Re: [fluka-discuss]: Minimum distance to nearest boundary

From: Chris Theis <>
Date: Thu, 13 Jul 2017 09:24:02 +0000

Hi Anton,

Thanks for the info. If you could tell me the name of the intersection routine then I can implement the rest myself.


On 13 Jul 2017, at 11:21, Anton Lechner <<>> wrote:

For a particle step - in particular for charged particle steps which are small - one often does not need an accurate value, but an approximate value can be sufficient. This approximate value can be smaller than the real minimum distance, but can give an advantage in CPU time as it can be much faster calculated than a more accurate value (which can anyway not always be obtained analytically). This distance is accessible in the variable (DDNEAR) in the common CMMDNR, but depending on the type of body, it might only be a rough estimate (smaller than the real minimum) or it is not calculated at all (in the latter case it is set to zero). If this distance zero or if it is smaller than the step length, then the geometry tracker is used to propagate the particle, but also in this case one does not need the minimum distance but one needs to determine the intersection with a surface in the particle direction (while the minimum distance can theoretically be in the opposite direction).

Chris Theis
CERN/HSE-RP - European Organization for Nuclear Research
1211 Geneva 23, Switzerland
Phone: +41 22 767 8069 Office: 892-2A-015
e-mail:<> www:

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Received on Thu Jul 13 2017 - 12:32:21 CEST

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