The data-flow example on the previous page introduces the terms "PENDF tape" and "GENDF tape." Because these files will be very important for all the NJOY examples, we define them more completely here:
  • PENDF tape: a pointwise version of an ENDF tape where any resonance parameters or nonlinear interpolation ranges have been converted into pointwise cross sections suitable for linear interpolation to within specified accuracy criteria. The File 1 comments have been simplified, although the directory is correct. Resonance parameters have been removed from File 2. Only Files 3, 6 (for thermal data only), and 13 are given for data; the other information, such as angle and energy distributions, must be read from the corresponding ENDF tape. Multiple temperatures may be given for a material by repeating each "MAT" in order of increasing temperature.

  • GENDF tape: a multigroup version of an ENDF tape with the group structures, temperatures, and background cross section defined in File 1, "vector" cross sections given in File 3, and group-to-group matrices given in File 6. Higher MF Files are used for photons and charged particles.
Using these standardized files supports the modular nature of NJOY. Different modules can sometimes be run in different orders and combined in various ways. Internally, all NJOY modules use a common set of subroutines for reading and writing the ENDF, PENDF, and GENDF "tapes" (they are located in the NJOY module).


23 January 2013 T-2 Nuclear Information Service