Water quality - Radon-222 - Part 4: Test method using two-phase liquid scintillation counting (ISO/DIS 13164-4:2022)

ISO 13164-4:2015 describes a test method for the determination of radon-222 (222Rn) activity concentration in non-saline waters by extraction and liquid scintillation counting.
The radon-222 activity concentrations, which can be measured by this test method utilizing currently available instruments, are at least above 0,5 Bq l−1 for a 10 ml test sample and a measuring time of 1 h.
This test method can be used successfully with drinking water samples and it is the responsibility of the laboratory to ensure the validity of this test method for water samples of untested matrices.
Annex A gives indication on the necessary counting conditions to meet the required detection limits for drinking water monitoring.

Qualité de l'eau - Radon 222 - Partie 4: Méthode d'essai par comptage des scintillations en milieu liquide à deux phases (ISO/DIS 13164-4:2022)

L'ISO 13164-4:2015 spécifie une méthode d'essai permettant de déterminer l'activité volumique du radon 222 (222Ra) dans des eaux non salines par extraction et comptage des scintillations en milieu liquide.
Les valeurs d'activité volumique du radon 222 qui peuvent être mesurées par cette méthode d'essai à l'aide d'instruments actuellement disponibles, sont au moins supérieures à 0,5 Bq l−1 pour une prise d'essai de 10 ml et un temps de comptage de 1 h.
Cette méthode d'essai peut être utilisée avec succès sur des échantillons d'eau potable et il appartient au laboratoire de s'assurer de la validité de cette méthode d'essai pour des échantillons d'eau provenant de matrices non testées.
L'Annexe A donne une indication sur les conditions de comptage nécessaires pour obtenir les limites de détection requises pour la surveillance de l'eau potable.

Kakovost vode - Radon Rn-222 - 4. del: Preskusna metoda s štetjem z dvofaznim tekočinskim scintilatorjem (ISO/DIS 13164-4:2022)

General Information

Status
Not Published
Technical Committee
Current Stage
4060 - Closure of enquiry - Enquiry
Due Date
02-May-2022
Completion Date
02-May-2022

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SLOVENSKI STANDARD
oSIST prEN ISO 13164-4:2022
01-april-2022
Kakovost vode - Radon Rn-222 - 4. del: Preskusna metoda s štetjem z dvofaznim
tekočinskim scintilatorjem (ISO/DIS 13164-4:2022)

Water quality - Radon-222 - Part 4: Test method using two-phase liquid scintillation

counting (ISO/DIS 13164-4:2022)

Qualité de l'eau - Radon 222 - Partie 4: Méthode d'essai par comptage des scintillations

en milieu liquide à deux phases (ISO/DIS 13164-4:2022)
Ta slovenski standard je istoveten z: prEN ISO 13164-4
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
17.240 Merjenje sevanja Radiation measurements
oSIST prEN ISO 13164-4:2022 en,fr,de

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

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oSIST prEN ISO 13164-4:2022
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oSIST prEN ISO 13164-4:2022
DRAFT INTERNATIONAL STANDARD
ISO/DIS 13164-4
ISO/TC 147/SC 3 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2022-02-07 2022-05-02
Water quality — Radon-222 —
Part 4:
Test method using two-phase liquid scintillation counting
Qualité de l'eau — Radon 222 —

Partie 4: Méthode d'essai par comptage des scintillations en milieu liquide à deux phases

ICS: 17.240; 13.060.60; 13.280
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
ISO/CEN PARALLEL PROCESSING
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 13164-4:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2022
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oSIST prEN ISO 13164-4:2022
ISO/DIS 13164-4:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022

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

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oSIST prEN ISO 13164-4:2022
ISO/DIS 13164-4:2022(E)
Contents Page

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

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

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

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

3 Terms, definitions and symbols .......................................................................................................................................................... 1

3.1 Terms and definitions ...................................................................................................................................................................... 1

3.2 Symbols ......................................................................................................................................................................................................... 2

4 Principle ........................................................................................................................................................................................................................ 2

