Particle

class plasmapy.particles.particle_class.Particle(argument: Union[str, numbers.Integral, plasmapy.particles.particle_class.Particle, plasmapy.particles.particle_class.CustomParticle], mass_numb: Optional[numbers.Integral] = None, Z: Optional[numbers.Integral] = None)

Bases: plasmapy.particles.particle_class.AbstractPhysicalParticle

A class for an individual particle or antiparticle.

Parameters

• argument (ParticleLike, excluding CustomParticle instances) – A string representing a particle, element, isotope, or ion; an integer representing the atomic number of an element; or a Particle instance.

• mass_numb (int, optional) – The mass number of an isotope or nuclide.

• Z (int, optional) – The integer charge of the particle.

Raises

• TypeError – For when any of the arguments or keywords is not of the required type.

• InvalidParticleError – Raised when the particle input does not correspond to a valid particle or is contradictory.

• InvalidElementError – For when an attribute is being accessed that requires information about an element, but the particle is not an element, isotope, or ion.

• InvalidIsotopeError – For when an attribute is being accessed that requires information about an isotope or nuclide, but the particle is not an isotope (or an ion of an isotope).

• ChargeError – For when either the charge or integer_charge attributes is being accessed but the charge information for the particle is not available.

• ParticleError – Raised for attempts at converting a Particle object to a bool.

See also

CustomParticle, DimensionlessParticle, ParticleList

Examples

Particles may be defined using a wide variety of aliases:

>>> proton = Particle('p+')
>>> electron = Particle('e-')
>>> neutron = Particle('neutron')
>>> deuteron = Particle('D', Z=1)
>>> triton = Particle('T+')
>>> alpha = Particle('He', mass_numb=4, Z=2)
>>> positron = Particle('positron')
>>> hydrogen = Particle(1)  # atomic number

The symbol attribute returns the particle’s symbol in the standard form.

>>> positron.symbol
'e+'

The element, isotope, and ionic_symbol attributes provide the symbols for each of these different types of particles.

>>> proton.element
'H'
>>> alpha.isotope
'He-4'
>>> deuteron.ionic_symbol
'D 1+'

The ionic_symbol attribute works for neutral atoms if charge information is available.

>>> deuterium = Particle("D", Z=0)
>>> deuterium.ionic_symbol
'D 0+'

If the particle doesn’t belong to one of those categories, then these attributes are None.

>>> positron.element is None
True

The attributes of a Particle instance may be used to test whether or not a particle is an element, isotope, or ion.

>>> True if positron.element else False
False
>>> True if deuterium.isotope else False
True
>>> True if Particle('alpha').is_ion else False
True

Many of the attributes provide physical properties of a particle.

>>> electron.integer_charge
-1
>>> proton.spin
0.5
>>> alpha.atomic_number
2
>>> deuteron.mass_number
2
>>> deuteron.binding_energy.to('MeV')
<Quantity 2.224... MeV>
>>> alpha.charge
<Quantity 3.20435...e-19 C>
>>> neutron.half_life
<Quantity 881.5 s>
>>> Particle('C-14').half_life.to(u.year)
<Quantity 5730. yr>
>>> deuteron.electron_number
0
>>> alpha.neutron_number
2

If a Particle instance represents an elementary particle, then the unary (invert) operator may be used to return the particle’s antiparticle.

>>> ~positron
Particle("e-")

A Particle instance may be used as the first argument to Particle.

>>> iron = Particle('Fe')
>>> iron == Particle(iron)
True
>>> Particle(iron, mass_numb=56, Z=6)
Particle("Fe-56 6+")

If the previously constructed Particle instance represents an element, then the Z and mass_numb arguments may be used to specify an ion or isotope.

>>> iron = Particle('Fe')
>>> Particle(iron, Z=1)
Particle("Fe 1+")
>>> Particle(iron, mass_numb=56)
Particle("Fe-56")

Adding particles together will create a ParticleList, which is a list-like collection of particles.

>>> proton + 2 * electron
ParticleList(['p+', 'e-', 'e-'])

The > operator can be used with Particle and/or ParticleList objects to return the nuclear reaction energy.

>>> deuteron + triton > alpha + neutron
<Quantity 2.81810898e-12 J>

The categories attribute and is_category method may be used to find and test particle membership in categories.

