# ENDF File Support – pyne.endf¶

Module for parsing and manipulating data from ENDF evaluations. Currently, it only can read several MTs from File 1, but with time it will be expanded to include the entire ENDF format.

All the classes and functions in this module are based on document ENDF-102 titled “Data Formats and Procedures for the Evaluated Nuclear Data File ENDF-6”. The latest version from June 2009 can be found at http://www-nds.iaea.org/ndspub/documents/endf/endf102/endf102.pdf

class pyne.endf.AdlerAdler

Adler-Adler resolved resonance formalism data. This is identified by LRF=4 in the ENDF-6 format.

Parameters: emin : float Minimum energy of the resolved resonance range in eV emax : float Maximum energy of the resolved resonance range in eV nro : int Flag designating energy-dependence of scattering radius (NRO). A value of 0 indicates it is energy-independent, a value of 1 indicates it is energy-dependent. naps : int Flag controlling use of the channel and scattering radius (NAPS)

Attributes

 spin (float) Spin of the target nucleus scattering_radius_ind (float) Scattering radius in units of 10^-12 cm LI (float) Flag indicating the kind of parameters AT, BT (ndarray) Background constants for the total cross section AC, BC (ndarray) Background constants for the radiative cross section AF, BF (ndarray) Background constants for the fission cross section resonances (list of AdlerResonance) List of resonances defined by Adler-Adler parameters
read()

Parameters: ev : Evaluation ENDF evaluation positioned at the start of a resonance range subsection
class pyne.endf.ArbitraryTabulated

Arbitrary tabulated function given in ENDF MF=5, LF=1 represented as

f(E \rightarrow E') = g(E \rightarrow E')

Attributes

 energy (ndarray) Array of incident neutron energies pdf (list of Tab1) Tabulated outgoing energy distribution probability density functions
class pyne.endf.EnergyDistribution

Energy distribution from ENDF MF=5.

Attributes

 lf (int) Flag specifying energy distribution.
class pyne.endf.Evaluation

ENDF material evaluation with multiple files/sections

The Evaluation class provides a means to parse data from an ENDF-6 format file and access it as stored internal Python objects. A summary of the parsing capabilities is as follows:

MF MT Description Complete
1 451 Descriptive data and directory Yes
1 452 Number of neutrons per fission Yes
1 455 Delayed neutron data Yes
1 456 Number of prompt neutrons per fission Yes
1 458 Components of fission energy release Yes
1 460 Delayed photon data Yes
2 151 Resonance parameters Yes
3
Reaction cross sections Yes
4
Angular distributions Yes
5
Energy distributions Yes
6
Product energy-angle distributions Yes
7 2 Thermal elastic scattering Yes
7 4 Thermal inelastic scattering Yes
8 454 Independent fission yields Yes
8 457 Radioactive decay data Yes
8 459 Cumulative fission yields Yes
8
9
10
Production cross sections for radionuclides Yes
12
Photon production yield data Yes
13
Photon production cross sections Yes
14
Photon angular distributions Yes
15
Continuous photon energy spectra Yes
23
Photon and electron cross sections Yes
26
Secondary distributions for electro-atomic data Yes
27
Atomic form factors Yes
28 533 Atomic relaxation data Yes
30 1 Directory and correspondance table No
30 2 Covariance matrix No
30
Sensitivities No
31
Covariances of fission No
32
Covariances of resonance parameters No
33
Covariances of neutron cross sections No
34
Covariances for angular distributions No
35
Covariances for energy distributions No
40

Attributes

 atomic_relaxation (dict) Dictionary containing atomic relaxation data from MF=28, MT=533. If the evaluation is not an atomic relaxation sublibrary, the dictionary is empty. decay (dict) Dictionary containing decay data from MF=8. If the evaluation is not from a decay sublibrary, the dictionary is empty. fission (dict) Dictionary containing fission-related data, such as neutrons release from fission (MF=1, MT=452,455,456), components of energy release (MF=1, MT=458), delayed photons from fission (MF=1, MT=460), and cumulative/independent fission yields (MF=8, MT=454,459). info (dict) Miscallaneous information about the evaluation. target (dict) Information about the target material, such as its mass, isomeric state, whether it’s stable, and whether it’s fissionable. projectile (dict) Information about the projectile such as its mass. reaction_list (list of 4-tuples) List of sections in the evaluation. The entries of the tuples are the file (MF), section (MT), number of records (NC), and modification indicator (MOD). reactions (collections.OrderedDict) Dictionary whose keys are MT numbers and values are Reaction instances. resonances (dict) Resolved resonance data from MF=2, MT=151. thermal_elastic (dict) Coherent and/or incoherent thermal elastic data from MF=7, MT=2. thermal_inelastic (dict) Incoherent thermal inelastic data from MF=7, MT=4.
read()

Reads reactions from the ENDF file of the Evaluation object. If no arguments are provided, this method will read all the reactions in the file. A single reaction can be read if provided.

