This file is provided to represent the distribution of reaction products (i.e., neutrons, photons, charged particles, and residual nuclei) in energy and angle. It works together with File 3, which contains the reaction cross sections, and replaces the combination of File 4 and File 5. Radioactive products are identified in File 8. The use of File 6 is recommended when the energy and angular distributions of the emitted particles must be coupled, when it is important to give a concurrent description of neutron scattering and particle emission, when so many reaction channels are open that it is difficult to provide separate reactions, or when accurate charged-particle or residual-nucleus distributions are required for particle transport, heat deposition, or radiation damage calculations.

For the purposes of this file, any reaction is defined by giving the production cross section for each reaction product in barns/steradian assuming azimuthal symmetry in normalized form as shown by the following equations:

In these equations, i denotes one particular product, E is the incident energy, E' is the energy of the product emitted with cosine μ, σ(E) is the interaction cross section (File 3), y_i is the product yield or multiplicity, and f_i is the normalized distribution with units (eV-unit cosine)^-1.

This representation ignores most correlations between products and most sequential reactions; that is, the distributions given here are those that would be seen by an observer outside of a "black box" looking at one particle at a time. The process being described may be a combination of several different reactions, and the product distributions may be described using several different representations, or "LAWS", as shown in the following table:

Formats

The following quantities are defined for all representations:

ZA,AWR

standard material charge and mass parameters.

LCT

reference system for secondary energy and angle (incident energy is always given in the LAB system).
LCT=1, laboratory (LAB) coordinates used for both.
LCT=2, center-of-mass (CM) system used for both.

NK

number of subsections in the this section (MT). Each subsection describes one reaction product. There can be more than one subsection for a given particle or residual nucleus (see LIP).

ZAP

product identifier 1000*Z+A with Z=0 for photons and A=0 for electrons and positrons. A section with A=0 can also be used to represent the average recoil energy or spectrum for an elemental target.

AWP

product mass in neutron units.

LIP

product modifier flag.

LAW

distinguishes between different representations for the distribution function f_i: see table above.

NR,NP,EINT

standard TAB1 parameters.

A section of File 6 has the following form:

     [MAT, 6, MT/ ZA, AWR, 0, LCT, NK, 0] HEAD
     [MAT, 6, MT/ ZAP, AWP, LIP, LAW, NR, NP/ EINT/ Y_1(E)] TAB1
                  [LAW-dependent structure for product 1]
                  ---------------------------
                  repeat TAB1 and LAW-dependent structures
                  for the rest of the NK subsections
                  ---------------------------
     [MAT, 6, MT/ 0.0, 0.0, 0, 0, 0, 0] SEND

File 6 should have a subsection for every product of the reaction or sum of reactions being described except for MT=3, 4, or 103-107 when they are bing used to represent lumped photons. The subsections are arranged in the following order: (1) particles (n, p, d, etc.) in order of ZAP and LIP, (2) residual nuclei and isomers in order of ZAP and LIP, (3) photons, and (4) electrons. The contents of the subsection for each LAW are described in the following pages:

Unknown Distribution (LAW=0)
Continuum Energy-Angle Distribution (LAW=1)
Two-Body Reaction Angular Distribution (LAW=2)
Isotropic Two-Body Distribution (LAW=3)
Recoil Distribution of a Two-Body Reaction (LAW=4)
Charged-Particle Elastic Scattering (LAW=5)
N-Body Phase-Space Distribution (LAW=6)
Laboratory Angle-Energy Law (LAW=7)