|Message: Re: Creating a helical solid in Geant 4||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
Dear Lech, It may be that you need to write a solid to describe the shape that you need. Creating a new shape for Geant4 is neither a small nor a very large undertaking - either cobbled-together using similar solids or creating one from scratch. I suggest to consider whether an existing solid, such as the torus, may offer a reasonable approximation for your measurement - or at least an estimate which could be useful. Of course you would need to adapt what you measure, e.g. by only firing optical photons in a particular direction or using a revised distribution of directions. If this is challenging, or only the full detailed solid can be used, then you should consider creating a class to describe this solid. The Toolkit developer's guide provides information on how to do this - and you can use an existing solid such as the Tubs or Torus as a starting point in creating the methods which are required. In this case, of course, you will need to determine - whether a position is inside the solid - how a straight line 'ray' intersects the surface of the solid - potentially this can be the same underlying method, with a few small customisations for starting inside or outside the solid, or it could be two different methods; - the DistanceToIn/Out( G4ThreeVector ) methods can return a very aproximate answer, so long as it is alway conservative (ie an underestimate) - the CalculateExtent method is critical, as the Navigator relies on the values it returns. If you go this way, and create a solid of your own, we can share some programs from our test suite to help you check its self-consistency. Best regards, John Apostolakis On 9/5/13 7:48 AM, Lech Wiktor Piotrowski wrote: *** Discussion title: Geometry In my case I test a wavelenghshifting fiber around a plastic scintilator cylinder. I have to find out the optimal pitch of the helix - the denser it is the bigger the area for photons to hit, but the longer the fiber and more absorption in it. So there is an optimum, and the helix is not dense. ------------------------------------------------------------- Visit this GEANT4 at hypernews.slac.stanford.edu<http://hypernews.slac.stanford.edu> message (to reply or unsubscribe) at: http://hypernews.slac.stanford.edu/HyperNews/geant4/get/geometry/1294/1/1/1/1.html [ MIME part of type text/html without a name stripped ]
|Inline Depth:||Outline Depth:||Add message:|