Quantities and units - Part 10: Atomic and nuclear physics (ISO 80000-10:2019)

This document gives names, symbols, definitions and units for quantities used in atomic and nuclear physics. Where appropriate, conversion factors are also given.

Größen und Einheiten - Teil 10: Atom- und Kernphysik (ISO 80000-10:2019)

Dieses Dokument enthält Benennungen, Formelzeichen, Definitionen und Einheiten für Größen, die in der Atom- und Kernphysik verwendet werden. Wo benötigt, sind auch Umrechnungsfaktoren aufgeführt.

Grandeurs et unités - Partie 10: Physique atomique et nucléaire (ISO 80000-10:2019)

Le présent document donne les noms, les symboles, les définitions et les unités des grandeurs utilisées en physique atomique et nucléaire. Des facteurs de conversion sont également indiqués, s'il y a lieu.

Veličine in enote - 10. del: Atomska in jedrska fizika (ISO 80000-10:2019)

Ta dokument podaja imena, simbole, definicije in enote za veličine, ki se uporabljajo v atomski in jedrski fiziki. Kadar je primerno, so navedeni tudi pretvorniki (pretvorni dejavniki).

General Information

Status
Published
Publication Date
08-Oct-2019
Technical Committee
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
09-Oct-2019
Completion Date
09-Oct-2019

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SLOVENSKI STANDARD
SIST EN ISO 80000-10:2019
01-december-2019
Nadomešča:
SIST EN ISO 80000-10:2013
Veličine in enote - 10. del: Atomska in jedrska fizika (ISO 80000-10:2019)
Quantities and units - Part 10: Atomic and nuclear physics (ISO 80000-10:2019)
Größen und Einheiten - Teil 10: Atom- und Kernphysik (ISO 80000-10:2019)

Grandeurs et unités - Partie 10: Physique atomique et nucléaire (ISO 80000-10:2019)

Ta slovenski standard je istoveten z: EN ISO 80000-10:2019
ICS:
01.060 Veličine in enote Quantities and units
07.030 Fizika. Kemija Physics. Chemistry
SIST EN ISO 80000-10:2019 en,fr,de

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

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SIST EN ISO 80000-10:2019
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SIST EN ISO 80000-10:2019
EN ISO 80000-10
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 01.060 Supersedes EN ISO 80000-10:2013
English Version
Quantities and units - Part 10: Atomic and nuclear physics
(ISO 80000-10:2019)

Grandeurs et unités - Partie 10: Physique atomique et Größen und Einheiten - Teil 10: Atom- und Kernphysik

nucléaire (ISO 80000-10:2019) (ISO 80000-10:2019)
This European Standard was approved by CEN on 5 May 2019.

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

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 80000-10:2019 E

worldwide for CEN national Members.
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SIST EN ISO 80000-10:2019
EN ISO 80000-10:2019 (E)
Contents Page

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

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SIST EN ISO 80000-10:2019
EN ISO 80000-10:2019 (E)
European foreword

This document (EN ISO 80000-10:2019) has been prepared by Technical Committee ISO/TC 12

"Quantities and units" in collaboration with Technical Committee CEN/SS F02 “Units and symbols” the

secretariat of which is held by CCMC.

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 April 2020, and conflicting national standards shall be

withdrawn at the latest by April 2020.

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 80000-10:2013.

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 80000-10:2019 has been approved by CEN as EN ISO 80000-10:2019 without any

modification.
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SIST EN ISO 80000-10:2019
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SIST EN ISO 80000-10:2019
INTERNATIONAL ISO
STANDARD 80000-10
Second edition
2019-08
Quantities and units —
Part 10:
Atomic and nuclear physics
Grandeurs et unités —
Partie 10: Physique atomique et nucléaire
Reference number
ISO 80000-10:2019(E)
ISO 2019
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SIST EN ISO 80000-10:2019
ISO 80000-10:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
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SIST EN ISO 80000-10:2019
ISO 80000-10:2019(E)
Contents Page

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

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

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

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

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

Bibliography .............................................................................................................................................................................................................................41

Alphabetical index .............................................................................................................................................................................................................42

© ISO 2019 – All rights reserved iii
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SIST EN ISO 80000-10:2019
ISO 80000-10:2019(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.o rg/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 12, Quantities and units, in collaboration

with Technical Committee IEC/TC 25, Quantities and units.