Valid particle categories include: 'actinide', 'alkali metal', 'alkaline earth metal', 'antibaryon', 'antilepton', 'antimatter', 'antineutrino', 'baryon', 'boson', 'charged', 'electron', 'element', 'fermion', 'halogen', 'ion', 'isotope', 'lanthanide', 'lepton', 'matter', 'metal', 'metalloid', 'neutrino', 'neutron', 'noble gas', 'nonmetal', 'positron', 'post-transition metal', 'proton', 'stable', 'transition metal', 'uncharged', and 'unstable'.

Instantiate a Particle object and set private attributes.

Attributes Summary

antiparticle	Return the corresponding antiparticle, or raise an ParticleError if the particle is not an elementary particle.
atomic_number	Return the number of protons in an element, isotope, or ion.
baryon_number	Return the number of baryons in a particle.
binding_energy	Return the nuclear binding energy in joules.
categories	Return the particle’s categories.
charge	Return the particle’s electron charge in coulombs.
electron_number	Return the number of electrons in an ion.
element	Return the atomic symbol if the particle corresponds to an element, and None otherwise.
element_name	Return the name of the element corresponding to this particle, or raise an InvalidElementError if the particle does not correspond to an element.
half_life	Return the particle’s half-life in seconds, or a str with half-life information.
integer_charge	Return the particle’s integer charge.
ionic_symbol	Return the ionic symbol if the particle corresponds to an ion or neutral atom, and None otherwise.
is_electron	Return True if the particle is an electron, and False otherwise.
is_ion	Return True if the particle is an ion, and False otherwise.
isotope	Return the isotope symbol if the particle corresponds to an isotope, and None otherwise.
isotope_name	Return the name of the element along with the isotope symbol if the particle corresponds to an isotope, and None otherwise.
isotopic_abundance	Return the isotopic abundance of an isotope.
json_dict	A json friendly dictionary representation of the particle.
lepton_number	Return 1 for leptons, -1 for antileptons, and 0 otherwise.
mass	Return the mass of the particle in kilograms.
mass_energy	Return the mass energy of the particle in joules.
mass_number	Return the number of nucleons in an isotope.
neutron_number	Return the number of neutrons in an isotope or nucleon.
nuclide_mass	Return the mass of the bare nucleus of an isotope or a neutron.
particle	Return the symbol of the particle, atom, isotope, or ion.
periodic_table	Return a namedtuple to access category, period, group, and block information about an element.
roman_symbol	Return the spectral name of the particle (i.e.
spin	Return the spin of the particle.
standard_atomic_weight	Return an element’s standard atomic weight in kg.
symbol	Return the symbol of the particle, atom, isotope, or ion.

Methods Summary

ionize([n, inplace])	Create a new Particle instance corresponding to the current Particle after being ionized n times.
is_category(*category_tuple[, require, …])	Determine if the particle meets categorization criteria.
recombine([n, inplace])	Create a new Particle instance corresponding to the current Particle after undergoing recombination n times.

Attributes Documentation

antiparticle

Return the corresponding antiparticle, or raise an ParticleError if the particle is not an elementary particle.

This attribute may be accessed by using the unary operator ~ acting on a Particle instance.

Examples

>>> electron = Particle('e-')
>>> electron.antiparticle
Particle("e+")

>>> antineutron = Particle('antineutron')
>>> ~antineutron
Particle("n")

atomic_number

Return the number of protons in an element, isotope, or ion.

If the particle is not an element, then this attribute will raise an InvalidElementError.

Examples

>>> proton = Particle('p+')
>>> proton.atomic_number
1
>>> curium = Particle('Cm')
>>> curium.atomic_number
96

baryon_number

Return the number of baryons in a particle.

This attribute will return the number of protons and neutrons minus the number of antiprotons and antineutrons. The baryon number is equivalent to the mass number for isotopes.

If the baryon number is unavailable, then this attribute will raise a MissingParticleDataError.

Examples

>>> alpha = Particle('alpha')
>>> alpha.baryon_number
4

binding_energy

Return the nuclear binding energy in joules.

This attribute will raise an InvalidIsotopeError if the particle is not a nucleon or isotope.

Examples

>>> alpha = Particle('alpha')
>>> alpha.binding_energy
<Quantity 4.53346...e-12 J>
>>> Particle('T').binding_energy.to('MeV')
<Quantity 8.481... MeV>

The binding energy of a nucleon equals 0 joules.

>>> neutron = Particle('n')
>>> proton = Particle('p+')
>>> neutron.binding_energy
<Quantity 0. J>
>>> proton.binding_energy
<Quantity 0. J>

categories

Return the particle’s categories.

