Nuclear Reaction Channels – pyne.xs.channels¶
This module provides an easy interface to very quickly grab multigroup cross sections from the cross section cache and collapse them to the appropriate group structure. Additionally, it provides interfaces for some higher level functionality, such as computing cross sections for materials, fission energy spectra, metastable ratios, etc.
-
pyne.xs.channels.sigma_f(nuc, temp=300.0, group_struct=None, phi_g=None, xs_cache=None)[source]¶ Calculates the neutron fission cross section for a nuclide.
- Parameters
- nucint, str, Material, or dict-like
A nuclide or nuclide-atom fraction mapping.
- tempfloat, optional
Temperature [K] of material, defaults to 300.0.
- group_structarray-like of floats, optional
Energy group structure E_g [MeV] from highest-to-lowest energy, length G+1, defaults to xs_cache[‘E_g’].
- phi_garray-like of floats, optional
Group fluxes [n/cm^2/s] matching group_struct, length G, defaults to xs_cache[‘phi_g’].
- xs_cacheXSCache, optional
Cross section cache to use, defaults to pyne.xs.cache.xs_cache.
- Returns
- sigma_f_gndarray
The fission cross-section, length G.
Notes
This always pulls the fission cross section out of the cache.
-
pyne.xs.channels.sigma_s_gh(nuc, temp=300.0, group_struct=None, phi_g=None, xs_cache=None)[source]¶ Calculates the neutron scattering kernel for a nuclide.
- Parameters
- nucint, str, Material, or dict-like
A nuclide or nuclide-atom fraction mapping.
- tempfloat, optional
Temperature [K] of material, defaults to 300.0.
- group_structarray-like of floats, optional
Energy group structure E_g [MeV] from highest-to-lowest energy, length G+1, defaults to xs_cache[‘E_g’].
- phi_garray-like of floats, optional
Group fluxes [n/cm^2/s] matching group_struct, length G, defaults to xs_cache[‘phi_g’].
- xs_cacheXSCache, optional
Cross section cache to use, defaults to pyne.xs.cache.xs_cache.
- Returns
- sig_s_ghndarray
The scattering kernel, shape GxG.
Warning
This function is currently a stub until the proper way to compute the scattering kernel is determined. This function is safe to use but the results are trivial. This function simply returns an array with the diagonal elements set to sigma_s as computed by pyne.xs.models.sigma_s(). This conserves the calculation of sigma_s_g by summing sigma_s_gh over the h-index.
Notes
This pulls the scattering length out of nuc_data library.
-
pyne.xs.channels.sigma_s(nuc, temp=300.0, group_struct=None, phi_g=None, xs_cache=None)[source]¶ Calculates the neutron scattering cross section for a nuclide.
\[\sigma_{s, g} = \sum_{h} \sigma_{s, g\to h} \]- Parameters
- nucint, str, Material, or dict-like
A nuclide or nuclide-atom fraction mapping.
- tempfloat, optional
Temperature [K] of material, defaults to 300.0.
- group_structarray-like of floats, optional
Energy group structure E_g [MeV] from highest-to-lowest energy, length G+1, defaults to xs_cache[‘E_g’].
- phi_garray-like of floats, optional
Group fluxes [n/cm^2/s] matching group_struct, length G, defaults to xs_cache[‘phi_g’].
- xs_cacheXSCache, optional
Cross section cache to use, defaults to pyne.xs.cache.xs_cache.
- Returns
- sig_s_gndarray
The scattering cross section, length G.
-
pyne.xs.channels.sigma_a_reaction(nuc, rx, temp=300.0, group_struct=None, phi_g=None, xs_cache=None)[source]¶ Calculates the neutron absorption reaction cross section for a nuclide.
- Parameters
- nucint, str, Material, or dict-like
A nuclide or nuclide-atom fraction mapping.
- rxstr
Reaction key. (‘gamma’, ‘alpha’, ‘p’, etc.)
- tempfloat, optional
Temperature [K] of material, defaults to 300.0.
- group_structarray-like of floats, optional
Energy group structure E_g [MeV] from highest-to-lowest energy, length G+1, defaults to xs_cache[‘E_g’].
- phi_garray-like of floats, optional
Group fluxes [n/cm^2/s] matching group_struct, length G, defaults to xs_cache[‘phi_g’].
- xs_cacheXSCache, optional
Cross section cache to use, defaults to pyne.xs.cache.xs_cache.
- Returns
- sigma_rx_gndarray
The collapsed absorption reaction cross section, length G.
