RE: [fluka-discuss]: GCR_IONF source units

From: Angelo Infantino <>
Date: Thu, 12 Nov 2015 17:55:16 +0100

Dear Roman,
I'll try to give you my answer based on my recent experience with the FLUKA-GCR. Anyway I ask to the developers to correct me in case I'm wrong.

When you ask to use the GCR source, FLUKA expects that you are using the model of the full Earth's atmosphere, as included in the FLUKA package, or a local atmosphere model created using the atmloc2011.f routine (please, for further details see the FLUKA manual, Chapter 16).

As reported in the manual:
"The set of FLUKA tools for cosmic ray simulation includes a set of core routines to manage event generation, geomagnetic effects and particle scoring, and the following stand-alone data files and programs: ..."

When using the full Earth's atmosphere or the local atmosphere FLUKA already knows the corresponding area of the regions of the atmosphere (namely Air001, Air002, etc) and all the other normalization factors to be applied to return the score in terms of flux (particle/cm2/s). This is usually extremely helpful, but when you create new regions you have to be very careful with this, indeed you see a "strange" value of the area in the USRBDX score you set.

Selecting "NO-NORM" in the GCR-SPE card you can get the RAW data from your simulation without any kind of further normalization applied. Please note that to be able to run the simulation you have to rename all the "izphiMV.spc" files (iz=1,...,28) as "izNO-NORM.spc", otherwise FLUKA is not able to recognize the primary source spectra.

I ran the input file that you posted in a previous discussion ( ) using the option reported above and I got a result in agreement with the primary source spectrum simulated. The USRBDX (the sum.lis file) reports correctly the area of your scoring surface (Detector n: 1( 1) usrbdx Area: 1256.63708 cmq,). Please note that without any other kind of normalization applied what you get is particle/cm2/sr/GeV per primary!!!

Hope this can help



Subject: [fluka-discuss]: GCR_IONF source units
Date: Thu, 12 Nov 2015 04:29:39 +0000

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Received on Thu Nov 12 2015 - 20:52:06 CET

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