RE: [fluka-discuss]: ICRES and IBRES not filled for neutron capture on 1H

From: Anton Lechner <>
Date: Thu, 3 Jul 2014 13:26:17 +0000

Dear Josh,

In your case of neutron capture on 1-H (assuming that point-wise cross sections are applied) you can find the deuteron on the FHEAVY stack. In particular, the deuteron is identified through KHEAVY(xx) being equal to 3. In a similar way as looping over GENSTK entries (e.g. to get the produced photon), you can loop over the fheavy stack to determine the deuteron, e.g.:
           DO IP = 1, NPHEAV
              IF(KHEAVY (IP) .EQ. 3) THEN
       * Write out energy:
                    WRITE(79, *) TKHEAV (IP)
               END IF
           END DO

Just for completeness (if you look at other interactions): the other particle codes in KHEAVY are 4 = 3-H, 5 = 3-He, 6 = 4-He,7-12 = "Heavy" fragment specified by IBHEAV (=charge) and ICHEAV (=mass).

Cheers, Anton

From: [] on behalf of Joshua Albert []
Sent: 03 July 2014 01:12
Subject: [fluka-discuss]: ICRES and IBRES not filled for neutron capture on 1H

Dear FLUKA experts,

I am continuing studies on cosmogenic neutron captures, and I have run into a small problem. I am able to get detailed information about most neutron captures by using usdraw and printing events with ICODE = 300 and ICRES and IBRES greater than 1. This is a good way to confirm how many of the residual nuclei (as tracked by usrrnc.f as well as regular resnuclei cards) come from neutron capture, and how many come from other processes.

Unfortunately, this does not work for capture on 1H. For some reason, ICRES and IBRES are both set to zero for this interaction, rather than 1 and 2, as one might expect. I can print out all secondary gammas with energies near 2.22 MeV, but this seems like a very inelegant solution, and may have additional complications. Do you know why ICRES and IBRES are not being properly set for this capture, and if there is a better workaround to positively identify neutron captures on 1H?

Thank you,
Received on Thu Jul 03 2014 - 16:53:05 CEST

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