Message: RE: Optical Photons Detection Not Logged In (login)
 Next-in-Thread Next-in-Thread
 Next-in-Forum Next-in-Forum

None RE: Optical Photons Detection 

Forum: Processes Involving Optical Photons
Re: None Optical Photons Detection (Victor)
Date: 06 Jul, 2011
From: Robert Penny <Robert Penny>

This is a multi-part message in MIME format.

------_=_NextPart_001_01CC3C35.749A10F3
Content-Type: text/plain;
 charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

Hi Victor,

I'm not one of the Geant support gurus, just a user.  However, it just =
so happens this is exactly the problem I've been working on today.  For =
what it's worth, this approach seems to be working for me.

I'm defining the photocathode as a dielectric_metal optical surface then =
attaching this to a logical border surface.  The absorption or detection =
happens as the optical photon tries to cross the film.  The trick is =
that the photon doesn't make it into the next volume.  You need to make =
the sensitive detector the volume the photon is leaving, and put the =
film (border surface) on the exit surface of the volume.  If you look at =
the last step taken in the sensitive detector you'll even find that the =
optical photon has deposited energy if it was a "detection" instead of =
an "absorption".

Make sure your sensitive detector bulk material is transparent (has an =
index).  I've just made a small disk of the same material as the PMT =
glass and placed it on the inner surface of the PMT window.  The logical =
border surface is the interface between this disk (Photocathode_phys) =
and the inner PMT vacuum (PMT_inner_phys).

The code snippet below is where I define the optical surfaces.  It =
doesn't include the definition of the bulk materials and volumes etc., =
but hopefully there will be enough here to get it to work in your case.

Hope this is of some help.

-Rob Penny (robert.d.penny@saic.com)

//
// PMT window to photocathode
//
  G4cout << "Constructing PMT - Photocathode surface" << G4endl;

  G4OpticalSurface* OpPmtPhotocathodeFilmSurface=20
      =3D new G4OpticalSurface("PhotocathodeWindowFilmSurface");

  OpPmtPhotocathodeFilmSurface->SetType(dielectric_metal);
  OpPmtPhotocathodeFilmSurface->SetFinish(polished);
  OpPmtPhotocathodeFilmSurface->SetModel(unified);

  G4MaterialPropertiesTable* MPT_Photocathode =3D new =
G4MaterialPropertiesTable();

  const G4int nEntries2 =3D 2;

  G4double RealIndex_Bialkali[nEntries2]  =3D { 2.7, 2.7 };
  G4double ImagIndex_Bialkali[nEntries2]  =3D { 1.5, 1.5 };
  G4double Efficiency_Bialkali[nEntries2] =3D { 1.0, 1.0 };

  MPT_Photocathode->AddProperty(
 "REALRINDEX",      PhotonEnergy2, RealIndex_Bialkali,  nEntries2);

  MPT_Photocathode->AddProperty(
 "IMAGINARYRINDEX", PhotonEnergy2, ImagIndex_Bialkali,  nEntries2);

  MPT_Photocathode->AddProperty(
 "EFFICIENCY",      PhotonEnergy2, Efficiency_Bialkali, nEntries2);

  =
OpPmtPhotocathodeFilmSurface->SetMaterialPropertiesTable(MPT_Photocathode=
);

  G4LogicalBorderSurface*=20
    PhotocathodeFilmLogicalBorderSurface=20
      =3D new G4LogicalBorderSurface(
       "PmtPhotocathodeFilmSurface",
       Photocathode_phys, PMT_inner_phys, OpPmtPhotocathodeFilmSurface);



-----Original Message-----
From: douglas@slac.stanford.edu on behalf of Victor Khristenko
Sent: Wed 7/6/2011 3:29 PM
To: opticalphotons-g4hn@slac.stanford.edu
Subject: Optical Photons Detection
=20

*** Discussion title: Processes Involving Optical Photons

--bcaec54ee01c3267e504a76e226e
Content-Type: text/plain; charset=3DISO-8859-1

Hi,

I'm trying to count optical photons which hit the PhotoMultiplier and I =
ran
into a problem :

There is a scintillator in front of the PM and  I put the optical =
surface in
front and try to check the boundary process, if it is detection then
increment the number of detected photons.
I took this idea from previous postings and from LXE example, which =
comes
with Geant4 Installation Package.
But I tried to use Sensitive detector at the same time, but it didn't =
give
me even a close number.

At the same time if I take OpticalSurface away, there are a lot if hits =
in
the sensitive detector.

Could you please explain which method is better and why does this =
happen???
My intentions is to count optical photons generated versus detected.

Thank you very much for your help!!!
Victor.

