Titles: NEUT ============= Contact: G. McGregor, Oxford. Revision History:- ================ 4.01 G. McGregor First version. 4.01 G. McGregor NaCl change. Titles Files ------------ The titles banks generated from the ENDF files can be found in the prod directory of SNOMAN and are named neutron_NZA_XXc.dat where NZA is the NZA number (NZA=Z*1000+A) and XX corresponds to the ENDF library (usually 60). There are also thermal tables: neutron_hwtr_01t.dat neutron_lwtr_01t.dat neutron_poly_01t.dat and the following resource files: NEUTRON_HEAVY_WATER.DAT NEUTRON_IMPURITIES.DAT NEUTRON_DEBUG.DAT Verification ------------ Description ----------- NEUT 1 :: FILE == NEUTRON_HEAVY_WATER.DAT Word Offset Content --------------------------------------------------------- 1 I Number of heavy water regions. i+.. (i=1,4,7,...) Following words are region specific. 1 I Region number. 2 F Light water fraction. 3 F Salt added (grams per gram of d2o). NEUT 2 :: FILE == NEUTRON_IMPURITIES.DAT Word Offset Content --------------------------------------------------------- 1 I Global impurities flag. 2 F Isotopic abundabce of O17 in D2O (as fraction of O16). i+.. (i=2,7,12,...) 1 I Region code of region with impurity. 2 I Local on/off flag. 3 I Z of impurity. 4 I A of impurity. 5 F D of impurity (atoms/cm3). NEUT 3 :: FILE == NEUTRON_DEBUG.DAT Word Offset Content --------------------------------------------------------- 1 I Debug energy window flag. 2 I Debug energy lower window flag. 3 F Lower window energy. 4 I Debug energy upper window flag. 5 F Upper window energy. 6 I Debug 1 step flag. 7 I Law count flag. 8-10 I Dummy words. 11 I Debug media flag. 12 I Debug media. 13 I Nuclide number. i+.. (i=13,17,21,...) 1 I Nuclide Z. 2 I Nuclide A. 3 F Nuclide density (number density). 4 I Nuclide thermal table (0/1/2). OTHER NEUT BANKS Bank number = 4 : neutron_lwtr_01y.dat 5 : neutron_hwrt_01t.dat 6 : neutron_poly_01t.dat NZA : all others These banks contain all the data required for neutron transport in a medium containing a single nuclide. Multiple nuclide media are simulated by selecting a nuclide from those available based on the relative cross sections for an interaction with each nuclide, and resolving the interaction using the single nuclide data table. There are two forms of nuclide data table, thermal and non-thermal. The non-thermal tables are the most common, and they are detailed below. Thermal tables have the same principle header and body structure, but the data words take very different meanings. On no account alter any part of these data tables! Data Words --------- Data types: B(bit), I, F, D(double), H(hollerith 4 char) Fixed length Database Header. See titles_dbhdr.html. Word Access Data word content. offset routine 1 D NDMASS Mass of the nuclide (relative to the mass of a neutron). 2 D NDTEMP Temperature of the table in MeV. 3-34 NDHDRI, Header (empty for non-thermal tables). NDHDRR 35-50 I NDNXS The NXS array (16 integer elements). 51-82 I NDJXS The JXS array (32 integer elements). 83+ D NDXSSI, The XSS array (double precision elements). NDXSSR Note that the ND* routines are used to provide access to the various parts of the NEUT bank. They make bank access much simpler to understand when reading code. The ND* calls translate to MTCONS calls with offsets into the bank. The NDXSSI routines provide integer conversion for what are read as double precision, the NDXSSR routines read the same words as double precision quantities. The code must know in advance whether it intends to read an integer or a double precision number. The offsets into the NDNXS and NDJXS arrays are detailed below, for both thermal and non-thermal tables. NDNXS Array in Non-Thermal Tables --------------------------------- 1 BL Length of second data block. 2 ZA ZA = (Z * 1000) + A . 3 NES Number of energies in main energy table. 4 NTR Number of reaction excluding elastic. 5 NR Number of reaction having secondary neutrons (ex. elastic). 6 NTRP Number of photon production reactions. 7-16 Not used. NDJXS Array in Non-Thermal Tables --------------------------------- 1 ESZ Location of the main energy table (usually =1). 2 NU Location of the fission nu data. 3 MTR Location of the MT array. 4 LQR Location of the Q-value array. 5 TYR Location of the reaction type array. 6 LSIG Location of the table of cross section locators. 7 SIG Location of the cross sections. 8 LAND Location of the table of angular distribution locators. 9 AND Location of the angular distributions. 10 LDLW Location of the table of energy distribution locators. 11 DLW Location of the energy distributions. 12 GPD Location of the photon producrtion data. 13 MTRP Location of the photon production MT array. 14 LSIGP Loc. of the table of photon prod. cross section locators. 15 SIGP Location of the photon production cross sections. 16 LANDP Loc. of the table of photon prod. ang. dist. locators. 17 ANDP Location of the photon production angular distributions. 18 LDLWP Loc. of the table of photon prod. energy dist. locators. 19 DLWP Location of the photon production energy distrbutions. 20 YP Location of the yield multipliers. 21 FIS Location of the total fission cross section. 22 END Location of the last word of this table. 23-32 Not used. Example: Access :: NESZ = NDJXS(TABLE,ESZ) . NESZ usually = 1. NDNXS Array in Thermal Tables ----------------------------- 1 BL Length of second data block. 2 IDPNI Inelastic scattering mode. 3 NIL Inelastic dimensioning parameter. 4 NIEB Number of inelastic exiting energies. 5 IDPNC Elastic scattering mode. 6 NCL Elastic dimensioning parameter. 7 IFENG Secondary energy mode. 8-16 Not used. Example: Access :: NIDPNI = NDNXS(TABLE,IDPNI) . NDJXS Array in Thermal Tables ----------------------------- 1 ITIE Location of inelastic energy table. 2 ITIX Location of inelastic cross sections. 3 ITXE Location of inelastic energy/angle distributions. 4 ITCE Location of elastic energy table. 5 ITCX Location of elastic cross sections. 6 ITCA Location of elastic angular distributions. 7-32 Not used. Example: Access :: NITIE = NDJXS(TABLE,ITIE) .