This second edition cancels and replaces the first edition (ISO 80000-10:2009), which has been

technically revised.
The main changes compared to the previous edition are as follows:
— the table giving the quantities and units has been simplified;
— some definitions and the remarks have been stated physically more precisely;

— definitions in this document have been brought in line with their equivalent ones in ICRU 85a.

A list of all parts in the ISO 80000 and IEC 80000 series can be found on the ISO and IEC websites.

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 2019 – All rights reserved
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SIST EN ISO 80000-10:2019
ISO 80000-10:2019(E)
Introduction
0 Special remarks
0.1 Quantities

Numerical values of physical constants in this document are quoted in the consistent values of the

fundamental physical constants published in CODATA recommended values. The indicated values are

the last known before publication. The user is advised to refer to the CODATA website for the latest

values, https: //physics .nist .gov/cuu/Constants/index .html.

The symbol  is the reduced Planck constant, it is equal to , where h is the Planck constant.

0.2 Special units

1 eV is the energy acquired by an electron in passing a potential difference of 1 V in vacuum.

0.3 Stochastic and non-stochastic quantities

Differences between results from repeated observations are common in physics. These can arise

from imperfect measurement systems, or from the fact that many physical phenomena are subject to

inherent fluctuations. Quantum-mechanical issues aside, one often needs to distinguish between a

stochastic quantity, the values of which follow a probability distribution, and a non-stochastic quantity

with its unique, expected value (expectation) of such distributions. In many instances the distinction

is not significant because the probability distribution is very narrow. For example, the measurement

of an electric current commonly involves so many electrons that fluctuations contribute negligibly to

inaccuracy in the measurement. However, as the limit of zero electric current is approached, fluctuations

can become manifest. This case, of course, requires a more careful measurement procedure, but perhaps

more importantly illustrates that the significance of stochastic variations of a quantity can depend on

the magnitude of the quantity. Similar considerations apply to ionizing radiation; fluctuations can play

a significant role, and in some cases need to be considered explicitly. Stochastic quantities, such as

the energy imparted and the specific energy imparted (item 10-81.2) but also the number of particle

traversals across microscopic target regions and their probability distributions, have been introduced

as they describe the discontinuous nature of the ionizing radiations as a determinant of radiochemical

and radiobiological effects. In radiation applications involving large numbers of ionizing particles, e.g. in

medicine, radiation protection and materials testing and processing, these fluctuations are adequately

represented by the expected values of the probability distributions. “Non-stochastic quantities” such

as particle fluence (item 10-43), absorbed dose (item 10-81.1) and kerma (item 10-86.1) are based on

these expected values.

This document contains definitions based on a differential quotient of the type dA/dB in which the

quantity A is of a stochastic nature, a situation common in ionizing radiation metrology. In these cases,

quantity A is understood as the expected or mean value whose element ΔA falls into element ΔB. The

differential quotient dA/dB is the limit value of the difference quotient ΔA/ΔB for ΔB → 0. In the remarks

of the definitions falling in this category, a reference to this paragraph is made.

© ISO 2019 – All rights reserved v
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SIST EN ISO 80000-10:2019
INTERNATIONAL STANDARD ISO 80000-10:2019(E)
Quantities and units —
Part 10:
Atomic and nuclear physics
1 Scope

This document gives names, symbols, definitions and units for quantities used in atomic and nuclear

physics. Where appropriate, conversion factors are also given.
2 Normative references
There are no normative references in this document.
3 Terms and definitions

The names, symbols, and definitions for quantities and units used in atomic and nuclear physics are

given in Table 1.

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

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
© ISO 2019 – All rights reserved 1
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2 © ISO 2019 – All rights reserved
Table 1 — Quantities and units used in atomic and nuclear physics
Item No. Quantity Unit Remarks
Name Symbol Definition

10-1.1 atomic number, Z number of protons in an atomic nucleus 1 A nuclide is a species of atom with speci-

fied numbers of protons and neutrons.
proton number
Nuclides with the same value of Z but
different values of N are called isotopes
of an element.
The ordinal number of an element in
the periodic table is equal to the atom-
ic number.
The atomic number equals the quo-
tient of the charge (IEC 80000-6) of
the nucleus and the elementary charge
(ISO 80000-1).

10-1.2 neutron number N number of neutrons in an atomic nucleus 1 Nuclides with the same value of N but

different values of Z are called isotones.
N – Z is called the neutron excess number.
10-1.3 nucleon number, A number of nucleons in an atomic nucleus 1 A = Z + N
mass number Nuclides with the same value of A are
called isobars.

