[fluka-discuss]: Re: Understanding the difference between USRBDX and USRTRACK card

From: Ferreira De Almeida Lourenco, Ana <am.lourenco_at_ucl.ac.uk>
Date: Mon, 13 Jul 2015 16:54:54 +0000

Dear All,


Apologies, please find attached the graph I was referring to in the previous e-mail.


Many thanks,

Ana


________________________________
De: owner-fluka-discuss_at_mi.infn.it <owner-fluka-discuss_at_mi.infn.it> em nome de Ferreira De Almeida Lourenco, Ana <am.lourenco_at_ucl.ac.uk>
Enviado: 13 de julho de 2015 14:20
Para: fluka-discuss_at_fluka.org
Assunto: [fluka-discuss]: Understanding the difference between USRBDX and USRTRACK card


Dear Fluka experts,


I simulated a proton beam in a target cylinder and I am scoring fluence in a ring detector that surrounds my target using a USRBDX and a USRTRACK card.


Results from USRBDX card are integrated over solid angle and were normalized to the area of the detector and multiplied by the energy bin width and by 2pi (one-way scoring) in order to get fluence in units of cm-2.


Results from USRTRACK card were normalized to the volume and multiplied by the energy width in order to get fluence in units of cm-2.


I understand that USRBDX is a boundary crossing fluence (or current) estimator, and USRTRACK is a track-length estimator but I am struggling to understand the differences between these two cards when looking at my results.


The graph below shows Fluence (cm-2/primary) differential in energy using a USRBDX card (outer boundary: from RING to AIR, inner boundary: from AIR2 to RING), and using a USRTRACK card.

[X]


Why is the fluence from USRBDX higher than the fluence from USRTRACK card? I am aware that in some Monte Carlo codes the way how fluence is estimated is just valid to convex volumes/surfaces. Is this the case for FLUKA? In my geometry I am scoring fluence in a concave surface/volume.


Please find in attachment my input file.


Many thanks,

Ana




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Received on Mon Jul 13 2015 - 20:30:30 CEST

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