Detect efficiency of neutron detector

Dear experts,
I want to simulate detect efficiency of my detector, so I use EVENTBIN with 5000 neutrons.According to n+6Li->a+T, we know that there will be one Helium and Triton generated if one neutron is react.When I see the “.fort” file, some event are 0 and some are decimal.
My first question is for every particle, the reaction is “yes” or “no”(“0” or “1”),why it appear decimal?
Second question is if my method to simulate detect efficiency correct and any suggestions?
Looking forward to your help.
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mix.inp (4.0 KB)

Dear Xiong,

the EVENTBIN scoring prints the result of the binning after every event (usually a single primary). Zero means, that there was no particle fluence scored in that event. Otherwise you get the results of every bin of the scoring. Since you only have one bin specified, you get only one number.

If you want to model a realistic detector, your scoring should be related to the actual detection process. (For example, energy deposition in a HPGe crystal.)

Cheers,
David

Dear @horvathd ,
I have only one bin, so every event will get one value, the value is particle fluence. What I confused is the particle fluence multiply surface area should be equal to number of particle, why it not equal to “1”(1 neutron react and generate 1 Helium and 1 Triton)?

Dear Xiong,

FLUKA estimates the fluence in a volume (USRBIN / EVENTBIN, USRTRACK scorings) as the density of particle tracks.

See slide 7 and 13 of https://indico.cern.ch/event/1012211/contributions/4247796/attachments/2257010/3829959/08_Scoring_I_2021_online.pdf

Alternatively, you may use the USRYIELD scoring with the Yield option EMERGING to estimate the number of produced secondaries per primary neutron in inelastic interactions.

Cheers,
David

Dear @horvathd ,
I have an extra question about detect efficiency.
In my simulation, the neutron source is isotropic, I want to get the efficiency defined like this:
efficiency=the neutron react with material/the neutron incident to the sensitive volume.
The file “***001.out” seems give efficiency=the neutron react with material/the neutron give at “START”,right?

Dear @xiongbp,

I’m not sure what do you mean by the efficiency given in the .out file. Could you elaborate?

Cheers,
David

Dear @horvathd ,
The follow snapshot is from a generated file named “sep001.out”, you know 6Li(n,a)T, so at the column
“3.3286E-01(40.5) …TRITON” or “3.3286E-01(40.5) …4-HELIUM” ,the “3.3286E-01” is the efficiency , is it correct?
I want to get efficiency defined like I said “efficiency=the neutron react with material/the neutron incident to the sensitive volume.” because if I give particle number at “start”, not all will go into sensitive volume.
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Dear @xiongbp,

yes, the number is the table is the number of specific particles created divided by the number of primaries run.

To get the ratio of particles created divided by the number of primaries reaching the volume, you could use an USRBDX one-way current scoring, to determine the ratio of the particles reaching the volume and number of primaries run.

Cheers,
David

Dear @horvathd
Thank you for your help.