Reaction

class curie.Reaction(reaction_name, library='best')[source]

Cross section data for nuclear reactions

Contains reaction cross sections as a function of incident energy, and some useful methods for manipulating cross section data, such as flux-averages, integrated cross-sections, and interpolation. All cross sections (and uncertainties) are in mb, and all energies are in MeV.

Parameters:

reaction_namestr: Name of the reaction, in nuclear reaction notation. E.g. ‘115IN(n,g)’, ‘235U(n,f)’, ‘139LA(p,x)134CE’, ‘Ra-226(n,2n)Ra-225’, ‘Al-27(n,a)’, etc.
librarystr, optional: Name of the library to use, or ‘best’ (default).

Attributes:

targetstr: The target nucleus. The IAEA monitor, IRDFF and TENDL residual-product libraries also carry natural elements, e.g. ‘natEl’.
incidentstr: Incident particle. E.g. ‘n’, ‘p’, ‘d’.
outgoingstr: Outgoing particle, or reaction shorthand. E.g. ‘2n’, ‘d’, ‘f’, ‘inl’, ‘x’. Will always be ‘x’ for (TENDL) residual product libraries.
productstr: The product isotope.
interp_configdict: Interpolation configuration, set as a property or through keyword arguments to interpolate/interpolate_unc. The one key is ‘interpolation’: ‘pchip-sqrt’ (default for the TENDL libraries) or ‘linear’ (default for ENDF, IRDFF and IAEA).
engnp.ndarray: Incident particle energy, in MeV.
xsnp.ndarray: Reaction cross section, in mb.
unc_xsnp.ndarray: Uncertainty in the cross section, in mb. If not provided by the library, default is zeros of same shape as xs.
namestr: Name of the reaction in nuclear reaction notation.
libraryci.Library: Nuclear reaction library. printing rx.library.name will give the name of the library.
TeXstr: LaTeX formatted reaction name.

Methods

`average`(energy, flux[, unc])	Flux averaged reaction cross section
`integrate`(energy, flux[, unc])	Reaction flux integral
`interpolate`(energy, **interp_config)	Interpolated cross section
`interpolate_unc`(energy, **interp_config)	Uncertainty in interpolated cross section
`plot`([energy, label, title])	Plot the cross section

Examples

>>> rx = ci.Reaction('226RA(n,2n)')
>>> print(rx.library.name)
ENDF/B-VIII.1
>>> rx = ci.Reaction('226RA(n,x)225RA')
>>> print(rx.library.name)
TENDL-2025
>>> rx = ci.Reaction('115IN(n,inl)')
>>> print(rx.library.name)
IRDFF-II

average(energy, flux, unc=False)[source]

Flux averaged reaction cross section

Calculates the flux-weighted average reaction cross section, using the input flux and energy grid.

Parameters:

energyarray_like: Incident particle energy, in MeV.
fluxarray_like: Incident particle flux as a function of the input energy grid.
uncbool, optional: If True, returns the both the flux average cross section and the uncertainty. If False, just the average cross section is returned. Default False.

Returns:

average_xsfloat or tuple: Flux-averaged reaction cross section if unc=False (default), or average and uncertainty, if unc=True.

Examples

>>> rx = ci.Reaction('Ni-58(n,p)')
>>> eng = np.linspace(1, 5, 20)
>>> phi = np.ones(20)
>>> print(rx.average(eng, phi))
210.3226525877...
>>> print(rx.average(eng, phi, unc=True))
(210.3226525877..., ...)

integrate(energy, flux, unc=False)[source]

Reaction flux integral

Integrate the product of the cross section and flux along the input energy grid.

Parameters:

energyarray_like: Incident particle energy, in MeV.
fluxarray_like: Incident particle flux as a function of the input energy grid.
uncbool, optional: If True, returns the both the flux integral and the uncertainty. If False, just the flux integral is returned. Default False.

Returns:

xs_integralfloat or tuple: Reaction flux integral if unc=False (default), or reaction flux integral and uncertainty, if unc=True.

Examples

>>> rx = ci.Reaction('Ni-58(n,p)')
>>> eng = np.linspace(1, 5, 20)
>>> phi = np.ones(20)
>>> print(rx.integrate(eng, phi))
885.5690635272...
>>> print(rx.integrate(eng, phi, unc=True))
(885.5690635272..., ...)

interpolate(energy, **interp_config)[source]

Interpolated cross section

Interpolation of the reaction cross section along the input energy grid. The scheme comes from interp_config (per-library defaults: ‘pchip-sqrt’ for the TENDL libraries — monotone PCHIP interpolation in sqrt(E)-sqrt(sigma) space, exact through the evaluated points with no overshoot at thresholds — and ‘linear’ for the pointwise-linearized ENDF, IRDFF and IAEA libraries). Energies outside the evaluated grid return 0 rather than an extrapolation.

Parameters:

energyarray_like: Incident particle energy, in MeV.
interp_configoptional keyword arguments: Updates to interp_config, applied before interpolating and kept for later calls, e.g. rx.interpolate(E, interpolation='linear').

Returns:

cross_sectionnp.ndarray: Interpolated cross section, in mb.

Examples

>>> rx = ci.Reaction('115IN(n,g)', 'IRDFF')
>>> print(rx.interpolate(0.5))
161.41646650941306
>>> print(rx.interpolate([0.5, 1.0, 5.0]))
[161.41646651 171.81486757 8.8822]

interpolate_unc(energy, **interp_config)[source]

Uncertainty in interpolated cross section

Interpolation of the uncertainty in the reaction cross section along the input energy grid, for libraries where uncertainties are provided, using the same interp_config scheme as interpolate.

Parameters:

energyarray_like: Incident particle energy, in MeV.
interp_configoptional keyword arguments: Updates to interp_config, applied before interpolating and kept for later calls.

Returns:

unc_cross_sectionnp.ndarray: Uncertainty in the interpolated cross section, in mb.

Examples

>>> rx = ci.Reaction('115IN(n,g)', 'IRDFF')
>>> print(rx.interpolate_unc(0.5))
3.9542683715745546
>>> print(rx.interpolate_unc([0.5, 1.0, 5.0]))
[3.95426837 5.88023936 0.4654]

plot(energy=None, label='reaction', title=False, **kwargs)[source]

Plot the cross section

Plots the energy differential cross section.

Parameters:

energyarray_like, optional: Energy grid along which to plot the cross section. If None, the energy grid provided by the library will be used.
labelstr, optional: Axes label. If label=’reaction’, the label will be the reaction name. If ‘library’, it will be the name of the cross section library. If ‘both’, then the reaction name and library will be given. If none of these options, pyplot will be called with ax.plot(..., label=label).
titlebool, optional: Display the reaction name as the plot title. Default, False.

Other Parameters:

**kwargs: Optional keyword arguments for plotting. See the plotting section of the curie API for a complete list of kwargs.

Examples

>>> rx = ci.Reaction('115IN(n,g)')
>>> rx.plot(scale='loglog')
>>> rx = ci.Reaction('35CL(n,p)')
>>> f, ax = rx.plot(return_plot=True)
>>> rx = ci.Reaction('35CL(n,el)')
>>> rx.plot(f=f, ax=ax, scale='loglog')