[Gate-users] Optical photon transport in Gate 6

[Vesna Cuplov]

Dear Marcin,

My problem is to get an idea of how position sensitive photomultiplier or
> SiPMT would see the photons coming from the crystal in the above example.
> Namely at which position on the surface of the PMT the photon would end up.
> When I visualize the hits in TreeViewer of root, I can see the photons only
> inside the crystal and not "passing" to PMT, or through the respective
> surface between pixel and PMT. Is anybody of  you doing anything similar,
> or
> understand better the functioning of the optical photon transport? I use
> vGate 1.0 (that is Gate 6.0 patch 1 in Ubuntu 9).
>

As far as I understood the Gate user's guide for optical photons you are
supposed to use
as SD the volume from which your photons are coming before touching the
surface of your
PMT (that is your detector). I guess pixel is your SD? Therefore all the
hits will only be
recorded in the pixel crystal, nothing inside the PMT. But you should see
the hits on the
surface between the pixel(SD) and the PMT if you used a dielectric-metal
surface. These
hits correspond to the position of the absorbed (detected) photons.

If you try the following settings in your Surface.xml file, you will
detected all the optical
photons on the surface (ex: perfect_apd) between the pixel (your SD) and
the PMT:

 <surface name="perfect_apd" type="dielectric_metal" sigmaalpha="0.0"
finish="ground">
    <propertiestable>
      <propertyvector name="SPECULARLOBECONSTANT" energyunit="eV">
    <ve energy="4.08" value="0"/>
    <ve energy="1.84" value="0"/>
      </propertyvector>
      <propertyvector name="SPECULARSPIKECONSTANT" energyunit="eV">
    <ve energy="4.08" value="0"/>
    <ve energy="1.84" value="0"/>
      </propertyvector>
      <propertyvector name="BACKSCATTERCONSTANT" energyunit="eV">
    <ve energy="4.08" value="0"/>
    <ve energy="1.84" value="0"/>
      </propertyvector>
      <propertyvector name="REFLECTIVITY" energyunit="eV">
    <ve energy="4.08" value="0.0"/>
    <ve energy="1.84" value="0.0"/>
      </propertyvector>
      <propertyvector name="EFFICIENCY" energyunit="eV">
    <ve energy="4.08" value="1."/>
    <ve energy="1.84" value="1."/>
      </propertyvector>
    </propertiestable>
  </surface>

Let me know if this helps.

vesna