Formal Specifications for File 3



The following is based on ENDF-102,
Data Formats and Procedures for the
Evaluated Nuclear Data File ENDF-6.

Reaction cross sections and auxiliary quantities are given in File 3 as functions of energy E, where E is the incident energy in the laboratory system. They are given as energy-cross section (or auxiliary data) pairs. An interpolation scheme is given that specifies the energy variation of the data for incident energies between a given energy point and the next higher point. File 3 is divided into sections, each containing the data for a particular reaction (MT number). The sections are ordered by increasing MT number. As usual, each section starts with a HEAD record and ends with a SEND record. The file ends with a FEND record.

Formats

The following quantities are defined:

ZA,AWR
standard material charge and mass parameters
QM
is the mass-difference Q value (eV), defined as the mass of the target and projectile minus the mass of the residual nucleus in the ground state and the masses of all other reaction products; that is, for

a+A->b+c+...+B,
QM=[(ma+mA) -(mb+mc+...+mB)] x U,

where the mass unit U is 9.3150146e8 eV for masses given in AU, the standard C12-based mass units, or 9.395728e8 eV for masses given in neutron masses (AWR).

QI
is the reaction Q value for the (lowest energy) state defined by the given MT value in a simple two-body reactions or a breakup reaction. It is defined as QM for the ground state of the residual nucleus (or intermediate system before breakup) minus the energy of the excited level in this system. Use QI=QM for reactions with no intermediate states in the residual nucleus and without complex breakup (LR=0).
LR
complex or "breakup" reaction flag. Indicates that additional particles not specified by the MT number will be emitted.
NR,NP,EINT
standard TAB1 parameters
S(E)
cross section (barns) for a particular reaction (or auxiliary quantity) given as a table of NP energy-cross section pairs.

The structure of a section is

     [MAT, 3, MT/ ZA, AWR, 0, 0, 0, 0] HEAD
     [MAT, 3, MT/ QM, QI, 0, LR, NR, NP/ EINT/ S(E)] TAB1
     [MAT, 3, 0/ 0.0, 0.0, 0, 0, 0, 0] SEND
This standardized shorthand notation is used throughout the ENDF format manual to show what parameters appear in the various fields.

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15 December 2012 T-2 Nuclear Information Service ryxm@lanl.gov