Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 2: Characterization of instrument response (ISO 20785-2:2020)

This document specifies methods and procedures for characterizing the responses of devices used
for the determination of ambient dose equivalent for the evaluation of exposure to cosmic radiation in
civilian aircraft. The methods and procedures are intended to be understood as minimum requirements.

Dosimetrie zu Expositionen durch kosmische Strahlung in Flugzeugen der zivilen Luftfahrt - Teil 2: Charakterisierung des Antwortverhaltens von Messinstrumenten (ISO 20785-2:2020)

Dieses Dokument legt Verfahren und Verfahrensabläufe für die Charakterisierung des Ansprechvermögens von Geräten zur Bestimmung der Umgebungs-Äquivalentdosis fest, mit der in der zivilen Luftfahrt die Exposi-tion durch kosmische Strahlung bestimmt wird. Die Verfahren und Abläufe sind als Mindestanforderungen zu verstehen.

Dosimétrie pour l'exposition au rayonnement cosmique à bord d'un avion civil - Partie 2: Caractérisation de la réponse des instruments (ISO 20785-2:2020)

Le présent document spécifie les méthodes et les modes opératoires permettant de caractériser les réponses des dispositifs utilisés pour déterminer l'équivalent de dose ambiant en vue de l'évaluation de l'exposition au rayonnement cosmique à bord d'un avion. Les méthodes et les modes opératoires doivent être considérés comme des exigences minimales.

Dozimetrija za merjenje izpostavljenosti kozmičnemu sevanju v civilnem letalskem prometu - 2. del: Karakterizacija odziva instrumenta (ISO 20785-2:2020)

General Information

Status
Published
Public Enquiry End Date
30-Apr-2019
Publication Date
16-Aug-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
13-Aug-2020
Due Date
18-Oct-2020
Completion Date
17-Aug-2020

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SLOVENSKI STANDARD
SIST EN ISO 20785-2:2020
01-oktober-2020
Nadomešča:
SIST EN ISO 20785-2:2017
Dozimetrija za merjenje izpostavljenosti kozmičnemu sevanju v civilnem letalskem
prometu - 2. del: Karakterizacija odziva instrumenta (ISO 20785-2:2020)

Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 2: Characterization

of instrument response (ISO 20785-2:2020)
Dosimetrie zu Expositionen durch kosmische Strahlung in Flugzeugen der zivilen

Luftfahrt - Teil 2: Charakterisierung des Antwortverhaltens von Messinstrumenten (ISO

20785-2:2020)

Dosimétrie pour l'exposition au rayonnement cosmique à bord d'un avion civil - Partie 2:

Caractérisation de la réponse des instruments (ISO 20785-2:2020)
Ta slovenski standard je istoveten z: EN ISO 20785-2:2020
ICS:
17.240 Merjenje sevanja Radiation measurements
49.020 Letala in vesoljska vozila na Aircraft and space vehicles in
splošno general
SIST EN ISO 20785-2:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 20785-2:2020
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SIST EN ISO 20785-2:2020
EN ISO 20785-2
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2020
EUROPÄISCHE NORM
ICS 13.280; 49.020 Supersedes EN ISO 20785-2:2017
English Version
Dosimetry for exposures to cosmic radiation in civilian
aircraft - Part 2: Characterization of instrument response
(ISO 20785-2:2020)

Dosimétrie pour l'exposition au rayonnement Dosimetrie für die Belastung durch kosmische

cosmique à bord d'un avion civil - Partie 2: Strahlung in Zivilluftfahrzeugen - Teil 2:

Caractérisation de la réponse des instruments (ISO Charakterisierung des Ansprechvermögens von

20785-2:2020) Messinstrumenten (ISO 20785-2:2020)
This European Standard was approved by CEN on 30 June 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20785-2:2020 E

worldwide for CEN national Members.
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SIST EN ISO 20785-2:2020
EN ISO 20785-2:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 20785-2:2020
EN ISO 20785-2:2020 (E)
European foreword

This document (EN ISO 20785-2:2020) has been prepared by Technical Committee ISO/TC 85 "Nuclear

energy, nuclear technologies, and radiological protection" in collaboration with Technical Committee