5 Reagents and apparatus .............................................................................................................................................................................. 2

5.1 Reagents ....................................................................................................................................................................................................... 2

5.2 Apparatus .................................................................................................................................................................................................... 3

6 Sampling ....................................................................................................................................................................................................................... 3

6.1 General ........................................................................................................................................................................................................... 3

6.2 Sampling with source preparation “on site” ................................................................................................................ 3

6.3 Sampling without “on site” source preparation ........................................................................................................ 3

7 Instrument set up and calibration ....................................................................................................................................................4

7.1 Preparation of calibration sources ....................................................................................................................................... 4

7.2 Optimization of counting conditions .................................................................................................................................. 4

7.3 Detection efficiency ........................................................................................................................................................................... 4

7.4 Blank sample preparation and measurement............................................................................................................. 5

8 Sample preparation and measurement ....................................................................................................................................... 5

9 Expression of results ....................................................................................................................................................................................... 6

9.1 Calculation of activity per unit of mass ............................................................................................................................ 6

9.2 Standard uncertainty ....................................................................................................................................................................... 6

9.3 Decision threshold .............................................................................................................................................................................. 6

9.4 Detection limit ........................................................................................................................................................................................ 7

9.5 Limits of the coverage intervals .............................................................................................................................................. 7

9.5.1 Limits of the probabilistically symmetric coverage interval ..................................................... 7

9.5.2 The shortest coverage interval .............................................................................................................................. 8

9.6 Calculations using the activity concentration ............................................................................................................ 8

10 Interference control .........................................................................................................................................................................................8

11 Quality control .......................................................................................................................................................................................................8

12 Test report .................................................................................................................................................................................................................. 8

Annex A (informative) Set-up parameters and validation data ...........................................................................................10

Bibliography .............................................................................................................................................................................................................................14

iii
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oSIST prEN ISO 13164-4:2022
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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 of 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

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 3,

Radioactivity measurements.

This second edition cancels and replaces the first edition (ISO 13164-4:2015), which has been

technically revised.
The main changes are as follows:
— xxx xxxxxxx xxx xxxx
A list of all the parts in the ISO 13164 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.
© ISO 2022 – All rights reserved
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oSIST prEN ISO 13164-4:2022
ISO/DIS 13164-4:2022(E)
Introduction

Radioactivity from several naturally-occurring and anthropogenic sources is present throughout

the environment. Thus, water bodies (e.g. surface waters, ground waters, sea waters) can contain

radionuclides of natural, human-made, or both origins:
40 3 14

— natural radionuclides, including K, H, C, and those originating from the thorium and uranium

226 228 234 238 210 210
decay series, in particular Ra, Ra, U, U, Po and Pb can be found in water for

natural reasons (e.g. desorption from the soil and washoff by rain water) or can be released from

technological processes involving naturally occurring radioactive materials (e.g. the mining and

processing of mineral sands or phosphate fertilizers production and use);

— human-made radionuclides such as transuranium elements (americium, plutonium, neptunium,

3 14 90

curium), H, C, Sr, and gamma emitting radionuclides can also be found in natural waters.

Small quantities of these radionuclides are discharged from nuclear fuel cycle facilities into the

environment as a result of authorized routine releases. Some of these radionuclides used for

medical and industrial applications are also released into the environment after use. Anthropogenic

radionuclides are also found in waters as a result of past fallout contaminations resulting from

the explosion in the atmosphere of nuclear devices and accidents such as those that occurred in

Chernobyl and Fukushima.

Radionuclide activity concentration in water bodies can vary according to local geological

characteristics and climatic conditions and can be locally and temporally enhanced by releases from

[1]

nuclear installation during planned, existing, and emergency exposure situations . Drinking-water

may thus contain radionuclides at activity concentrations which could present a risk to human health.