10-2 rest mass, m(X) for particle X, mass (ISO 80000-4) of that particle at rest in kg EXAMPLE

an inertial frame
proper mass m u m(H O) for a water molecule, m for an
X 2 e
electron.
Rest mass is often denoted m .
1 u is equal to 1/12 times the mass of a
free carbon 12 atom, at rest and in its
ground state.
1 Da = 1 u
10-3 rest energy E energy E (ISO 80000-5) of a particle at rest: J
0 0
N m
Em= c
00 0
2 −2
kg m s
where
m is the rest mass (item 10-2) of that particle, and
c is speed of light in vacuum (ISO 80000-1)
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Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition

10-4.1 atomic mass m(X) rest mass (item 10-2) of an atom X in the ground state kg

m(X)
is called the relative atomic mass.
m u
1 u is equal to 1/12 times the mass of a
free carbon 12 atom, at rest and in its
ground state.
1 Da = 1 u

10-4.2 nuclidic mass m(X) rest mass (item 10-2) of a nuclide X in the ground state kg 1 u is equal to 1/12 times the mass of a

free carbon 12 atom, at rest and in its
m u
ground state.
1 Da = 1 u

10-4.3 unified atomic mass m 1/12 of the mass (ISO 80000-4) of an atom of the nuclide kg 1 u is equal to 1/12 times the mass of a

constant C in the ground state at rest free carbon 12 atom, at rest and in its
ground state.
1 Da = 1 u
10-5.1 elementary charge e one of the fundamental constants in the SI system C
(ISO 80000-1), equal to the charge of the proton and oppo-
s A
site to the charge of the electron

10-5.2 charge number, c for a particle, quotient of the electric charge (IEC 80000-6) 1 A particle is said to be electrically neu-

and the elementary charge (ISO 80000-1) tral if its charge number is equal to zero.

ionization number
The charge number of a particle can be
positive, negative, or zero.
The state of charge of a particle may be
presented as a superscript to the symbol
of that particle, e.g.
+ ++ 3+ - -- 3-
H , He , Al , Cl , S , N .
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4 © ISO 2019 – All rights reserved
Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition

10-6 Bohr radius a radius (ISO 80000-3) of the electron orbital in the hydro- m The radius of the electron orbital in the

gen atom in its ground state in the Bohr model of the atom: H atom in its ground state is a in the

Bohr model of the atom.
4πε 
−10
ångström (Å), 1 Å: = 10 m
a =
where
ε is the electric constant (IEC 80000-6),
 is the reduced Planck constant (ISO 80000-1),
m is the rest mass (item 10-2) of electron, and
e is the elementary charge (ISO 80000-1)

10-7 Rydberg constant R spectroscopic constant that determines the wave numbers m The quantity R = R hc is called the

∞ y ∞ 0
of the lines in the spectrum of hydrogen: Rydberg energy.
R =
8πε ahc
00 0
where
e is the elementary charge (ISO 80000-1),
ε is the electric constant (IEC 80000-6),
a is the Bohr radius (item 10-6),
h is the Planck constant (ISO 80000-1), and
c is the speed of light in vacuum (ISO 80000-1)
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Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition

10-8 Hartree energy E energy (ISO 80000-5) of the electron in a hydrogen atom eV The energy of the electron in an H atom

in its ground state: J in its ground state is E .
h 2 −2
kg m s
E =
4πε a
where
e is the elementary charge (ISO 80000-1),
ε is the electric constant (IEC 80000-6), and
a is the Bohr radius (item 10-6)

10-9.1 magnetic dipole μ for a particle, vector (ISO 80000-2) quantity causing a m A For an atom or nucleus, this energy is

moment change to its energy (ISO 80000-5) ΔW in an external mag- quantized and can be written as:

netic field of field flux density B (IEC 80000-6):
W = g μ M B
ΔW = −μ · B
where
g is the appropriate g factor (item 10-
14.1 or item 10-14.2), μ is mostly the
Bohr magneton or nuclear magneton
(item 10-9.2 or item 10-9.3), M is mag-
netic quantum number (item 10-13.4),
and B is magnitude of the magnetic flux
density.
See also IEC 80000-6.
10-9.2 Bohr magneton μ magnitude of the magnetic moment of an electron in a m A
state with orbital angular momentum quantum number
l=1 (item 10-13.3) due to its orbital motion:
μ =
where
e is the elementary charge (ISO 80000-1),
 is the reduced Planck constant (ISO 80000-1), and
m is the rest mass (item 10-2) of electron
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6 © ISO 2019 – All rights reserved
Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition

