Last version:
FLUKA 2021.2.2, September 25th 2021
(last respin )
flair-2.3-0b 30-Jul-2021


-- Fluka Release
( 25.09.2021 )

FLUKA 2021.2.2 has been released.
Fluka Release 30.07.2021 FLUKA 2021.2.1 has been released.
Fluka Major Release 18.05.2021 FLUKA 2021.2.0 has been released.
Congratulations from INFN: ,
Dear Paola,
I wish to congratulate you and all the authors and collaborators for this new Fluka release, which looks at the future and confirms the support of INFN in the development and continuous improvement of this code.
best regards
Diego Bettoni
INFN Executive Committee

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defines input/output files to be connected at run-time

     WHAT(1) > 0. : logical unit number of a FORMATTED file to be opened
             < 0. : logical unit number of an UNFORMATTED file to be

             Default : no default (WHAT(1) must not be = 0.)

     WHAT(2-6)    : not used

     SDUM = NEW      : the file is opened with status 'NEW'
          = OLD      : the file is opened with status 'OLD'
          = UNKNOWN  : the file is opened with status 'UNKNOWN'
          = READONLY : the file is opened with status 'OLD' and (only
                       on VAX VMS/OpenVMS) in mode 'READONLY'
          = SCRATCH  : the file is opened with status 'SCRATCH'

          Default: SDUM = OLD if |WHAT(1)| = 9, 12, 13, 14
                        = NEW otherwise

If SDUM is not = SCRATCH, the name of the file to be opened must be given in the card which immediately follows.

     Default (option OPEN not given): no file is opened at run time. In
             this case the I/O files must be pre-connected via ASSIGN on
             VAX VMS/OpenVMS (see (3)). On UNIX and Linux, the rfluka
             script provided with the FLUKA code creates the necessary
             symbolic links. On some UNIX systems (e.g. HPUX-9),
             OPEN MUST be given in any case for the data files.


  • 1) The input/output files used by FLUKA are of several kinds:

  • Standard input (logical unit 5) and standard output (logical unit 11) must be redirected via < and > (on UNIX and Linux), or pre-connected via FILEDEF, ASSIGN, etc. on other systems.
  • cross section unformatted data files (logical unit numbers 9, 13 and 14) can be opened with the OPEN option (SDUM = OLD or READONLY), or can be pre-connected (on most UNIX systems,
    preconnection is obtained by means of symbolic links).
    If OPEN is used, the full file name must be given in the card which follows.
  • Scratch files (unit 8 for EMF auxiliary output and unit 16 for Combinatorial Geometry working space) can also be OPENed (with SDUM = SCRATCH) or pre-connected (not on UNIX).
    No file name card must be given for scratch files.
  • The "next seeds" file from the random number generator (logical unit number 2) can be opened by any of the three ways described above (i.e. by OPEN, by pre-connection or automatically) on any of the supported systems.
  • Error message file (logical unit number 15) and estimator output files (created by scoring options such as USRBIN, USRBDX, DETECT etc.):
  • On UNIX systems, they can either be opened by the user (with option OPEN, SDUM = NEW or UNKNOWN and file name given on the next card) or automatically by the program with a default name of the form or, where xxx is the logical unit number.
  • On VAX VMS/OpenVMS, all the three possibilities are available:
    pre-connection, OPEN option and automatic opening with a default name of the form FORxxx.DAT.

  • Files created by user-written code: all the three possibilities are available. Of course, a Fortran statement OPEN can also be used in this case.

  • 2) It is possible to pre-connect some of the files and to OPEN others.


 *   opening the file with the random number seeds for the next run
 OPEN              2.                                                  NEW
 *   the neutron cross section file
 OPEN             -9.                                                  READONLY
 *   the working space for Combinatorial Geometry
 OPEN             16.                                                  SCRATCH

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