Examples

>>> gold = Particle('Au')
>>> 'transition metal' in gold.categories
True
>>> 'antilepton' in gold.categories
False

charge

Return the particle’s electron charge in coulombs.

This attribute will raise a ChargeError if the charge has not been specified.

Examples

>>> electron = Particle('e-')
>>> electron.charge
<Quantity -1.60217662e-19 C>

electron_number

Return the number of electrons in an ion.

This attribute will return the number of bound electrons in an ion, or 1 for an electron.

If this particle is not an ion or electron, then this attribute will raise an InvalidIonError.

Examples

>>> Particle('Li 0+').electron_number
3
>>> Particle('e-').electron_number
1

element

Return the atomic symbol if the particle corresponds to an element, and None otherwise.

Examples

>>> alpha = Particle('alpha')
>>> alpha.element
'He'

element_name

Return the name of the element corresponding to this particle, or raise an InvalidElementError if the particle does not correspond to an element.

Examples

>>> tritium = Particle('T')
>>> tritium.element_name
'hydrogen'

half_life

Return the particle’s half-life in seconds, or a str with half-life information.

Particles that do not have sufficiently well-constrained half-lives will return a str containing the information that is available about the half-life and issue a MissingParticleDataWarning.

Examples

>>> neutron = Particle('n')
>>> neutron.half_life
<Quantity 881.5 s>

integer_charge

Return the particle’s integer charge.

This attribute will raise a ChargeError if the charge has not been specified.

Examples

>>> muon = Particle('mu-')
>>> muon.integer_charge
-1

ionic_symbol

Return the ionic symbol if the particle corresponds to an ion or neutral atom, and None otherwise.

Examples

>>> deuteron = Particle('deuteron')
>>> deuteron.ionic_symbol
'D 1+'
>>> hydrogen_atom = Particle('H', Z=0)
>>> hydrogen_atom.ionic_symbol
'H 0+'

is_electron

Return True if the particle is an electron, and False otherwise.

Examples

>>> Particle('e-').is_electron
True
>>> Particle('e+').is_electron
False

is_ion

Return True if the particle is an ion, and False otherwise.

Examples

>>> Particle('D+').is_ion
True
>>> Particle('H-1 0+').is_ion
False
>>> Particle('e+').is_ion
False

isotope

Return the isotope symbol if the particle corresponds to an isotope, and None otherwise.

Examples

>>> alpha = Particle('alpha')
>>> alpha.isotope
'He-4'

isotope_name

Return the name of the element along with the isotope symbol if the particle corresponds to an isotope, and None otherwise.

If the particle is not a valid element, then this attribute will raise an InvalidElementError. If it is not an isotope, then this attribute will raise an InvalidIsotopeError.

Examples

>>> deuterium = Particle("D")
>>> deuterium.isotope_name
'deuterium'
>>> iron_isotope = Particle("Fe-56", Z=16)
>>> iron_isotope.isotope_name
'iron-56'

isotopic_abundance

Return the isotopic abundance of an isotope.

If the isotopic abundance is not available, this attribute will raise a MissingParticleDataError. If the particle is not an isotope or is an ion of an isotope, then this attribute will raise an InvalidIsotopeError.

Examples

>>> D = Particle('deuterium')
>>> D.isotopic_abundance
0.000115

json_dict

A json friendly dictionary representation of the particle. (see AbstractParticle.json_dict for more details)

Examples

>>> lead = Particle('lead')
>>> lead.json_dict
{'plasmapy_particle': {'type': 'Particle',
    'module': 'plasmapy.particles.particle_class',
    'date_created': '...',
    '__init__': {'args': ('Pb',), 'kwargs': {}}}}
>>> electron = Particle('e-')
>>> electron.json_dict
{'plasmapy_particle': {'type': 'Particle',
    'module': 'plasmapy.particles.particle_class',
    'date_created': '...',
    '__init__': {'args': ('e-',), 'kwargs': {}}}}

lepton_number

Return 1 for leptons, -1 for antileptons, and 0 otherwise.

This attribute returns the number of leptons minus the number of antileptons, excluding bound electrons in an atom or ion.

If the lepton number is unavailable, then this attribute will raise a MissingParticleDataError.

Examples

>>> Particle('e-').lepton_number
1
>>> Particle('mu+').lepton_number
-1
>>> Particle('He-4 0+').lepton_number
0

mass

Return the mass of the particle in kilograms.

