Dear Sizwe,
Bear in mind that the computer does calculations with finite (double)
precision. If you define touching surfaces, roundoff errors can
potentially lead to a wrong determination of which side of the surface a
particle is in, and in the worst of cases even lead to an unintended
space between the two (intended touching) surfaces. See the Geometry
lecture of the course, slide ~40, for a visual impression of this.
Hoping this is reasonably accurate,
Cesc
On Fri, Jun 08 2018, at 22:09 +0200, SIZWE SCELO MHLONGO wrote:
>
>Dear Cesc,
>
>Thank you for your help, I didn't realize regions had to share a boundary
>in order to be able to score boundary crossing particles between them. Just
>a follow up question, what kind of problems is one likely to come across if
>two regions share a boundary without a plane? Does it cause errors in the
>geometry or in the results? I ask because I have used the USRBDX card to
>score photon energies and I do not see some of the expected energies.
>Thanks.
>
>Regards,
>
>Sizwe
>
>On Fri, Jun 8, 2018 at 9:37 PM, Francesc Salvat-Pujol <
>francesc.salvat.pujol_at_cern.ch> wrote:
>
>> Dear Sizwe,
>>
>> I'm afraid the problem is that regions Bottle and Detector in your
>> geometry do not seem to share any "boundary" (see the zoomed-in
>> screenshot), so there cannot be a boundary crossing from Bottle to
>> Detector, hence the empty USRBDX scoring you observe.
>>
>> Note that the Detector region is defined in terms of +body6,
>>
>> RCC body6 0.001 0.0 22.601 0.0 0.0 .449 1.6
>>
>> which starts at (x,y,z)=(0.001,0.0,22.601) and extends farther along z,
>> whereas the Bottle region is defined in terms of
>>
>> RCC body1 0.0 0.0 16.7 0.0 0.0 5.9 1.6
>>
>> which starts at (0,0,16.7) and extends up to (0.0, 0.0, 22.6), i.e.,
>> .001 cm short of where the Detector starts in z.
>>
>> I would avoid defining regions with touching surfaces (it has trouble
>> written all over it). Instead of having two "touching" RCCs, define a
>> bigger one and use an XYP to separate between Bottle and Detector.
>>
>> Hope this helps,
>>
>> Cesc
>>
>> On Thu, Jun 07 2018, at 18:02 +0200, SIZWE SCELO MHLONGO wrote:
>>
>>>
>>> Dear FLUKA experts and fellow users,
>>>
>>> I've installed the latest FLUKA version
>>> (fluka2011.2x-linux-gfor64bit-6.4-AA) in a 64 bit machine (OS:Ubuntu
>>> 16.04). Most of my input files run and finish okay. My only problem is
>>> that
>>> the USRBDX card no longer scores the photon fluence as it did in the
>>> previous version, do you know what the problem could be? I've also
>>> attached
>>> one of the input files. Thanks.
>>>
>>> Regards,
>>>
>>> Sizwe
>>>
>>> --
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Disclaimer - This e-mail is subject to UWC policies and e-mail
>>> disclaimer published on our website at:
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>>>
>>>
>>>
>>>
>>>
>>
>>
>> --
>> Francesc Salvat Pujol
>> CERN-EN/STI
>> CH-1211 Geneva 23
>> Switzerland
>> Tel: +41 22 76 64011
>> Fax: +41 22 76 69474
>>
>
>--
>
>
>
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>
>
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>
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>
>
>Disclaimer - This e-mail is subject to UWC policies and e-mail
>disclaimer published on our website at:
>https://www.uwc.ac.za/Pages/emaildisclaimer.aspx
><https://www.uwc.ac.za/Pages/emaildisclaimer.aspx>
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--
Francesc Salvat Pujol
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
Tel: +41 22 76 64011
Fax: +41 22 76 69474
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Received on Tue Jun 12 2018 - 10:43:35 CEST