Strange outputs from data usrdraw. How to interpret them?

Dear Fluka users,
From the discussion with @adonadon in this post Unique ID particle using MGDRAW some issues scaped from the initial question and that’s why I’m opening this new post.

I’m running a simulation with a single high energetic particle (proton 10 PeV) from the top of the atmosphere and extracting information about charged kaons, pions, and muons through the atmosphere regions and underground. To do so, I’m using the subroutine USRDRAW.

Among other things, I’m following the particle shower and marking with a unique_id where the particles have been created and where they have died in the simulation. Nonetheless, there are some outputs that I don’t know how to interpret and if the error comes from my code or another source.

As an example, find below a sliced table with the index (no named), the ICODE of usrdraw (icode), kinetic energy (ekin), the id of the particle (id), ltrack, the parent id (id_anc), and the unique_id generated from post-processing. I got the id_anc using the surpf.f and LLOUSE flag in mgdraw. In general, the results make sense and work well except in some cases.

The first two rows are the last steps of a muon+. The id and id_anc are the same because the muon is transported. Another muon+ is created at index 2297 by decay (icode 102) from a pi- (id_anc 13) and the next rows show its transport.
What I don’t know how to interpret is the creation of that pi- (index 2291) which shows a pi+ as parent id (id_anc 14). This combination of 13 as id and 14 as id_anc and vice versa happens sometimes.
It also appears a few times Kaon- creating a pion+ and vice-versa.

I’m also attaching the user routines, the input file and the material cards in case these are useful for the analysis.

decay_acc.inp (9.4 KB)
atmomat.cards (28.7 KB)
stuprf.f (1.9 KB)
USRDRAW2.f (6.7 KB)

Thank you in advance,

Jordi

Dear @tuneu,

Thanks for opening the new thread and for your question.

I looked into the routine, and there is no problem there.
It is just a matter of how you interpreted the results.

So, you said the following:

What I don’t know how to interpret is the creation of that pi- (index 2291) which shows a pi+ as parent id (id_anc 14). This combination of 13 as id and 14 as id_anc and vice versa happens sometimes.
It also appears a few times Kaon- creating a pion+ and vice-versa.

First, a minor thing: 13 is for pi+, and 14 for pi-. Then, the parent is the pi- and the new particle a pi+ (I know it was just a typo, but I have to say it)

Second, as you correctly said:

Another muon+ is created at index 2297 by decay (icode 102) from a pi- (id_anc 13) and the next rows show its transport.

The row 2296 says that pi+ decayed, and in row 2297 a mu+ (id 10) is generated.

BUT, in row 2291 it just says that the parent of your pi- is a pi+ (id 14). The icode 103 expresses that there is a generation of delta rays by the pi-. You do not have information about how the pi+ generated the pi-.
To conclude, if you look in the file generated by MGDRAW, you will find a row with:
ICODE = 101, ID(JTRACK) = 14 and LTRACK = 2. Which means that your pi+ had a nuclear inelastic interaction, and this process generated the pi- that you observe in row 2291.

Similar situation for the K- creating a pi+.

I hope this clarifies a bit what you are observing.
Do not doubt in asking in case you need more assistance.

Have a nice weekend,
André

Dear @adonadon,

Thanks for your points on this question. I was misinterpreting some of the outputs.

Have a nice week!

Jordi

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