Parameters: reactions : tuple or list of tuple, optional A single reaction in the following format: (MF, MT) skip_mf : list of int, optional Files (MF) which should not be read skip_mt : list of int, optional Reactions (MT) which should not be read
class pyne.endf.Evaporation

Evaporation spectrum given in ENDF MF=5, LF=9 represented as

f(E \rightarrow E') = \frac{E'}{I} e^{-E'/\theta(E)}

Attributes

 theta (Tab1) Tabulated function of incident neutron energy u (float) Constant introduced to define the proper upper limit for the final particle energy such that 0 \le E' \le E - U
class pyne.endf.GeneralEvaporation

General evaporation spectrum given in ENDF MF=5, LF=5 represented as

f(E \rightarrow E') = g(E'/\theta(E))

Attributes

 theta (Tab1) Tabulated function of incident neutron energy E g (Tab1) Tabulated function of x = E'/\theta(E) u (float) Constant introduced to define the proper upper limit for the final particle energy such that 0 \le E' \le E - U
class pyne.endf.Library

A class for a file which contains multiple ENDF evaluations.

get_rx(nuc, mf, mt, lines=0)

Grab the data from one reaction type.

Parameters: nuc : int id form of material to read from. mf : int ENDF file number (MF). mt : int ENDF reaction number (MT). lines : int Number of lines to read from this reaction, starting from the top. Default value is 0, which reads in the entire reaction. data : NumPy array Contains the reaction data in an Nx6 array.
get_xs(nuc, mt, nuc_i=None)

Grab cross-section data.

Parameters: nuc: int id of nuclide to read. mt: int ENDF reaction number to read. nuc_i: int id of isotope to read. Defaults to nuc. tuple Returns a tuple with xs data in tuple[0] and flags in tuple[1].
integrate_tab_range(intscheme, e_int, xs, low=None, high=None)

Integrates across one tabulation range.

Parameters: intscheme : int or float The interpolation scheme used in this range. e_int : array The energies at which we have xs data. xs : array The xs data corresponding to e_int. low, high : float Lower and upper bounds within the tabulation range to start/stop at. sigma_g : float The group xs.
load()

Read the ENDF file into a NumPy array.

Returns: data : np.array, 1d, float64 Returns a 1d float64 NumPy array.
class pyne.endf.MadlandNix

Energy-dependent fission neutron spectrum (Madland and Nix) given in ENDF MF=5, LF=12 represented as

f(E \rightarrow E') = \frac{1}{2} [ g(E', E_F(L)) + g(E', E_F(H))]

where

g(E',E_F) = \frac{1}{3\sqrt{E_F T_M}} \left [ u_2^{3/2} E_1 (u_2) - u_1^{3/2} E_1 (u_1) + \gamma \left ( \frac{3}{2}, u_2 \right ) - \gamma \left ( \frac{3}{2}, u_1 \right ) \right ] \\ u_1 = \left ( \sqrt{E'} - \sqrt{E_F} \right )^2 / T_M \\ u_2 = \left ( \sqrt{E'} + \sqrt{E_F} \right )^2 / T_M.

Attributes

 efl, efh (float) Constants which represent the average kinetic energy per nucleon of the fission fragment (efl = light, efh = heavy) tm (Tab1) Parameter tabulated as a function of incident neutron energy
class pyne.endf.Maxwellian

Simple Maxwellian fission spectrum given in ENDF MF=5, LF=7 represented as

f(E \rightarrow E') = \frac{\sqrt{E'}}{I} e^{-E'/\theta(E)}

Attributes

 theta (Tab1) Tabulated function of incident neutron energy u (float) Constant introduced to define the proper upper limit for the final particle energy such that 0 \le E' \le E - U
class pyne.endf.MultiLevelBreitWigner

Multi-level Breit-Wigner resolved resonance formalism data. This is identified by LRF=2 in the ENDF-6 format.