10-9.3 nuclear magneton μ absolute value of the magnetic moment of a nucleus: m A Subscript N stands for nucleus. For the

neutron magnetic moment, subscript
n is used. The magnetic moments of
μ =
protons and neutrons differ from this
quantity by their specific g factors (item
where
10-14.2).
e is the elementary charge (ISO 80000-1),
 is the reduced Planck constant (ISO 80000-1), and
m is the rest mass (item 10-2) of proton
2 −1

10-10 spin s vector (ISO 80000-2) quantity expressing the internal kg m s Spin is an additive vector quantity.

angular momentum (ISO 80000-4) of a particle or a par-
ticle system

10-11 total angular J vector (ISO 80000-2) quantity in a quantum system J s In atomic and nuclear physics, orbital

momentum composed of the vectorial sum of angular momentum L eV s angular momentum is usually denoted

(ISO 80000-4) and spin s (item 10-10) by l or L.
2 −1
kg m s
The magnitude of J is quantized so that:
J =+ jj()1
where j is the total angular momentum
quantum number (item 10-13.6).
Total angular momentum and magnetic
dipole moment have the same direction.
j is not the magnitude of the total
angular momentum J but its projection
onto the quantization axis, divided by  .
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Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition
2 −1 −1 2 −1 −1

10-12.1 gyromagnetic ratio, γ proportionality constant between the magnetic dipole A m J s 1 A·m /(J·s) = 1 A·s/kg = 1 T ·s

moment and the angular momentum:
magnetogyric ratio, A s/kg The systematic name is “gyromagnetic
μ = γ J coefficient”, but “gyromagnetic ratio” is
gyromagnetic coef- kg s A
more usual.
ficient where
The gyromagnetic ratio of the proton is
μ is the magnetic dipole moment (item 10-9.1), and
denoted by γ .
J is the total angular momentum (item 10-11)
The gyromagnetic ratio of the neutron is
denoted by γ .
2 −1 −1 2 −1 −1

10-12.2 gyromagnetic ratio γ proportionality constant between the magnetic dipole A m J s 1 A·m /(J·s) = 1 A·s/kg = 1 T ·s

of the electron, moment and the angular momentum of the electron
A s/kg
magnetogyric ratio μ = γ J
e −1
kg s A
of the electron,
where
gyromagnetic coeffi-
μ is the magnetic dipole moment (item 10-9.1), and
cient of the electron
J is the total angular momentum (item 10-11)
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8 © ISO 2019 – All rights reserved
Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition

10-13.1 quantum number N number describing a particular state of a quantum system 1 Electron states determine the binding

L energy E = E(n,l,m,j,s,f ) in an atom.
Upper case letters N, L, M, J, S, F are usu-
ally used for the whole system.
The spatial probability distribution of an
electron is given by │Ψ│ , where Ψ is its
wave function. For an electron in an H
atom in a non-relativistic approximation,
the wave function can be presented as:
ψ (rR,,ϑφ)(=⋅rY)(ϑφ,)
nl l
where
r ,,ϑφ are spherical coordinates
(ISO 80000-2) with respect to the
nucleus and to a given (quantization)
axis, Rr() is the radial distribution
function, and Y (,ϑφ) are spherical
harmonics.
In the Bohr model of one-electron atoms,
n, l, and m define the possible orbits of
an electron about the nucleus.

10-13.2 principal quantum n atomic quantum number related to the number n−1 of 1 In the Bohr model, n = 1,2,…,∞ is related

number radial nodes of one-electron wave functions to the binding energy of an electron and

the radius of spherical orbits (principal
axis of the elliptic orbits).
For an electron in an H atom, the
semi-classical radius of its orbit is
r = a n and its binding energy is
n 0
E = E /n .
n H
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© ISO 2019 – All rights reserved 9
Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition
10-13.3 orbital angular l atomic quantum number related to the orbital angular 1
momentum quantum momentum l of a one-electron state l =− ll()1 , ln=−01,,, 1
number
where
l is the orbital angular momentum and
 is the reduced Planck constant
(ISO 80000-1).
If reference is made to a specific particle
i, the symbol l is used instead of l;
if reference is made to the whole system,
the symbol L is used instead of l.
An electron in an H atom for l = 0 appears
as a spherical cloud. In the Bohr model, it
is related to the form of the orbit.

