RESNCUCLE to count neutron captures in Gd per event

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1

Dear experts,

I have a (Polyethylene+Gd)==Detector compound and hitting it with protons of 10 GeV that are passing through a Lead brick. I would like to count how many neutron captures are taken place inside the Detector. After having activated pointwise cross-section treatment I used the RESNUCLE estimator as:
RESNUCLE 3. -46. regDE4 ResDet

Then, I opened the produced (after the run) sum.lis file and I got:
Detector n: 1 ResDet
(Region 4 Volume: 1.00000000 cmc,
distr. type : 3 ,
Z_max: 68 , N-Z_max: 35 , N-Z_min: -4 )

 Tot. response (n/cmc/pr)   806.565002       +/-   99.0000000      %
 ( --> Nuclei/pr            806.565002       +/-   99.0000000      % )

**** Isotope Yield as a function of Mass Number **** **** (nuclei / cmc / pr) ****

A_min: 1 - A_max: 171

A: 161 6.4999998E-02 +/- 9.9000000E+01 %
A: 160 1.6000000E-01 +/- 9.9000000E+01 %
A: 159 5.0800002E-01 +/- 9.9000000E+01 %
A: 158 1.3716000E+01 +/- 9.9000000E+01 %
A: 157 8.8500002E-01 +/- 9.9000000E+01 %
A: 156 7.8329999E+00 +/- 9.9000000E+01 %

I added: from isotopes “A 156” 7.83 and “A 158” 1.3716000E+01 ~ 21.5 (dominant neutron-capture channels of Gd).
Since I have not declared any volume, I suppose this sum 21.5 is expressed in nuclei/particle.
Thus, can I say that I expect to have 21.5 neutron captured / proton?
If not, how I could extract this estimate without investing time with mgdraw?
In addition, how one could get the number of captures (Gd/H) but on event by event so that to have a distribution with a mean value ~ the one we are getting from RESNUCLE?

Thanks a lot in advance

Best regards

Georgios

4

Hello Georgios,

You are right, as nicely explained in last FLUKA beginner’s course lecture on RP calculations, the results you obtain will be expressed as the amount of nuclei per primary particle simulated [#nuclei / primary] since you did not specify a region volume or mass.

You could try to combine RESNUCLEi with EVENTBIN to get an event-by-event summary of the residual nuclei produced on a Region basis. However, I have no experience with this and the output might be difficult to process. To make things cleaner and to give you better flexibility, I’m afraid that the use of an mgdraw.f routine is the best way forward. Perhaps the best starting point would be this discussion where the full isotope information is extracted. You can then select with ICRES (= residual nucleus atomic number) and IBRES (= residual nucleus mass number) on the isotopes you would like to consider. In addition, you would need to update the mgdraw routine such as to filter on the primary number NCASE.

Let me know if it works!

Andreas