Parameters: emin : float Minimum energy of the resolved resonance range in eV emax : float Maximum energy of the resolved resonance range in eV nro : int Flag designating energy-dependence of scattering radius (NRO). A value of 0 indicates it is energy-independent, a value of 1 indicates it is energy-dependent. naps : int Flag controlling use of the channel and scattering radius (NAPS)

Attributes

 spin (float) Spin of the target nucleus scattering_radius_ind (float) Scattering radius in units of 10^-12 cm resonances (list of Resonance) List of resolved resonances l_values (ndarray of int) Neutron orbital angular momentum values q (ndarray of float) Q-value to be added to incident particle’s center-of-mass energy to determine the channel energy for use in the penetrability factor. Given as a function of the l-value. competitive (ndarray of bool) Whether a competitive width is given for each l-value.
read()

Read multi-level Breit-Wigner resonance data from an ENDF evaluation.

Parameters: ev : Evaluation ENDF evaluation positioned at the start of a resonance range subsection
class pyne.endf.RMatrixLimited

R-Matrix Limited resolved resonance formalism data. This is identified by LRF=7 in the ENDF-6 format.

Parameters: emin : float Minimum energy of the resolved resonance range in eV emax : float Maximum energy of the resolved resonance range in eV nro : int Flag designating energy-dependence of scattering radius (NRO). A value of 0 indicates it is energy-independent, a value of 1 indicates it is energy-dependent. naps : int Flag controlling use of the channel and scattering radius (NAPS)

Attributes

 IFG (int) Flag indicating whether channel widths in eV or reduced-width amplitudes in eV^1/2 are given KRM (int) Flag to specify which formulae for the R-matrix are to be used particle_pairs (list of dict) List of particle pairs. Each particle pair is represented by a dictionary that contains the mass, atomic number, spin, and parity of each particle as well as other characteristics. spin_groups (list of dict) List of spin groups. Each spin group is characterized by channels, resonance energies, and resonance widths.
read()

Read R-Matrix limited resonance data from an ENDF evaluation.

Parameters: ev : Evaluation ENDF evaluation positioned at the start of a resonance range subsection
class pyne.endf.Reaction

Data for a single reaction including its cross section and secondary angle/energy distribution.

Parameters: mt : int The MT number from the ENDF file.

Attributes

 angular_distribution (AngularDistribution) Angular distribution represented as a tabulated function or as moments of a Legendre polynomial expansion from MF=4. complex_breakup_flag (int) Complex breakup flag. xs (Tab1) Tabulated cross section as a function of incident energy from MF=3. energy_distribution (list of EnergyDistribution) List of partial energy distributions for the reaction from MF=5. files (list of int) List of files (MF) that have been read for this reaction MT (int) The MT number from the ENDF file. multiplicities (dict) Multiplicities for production of radioactive nuclides as given in MF=9. product_distribution (list of dict) Secondary energy or correlated energy-angle distribution from MF=6. production (dict) Cross sections for production of radioactive nuclides as given in MF=10. Q_mass_difference (float) Mass difference Q value in eV Q_reaction (float) Reaction Q value in eV radionuclide_production (list of dict) List of radioactive nuclides produced as given in MF=8. reference_frame ({‘laboratory’, ‘center-of-mass’, ‘light-heavy’}) Indicates what reference frame is used for outgoing energies and angles. Only relevant for product energy-angle distributions read in MF=6. subshell_binding_energy (float) Subshell binding energy in eV as given in MF=23. Only relevant for photoelectric subshell ionization reactions in a photo-atomic sublibrary. fluorescence_yield (float) Fluorescence yield (eV/photoionization) as given in MF=23. Only relevant for photoelectric subshell ionization reactions in a photo-atomic sublibrary. products (list of dict) Secondary photon and electron distributions for electro-atomic reactions as given in MF=26. scattering_factor (Tab1) Coherent or incoherent form factor as given in MF=27. anomalous_scattering_imaginary (Tab1) Imaginary component of the anomalous scattering factor as given in MF=27. anomalous_scattering_real (Tab1) Real component of the anomalous scattering factor as given in MF=27.
class pyne.endf.ReichMoore

Reich-Moore resolved resonance formalism data. This is identified by LRF=3 in the ENDF-6 format.

Parameters: emin : float Minimum energy of the resolved resonance range in eV emax : float Maximum energy of the resolved resonance range in eV nro : int Flag designating energy-dependence of scattering radius (NRO). A value of 0 indicates it is energy-independent, a value of 1 indicates it is energy-dependent. naps : int Flag controlling use of the channel and scattering radius (NAPS)

Attributes

 resonances (dict) Dictionary whose keys are (l, J) pairs and values are instances are lists of Resonance instances. spin (float) Spin of the target nucleus scattering_radius_ind (float) Energy-independent scattering radius in units of 10^-12 cm scattering_radius (Tab1) Scattering radius in units of 10^-12 cm as a function of energy LAD (int) Indicate whether parameters can be used to compute angular distributions NLSC (int) Number of l-values which must be used to converge the calculation apl (ndarray of float) l-dependent scattering radius l_values (ndarray of int) Neutron orbital angular momentum values
read()

Read Reich-Moore resonance data from an ENDF evaluation.

