Help with an error: error in opening Fad/F_neu_OO.dat

Dear Fluka users,

I’m running some cosmic rays simulations. They ran without errors when I set a fixed zenith angle (0, 30, 50, and 70 degrees). When I tried a uniform angle in phi and zenith angle between 20 snd 60 deg using the source_newgen.f it also seems running fine but suddenly I get an error message:

======================== Running FLUKA for cycle # 1200 ========================
Removing links
Removing temporary files
Saving output and random number seed
Error: No ranshower_uniform_angle_w21201 generated!


The error appears after some successful cycles. Also, I’m running some parallel simulations and I don’t get this error all the time, which makes me think that could be a specific position of the randomized primary particle, maybe related to the magnetic field inputs. Find attached the .err, .log, and .inp files. Some hint about where could be the error?

shower_uniform_angle_w2.inp (9.6 KB)
shower_uniform_angle_w21200.log (1.0 KB)
shower_uniform_angle_w21200.err (3.8 KB)

this does not seem to be a FLUKA error, rather a system error, since FLUKA cannot access the indicated file (that should happily sit in the data/Fad subdirectory of your FLUKA installation, as you can check). This access is requested just the first time the BME pre-equilibrium module is invoked, and - if the concerned file is actually there - its failure points to a temporary filesystem issue.

Thanks for your quick answer Francesco.

I thought about something related to Fluka because when I repeated the simulation with the same seed, the error appears in the same cycle. When I changed the seed number or the error doesn’t appears or I get it in a different cycle.

I will consult about this with the system administrators since I don’t run it on my computer. As soon as I have feedback from them (probably next week) I’ll back here for comments and close the topic.



Dear Jordi, your accurate report is appreciated.
The seed dependence can be explained by the fact that the access attempt is (not) made at the same point. Still, the systematic access failure is intriguing. Can you please already confirm that the concerned file is actually there and you - as system user - can read it?

Dear Francesco,

The file exists at …/fluka4-3.1/data/Fad.
After some other issues with the same directory (Fad, DDS,…), the error seemed to be a problem with permissions at Fluka installation subdirectories. After I got those permissions I could advance the stuck cycle and it looks is now working as expected.

Thanks for your help.

All the best,


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