Particle

Bases: AbstractPhysicalParticle

A class for an individual particle or antiparticle.

Parameters:

argument (particle-like) – A string representing a particle, element, isotope, or ion; an integer representing the atomic number of an element; or a Particle.
mass_numb (integer, keyword-only, optional) – The mass number of an isotope.
Z (integer, keyword-only, optional) – The charge number of an ion or neutral atom.

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 charge_number 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.

Notes

Valid particle categories include: "actinide", "alkali metal", "alkaline earth metal", "antibaryon", "antilepton", "antimatter", "antineutrino", "baryon", "boson", "charged", "custom", "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".

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.charge_number
-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. Please refer to is_category for more details, including a list of all valid particle categories.

Attributes Summary

`antiparticle`	The antiparticle corresponding to the particle.
`atomic_number`	The number of protons in an element, isotope, or ion.
`baryon_number`	The number of baryons in a particle.
`binding_energy`	The particle's nuclear binding energy.
`categories`	The particle's categories.
`charge`	The particle's electrical charge in coulombs.
`charge_number`	The particle's electrical charge in units of the elementary charge.
`electron_number`	The number of electrons in an ion.
`element`	The atomic symbol if the particle corresponds to an element, and `None` otherwise.
`element_name`	The name of the element corresponding to this particle.
`half_life`	The particle's half-life in seconds, or a `str` with half-life information.
`ionic_symbol`	The ionic symbol if the particle corresponds to an ion or neutral atom, and `None` otherwise.
`is_electron`	`True` if the particle is an electron, and `False` otherwise.
`is_ion`	`True` if the particle is an ion, and `False` otherwise.
`isotope`	The isotope symbol if the particle corresponds to an isotope, and `None` otherwise.
`isotope_name`	The name of the element along with the isotope symbol if the particle corresponds to an isotope, or `None` if it does not.
`isotopic_abundance`	The isotopic abundance of an isotope.
`json_dict`	A JSON friendly dictionary representation of the particle.
`lepton_number`	`1` for leptons, `-1` for antileptons, and `0` otherwise.
`mass`	The mass of the particle in kilograms.
`mass_energy`	The mass energy of the particle in joules.
`mass_number`	The total number of protons and neutrons in an isotope or nuclide.
`neutron_number`	The number of neutrons in an isotope or nucleon.
`nuclide_mass`	The mass of the bare nucleus of an isotope or a neutron.
`periodic_table`	A `namedtuple` that provides access to category, period, group, and block information about an element.
`roman_symbol`	The spectral name of the particle (i.e. the ionic symbol in Roman numeral notation).
`spin`	The intrinsic spin of the particle.
`standard_atomic_weight`	The element's standard atomic weight in kg.
`symbol`	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.
`json_dump`(fp, **kwargs)	Write the particle's `json_dict` to the `fp` file object using `json.dump`.
`json_dumps`(**kwargs)	Serialize the particle's `json_dict` into a JSON formatted `str` using `json.dumps`.
`recombine`([n, inplace])	Create a new `Particle` instance corresponding to the current `Particle` after undergoing recombination `n` times.

Attributes Documentation

antiparticle

The antiparticle corresponding to the particle.

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

Raises:: ParticleError – If the particle is not an elementary particle and does not have a defined antiparticle.

Examples

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

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

atomic_number

The number of protons in an element, isotope, or ion.

Raises:: InvalidElementError – If the particle does not correspond to an element.

Examples

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

baryon_number

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.

Raises:: MissingParticleDataError – If the baryon number is unavailable.

Examples

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

binding_energy

The particle’s nuclear binding energy.

Raises:: 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

The particle’s categories.

Examples

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

charge

The particle’s electrical charge in coulombs.

If the charge has not been specified, this attribute will return nan C.

Examples

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

charge_number

The particle’s electrical charge in units of the elementary charge.

Raises:: ChargeError – If the charge has not been specified.

Examples

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

electron_number

The number of electrons in an ion.

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

Raises:: InvalidIonError – If this particle is not an ion or electron.

Examples

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

element

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

Examples

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

element_name

The name of the element corresponding to this particle.

Raises:: InvalidElementError – If the particle does not correspond to an element.

Examples

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

half_life

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>

ionic_symbol

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

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

Examples

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

is_ion

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

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

Examples

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

isotope_name

The name of the element along with the isotope symbol if the particle corresponds to an isotope, or None if it does not.

Raises:

InvalidElementError – If the particle is not a valid element.
InvalidIsotopeError – If the particle is not a valid isotope.

Examples

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

isotopic_abundance

The isotopic abundance of an isotope.

Raises:

InvalidIsotopeError – If the particle does not correspond to an isotope.
MissingParticleDataError – If the isotopic abundance is not available.

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

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.

Raises:: MissingParticleDataError – If the lepton number is unavailable.

Examples

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

mass

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 charge number and the electron mass.

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

If the mass of the particles is unavailable, this attribute will return nan kg.

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

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 unavailable, this attribute will return nan kg.

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

The total number of protons and neutrons in an isotope or nuclide.

Raises:: InvalidIsotopeError – If the particle does not correspond to an isotope.

Examples

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

neutron_number

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

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

If the particle’s base mass is unavailable, this attribute will return nan kg.

Raises:: InvalidIsotopeError – If the particle is not an isotope or neutron.

Examples

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

periodic_table

A namedtuple that provides access to category, period, group, and block information about an element.

Raises:: InvalidElementError – If the particle is not an element, isotope, or ion.

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

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 charge number. 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

The intrinsic 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

The element’s standard atomic weight in kg.

If the element does not have a defined standard atomic weight, this attribute will return nan kg.

Raises:: InvalidElementError – If the particle is not an element or corresponds to an isotope or ion.

Examples

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

symbol

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: Integral = 1, inplace: bool = False)[source]

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.

New in version 0.8: If the Particle instance has no charge information (e.g., Particle("Li")), this method assumes it to be electrically neutral.

Parameters:

n (positive integer, default: 1) – The number of bound electrons to remove from the Particle object.
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.
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+")
>>> Particle("Li").ionize(3)
Particle("Li 3+")

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 of str, keyword-only, optional) – One or more particle categories. This method will return False if the particle does not belong to all of these categories.
any_of (str or iterable of str, keyword-only, optional) – One or more particle categories. This method will return False if the particle does not belong to at least one of these categories.
exclude (str or iterable of str, keyword-only, optional) – One or more particle categories. This method will return False if the particle belongs to any of these categories.