Question regarding DETECT scoring

Dear FLUKA experts,

I am trying to compare the efficiencies of several neutron detector. My approach of doing this is to use DETECT card to get the ratio of number of neutrons that deposited energy in the detector vs. the total number of neutrons that pass through the detector for each of them.

However, I run into some confusion when trying to interpret my result. The y-value sum up to be 1 from the DETECT card. I did some digging and found out in the forum that “the results will be normalized to
one primary photon ABSORBED in the detector (photons not hitting the detector or
passing through the detector without being absorbed will not contribute to
the normalization).” in a thread talking about detecting photons. Nevertheless, this just adds more confusion. Does this mean that in my scoring that all primary neutrons absorbed are accounted for in the detector? How could I achieve what I am trying to do? I think I can get the number of neutrons passing through the detector easily by using a USRBDX card. But how can I acquire the number of neutrons (and their descendants) that deposit energy into the detector?

The attached are my files should you feel helpful in solving the problem.
GND_BF3_17_tab.lis (45.1 KB) GND_BF3.inp (1.9 KB)

Thanks in advance.


Dear Martin,

The results of the DETECT card are only normalized by absorbed primaries in the special case when the Trigger option is set to Coincidence, and the trigger region is same as the detector one.

If you are interested the number actual number of events (beside the spectrum) then you need to leave the Trigger option empty, and not setting a trigger region. In this case the result will be normalized to started primaries.

However, if you have the Emin set to 0.0e0, then all events with zero energy deposition will be counted into the first bin, creating a peak there. To prevent this, you can set Emin to a negligible value (like 1.0e-15, or less) to cut the events with zero energy deposition.


1 Like

Thank you for helping me again, David. This information is really helpful.