CEN/TC 430 “Nuclear energy, nuclear technologies, and radiological protection” the secretariat of

which is held by AFNOR.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by February 2021, and conflicting national standards

shall be withdrawn at the latest by February 2021.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 20785-2:2017.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 20785-2:2020 has been approved by CEN as EN ISO 20785-2:2020 without any

modification.
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SIST EN ISO 20785-2:2020
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SIST EN ISO 20785-2:2020
INTERNATIONAL ISO
STANDARD 20785-2
Second edition
2020-07
Dosimetry for exposures to cosmic
radiation in civilian aircraft —
Part 2:
Characterization of instrument
response
Dosimétrie pour l'exposition au rayonnement cosmique à bord d'un
avion civil —
Partie 2: Caractérisation de la réponse des instruments
Reference number
ISO 20785-2:2020(E)
ISO 2020
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SIST EN ISO 20785-2:2020
ISO 20785-2:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
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SIST EN ISO 20785-2:2020
ISO 20785-2:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

3.1 General terms ........................................................................................................................................................................................... 1

3.2 Terms related to quantities and units ................................................................................................................................. 5

3.3 Atmospheric radiation field ......................................................................................................................................................... 7

4 General considerations .................................................................................................................................................................................. 8

4.1 The cosmic radiation field in the atmosphere ............................................................................................................. 8

4.2 General considerations for the dosimetry of the cosmic radiation field in aircraft

and requirements for the characterization of instrument response ........................................................ 9

4.3 General considerations for measurements at aviation altitudes ..............................................................10

5 Calibration fields and procedures ...................................................................................................................................................12

5.1 General considerations .................................................................................................................................................................12

5.2 Characterization of an instrument ......................................................................................................................................14

5.2.1 Determination of the dosimetric characteristics of an instrument ..................................14

5.2.2 Reference radiation fields .....................................................................................................................................16

5.2.3 Scattered radiation ........................................................................................................................................... ...........16

5.2.4 Effect of other types of radiation ....................................................................................................................16

5.2.5 Requirements for characterization in non-reference conditions .......................................17

5.2.6 Use of numerical simulations ............................................................................................................................17

5.3 Instrument-related software ...................................................................................................................................................17

5.3.1 Software development procedures ...............................................................................................................17

5.3.2 Software testing .............................................................................................................................................................18

5.3.3 Data analysis using spreadsheets ...................................................................................................................18

6 Uncertainties .........................................................................................................................................................................................................18

7 Remarks on performance tests ..........................................................................................................................................................18

Annex A (informative) Representative particle fluence energy distributions for the cosmic

radiation field at flight altitudes for solar minimum and maximum conditions and

for minimum and maximum vertical cut-off rigidity ..................................................................................................19

Annex B (informative) Radiation fields recommended for use in calibrations ....................................................25

Annex C (informative) Comparison measurements ...........................................................................................................................29

Annex D (informative) Charged-particle irradiation facilities ...............................................................................................31

Bibliography .............................................................................................................................................................................................................................32

© ISO 2020 – All rights reserved iii
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SIST EN ISO 20785-2:2020
ISO 20785-2:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards 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, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility 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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO's adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,

and radiological protection, Subcommittee SC 2, Radiation protection.

This second edition cancels and replaces the first edition (ISO 20785-2:2011), which has been technically

revised. The main changes compared to the previous edition are as follows:
— revision of the definitions of the terms;
— updated references.
A list of all the parts in the ISO 20785 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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SIST EN ISO 20785-2:2020
ISO 20785-2:2020(E)
Introduction

Aircraft crews are exposed to elevated levels of cosmic radiation of galactic and solar origin and

secondary radiation produced in the atmosphere, the aircraft structure and its contents. Following

[1]

recommendations of the International Commission on Radiological Protection in Publication 60 ,

[2]

confirmed by Publication 103 , the European Union (EU) introduced a revised Basic Safety Standards

[3] [4]

Directive and International Atomic Energy Agency (IAEA) issued a revised Basic Safety Standards.

Those standards included exposure to natural sources of ionizing radiation, including cosmic radiation,

as occupational exposure. The EU Directive requires account to be taken of the exposure of aircraft crew

liable to receive more than 1 mSv per year. It then identifies the following four protection measures:

a) to assess the exposure of the crew concerned;

b) to take into account the assessed exposure when organizing working schedules with a view to

reducing the doses of highly exposed crew;
c) to inform the workers concerned of the health risks their work involves; and

d) to apply the same special protection during pregnancy to female crew in respect of the “child to be

born” as to other female workers.

The EU Council Directive has already been incorporated into laws and regulations of EU member

states and is being included in the aviation safety standards and procedures of the European Air Safety

Agency. Other countries, such as Canada and Japan, have issued advisories to their airline industries to

manage aircraft crew exposure.