See also
pyne.xs.data_source.RX_TYPESpyne.xs.data_source.RX_TYPES_MAP
Notes
This always pulls the absorption reaction cross-section out of the nuc_data.
-
pyne.xs.channels.metastable_ratio(nuc, rx, temp=300.0, group_struct=None, phi_g=None, xs_cache=None)[source]¶ Calculates the ratio between a reaction that leaves the nuclide in a metastable state and the equivalent reaction that leaves the nuclide in the ground state. This allows the calculation of metastable cross sections via sigma_ms = ratio * sigma_ground.
- Parameters
- nucint, str, Material, or dict-like
A nuclide or nuclide-atom fraction mapping.
- rxstr
Reaction key. (‘gamma’, ‘alpha’, ‘p’, etc.)
- tempfloat, optional
Temperature [K] of material, defaults to 300.0.
- group_structarray-like of floats, optional
Energy group structure E_g [MeV] from highest-to-lowest energy, length G+1, defaults to xs_cache[‘E_g’].
- phi_garray-like of floats, optional
Group fluxes [n/cm^2/s] matching group_struct, length G, defaults to xs_cache[‘phi_g’].
- xs_cacheXSCache, optional
Cross section cache to use, defaults to pyne.xs.cache.xs_cache.
- Returns
- ratio_rx_gndarray
An array of the ratio of the metastable cross section for a reaction to the ground state reaction.
See also
pyne.xs.data_source.RX_TYPESpyne.xs.data_source.RX_TYPES_MAP
Notes
This always pulls the absorption reaction cross section out of the cache.
-
pyne.xs.channels.sigma_a(nuc, temp=300.0, group_struct=None, phi_g=None, xs_cache=None)[source]¶ Calculates the neutron absorption cross section for a nuclide.
- Parameters
- nucint, str, Material, or dict-like
A nuclide or nuclide-atom fraction mapping.
- tempfloat, optional
Temperature [K] of material, defaults to 300.0.
- group_structarray-like of floats, optional
Energy group structure E_g [MeV] from highest-to-lowest energy, length G+1, defaults to xs_cache[‘E_g’].
- phi_garray-like of floats, optional
Group fluxes [n/cm^2/s] matching group_struct, length G, defaults to xs_cache[‘phi_g’].
- xs_cacheXSCache, optional
Cross section cache to use, defaults to pyne.xs.cache.xs_cache.
- Returns
- sigma_a_gndarray
The collapsed absorption cross section, length G.
Notes
This always pulls the absorption cross section out of the cache.
-
pyne.xs.channels.chi(nuc, temp=300.0, group_struct=None, phi_g=None, xs_cache=None, eres=101)[source]¶ Calculates the neutron fission energy spectrum for a nuclide.
- Parameters
- nucint, str, Material, or dict-like
A nuclide or nuclide-atom fraction mapping.
- tempfloat, optional
Temperature [K] of material, defaults to 300.0.
- group_structarray-like of floats, optional
Energy group structure E_g [MeV] from highest-to-lowest energy, length G+1, defaults to xs_cache[‘E_g’].
- phi_garray-like of floats, optional
Group fluxes [n/cm^2/s] matching group_struct, length G, defaults to xs_cache[‘phi_g’].
- xs_cacheXSCache, optional
Cross section cache to use, defaults to pyne.xs.cache.xs_cache.
- eresint, optional
Number of energy-points to integrate over per group.
- Returns
- chi_gndarray
The fission energy spectrum, length G.
See also
pyne.xs.models.chiused under the covers by this function.
-
pyne.xs.channels.sigma_t(nuc, temp=300.0, group_struct=None, phi_g=None, xs_cache=None)[source]¶ Calculates the total neutron cross section for a nuclide.
\[\sigma_{t, g} = \sigma_{a, g} + \sigma_{s, g}\]- Parameters
- nucint, str, Material, or dict-like
A nuclide or nuclide-atom fraction mapping.
- tempfloat, optional
Temperature [K] of material, defaults to 300.0.
- group_structarray-like of floats, optional
Energy group structure E_g [MeV] from highest-to-lowest energy, length G+1, defaults to xs_cache[‘E_g’].
- phi_garray-like of floats, optional
Group fluxes [n/cm^2/s] matching group_struct, length G, defaults to xs_cache[‘phi_g’].
- xs_cacheXSCache, optional
Cross section cache to use, defaults to pyne.xs.cache.xs_cache.
- Returns
- sig_t_gndarray
The total cross section, length G.
