Energy deposition drops to 0

Dear experts,

I am scoring the edep within the detector region, using plane source ( 30x60 cm2, totally cover the detector).
When incident photons with energy 129keV, I got a edep (none zero). However, when I changed the incident photons energy to 29keV, I got zero edep.
In theory, 29keV incident photons can transport to the detector region and deposit energy within it.
Can’t figure out why the edep suddenly drops to zero.
Any suggestions are appreciated! The following is the input file.
test.inp (4.4 KB)

Best regards,

Dear Honghu,

using the PRECISION default, FLUKA only transport electrons and photons down to 100 keV kinetic energy.

You can lower this limit to 1 keV for electrons and 100 eV for photons uding the EMFCUT card.

Don’t forget to set up both the PROD-CUT (production) and transport thresholds, to create and transport the particles with these limits.


Also, you might want to check the direction and the size of your beam. The beam is directed along the z-axis while your system seems oriented along the y-axis. The beam size is also larger than your system.
It might be useful to add a USRBIN scoring of ALL-PART fluence.

A post was split to a new topic: USRBDX result lower than expected

Dear amario,

Thanks for your suggestions, USRBIN scoring of ALL-PART is added and checked, the photons can cover the system and interact with the detector.

Best regards,