For regulatory and legislative purposes, the radiation protection quantities of interest are the

equivalent dose (to the foetus) and the effective dose. The cosmic radiation exposure of the body is

essentially uniform, and the maternal abdomen provides no effective shielding to the foetus. As a result,

the magnitude of equivalent dose to the foetus can be put equal to that of the effective dose received

by the mother. Doses on board aircraft are generally predictable, and events comparable to unplanned

exposure in other radiological workplaces cannot normally occur (with the rare exceptions of extremely

intense and energetic solar particle events). Personal dosimeters for routine use are not considered

necessary. The preferred approach for the assessment of doses of aircraft crew, where necessary, is to

calculate directly the effective dose per unit time, as a function of geographic location, altitude and solar

cycle phase, and to combine these values with flight and staff roster information to obtain estimates of

[5] [6]

effective doses for individuals. This approach is supported by the ICRP in Publications 75 and 132

and in guidance from the European Commission.

The role of calculations in this procedure is unique in routine radiation protection, and it is widely

[7]

accepted that the calculated doses should be validated by measurement . Effective dose is not directly

measurable. The operational quantity of interest is the ambient dose equivalent, H*(10). In order to

validate the assessed doses obtained in terms of effective dose, calculations can be made of ambient

dose equivalent rates or route doses in terms of ambient dose equivalent, and values of this quantity

determined by measurements traceable to national standards and taking instrument responses and

related uncertainties properly into account. The validation of calculations of ambient dose equivalent

for a particular calculation method may be taken as a validation of the calculation of effective dose by

the same computer code, but this step in the process might need to be confirmed. The alternative is to

establish, a priori, that the operational quantity ambient dose equivalent is a good estimator of effective

dose and equivalent dose to the foetus for the radiation fields being considered, in the same way that

the use of the operational quantity personal dose equivalent is justified for the estimation of effective

dose for ground-based radiation workers.

The radiation field in aircraft at altitude is complex, with many types of ionizing radiation present,

with energies ranging up to many GeV. The instrument response to particles and energies of the

atmospheric radiation field that are not covered by reference fields are carefully taken into account in

the evaluation of measurement results. While, in many cases, the methods used for the determination

of ambient dose equivalent in aircraft are similar to those used at high-energy accelerators in

research laboratories. Therefore, it is possible to recommend dosimetric methods and methods for

© ISO 2020 – All rights reserved v
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SIST EN ISO 20785-2:2020
ISO 20785-2:2020(E)

the calibration of dosimetric devices, as well as the techniques for maintaining the traceability of

dosimetric measurements to national standards. Dosimetric measurements made to evaluate ambient

dose equivalent should be performed using accurate and reliable methods that ensure the quality of

readings provided to workers and regulatory authorities. The purpose of this document is to specify

procedures for the determination of the responses of instruments in different reference radiation

fields, as a basis for proper characterization of instruments used for the determination of ambient dose

equivalent in aircraft at altitude.

Requirements for the determination and recording of the cosmic radiation exposure of aircraft crew have

been introduced into the national legislation of EU member states and other countries. Harmonization

of methods used for determining ambient dose equivalent and for calibrating instruments is desirable

to ensure the compatibility of measurements performed with such instruments.

This document is intended for the use of primary and secondary calibration laboratories for ionizing

radiation, by radiation protection personnel employed by governmental agencies, and by industrial

corporations concerned with the determination of ambient dose equivalent for aircraft crew.

vi © ISO 2020 – All rights reserved
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SIST EN ISO 20785-2:2020
INTERNATIONAL STANDARD ISO 20785-2:2020(E)
Dosimetry for exposures to cosmic radiation in civilian
aircraft —
Part 2:
Characterization of instrument response
1 Scope

This document specifies methods and procedures for characterizing the responses of devices used

for the determination of ambient dose equivalent for the evaluation of exposure to cosmic radiation in

civilian aircraft. The methods and procedures are intended to be understood as minimum requirements.

2 Normative references

The following five documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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/IEC Guide 98-1, Uncertainty of measurement — Part 1: Introduction to the expression of uncertainty

in measurement

ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in

me a s ur ement (GUM: 1995)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 General terms
3.1.1
angle of radiation incidence

angle between the direction of radiation incidence and the reference direction of the instrument

3.1.2
calibration

operation that, under specified conditions, establishes a relation between the conventional quantity,

H , and the indication, G

Note 1 to entry: A calibration can be expressed by a statement, calibration function, calibration diagram,

calibration curve or calibration table. In some cases, it can consist of an additive or multiplicative correction of

the indication with associated measurement uncertainty.

Note 2 to entry: It is important not to confuse calibration with adjustment of a measuring system, often

mistakenly called “self-calibration”, or with verification of calibration.
© ISO 2020 – All rights reserved 1
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SIST EN ISO 20785-2:2020
ISO 20785-2:2020(E)
3.1.3
calibration coefficient
coeff

quotient of the conventional quantity value to be measured and the corrected indication of the

instrument

Note 1 to entry: The calibration coefficient is equivalent to the calibration factor multiplied by the instrument

constant.

