Electro-Nuclear simulation in FLUKA model

Physics, Transport and Magnetic Fields
1

Hello Fluka experts!
I have a question regarding the model in use for electro-nuclear interactions in the simulation. As mentioned in previous posts I am investigating electrons imping on a tungsten target. The beam electron has 3.2GeV energy.
NumNucsEcorr.pdf (24.2 KB)

In the given plot I show the number of hadrons per event vs the recoil energy of the electron. No cuts are applied, all events are taken into account, even if the electron has 1GeV of energy before the eNuc interaction. At max the electron can have the 3.2GeV energy, but again, it can also have interacted before the eNuc interaction (and thus have lost some of the initial energy).
My question is now: why are there so little events with 0 hadrons and why is it more likely to have 1 or 2 hadrons? In the plot there is a visible increase in likelyhood of such events. Is this due to the model used, or is this completely physics based and should be expected? To me it does not make sense however, why this should be physically more likely. But since I do not know the source code, I cannot double check if that causes the statistics in the plot.

Especially interesting to me are also events where the incoming electron has e.g. 1.1GeV energy and the recoiling electron has 1GeV, but a proton is sent off. Does this energy come from the nucleus of the tungsten atoms? Or is this a issue with the model in place?

I would be very happy about some clarification, but it has no time stress. I can understand if through the holidays, answers take some more time.

Best wishes,
Laney Klipphahn

2

The model used, as implemented in the source code, is physics based.
Since you are looking at the outcome of electro-nuclear reactions that actually took place, it’s natural to find one or more hadrons as reaction products, otherwise the absence of hadron emission would imply that no reaction took place (apart from the extreme case of pure gamma de-excitation).
In this regard, the 100 MeV amount lost by the electron in the interaction with the tungsten nucleus according to your figures, is more than enough to emit a proton from the nucleus, being well above the respective separation energy. Therefore, I see no issue with the model in place.