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None Re: doped material properties 

Forum: Processes Involving Optical Photons
Re: None doped material properties (Jason Maldonis)
Date: 23 Jun, 2011
From: Joel Long <Joel Long>

Jason,

Properties related to optical physics (scintillation behavior, etc) are not handled the same way as other properties. Those properties are set via the G4MaterialPropertiesTable associated with a G4Material. In principle, you could "pass" these properties to your new, mixed material, but giving the new material a copy of the same G4MaterialPropertiesTable (if it has a copy constructor, I haven't checked), but this is almost certainly a bad idea - the new material will not have all the same properties. Some things, like its fast and slow time constants, may be, but its absorption spectrum will be completely different because of the other material mixed in. Geant4 cannot calculate these sorts of properties because they are macroscopic, dependent on things like molecular arrangement, not simple atomic composition. *We* know there is a huge difference between diamond and carbon; Geant4 just knows that one is more dense.

Hope this helps, Joel

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None Re: doped material properties  by Jason Maldonis <Jason Maldonis>,   23 Jun, 2011
Re: None Re: doped material properties (Joel Long)
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Yes that helps a lot. We decided to instead literally create tiny particles
(rectangles or spheres) and phyiscally "dope" the plastic material with
them. The problem with defining the parameters for the final material (the
one we wanted to create out of the plastic and scintillator) is simply that
we do not know them! So hopefully randomly filling the plastic with a
scintillator will work.
Thanks for your help!

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Yes that helps a lot. We decided to instead literally create tiny particles=
 (rectangles or spheres) and phyiscally &quot;dope&quot; the plastic materi=
al with them. The problem with defining the parameters for the final materi=
al (the one we wanted to create out of the plastic and scintillator) is sim=
ply that we do not know them! So hopefully randomly filling the plastic wit=
h a scintillator will work.<div>

Thanks for your help!</div>

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Idea Re: doped material properties  by Joel Long <Joel Long>,   23 Jun, 2011
Re: None Re: doped material properties (Jason Maldonis)
On Thu, 23 Jun 2011 19:41:39 GMT, Jason Maldonis wrote:
> --001636e1ebc7d2c50004a666452d
> Content-Type: text/plain; charset=ISO-8859-1
> 
> Yes that helps a lot. We decided to instead literally create tiny particles
> (rectangles or spheres) and phyiscally "dope" the plastic material with
> them. The problem with defining the parameters for the final material (the
> one we wanted to create out of the plastic and scintillator) is simply that
> we do not know them! So hopefully randomly filling the plastic with a
> scintillator will work.
> Thanks for your help!
> 

As a starting point, I would suggest using the "scintillation" properties (fast response, slow response, emission spectrum, etc) from your actual scintillating material, and using "optical" properties (absorption spectrum, index of refraction, etc) from your plastic. Unless you are doping quite heavily (to the point that "doping" is hardly the right word), the optical properties of the combined substance should be nearly the same as those of the plastic alone. If I may ask, what is the mix ratio?

Joel

None Re: doped material properties  by Jason Maldonis <Jason Maldonis>,   23 Jun, 2011
Re: Idea Re: doped material properties (Joel Long)
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That's exactly what we were thinking too. The mix ratio is 100:1, so 1%. Not
a whole lot so it shouldn't change the "optical" properties much at all but
it should add scintillation.
We didn't think about the simulation being slow... I'm just about done
writing the random number distribution though so we will try it and see how
it goes.
Jason



On Thu, Jun 23, 2011 at 2:55 PM, Joel Long <jllong@sandia.gov> wrote:

