WRITE in usrroutine print multiple times the same result

Scoring
1

Dear Fluka team,
I am doing a simple calculation in which I have put a unique USRBDX card in order to score neutron production in a material. I am writting in a user routine the energy and direction of neutrons, trying to not be constraint by the neutron group binning.
I use a FLUSCW.f routine in which I write the direction and energy of particles as shown below:

     FLUSCW = ONEONE
      LSCZER = .FALSE.
      IF (ISCRNG .EQ. 1) THEN
      	IF (LFIRST) THEN
	  LFIRST = .FALSE.
	  OPEN(51,FILE='score')
	ENDIF
      	IF (Ij .EQ. 8) THEN
	    WRITE(51,*) 'Scoring neutron', -Pla, Txx, Tyy, Tzz
	ENDIF
      ENDIF
      RETURN

In my output file, I am surprised I find multiple time the same result:

Scoring neutron   1.5808131412349047E-002 -0.75066991467072497       0.18094721006154135       0.63541544392561855     
 Scoring neutron   1.5808131412349047E-002 -0.75066991467072497       0.18094721006154135       0.63541544392561855     
 Scoring neutron   1.5808131412349047E-002 -0.75066991467072497       0.18094721006154135       0.63541544392561855     
 Scoring neutron   1.5808131412349047E-002 -0.75066991467072497       0.18094721006154135       0.63541544392561855     
 Scoring neutron   1.5808131412349047E-002 -0.75066991467072497       0.18094721006154135       0.63541544392561855     
 Scoring neutron   1.5808131412349047E-002 -0.75066991467072497       0.18094721006154135       0.63541544392561855     
 Scoring neutron   1.5808131412349047E-002 -0.75066991467072497       0.18094721006154135       0.63541544392561855     
 Scoring neutron   1.5808131412349047E-002 -0.75066991467072497       0.18094721006154135       0.63541544392561855     
 Scoring neutron   1.5808131412349047E-002 -0.75066991467072497       0.18094721006154135       0.63541544392561855     
 Scoring neutron   1.5808131412349047E-002 -0.75066991467072497       0.18094721006154135       0.63541544392561855     
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   3.3150464569692062E-002  0.98947064139413332       0.10959543198601975       -9.4534073787604686E-002
 Scoring neutron   1.4771496845706906E-003 -0.70335847572024257       0.60166024823776709      -0.37853903408098544

Is there a specific reason for which the same result is shown multiple times?
Thanks in advance.
Best

2

Hi @thomas.f,
this is due to the multi-group treatment of neutrons with energy below 20 MeV.
3 discrete angles are available for each group transition and for each element or isotope.
Please refer to the manual, section 10.1.1 for more details.
So if you are interested in angular distribution from single scattering, FLUKA is not the proper tool in this energy range.
Cheers luigi

3

Thank you Luigi for the information.
Could you please give me more details about the 3 discrete angles? If I consider only one time the multiple results, I should be able to get neutron angular distribution without being constraint by the 260 energy groups?
Best.

4

Hi @thomas.f,
as said in my previous email, you cannot get a significant angular distribution for neutrons below 20 MeV at the level of single interaction.
Instead, at a region boundary, the neutron angular distribution is meaningful provided the neutron has undergone few collisions.

Finally, for sake of completeness, the scattering angle matrix can be printed in the output file with the LOW-NEUT card with WHAT(4)=3.

Best, luigi