RE: The maximum number of binnings in USRBIN

From: Anton Lechner <>
Date: Sat, 31 Aug 2013 11:30:33 +0000

Dear Chenyuan,

You misunderstood the comment in the manual: "maximum number of binnings" refers to the number of USRBINs you can have and not to the number of bins (see Manual: "A 'binning' is a regular spatial mesh"). The number of bins you can have is limited by the memory available for scorings:
*) See following answer on the FLUKA discuss list: the memory allocation is hard-wired in the library and is 360 MB
*) It is not important how many bins you have per USRBIN, but how many you have in total for all USRBINs
*) Your mesh of 10000*10000*1 occupies 800 MB and is hence far beyond the limit of allocated memory

Apart from this, I have some further comments:
*) Even if such a large number of bins would be possible, you should ask yourself if it would make sense. First, your smallest geometric structure is 20 um in x and 6 mm in y, while you aim for a bin size of less than 1 um in both x and y. Secondly, such a large number of bins would probably be challenging in terms of statistical error.
*) Your primary electrons have an energy of 160 keV, but the transport cut-off and production threshold set by PRECISIO is 100 keV. You should ask yourself if this difference between primary energy and cut is sufficient for your problem. You can set lower cut values with the EMFCUT card.
*) Note that if you have such low primary electron energies and um geometries, you should consider applying single scattering. I also quote the FLUKA manual: "The minimum recommended energy for PRIMARY electrons is about 50 to 100 keV for low-Z materials and 100-200 keV for heavy materials, unless the single scattering algorithm is used. Single scattering transport allows to overcome most of the limitations at low energy for the heaviest materials at the price of some increase in CPU time."

Cheers, Anton

From: [] on behalf of []
Sent: 31 August 2013 05:19
Subject: The maximum number of binnings in USRBIN

Dear Fluka experts,

I have a question about the maximum number of binnings that I can define in USRBIN.It seems to go wrong when I set the number of
binnings=10000 or 8000 in my input file.But when I set the number of binnings=1000,it runs normal. Meanwhile,I note in the Fluka
manual"The maximum number of binnings that the user can define is 400. This value can be changed by modifying the parameter MXUSBN
in member USRBIN of the flukapro library or directory and then re-compiling and linking Fluka." In the manual,It says the maximum
number of binnings that the user can define is 400.But when I set the number of binnings=1000,I do not modify the parameter
MXUSBN.But the fluka runs normal.The attachments are my input file and .out file.Could you help me?

Thanks for any suggestions.

Received on Sat Aug 31 2013 - 14:50:10 CEST

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