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Forum: Event and Track Management
Re: None Ion beam disappears entering in quadrupole field (Jorge Gallardo)
Re: Feedback Re: Ion beam disappears entering in quadrupole field (Gumplinger Peter)
Re: None Re: Ion beam disappears entering in quadrupole field (Jorge Gallardo)
Re: Feedback Re: Ion beam disappears entering in quadrupole field (Gumplinger Peter)
Date: 21 Mar, 2014
From: Jorge Gallardo <Jorge Gallardo>

>
>
> This is only true if you positioned the quadrupole (logical) volume
> without rotation or you rotate only around z. In all cases where you
> rotate around x and/or y the two don't coincide.
>

Yes, the quadrupole is set without rotation, then I suppose that the
z-local-axis coincide with the z-global one, Being z the beam axis.


> If you rotate around Z, all you are doing is rotate the quadrupole
> around its length axis. Is this what you want?


Yes, in order to simulate a quadrupole triplet, I need three quadrupole
fields. The quadrupole in the middle of the triplet is rotated 90 degrees
in z-axis relative to the other two. The three quadrupoles are different
instances of the same class, differing just in that angular argument when
constructed.


> Well, shouldn't 'Rot' not be 'trip_rot'?
>

I'm sorry, in order to save space in the latter post I have edited the code
then I pasted wrong. Let's say:  Rot = trip_rot

>
> Why anti-intuitive? If you want the axis of the quadropole away from the
> global z-axis but still in the horizontal plane, how do you have to
> rotate a lengthy box (in real live)? ... around y!


I suppose that the G4QuadrupoleMagField class was made by Geant4 in order
> to focus/rearrange beams in accelerator experimental beamlines, and if
> true, the z-axis should be the default axis of the beam to focus, (because
> is clear that the three main-axes of the quadrupole are not equivalent)...
> Then, seems to me a little anti-natural to needing to rotate the quadrupole
> in the other axes (X and Y)... But if I'm wrong, maybe X (or Y) the default
> axis (or even an non orthogonal one) for the beam.
>
>

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1 Feedback: Re: Ion beam disappears entering in quadrupole field   (Gumplinger Peter - 21 Mar, 2014)
(_ None: Re: Ion beam disappears entering in quadrupole field   (jorge gallardo - 01 Apr, 2014)
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