The radionuclides present in liquid effluents are usually controlled before being discharged into

[2]

the environment and water bodies. Drinking waters are monitored for their radioactivity as

[3]

recommended by the World Health Organization (WHO) so that proper actions can be taken to ensure

that there is no adverse health effect to the public. Following these international recommendations,

national regulations usually specify radionuclide authorized concentration limits for liquid effluent

discharged to the environment and radionuclide guidance levels for waterbodies and drinking waters

for planned, existing, and emergency exposure situations. Compliance with these limits can be assessed

[4]

using measurement results with their associated uncertainties as specified by ISO/IEC Guide 98-3

[5]
and ISO 5667-20 .

Depending on the exposure situation, there are different limits and guidance levels that would result

in an action to reduce health risk. As an example, during a planned or existing situation, the WHO

226

guidelines for guidance level in drinking water is 1 Bq·l−1 for Ra activity concentration.

NOTE 1 The guidance level is the activity concentration with an intake of 2 l d of drinking water for one year

that results in an effective dose of 0,1 mSv a for members of the public. This is an effective dose that represents

[3]

a very low level of risk and which is not expected to give rise to any detectable adverse health effects .

[6]

In the event of a nuclear emergency, the WHO Codex Guideline Levels mentioned that the activity

−1 226
concentration might not be greater than XBq l for Ra.

NOTE 2 The Codex guidelines levels (GLs) apply to radionuclides contained in foods destined for human

consumption and traded internationally, which have been contaminated following a nuclear or radiological

emergency. These GLs apply to food after reconstitution or as prepared for consumption, i.e. not to dried or

concentrated foods, and are based on an intervention exemption level of 1 mSv in a year for members of the

[6].
public (infant and adult)

Thus, the test method can be adapted so that the characteristic limits, decision threshold, detection

limit and uncertainties ensure that the radionuclide activity concentrations test results can be verified

to be below the guidance levels required by a national authority for either planned/existing situations

[7],[8]
or for an emergency situation .

Usually, the test methods can be adjusted to measure the activity concentration of the radionuclide(s)

in either wastewaters before storage or in liquid effluents before being discharged to the environment.

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oSIST prEN ISO 13164-4:2022
ISO/DIS 13164-4:2022(E)

The test results will enable the plant/installation operator to verify that, before their discharge,

wastewaters/liquid effluent radioactive activity concentrations do not exceed authorized limits.

The test method(s) described in this document may be used during planned, existing and emergency

exposure situations as well as for wastewaters and liquid effluents with specific modifications that

could increase the overall uncertainty, detection limit, and threshold.

The test method(s) may be used for water samples after proper sampling, sample handling, and test

sample preparation (see the relevant part of ISO 5667 series).

The radon activity concentration in surface water is very low, usually below 1 Bq l . In groundwater, the

−1 −1 −1

activity concentration varies from 1 Bq l up to 50 Bq l in sedimentary rock aquifers, from 10 Bq l

−1 −1 −1

up to 300 Bq l in wells, and from 100 Bq l up to 1 000 Bq l in crystalline rocks. The highest activity

[9]

concentrations are normally measured in rocks with high concentration of uranium .

High variations in the activity concentrations of radon in aquifers have been observed. Even in a region

with relatively uniform rock types, some well water can exhibit radon activity concentration greatly

higher than the average value for the same region. Significant seasonal variations have also been

[10]
recorded (see ISO 13164-1:2013, Annex A ).

Water can dissolve chemical substances as it passes from the soil surface to an aquifer or spring waters.

The water can pass through or remain for some time in rock, some formations of which can contain a

high concentration of natural radionuclides. Under favourable geochemical conditions, the water can

selectively dissolve some of these natural radionuclides.

Nevertheless, in circumstances where high radon concentrations might be expected in drinking-water,

it is prudent to measure for radon and, if high concentrations are identified, consider whether measures

[1]
to reduce the concentrations present are justified .

This document has been developed to support the need of test laboratories carrying out these

measurements, that are sometimes required by national authorities, as they may have to obtain a

specific accreditation for radionuclide measurement in drinking water samples.

