ISOTXS Output

The ISOTXS format has some shortcomings as a general library format; however, it is well suited as an output format from TRANSX because many codes can use it as input. For the convenience of the TRANSX user, the ISOTXS format is reproduced here. When selecting ISOTXS output, the edit names can be STRPL, SNGAM, SFIS, CHISO, SNALF, SNP, SN2N, SND, or SNT. The first and second must be present (TRD and NG, respectively), and SFIS must be present (if not zero) to allow nubar to be calculated from nu*sigmaf. The others are optional. As an example,

  $ IOUT=6, NED=9, NEDS=9
  ...
  CHISO  STRPL  SNGAM  SFIS  SN2N
  SNALF  SNP  SND  SNT/
  1  CHI/
  2  TRD/
  3  NG/
  4  NFTOT/
  5  N2N/
  6  NA/
  7  NP/
  8  ND/
  9  NT/
  ....

The ordering of the names is not important. Note that the edit specifications for SND could load HEAT or DAME into the corresponding position rather than the (n,d) cross section. This kind of trick must be used with care because some SN codes may calculate their particle-balance-absorption edit from SNGAM +SFIS+SNALF+SNF+SND +SNT-SN2N. A separate vector chi is computed for each isotope with fission, but no set chi vector or matrix is provided.

The output coding produces a total scattering matrix only. It uses the option in which a different ``block'' is used for each Legendre order. Subblocking is not used, so the scattering blocks each consist of a single record containing all source and sink groups for that order. No attempt is made to take full advantage of JBAND and IJJ to remove zeroes, but the matrices are triangularized and truncated using MAXUP and MAXDN for some savings in output file size.

The parameters AMASS through KBR in the isotope control record are set to zero.

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