Parameters: ev : Evaluation ENDF evaluation positioned at the start of a resonance range subsection
class pyne.endf.ResonanceRange

Resolved resonance formalism data as given in MF=2, MT=151.

Parameters: emin : float Minimum energy of the resolved resonance range in eV emax : float Maximum energy of the resolved resonance range in eV nro : int Flag designating energy-dependence of scattering radius (NRO). A value of 0 indicates it is energy-independent, a value of 1 indicates it is energy-dependent. naps : int Flag controlling use of the channel and scattering radius (NAPS)

Attributes

 energy_min (float) Minimum energy of the resolved resonance range in eV energy_max (float) Maximum energy of the resolved resonance range in eV nro (int) Flag designating energy-dependence of scattering radius (NRO). A value of 0 indicates it is energy-independent, a value of 1 indicates it is energy-dependent. naps (int) Flag controlling use of the channel and scattering radius (NAPS)
class pyne.endf.ScatteringRadius

Energy range with no resonances and only a scattering radius.

Parameters: emin : float Minimum energy of the resolved resonance range in eV emax : float Maximum energy of the resolved resonance range in eV nro : int Flag designating energy-dependence of scattering radius (NRO). A value of 0 indicates it is energy-independent, a value of 1 indicates it is energy-dependent. naps : int Flag controlling use of the channel and scattering radius (NAPS)
class pyne.endf.SingleLevelBreitWigner

Single-level Breit-Wigner resolved resonance formalism data. This is identified by LRF=1 in the ENDF-6 format.

Parameters: emin : float Minimum energy of the resolved resonance range in eV emax : float Maximum energy of the resolved resonance range in eV nro : int Flag designating energy-dependence of scattering radius (NRO). A value of 0 indicates it is energy-independent, a value of 1 indicates it is energy-dependent. naps : int Flag controlling use of the channel and scattering radius (NAPS)
class pyne.endf.Tab1

A one-dimensional tabulated function.

Parameters: x : array_like Independent variable y : array_like Dependent variable nbt : array_like of int Breakpoints for interpolation regions interp : array_like of int Interpolation scheme identification number, e.g., 3 means y is linear in ln(x).
classmethod from_file(fh)

Create Tab1 object using open file handle.

Parameters: fh : file File open and positioned to the start of a TAB1 record.
integral()

Integral of the tabulated function over its tabulated range.

Returns: ndarray Array of same length as the tabulated data that represents partial integrals from the bottom of the range to each tabulated point.
class pyne.endf.Unresolved

Unresolved resonance parameters as identified by LRU=2 in MF=2.

Parameters: emin : float Minimum energy of the unresolved resonance range in eV emax : float Maximum energy of the unresolved resonance range in eV nro : int Flag designating energy-dependence of scattering radius (NRO). A value of 0 indicates it is energy-independent, a value of 1 indicates it is energy-dependent. naps : int Flag controlling use of the channel and scattering radius (NAPS)

Attributes

 scattering_radius (float) Scattering radius in units of 10^-12 cm LSSF (int) Flag governing interpretation of file 3 cross sections spin (float) Spin of the target nucleus l_values (ndarray of int) Neutron orbital angular momentum values parameters (dict of dict) Dictionary whose keys are l-values and whose values are dictionaries containing unresolved resonance parameters
read()

Read unresolved resonance data from an ENDF evaluation.

Parameters: ev : Evaluation ENDF evaluation positioned at the start of a resonance range subsection
class pyne.endf.Watt

Energy-dependent Watt spectrum given in ENDF MF=5, LF=11 represented as

f(E \rightarrow E') = \frac{e^{-E'/a}}{I} \sinh \left ( \sqrt{bE'} \right )

Attributes

 a, b (Tab1) Energy-dependent parameters tabulated as function of incident neutron energy u (float) Constant introduced to define the proper upper limit for the final particle energy such that 0 \le E' \le E - U
pyne.endf.at_end_of_tape()

Indicate whether file is positioned at the end of an ENDF tape.

Parameters: f : file_like File to check bool Whether the file is at the end of the ENDF tape
pyne.endf.seek_file_end()

Position the file at the end of the ENDF file (MF) currently being read.

Parameters: f : file_like File to position
pyne.endf.seek_material_end()

Position the file at the end of the ENDF material (MAT) currently being read.

Parameters: f : file_like File to position
pyne.endf.seek_section_end()

Position the file at the end of the ENDF section (MT) currently being read.

Parameters: f : file_like File to position