This document is one of a set of International Standards on test methods dealing with the measurement

of the activity concentration of radionuclides in water samples.
© ISO 2022 – All rights reserved
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oSIST prEN ISO 13164-4:2022
DRAFT INTERNATIONAL STANDARD ISO/DIS 13164-4:2022(E)
Water quality — Radon-222 —
Part 4:
Test method using two-phase liquid scintillation counting

WARNING — Persons using this document should be familiar with normal laboratory practice.

This document does not purport to address all of the safety issues, if any, associated with its use.

It is the responsibility of the user to establish appropriate safety and health practices and to

ensure compliance with any national regulatory conditions.

IMPORTANT — It is absolutely essential that tests conducted in accordance with this document

be carried out by suitably qualified staff.
1 Scope
222

This document describes a test method for the determination of radon-222 ( Rn) activity

concentration in non-saline waters by extraction and liquid scintillation counting.

The radon-222 activity concentrations, which can be measured by this test method utilizing currently

available instruments, are at least above 0,5 Bq l for a 10 ml test sample and a measuring time of 1 h.

This test method can be used successfully with drinking water samples and it is the responsibility of

the laboratory to ensure the validity of this test method for water samples of untested matrices.

Annex A gives indication on the necessary counting conditions to meet the required detection limits for

drinking water monitoring.
2 Normative references

The following 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 3696, Water for analytical laboratory use — Specification and test methods

ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes

ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples

ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

3 Terms, definitions and symbols
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 80000-10 apply.

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

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
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oSIST prEN ISO 13164-4:2022
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3.2 Symbols

For the purposes of this document, the symbols given in ISO 80000-10 and the following apply.

a massic activity of the sample Bq·g
a massic activity of the standard solution at the measuring time Bq·g
a* decision threshold for the total massic activity Bq·g
# −1
a detection limit for the total massic activity Bq·g
⊲ ⊳ −1

a , a Lower and upper limits of the probabilistically symmetric coverage interval Bq·g

⊲ ⊳ −1
a , a Lower and upper limits of the shortest coverage interval Bq·g
c activity concentration Bq·l
m mass of the test sample g
m mass of standard solution used for the preparation of the counting standard g
r blank sample count rate s
r sample gross count rate s
r count rate of the standard in the counting window (alpha + beta) s
t blank sample counting time s
t test sample counting time s
t calibration sample counting time s
u(a) standard uncertainty associated with the measurement result Bq·g
U expanded uncertainty, calculated using U = ku(a), with k = 2 Bq·g
w coefficient equal to 1/(ε m) g
ε total efficiency
ρ density g·l
4 Principle
222

Rn is extracted from aqueous solution by means of a scintillation cocktail not miscible with water

(without emulsifier) inside the scintillation vial and counted as the equilibrium with its short-lived

[11] [12] [13] [14]
decay products is reached.

The aqueous sample is drawn with a gas-tight syringe from inside the water volume (i.e. well below

surface) to avoid radon losses during sampling and transferred into a scintillation vial containing

the desired amount of scintillation cocktail. For the same reason, the water sample is injected below

the cocktail surface. The vial is tightly capped, shaken and kept for 3 h preferably in the dark and at

controlled temperature. The sample is then counted by a liquid scintillation counter. Either total counts

222

(alpha + beta) or alpha only counts are considered. In these conditions Rn and its short-lived progeny

218 214 214 214
( Po, Pb, Bi, and Po) are measured.
5 Reagents and apparatus
5.1 Reagents

All reagents shall be of recognized analytical grade and, except for 5.1.4, shall not contain any detectable

alpha and beta activity.
5.1.1 Water, distilled or deionized, complying with ISO 3696, grade 3.
222

Deionized water can contain detectable amounts of Rn and short-lived daughters. It is, therefore,

strongly recommended that water be boiled under vigorous stirring and allowed to stand for 1 day

before use. Otherwise, purge it with nitrogen for about 1 h for 2 l.
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oSIST prEN ISO 13164-4:2022
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5.1.2 Scintillation cocktail, commercially available scintillation cocktails, not water miscible.