--bcaec54ee01c3267e504a76e226e
Content-Type: text/html; charset=3DISO-8859-1
Content-Transfer-Encoding: quoted-printable

Hi, <br><br>I'm trying to count optical photons which hit the =
PhotoMult=3D
iplier and I ran into a problem :<br><br>There
 is a scintillator in front of the PM and=3DA0 I put the optical surface =
in=3D
=3D20
front and try to check the boundary process, if it is detection =
then=3D20
increment the number of detected photons.<br>
I took this idea from previous postings and from LXE example, which =
comes w=3D
ith Geant4 Installation Package.<br>But I tried to use Sensitive =
detector a=3D
t the same time, but it didn't give me even a close number. <br><br>

At the same time if I take OpticalSurface away, there are a lot if hits =
in =3D
the sensitive detector.<br><br>Could you please explain which method is =
bet=3D
ter and why does this happen??? My intentions is to count optical =
photons g=3D
enerated versus detected.<br>
<br><font color=3D3D"#888888">Thank you very much for your =
help!!!<br>Victor.=3D
<br></font>

--bcaec54ee01c3267e504a76e226e--

-------------------------------------------------------------
Visit this GEANT4 at hypernews.slac.stanford.edu message (to reply or =
unsubscribe) at:=20
http://hypernews.slac.stanford.edu/HyperNews/geant4/get/opticalphotons/40=
2.html=20


------_=_NextPart_001_01CC3C35.749A10F3
Content-Type: text/html;
 charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; =
charset=3Diso-8859-1">
<META NAME=3D"Generator" CONTENT=3D"MS Exchange Server version =
6.5.7655.4">
<TITLE>RE: Optical Photons Detection</TITLE>
</HEAD>
<BODY>
<!-- Converted from text/plain format -->