>
> *** Discussion title: Processes Involving Optical Photons
>
> On Thu, 23 Jun 2011 19:41:39 GMT, Jason Maldonis wrote:
>
> > --001636e1ebc7d2c50004a666452d
> > Content-Type: text/plain; charset=ISO-8859-1
> >
> > Yes that helps a lot. We decided to instead literally create tiny
> particles
> > (rectangles or spheres) and phyiscally "dope" the plastic material with
> > them. The problem with defining the parameters for the final material
> (the
> > one we wanted to create out of the plastic and scintillator) is simply
> that
> > we do not know them! So hopefully randomly filling the plastic with a
> > scintillator will work.
> > Thanks for your help!
> >
>
> As a starting point, I would suggest using the "scintillation"
> properties (fast response, slow response, emission spectrum, etc) from
> your actual scintillating material, and using "optical" properties
> (absorption spectrum, index of refraction, etc) from your plastic.
> Unless you are doping quite heavily (to the point that "doping" is
> hardly the right word), the optical properties of the combined substance
> should be nearly the same as those of the plastic alone. If I may ask,
> what is the mix ratio?
>
> Joel
>
> -------------------------------------------------------------
> Visit this GEANT4 at hypernews.slac.stanford.edu message (to reply or
> unsubscribe) at:
>
> http://hypernews.slac.stanford.edu/HyperNews/geant4/get/opticalphotons/394/1/2/1.html
>

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That&#39;s exactly what we were thinking too. The mix ratio is 100:1, so 1%=
. Not a whole lot so it shouldn&#39;t change the &quot;optical&quot; proper=
ties much at all but it should add scintillation.<div>We didn&#39;t think a=
bout the simulation being slow... I&#39;m just about done writing the rando=
m number distribution though so we will try it and see how it goes.<br clea=
r=3D"all">

Jason<br><br><br><br><div class=3D"gmail_quote">On Thu, Jun 23, 2011 at 2:5=
5 PM, Joel Long <span dir=3D"ltr">&lt;<a href=3D"mailto:jllong@sandia.gov">=
jllong@sandia.gov</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote=
" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">

<div class=3D"im"><br>
*** Discussion title: Processes Involving Optical Photons<br>
<br>
</div><div class=3D"im">On Thu, 23 Jun 2011 19:41:39 GMT, Jason Maldonis wr=
ote:<br>
<br>
&gt; --001636e1ebc7d2c50004a666452d<br>
&gt; Content-Type: text/plain; charset=3DISO-8859-1<br>
&gt;<br>
</div><div><div></div><div class=3D"h5">&gt; Yes that helps a lot. We decid=
ed to instead literally create tiny particles<br>
&gt; (rectangles or spheres) and phyiscally &quot;dope&quot; the plastic ma=
terial with<br>
&gt; them. The problem with defining the parameters for the final material =
(the<br>
&gt; one we wanted to create out of the plastic and scintillator) is simply=
 that<br>
&gt; we do not know them! So hopefully randomly filling the plastic with a<=
br>
&gt; scintillator will work.<br>
&gt; Thanks for your help!<br>
&gt;<br>
<br>
</div></div>As a starting point, I would suggest using the &quot;scintillat=
ion&quot;<br>
properties (fast response, slow response, emission spectrum, etc) from<br>
your actual scintillating material, and using &quot;optical&quot; propertie=
s<br>
(absorption spectrum, index of refraction, etc) from your plastic.<br>
Unless you are doping quite heavily (to the point that &quot;doping&quot; i=
s<br>
hardly the right word), the optical properties of the combined substance<br=
>
should be nearly the same as those of the plastic alone. If I may ask,<br>
what is the mix ratio?<br>
<br>
Joel<br>
<div class=3D"im"><br>
-------------------------------------------------------------<br>
Visit this GEANT4 at <a href=3D"http://hypernews.slac.stanford.edu" target=
=3D"_blank">hypernews.slac.stanford.edu</a> message (to reply or unsubscrib=
e) at:<br>
</div><a href=3D"http://hypernews.slac.stanford.edu/HyperNews/geant4/get/op=
ticalphotons/394/1/2/1.html" target=3D"_blank">http://hypernews.slac.stanfo=
rd.edu/HyperNews/geant4/get/opticalphotons/394/1/2/1.html</a><br>
</blockquote></div><br></div>

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More Re: doped material properties  by Joel Long <Joel Long>,   23 Jun, 2011
Re: Idea Re: doped material properties (Joel Long)
As a side note, I would guess that your "manual" mixing will run into difficulties - if you use small enough bits to get reasonably accurate results, the sheer number of volumes is going to make the simulation incredibly slow. At least, that would be my guess - I've never tried mixing that way.

None Re: doped material properties  by Joel Long <Joel Long>,   23 Jun, 2011
Re: None Re: doped material properties (Joel Long)
Gah, between diamond and graphite. That's what I get for not checking my post carefully.

Joel

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