Dear FLUKA expert, I am simulating electron beam bombardment on a tantalum target. May I ask if AUXSCORE can be used to distinguish the contributions of electrons and neutrons in DPA calculations? Here is my input file.
40MeV_Ta_DPA.inp (3.6 KB)
The neutron contribution calculated using AUXSCORE is 0, but if I set the initial particle to proton, the neutron contribution appears. What is the reason for this? Thank you for any response!
Hi Ashton,
Scoring DPA by parent particle can be tricky. When neutrons undergo elastic scattering they create recoil ions, and these recoil ions are what actually produce lattice damage. So, if you try to attribute the DPA only to the neutrons, you miss this major contribution from the recoils.
With proton irradiation, neutrons are generated as secondaries through inelastic scattering, with a different spectrum, and a fraction of those neutrons can indeed be recorded with the AUXSCORE.
You can see this effect even more clearly if you treat neutrons as the primary beam: as you scan the incident neutron energy (e.g. from 1 to 5 MeV), the overall DPA changes while the direct neutron contribution remains negligible.
If you’d like to dig deeper, the comscw.f user routine (see slide 13 of https://indico.cern.ch/event/1200922/contributions/5411837/attachments/2661810/4611453/08_User_routines_2023_Advanced_ANL.pdf) lets you filter the particles that generate each displacement damage.
An example of what you could want to do could be:
IF (JTRACK .GT. 62) THEN
IDP = J0TRCK
IF(IDP .EQ. 0) CALL FLABRT ( 'COMSCW', 'J0TRCK=0 ?!' )
ELSE
IDP = JTRACK
IF(IDP .EQ. 0) CALL FLABRT ( 'COMSCW', 'JTRACK=0 ?!' )
END IF
IF( IDP .GE. -1 ) LSCZER = .TRUE. !Exclude all non-ions
Keep in mind that there is a very simple way of understanding the contributions of neutrons in your simulations: simply turn off the phonuclear interactions and check the difference!
I hope this was helpful for you, let me know if you have any further questions.
Cheers,
Daniele