse Counting System Dead Time Determination by Measuring Isotopic Ratios with SIMS

SIGNIFICANCE AND USE
5.1 Electron multipliers are commonly used in pulse-counting mode to detect ions from magnetic sector mass spectrometers. The electronics used to amplify, detect and count pulses from the electron multipliers always have a characteristic time interval after the detection of a pulse, during which no other pulses can be counted. This characteristic time interval is known as the “dead time.” The dead time has the effect of reducing the measured count rate compared with the “true” count rate.  
5.2 In order to measure count rates accurately over the entire dynamic range of a pulse counting detector, such as an electron multiplier, the dead time of the entire pulse counting system must be well known. Accurate count rate measurement forms the basis of isotopic ratio measurements as well as elemental abundance determinations.  
5.3 The procedure described herein has been successfully used to determine the dead time of counting systems on SIMS instruments.6 The accurate determination of the dead time by this method has been a key component of precision isotopic ratio measurements made by SIMS.
SCOPE
1.1 This practice provides the Secondary Ion Mass Spectrometry (SIMS) analyst with a method for determining the dead time of the pulse-counting detection systems on the instrument. This practice also allows the analyst to determine whether the apparent dead time is independent of count rate.  
1.2 This practice is applicable to most types of mass spectrometers that have pulse-counting detectors.  
1.3 This practice does not describe methods for precise or accurate isotopic ratio measurements.  
1.4 This practice does not describe methods for the proper operation of pulse counting systems and detectors for mass spectrometry.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

  • Standard
    3 pages
    English language
    sale 15% off