5.1.3 Ethanol, 95 %.
5.1.4 Radium standard solution.
226

Ra standard solutions shall be provided with calibration certificates containing at least the

activity concentration, measurement uncertainty and/or statement of compliance with an identified

metrological specification.
5.2 Apparatus
5.2.1 Balance.
5.2.2 Wide-mouth glass sample bottles, volume from 500 ml to 1 l.
5.2.3 Wide-mouth flask, volume from 500 ml to 1 l.
5.2.4 Gas-tight syringe.

5.2.5 Liquid scintillation counter, preferably with thermostated counting chamber and preferably

ultra-low level counter to achieve better detection limits.
5.2.6 Polyethylene scintillation vials, PTFE coated, volume 20 ml.
5.2.7 Glass scintillation vials, low potassium glass, volume 20 ml.

NOTE PTFE coated polyethylene vials are the best choice since they prevent both the diffusion of the cocktail

into the wall of the vial, radon loss and the absorption of radon from the external environment. Glass vials exhibit

a considerably higher background due to K content.
6 Sampling
6.1 General

Sampling, handling and storage of the water samples shall be done as specified in ISO 5667-1 and

ISO 5667-3.

Since radon is easily desorbed from water sample, care should be taken to avoid analyte losses during

the sampling.
6.2 Sampling with source preparation “on site”

Attach a plastic tube to a faucet with a proper fitting. Insert the other end of the tube in a wide-mouth

flask (5.2.3). Allow a steady water stream to get out and overflow the flask for approximately 2 min.

Adjust the flux to avoid turbulence, bubbles, and empty volumes both in the tube and in the flask.

Draw the water sample aliquot with a gas-tight syringe (5.2.4) inserting the needle well below the

surface. Sampling time shall be recorded to calculate decay correction.
6.3 Sampling without “on site” source preparation

Attach a plastic tube to a faucet with a proper fitting. Insert the other end of the tube in a wide-

mouth borosilicate bottle (5.2.2). Allow a steady water stream to flow out and overflow the bottle for

approximately 2 min. Adjust flux to avoid turbulence, bubbles, and empty volumes both in the tube and

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oSIST prEN ISO 13164-4:2022
ISO/DIS 13164-4:2022(E)

in the bottle. Gently extract the tube and screw tightly the cap avoiding any air head space. A 1 l bottle

is generally suitable for the sampling. Sampling time shall be recorded to calculate decay correction.

The sample should be transported into laboratory and analysed possibly within 48 h. The sample

should neither be frozen nor overheated. Its preservation at temperature not higher than that of the

sampled water is recommended.
7 Instrument set up and calibration
7.1 Preparation of calibration sources
226

Transfer an accurately known amount, m , of the Ra standard solution (5.1.4) into a 20 ml scintillation

vial (5.2.6 or 5.2.7). Let the massic activity at the measuring time be a . Dilute with laboratory water

(5.1.1) (see ISO 3696) to the previously chosen mass (e.g. 10 g). Add the scintillation cocktail (5.1.2).

Store the sample for at least 25 days to allow the achievement of secular equilibrium. A standard

222
solution of Rn can also be used if available.

Shake vigorously the vial for some seconds. A vortex mixer could also be used for shaking. After phase

226

separation, a waiting time of at least 3 h shall be used before starting counting. Since Ra is not

extracted into the organic phase, its alpha emission would not affect detection efficiency calibration for

222
Rn.
7.2 Optimization of counting conditions

Both alpha + beta counting or alpha counting using alpha-beta discrimination can be used (see

manufacturer instructions).

When using alpha-beta discrimination, both alpha background and efficiency are usually lower; in

practice it is found that a much lower detection limit can be achieved.

Set the counting window so that the channels affected by photo and chemo-luminescence are excluded.

NOTE Since no water is present in the scintillation cocktail phase, the quenching is low and constant, thus no

quenching correction is needed.
7.3 Detection efficiency

Let the counting rate be r for the counts of the calibration source in the counting window (alpha + beta).

Determine the detection efficiency:
rr−
S 0
ε = (1)
am⋅
Acceptance limits for efficiency should be defined.

NOTE ε includes both counting and extraction efficiency. Usual values are in the range of 400 % to 500 %

222
...

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