EXT_SpeciesType.md

Convention for Specifying Particle Species

openPMD extension name: SpeciesType

Introduction

This convention is for standardizing the names of particle species, e.g. in particle physics.

Additional Record Attribute

The following additional attribute for openPMD mesh records and particle groups is defined in this extension:

• speciesType
  • type: (string)
  • scope: optional
  • description: particle species in this record. If there are multiple species to be specified, they can be specified using a semicolon separated list.
  • allowed values:
    • see the lists below and additionally
    • other if none of the ones below applies, user are free to append a free text after a colon, e.g. other:neutralino or other:cherry
  • examples:
    • electron (e.g. on an electron particle record or an electron density mesh record)
    • electron;proton;#12C (e.g. on a mesh record for a plasma's local charge density)
    • other:apple;other:orange (for a record mixing apples & oranges)

This attribute can be used with any record (including mesh records).

Elementary Particles

Namings for fundamental fermions and their anti-matter particles.

Quarks:

• up, anti-up
• down, anti-down
• charm, anti-charm
• strange, anti-strange
• top, anti-top
• bottom, anti-bottom

Leptons:

• electron, positron
• electron-neutrino, anti-electron-neutrino
• muon, anti-muon
• muon-neutrino, anti-muon-neutrino
• tau, anti-tau
• tau-neutrino, anti-tau-neutrino

Gauge & Higgs Bosons:

• photon
• gluon
• w-boson
• z-boson
• higgs

Hadrons and Jets

We currently do not define spellings of hadrons besides the commonly used ones below and suggest for this version to use other: with namings from the particle data group (PDG). Other means of grouping e.g. jets can be used, e.g. additional attributes outside of the definition of this extension.

Examples:

• proton, anti-proton
• neutron, anti-neutron
• other:sigma, other:anti-sigma
• other:kaon, ...

Atoms & Isotopes

Element namings follow the abbreviated namings of the periodic table, defined by The International Union of Pure and Applied Chemistry (IUPAC). An example would be Si for silicon.

Specifications of isotopes are denoted by a pound symbol # followed by the isotopic number followed by the chemical symbol, e.g.: #3He for Helium-3.

The charge state is not encoded by the speciesType attribute. Any extension using this standard can define how to specify the charge state.

Molecules

Use standard chemical notation, e.g.: H20.

The isotope prefix can be used with molecules as well. Examples for heavy water: #2H2O for two deuterium and #2HHO for one deuterium.