Note 2 to entry: The reciprocal of the calibration coefficient, N , is the response.

coeff

Note 3 to entry: For the calibration of some instruments, e.g. ionization chambers, the instrument constant and

the calibration factor are not identified separately but are applied together as the calibration coefficient.

Note 4 to entry: It is necessary, in order to avoid confusion, to state the quantity to be measured, for example:

the calibration coefficient with respect to fluence, N , the calibration coefficient with respect to kerma, N , the

Φ K
calibration coefficient with respect to absorbed dose, N .
3.1.4
calibration factor
fact

factor by which the product of the corrected indication and the associated instrument constant of the

instrument is multiplied to obtain the conventional quantity value to be measured under reference

conditions
Note 1 to entry: The calibration factor is dimensionless.

Note 2 to entry: The corrected indication is the indication of the instrument corrected for the effect of influence

quantities, where applicable.

Note 3 to entry: The value of the calibration factor can vary with the magnitude of the quantity to be measured.

In such cases, a detector assembly is said to have a non-constant response.
3.1.5
measured quantity value
measured value of a quantity
measured value
quantity value representing a measurement result

Note 1 to entry: For a measurement involving replicate indications, each indication can be used to provide a

corresponding measured quantity value. This set of measured quantity values can be used to calculate a

resulting measured quantity value, such as an average or a median value, usually with a decreased associated

measurement uncertainty.

Note 2 to entry: When the range of the true quantity values believed to represent the measurand is small

compared with the measurement uncertainty, a measured quantity value can be considered to be an estimate

of an essentially unique true quantity value and is often an average or a median of individual measured quantity

values obtained through replicate measurements.

Note 3 to entry: In the case where the range of the true quantity values believed to represent the measurand is

not small compared with the measurement uncertainty, a measured value is often an estimate of an average or a

median of the set of true quantity values.

Note 4 to entry: In ISO/IEC Guide 98-3:2008, the terms “result of measurement” and “estimate of the value of the

measurand” or just “estimate of the measurand” are used for “measured quantity value”.

2 © ISO 2020 – All rights reserved
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SIST EN ISO 20785-2:2020
ISO 20785-2:2020(E)
3.1.6
conventional quantity value
conventional value of a quantity
conventional value
quantity value attributed by agreement to a quantity for a given purpose

Note 1 to entry: The term “conventional true quantity value” is sometimes used for this concept, but its use is

discouraged.

Note 2 to entry: Sometimes, a conventional quantity value is an estimate of a true quantity value.

Note 3 to entry: A conventional quantity value is generally accepted as being associated with a suitably small

measurement uncertainty, which might be zero.
[8][9][10]

Note 4 to entry: In ISO 20785 series , the conventional quantity value is the best estimate of the value of

the quantity to be measured, determined by a primary or a secondary standard which is traceable to a primary

standard.
3.1.7
correction factor

factor applied to the indication (3.1.9) to correct for deviation of measurement conditions from reference

conditions

Note 1 to entry: If the correction of the effect of the deviation of an influence quantity requires a factor, the

influence quantity is of type F.
3.1.8
correction summand

summand applied to the indication (3.1.9) to correct for the zero indication or the deviation of the

measurement conditions from the reference conditions

Note 1 to entry: If the correction of the effect of the deviation of an influence quantity requires a summand, the

influence quantity is of type S.
3.1.9
indication
quantity value provided by a measuring instrument or a measuring system

Note 1 to entry: An indication can be presented in visual or acoustic form or can be transferred to another device.

An indication is often given by the position of a pointer on the display for analogue outputs, a displayed or printed

number for digital outputs, a code pattern for code outputs, or an assigned quantity value for material measures.

Note 2 to entry: An indication and a corresponding value of the quantity being measured are not necessarily

values of quantities of the same kind.
3.1.10
influence quantity

quantity that, in a direct measurement, does not affect the quantity that is actually measured, but

affects the relation between the indication (3.1.9) and the measurement result

Note 1 to entry: An indirect measurement involves a combination of direct measurements, each of which can be

affected by influence quantities.

Note 2 to entry: In ISO/IEC Guide 98-3:2008, the concept “influence quantity” is defined as

[11]

in ISO/IEC Guide 99:2007 , covering not only the quantities affecting the measuring system, as in the definition

above, but also those quantities that affect the quantities actually measured. Also, in ISO/IEC Guide 98-3, this

concept is not restri
...

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