If the particle is an element and not an isotope or ion, then this attribute will return the standard atomic weight, if available.

If the particle is an isotope but not an ion, then this attribute will return the isotopic mass, including bound electrons.

If the particle is an ion, then this attribute will return the mass of the element or isotope (as just described) minus the product of the integer charge and the electron mass.

For special particles, this attribute will return the standard value for the particle’s mass.

If the mass is unavailable (e.g., for neutrinos or elements with no standard atomic weight), then this attribute will raise a MissingParticleDataError.

Examples

>>> Particle('He').mass
<Quantity 6.64647...e-27 kg>
>>> Particle('He+').mass
<Quantity 6.64556...e-27 kg>
>>> Particle('He-4 +1').mass
<Quantity 6.64556...e-27 kg>
>>> Particle('alpha').mass
<Quantity 6.64465...e-27 kg>

mass_energy

Return the mass energy of the particle in joules.

If the particle is an isotope or nuclide, return the mass energy of the nucleus only.

If the mass of the particle is not known, then raise a MissingParticleDataError.

Examples

>>> proton = Particle('p+')
>>> proton.mass_energy
<Quantity 1.503277...e-10 J>

>>> protium = Particle('H-1 0+')
>>> protium.mass_energy
<Quantity 1.503277...e-10 J>

>>> electron = Particle('electron')
>>> electron.mass_energy.to('MeV')
<Quantity 0.510998... MeV>

mass_number

Return the number of nucleons in an isotope.

This attribute will return the number of protons plus the number of neutrons in an isotope or nuclide.

If the particle is not an isotope, then this attribute will raise an InvalidIsotopeError.

Examples

>>> alpha = Particle('helium-4 2+')
>>> alpha.mass_number
4

neutron_number

Return the number of neutrons in an isotope or nucleon.

This attribute will return the number of neutrons in an isotope, or 1 for a neutron.

If this particle is not an isotope or neutron, then this attribute will raise an InvalidIsotopeError.

Examples

>>> alpha = Particle('He-4++')
>>> alpha.neutron_number
2
>>> Particle('n').neutron_number
1

nuclide_mass

Return the mass of the bare nucleus of an isotope or a neutron.

This attribute will raise a InvalidIsotopeError if the particle is not an isotope or neutron, or a MissingParticleDataError if the isotope mass is not available.

Examples

>>> deuterium = Particle('D')
>>> deuterium.nuclide_mass
<Quantity 3.34358372e-27 kg>

particle

Return the symbol of the particle, atom, isotope, or ion.

Deprecated since version 0.6.0: Particle.particle has been deprecated and will be removed in a subsequent release of PlasmaPy. Use Particle.symbol instead.

periodic_table

Return a namedtuple to access category, period, group, and block information about an element.

If the particle is not an element, isotope, or ion, then this attribute will raise an InvalidElementError.

Examples

>>> gold = Particle('Au')
>>> gold.periodic_table.category
'transition metal'
>>> gold.periodic_table.period
6
>>> gold.periodic_table.group
11
>>> gold.periodic_table.block
'd'

roman_symbol

Return the spectral name of the particle (i.e. the ionic symbol in Roman numeral notation). If the particle is not an ion or neutral atom, return None. The roman numeral represents one plus the integer charge. Raise ChargeError if no charge has been specified and OutOfRangeError if the charge is negative.

Examples

>>> proton = Particle('proton')
>>> proton.roman_symbol
'H-1 II'
>>> hydrogen_atom = Particle('H', Z=0)
>>> hydrogen_atom.roman_symbol
'H I'

spin

Return the spin of the particle.

If the spin is unavailable, then a MissingParticleDataError will be raised.

Examples

>>> positron = Particle('e+')
>>> positron.spin
0.5

standard_atomic_weight

Return an element’s standard atomic weight in kg.

If the particle is isotope or ion or not an element, this attribute will raise an InvalidElementError.

If the element does not have a defined standard atomic weight, this attribute will raise a MissingParticleDataError.

Examples

>>> oxygen = Particle('O')
>>> oxygen.standard_atomic_weight
<Quantity 2.656696...e-26 kg>

symbol

Return the symbol of the particle, atom, isotope, or ion.

This attribute will return the canonical symbol for special particles (e.g., "p+", "e-", or "n"), the atomic symbol for elements (e.g., "Fe"), the isotopic symbol for isotopes (e.g., "D" or "Fe-56"), and the ionic symbol for ions (e.g., "N 1+" or "He-4 1+").