<P><FONT SIZE=3D2>Hi Victor,<BR>
<BR>
I'm not one of the Geant support gurus, just a user.&nbsp; However, it =
just so happens this is exactly the problem I've been working on =
today.&nbsp; For what it's worth, this approach seems to be working for =
me.<BR>
<BR>
I'm defining the photocathode as a dielectric_metal optical surface then =
attaching this to a logical border surface.&nbsp; The absorption or =
detection happens as the optical photon tries to cross the film.&nbsp; =
The trick is that the photon doesn't make it into the next volume.&nbsp; =
You need to make the sensitive detector the volume the photon is =
leaving, and put the film (border surface) on the exit surface of the =
volume.&nbsp; If you look at the last step taken in the sensitive =
detector you'll even find that the optical photon has deposited energy =
if it was a &quot;detection&quot; instead of an =
&quot;absorption&quot;.<BR>
<BR>
Make sure your sensitive detector bulk material is transparent (has an =
index).&nbsp; I've just made a small disk of the same material as the =
PMT glass and placed it on the inner surface of the PMT window.&nbsp; =
The logical border surface is the interface between this disk =
(Photocathode_phys) and the inner PMT vacuum (PMT_inner_phys).<BR>
<BR>
The code snippet below is where I define the optical surfaces.&nbsp; It =
doesn't include the definition of the bulk materials and volumes etc., =
but hopefully there will be enough here to get it to work in your =
case.<BR>
<BR>
Hope this is of some help.<BR>
<BR>
-Rob Penny (robert.d.penny@saic.com)<BR>
<BR>
//<BR>
// PMT window to photocathode<BR>
//<BR>
&nbsp; G4cout &lt;&lt; &quot;Constructing PMT - Photocathode =
surface&quot; &lt;&lt; G4endl;<BR>
<BR>
&nbsp; G4OpticalSurface* OpPmtPhotocathodeFilmSurface<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =3D new =
G4OpticalSurface(&quot;PhotocathodeWindowFilmSurface&quot;);<BR>
<BR>
&nbsp; OpPmtPhotocathodeFilmSurface-&gt;SetType(dielectric_metal);<BR>
&nbsp; OpPmtPhotocathodeFilmSurface-&gt;SetFinish(polished);<BR>
&nbsp; OpPmtPhotocathodeFilmSurface-&gt;SetModel(unified);<BR>
<BR>
&nbsp; G4MaterialPropertiesTable* MPT_Photocathode =3D new =
G4MaterialPropertiesTable();<BR>
<BR>
&nbsp; const G4int nEntries2 =3D 2;<BR>
<BR>
&nbsp; G4double RealIndex_Bialkali[nEntries2]&nbsp; =3D { 2.7, 2.7 =
};<BR>
&nbsp; G4double ImagIndex_Bialkali[nEntries2]&nbsp; =3D { 1.5, 1.5 =
};<BR>
&nbsp; G4double Efficiency_Bialkali[nEntries2] =3D { 1.0, 1.0 };<BR>
<BR>
&nbsp; MPT_Photocathode-&gt;AddProperty(<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
&quot;REALRINDEX&quot;,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; PhotonEnergy2, =
RealIndex_Bialkali,&nbsp; nEntries2);<BR>
<BR>
&nbsp; MPT_Photocathode-&gt;AddProperty(<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &quot;IMAGINARYRINDEX&quot;, =
PhotonEnergy2, ImagIndex_Bialkali,&nbsp; nEntries2);<BR>
<BR>
&nbsp; MPT_Photocathode-&gt;AddProperty(<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
&quot;EFFICIENCY&quot;,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; PhotonEnergy2, =
Efficiency_Bialkali, nEntries2);<BR>
<BR>
&nbsp; =
OpPmtPhotocathodeFilmSurface-&gt;SetMaterialPropertiesTable(MPT_Photocath=
ode);<BR>
<BR>
&nbsp; G4LogicalBorderSurface*<BR>
&nbsp;&nbsp;&nbsp; PhotocathodeFilmLogicalBorderSurface<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =3D new G4LogicalBorderSurface(<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
&quot;PmtPhotocathodeFilmSurface&quot;,<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Photocathode_phys, PMT_inner_phys, =
OpPmtPhotocathodeFilmSurface);<BR>
<BR>
<BR>
<BR>
-----Original Message-----<BR>
From: douglas@slac.stanford.edu on behalf of Victor Khristenko<BR>
Sent: Wed 7/6/2011 3:29 PM<BR>
To: opticalphotons-g4hn@slac.stanford.edu<BR>
Subject: Optical Photons Detection<BR>
<BR>
<BR>
*** Discussion title: Processes Involving Optical Photons<BR>
<BR>
--bcaec54ee01c3267e504a76e226e<BR>
Content-Type: text/plain; charset=3DISO-8859-1<BR>
<BR>
Hi,<BR>
<BR>
I'm trying to count optical photons which hit the PhotoMultiplier and I =
ran<BR>
into a problem :<BR>
<BR>
There is a scintillator in front of the PM and&nbsp; I put the optical =
surface in<BR>
front and try to check the boundary process, if it is detection then<BR>
increment the number of detected photons.<BR>
I took this idea from previous postings and from LXE example, which =
comes<BR>
with Geant4 Installation Package.<BR>
But I tried to use Sensitive detector at the same time, but it didn't =
give<BR>
me even a close number.<BR>
<BR>
At the same time if I take OpticalSurface away, there are a lot if hits =
in<BR>
the sensitive detector.<BR>
<BR>
Could you please explain which method is better and why does this =
happen???<BR>
My intentions is to count optical photons generated versus detected.<BR>
<BR>
Thank you very much for your help!!!<BR>
Victor.<BR>
<BR>
--bcaec54ee01c3267e504a76e226e<BR>
Content-Type: text/html; charset=3DISO-8859-1<BR>
Content-Transfer-Encoding: quoted-printable<BR>
<BR>
Hi, &lt;br&gt;&lt;br&gt;I'm trying to count optical photons which hit =
the PhotoMult=3D<BR>
iplier and I ran into a problem :&lt;br&gt;&lt;br&gt;There<BR>
&nbsp;is a scintillator in front of the PM and=3DA0 I put the optical =
surface in=3D<BR>
=3D20<BR>
front and try to check the boundary process, if it is detection =
then=3D20<BR>
increment the number of detected photons.&lt;br&gt;<BR>
I took this idea from previous postings and from LXE example, which =
comes w=3D<BR>
ith Geant4 Installation Package.&lt;br&gt;But I tried to use Sensitive =
detector a=3D<BR>
t the same time, but it didn't give me even a close number. =
&lt;br&gt;&lt;br&gt;<BR>
<BR>
At the same time if I take OpticalSurface away, there are a lot if hits =
in =3D<BR>
the sensitive detector.&lt;br&gt;&lt;br&gt;Could you please explain =
which method is bet=3D<BR>
ter and why does this happen??? My intentions is to count optical =
photons g=3D<BR>
enerated versus detected.&lt;br&gt;<BR>
&lt;br&gt;&lt;font color=3D3D&quot;#888888&quot;&gt;Thank you very much =
for your help!!!&lt;br&gt;Victor.=3D<BR>
&lt;br&gt;&lt;/font&gt;<BR>
<BR>
--bcaec54ee01c3267e504a76e226e--<BR>
<BR>
-------------------------------------------------------------<BR>
Visit this GEANT4 at hypernews.slac.stanford.edu message (to reply or =
unsubscribe) at:<BR>
<A =
HREF=3D"http://hypernews.slac.stanford.edu/HyperNews/geant4/get/opticalph=
otons/402.html">http://hypernews.slac.stanford.edu/HyperNews/geant4/get/o=
pticalphotons/402.html</A><BR>
<BR>
</FONT>
</P>

</BODY>
</HTML>
------_=_NextPart_001_01CC3C35.749A10F3--

 Add Message Add Message
to: "RE: Optical Photons Detection"

 Subscribe Subscribe

This site runs SLAC HyperNews version 1.11-slac-98, derived from the original HyperNews