Global data

This section describes the data in the global data section and the ndf access routines used to retrieve this data.

Date: Date is an integer date in the form YYMMDD (e.g., 991031 for 31-Oct-1999). Originally this date was the day on which the file was processed. Currently, as of about 1-Oct-2000, the date is used to uniquely identify a file. Dates in files generated before about 1-Oct-2000 are not guaranteed to be unique. See routines ndfinit, ndfcinit and ndfcopen.

Group id: The incident particle's group id from the bdfls file used to generate the ndfy_{$\bf i$} file. See routines ndfgid and ndfcgid.

Number of groups: The number of incident particle groups used to generate the ndfy_{$\bf i$} file. This is designated as ng in this document. See routines ndfngroups, ndfcngroups, ndfngroup and ndfcngroup.

Group boundaries: The incident particle's group boundaries used to generate the ndfy_{$\bf i$} file. See routines ndfgp and ndfgid. This data has units of MeV.

Group speeds: The incident particle's group averaged speeds (see Eqs. 5 and  13). See routines ndfsp and ndfcsp. This data has units of cm/sh where sh = 10^-8 second.

Group flux: The grouped flux used to generate the ndfy_{$\bf i$} file (see Eqs. 6, 7 and 8). Typically, the ndfy_{$\bf i$} file is generated with a flat flux with only the l = 0 Legendre order specified. There is no routine which returns the flux used to generate the ndfy_{$\bf i$} file. If ndfgroup has been called then ndfflxw, ndfflxw_l, ndfwsp, ndfcflxw, ndfcflxw_l or ndfcwsp can be called to obtained the grouped flux for the flux specified with the flux id argument of ndfgroup.

yo descriptor: The list of transportable outgoing particles and relevant information. The number of transportable outgoing particles is obtained from ndfnyos or ndfcnyos and the list is obtained from ndfyos or ndfcyos (also see ndfyo or ndfcyo). When a ndfy_{$\bf i$} file is generated the transfer matrix for transportable incident particle going to a transportable outgoing particle is calculated. During this calculation the processing code is instructed, through a flag labeled iecflg, to conserve either transportable outgoing particle number, energy, or number-and-energy. (Traditionally, conservation of number (iecflg = 0) is used for neutrons, conservation of number-and-energy (iecflg = 3) is used for charge particles and conservation of energy (iecflg = 1) is used for gammas.) This flag is stored in the file and used when collapsing. It can be accessed using the routine ndfyo_info or ndfcyo_iecflg. When the transportable outgoing particle is the same as the transportable incident particle (i.e., y_i = y_o) then the matrix generated has dimension ng x ng. When the transportable outgoing particle is different than the transportable incident particle (i.e., y_i$\ne$ y_o) then the matrix generated has dimension nh x ng. The value of nh can be accessed using ndfyo_info or ndfcyo_nego. There exist an iecflg and nh for each transportable outgoing particle type.

Target list: The integer list of targets in the ndfy_{$\bf i$} file. The targets are listed in terms of their ZA = 1000 x Z + A (e.g., ²³⁸U as ZA = 92238). See routines ndfnistab, ndfistab, ndfcnistab and ndfcistab.