Examples

>>> electron = Particle('positron')
>>> electron.symbol
'e+'
>>> deuteron = Particle('D 1+')
>>> deuteron.symbol
'D 1+'

Methods Documentation

ionize(n: numbers.Integral = 1, inplace: bool = False)

Create a new Particle instance corresponding to the current Particle after being ionized n times.

If inplace is False (default), then return the ionized Particle.

If inplace is True, then replace the current Particle with the newly ionized Particle.

Parameters

• n (positive integer) – The number of bound electrons to remove from the Particle object. Defaults to 1.

• inplace (bool, optional) – If True, then replace the current Particle instance with the newly ionized Particle.

Returns

particle – A new Particle object that has been ionized n times relative to the original Particle. If inplace is False, instead return None.

Return type

Particle

Raises

• InvalidElementError – If the Particle is not an element.

• ChargeError – If no charge information for the Particle object is specified.

• InvalidIonError – If there are less than n remaining bound electrons.

• ValueError – If n is not positive.

Examples

>>> Particle("Fe 6+").ionize()
Particle("Fe 7+")
>>> helium_particle = Particle("He-4 0+")
>>> helium_particle.ionize(n=2, inplace=True)
>>> helium_particle
Particle("He-4 2+")

is_category(*category_tuple, require: Optional[Union[str, Iterable[str]]] = None, any_of: Optional[Union[str, Iterable[str]]] = None, exclude: Optional[Union[str, Iterable[str]]] = None) → bool

Determine if the particle meets categorization criteria.

Return True if the particle is consistent with the provided categories, and False otherwise.

Parameters

• *category_tuple – Required categories in the form of one or more str objects or an iterable.

• require (str or iterable providing str objects, optional, keyword-only) – One or more categories. This method will return False if the Particle does not belong to all of these categories.

• any_of (str or iterable providing str objects, optional, keyword-only) – One or more categories. This method will return False if the Particle does not belong to at least one of these categories.

• exclude (str or iterable providing str objects, optional, keyword-only) – One or more categories. This method will return False if the Particle belongs to any of these categories.

Notes

A set containing all valid categories may be accessed by the valid_categories attribute of is_category.

Examples

Required categories may be entered as positional arguments, including as a list, set, or tuple of required categories.

>>> electron = Particle("e-")
>>> electron.is_category("lepton")
True
>>> electron.is_category("lepton", "baryon")
False
>>> electron.is_category(["fermion", "matter"])
True

Required arguments may also be provided using the require keyword argument.

>>> electron.is_category(require="lepton")
True
>>> electron.is_category(require=["lepton", "baryon"])
False

This method will return False if the particle does not belong to at least one of the categories provided with the any_of keyword argument.

>>> electron.is_category(any_of=["lepton", "baryon"])
True
>>> electron.is_category(any_of=("noble gas", "lanthanide", "halogen"))
False

This method will return False if the particle belongs to any of the categories provided in the exclude keyword argument.

>>> electron.is_category(exclude="baryon")
True
>>> electron.is_category(exclude={"lepton", "baryon"})
False

The require, any_of, and exclude keywords may be combined. If the particle matches all of the provided criteria, then is_category will return True.

>>> electron.is_category(
...     require="fermion", any_of={'lepton', 'baryon'}, exclude='charged',
... )
False

recombine(n: numbers.Integral = 1, inplace=False)

Create a new Particle instance corresponding to the current Particle after undergoing recombination n times.

If inplace is False (default), then return the Particle that just underwent recombination.

If inplace is True, then replace the current Particle with the Particle that just underwent recombination.

Parameters

• n (positive integer) – The number of electrons to recombine into the Particle object.

• inplace (bool, optional) – If True, then replace the current Particle instance with the Particle that just underwent recombination.

Returns

particle – A new Particle object that has undergone recombination n times relative to the original Particle. If inplace is False, instead return None.

Return type

Particle

Raises

• InvalidElementError – If the Particle is not an element.

• ChargeError – If no charge information for the Particle object is specified.

• ValueError – If n is not positive.

Examples

>>> Particle("Fe 6+").recombine()
Particle("Fe 5+")
>>> helium_particle = Particle("He-4 2+")
>>> helium_particle.recombine(n=2, inplace=True)
>>> helium_particle
Particle("He-4 0+")