Overview
EN ISO 80000-10:2019 - Quantities and units - Part 10: Atomic and nuclear physics (ISO 80000-10:2019) provides standardized names, symbols, definitions and units for quantities used in atomic and nuclear physics. The second edition (2019) supersedes the 2013 version and aligns many definitions with CODATA recommended values and ICRU guidance. Where appropriate, the standard also gives conversion factors and guidance on interpreting stochastic versus nonβstochastic quantities in radiation metrology.
Key topics
- Standardized quantity names and symbols: A consolidated Table 1 lists commonly used quantities such as atomic number (Z), neutron number (N), nucleon number (A), rest mass, rest energy, atomic/nuclidic mass, and unified atomic mass constant.
- Special units and definitions: Definitions include practical units and conventions (e.g., 1 eV defined as the energy gained by an electron across 1 V in vacuum).
- Atomic and spectroscopic constants: Items such as Bohr radius, Rydberg constant, and Hartree energy are defined with their unit context and remarks.
- Electromagnetic and magnetic quantities: Quantities like elementary charge, charge number, and magnetic dipole moment are covered with SI links and applicable remarks.
- Stochastic vs nonβstochastic quantities: The standard clarifies how to treat quantities that are expected values of stochastic processes (important in ionizing radiation measurements) and defines differential quotients like dA/dB in that context.
- Reference data practices: Numerical values of physical constants are referenced to CODATA; users are advised to consult CODATA for upβtoβdate values.
Applications
EN ISO 80000-10:2019 is practical for any activity that requires consistent expression of atomic and nuclear quantities:
- Metrology and calibration of instruments used in atomic, nuclear and radiation measurements.
- Nuclear engineering and reactor physics for reporting material compositions, masses and energies.
- Radiation protection and medical physics, where clear definitions of doseβrelated and stochastic quantities matter.
- Spectroscopy and atomic physics research, for consistent use of spectroscopic constants and units.
- Standards, documentation and education, ensuring uniform terminology across publications, reports and curricula.
Who should use this standard
- Physicists, metrologists and instrumentation engineers
- Medical physicists and radiological protection specialists
- Nuclear engineers and materials scientists
- Standardization committees, technical authors and educators
Related standards
- ISO 80000-series (general quantities and units) - ensures coherence across parts
- ISO 80000-1 (general SI units and conventions)
- IEC/ISO references for electrical quantities (IEC 80000-6) and CODATA (for fundamental constants)
Using EN ISO 80000-10:2019 helps ensure clear, interoperable reporting and calculation across atomic and nuclear science, improving reproducibility, regulatory compliance and international communication.
