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The first line is the HEAD record; it contains the ZA
value (100*Z+A) and the AWR value (ratio of target mass to
neutron mass). The second card starts the TAB1 record and
contains the reaction Q value (-8.4738 MeV) and some counts.
The third line contains some interpolation information.
Finally, the rest of the record contains the tabulation
given as energy, cross section pairs with energies in eV and
cross sections in barns. Therefore, we can immediately
read off the 14 MeV cross section of .04663 barns. The
last line in the section is just the normal SEND record.
Note that this is an endothermic reaction (negative Q value),
and it has a threshold energy of 8.7781 MeV. We can also
compute the threshold from the Q value using
-Q*(AWR+1)/AWR,
which gives 8.778131 MeV. It is important to have the
first energy point greater than or equal to the computed
threshold in some applications, and NJOY checks this.
To fully understand this example, we need to have a more
formal definition for the contents of a cross section
record, more details on how Q values are used (why are
there two values given?), and a description of how
interpolation is used to define cross section values
between the grid points given.
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