[Gate-users] generic trapezoid volume (pinhole)

[Tasneem Rahman]

Hi John,

Can you please tell me how can I subtract objects from one another in Gate_v6.1? For instance if I make one solid box and if I make another cylinder as a daughter of the box, then can I subtract the cylinder from the box? Will it make a hole like that? Please let me know. Thanks.

Cheers,

Smita

From: gate-users-bounces at lists.opengatecollaboration.org [mailto:gate-users-bounces at lists.opengatecollaboration.org] On Behalf Of John Apostolakis
Sent: Wednesday, 28 May 2014 3:25 AM
To: Débora Salvado
Cc: <gate-users at lists.opengatecollaboration.org>
Subject: Re: [Gate-users] generic trapezoid volume (pinhole)

I am not sure if this will help:

If all your pinholes are the same shape (or can be created by subtracting the same "generic trapezoid" shape from the bigger shape) then in Geant4 at least you only need to define one 'solid'.

Then you subtract it multiple times, with each copy positioned at a different location and/or with a different orientation.  ( The orientation will be governed by the rotation matrix and the translation that you give it.)

I hope that I understood your issue - or that someone else can add the specialised GATE knowledge necessary to give better advice.

Regards,
John
===================================================

On May 27, 2014, at 5:50 PM, Débora Salvado wrote:


Dear GATE users,
I'm trying to use the "generic trapezoid" volume to define a multi-pinhole collimator, with each pinhole focusing different parts of the FOV.
Consider the following set-up:

/gate/world/daughters/name trap1
/gate/world/daughters/insert  trap
/gate/trap1/geometry/setDx1   26. mm
/gate/trap1/geometry/setDx2   26. mm
/gate/trap1/geometry/setDz    5. mm
/gate/trap1/geometry/setTheta 0. deg
/gate/trap1/geometry/setDy1   26. mm
/gate/trap1/geometry/setDy2   21. mm
/gate/trap1/geometry/setDx3   21. mm
/gate/trap1/geometry/setDx4   21. mm
/gate/trap1/geometry/setPhi   90. deg
/gate/trap1/geometry/setAlp1  0. deg
/gate/trap1/geometry/setAlp2  0. deg
/gate/trap1/setMaterial  Air
/gate/trap1/placement/setTranslation  0. 0. 0. mm
When I change the "theta" parameter, the face at +pDz goes up or down in the Y direction.
How can I make that same face move in the X direction (right or left)?
I tried to modify the phi/Alp1/Alp2 parameters, but the visualization either stays the same or it gives me an error...

Thank you in advance,

Debora Salvado
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