Physics Rules

This is a collection of physics rules that should be checked.

Cross Section Errors

1. Monotonically increasing energy grid
   1. Discontinuity with > 2 equivalent energy points.
2. Strictly positive energy values
3. No negative cross section values
4. Kinematic threshold for threshold reactions The kinematic threshold is defined as

   Th = -Q (A+A_n)/A
   

   Where Q is the Q-value, A and A_n are the atomic mass numbers for the nucleus and the incident particle (i.e., neutron) respectively.
5. Do partial cross sections sum to total?
6. Check abnormally large (e.g., > 1E6) or abnormally small (e.g., ≤ 1E-6) cross section values. This is a rule that could be parameterized so that something really bad is an error, whereby something just kind of big would be flagged as a warning. It also has to be knowledgeable of charged particle reactions which have a Coulomb barrier.

Secondary Distribution Errors

1. Monotonically increasing energy grid
2. Monotonically increasing cosine grid
3. Secondary energy ≤ to incident energy There are certainly some exceptions to this, but as a general rule, this should stand.
4. No negative angular probability values
5. No abnormally small angular probability values

Multiplicity Errors

1. Monotonically increasing energy grid
2. No negative multiplicity values
3. No abnormally large or small multiplicity values

Fission ν Errors

Fission ν errors are just a special case of multiplicity errors

1. Monotonically increasing energy grid
2. No negative ν values
3. Delayed neutron fraction must sum to 1.0

Resonance Errors

Resolved Resonance Region

Unresolved Resonance Region

1. Partial reactions sum to total
2. No negative probability table values

Derived Data Errors

1. Strictly positive heating values Heating values that are zero, or negative, indicate a bad evaluation.
2. No abnormally large heating values