10-13.4 magnetic quantum m atomic quantum number related to the z component l , j or 1

z z
lm=  , jm=  , and sm=  , with the
zl zj zs
number s , of the orbital, total, or spin angular momentum
ranges from −l to l, from −j to j, and ±1/2,
respectively.
m refers to a specific particle i. M is used
for the whole system.
Subscripts l, s, j, etc., as appropriate, in-
dicate the angular momentum involved.
 is the reduced Planck constant
(ISO 80000-1).

10-13.5 spin quantum s characteristic quantum number s of a particle, related to 1 Spin quantum numbers of fermions are

number its spin (item 10-10), s: odd multiples of 1/2, and those of bos-
ons are integers.
s =+ ss()1
where  is the reduced Planck constant (ISO 80000-1)
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10 © ISO 2019 – All rights reserved
Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition

10-13.6 total angular j quantum number in an atom describing the magnitude of 1 j refers to a specific particle i; J is used

momentum quantum total angular momentum J (item 10-11) for the whole system.
number
The quantum number J and the magni-
tude of total angular momentum J (item
10-11) are different quantities.
The two values of j are l±1/2. (See item
10-13.3.)

10-13.7 nuclear spin I quantum number related to the total angular momentum 1 Nuclear spin is composed of spins of the

quantum number (item 10-11), J, of a nucleus in any specified state, normally nucleons (protons and neutrons) and

called nuclear spin: their (orbital) motions.
In principle there is no upper limit for
J =+ II()1
the nuclear spin quantum number. It has
possible values I = 0,1,2,… for even A and
where  is the reduced Planck constant (ISO 80000-1)
1 3
I= ,, for odd A.
2 2
In nuclear and particle physics, J is
often used.

10-13.8 hyperfine structure F quantum number of an atom describing the inclination of 1 The interval of F is │I−J│, │I−J│+1, ..., I−J.

quantum number the nuclear spin with respect to a quantization axis given
This is related to the hyperfine splitting
by the magnetic field produced by the orbital electrons
of the atomic energy levels due to the
interaction between the electron and
nuclear magnetic moments.

10-14.1 Landé factor, g quotient of the magnetic dipole moment of an atom, and 1 These quantities are also called g values.

the product of the total angular momentum quantum num-
g factor of atom The Landé factor can be calculated from
ber and the Bohr magneton:
the expression:
g= gL(),,SJ =+11()g −
J⋅μ
JJ+11++SS −+LL 1
() () ()
where ×
21JJ()+
μ is magnitude of magnetic dipole moment (item 10-9.1),
where g is the g factor of the electron.
J is total angular momentum quantum number (item
10-13.6), and
μ is the Bohr magneton (item 10-9.2)
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ISO 80000-10:2019(E)
© ISO 2019 – All rights reserved 11
Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition

10-14.2 g factor of nucleus or g quotient of the magnetic dipole moment of an atom, and 1 The g factors for nuclei or nucleons are

nuclear particle the product of the nuclear spin quantum number and the known from measurements.

nuclear magneton:
I⋅μ
where
μ is magnitude of magnetic dipole moment (item 10-9.1),
I is nuclear spin quantum number (item 10-13.7), and
μ is the nuclear magneton (item 10-9.3)

10-15.1 Larmor angular ω angular frequency (ISO 80000-3) of the electron angular rad s

frequency momentum (ISO 80000-4) vector precession about the
axis of an external magnetic field:
ω = B
where
e is the elementary charge (ISO 80000-1),
m is the rest mass (item 10-2) of electron, and
B is magnetic flux density (IEC 80000-6)

10-15.2 Larmor frequency ν quotient of Larmor angular frequency (ISO 80000-3) and 2π s

10-15.3 nuclear precession ω frequency (ISO 80000-3) by which the nucleus angular rad s

angular frequency momentum vector (ISO 80000-4) precesses about the axis
of an external magnetic field:
ω = γ B
where
γ is the gyromagnetic ratio (item 10-12.1), and
B is magnetic flux density (IEC 80000-6)
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SIST EN ISO 80000-10:2019
ISO 80000-10:2019(E)
12 © ISO 2019 – All rights reserved
Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition
10-16 cyclotron angular ω quotient o
...

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