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Hello,<br>
<br>
In principle, the optical absorption length is the average distance
traveled by the photon before being absorbed by the medium. This
absorption length must be given by the user of GATE in the file
"Materials.xml". But I think that there is bug in considering the user
entered absorption length by Geant4. I noticed this problem with GATE
6.1 compiled with geant4.9.4.p01. In fact, I added the optical
properties of the the the liquid xenon in the "Materials.xml" file with
absorption length of about 35 cm, but in the tracking of Geant4 I see
that the track length of optical photons before absorption is of
random values between 1 and 11 cm !.<br>
<br>
Abdul Fattah<br>
<br>
Vesna Cuplov wrote:
<blockquote
cite="mid:CAOibXMH9UDiMtRx4VzZtFKv=hvPcMrpQ+LG2ro2vDm-L2RKung@mail.gmail.com"
type="cite"><br>
The optical photon travels in the medium through steps. The step length
is calculated from the probability of interaction based on <br>
the physics process (absorption, scattering, ....) cross section. The
process that is applied is the one that produced the minimum <br>
step length. <br>
<br>
<br>
<br>
<div class="gmail_quote">On Mon, Jan 7, 2013 at 9:35 PM, Jenny
Nilsson <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:jenny.nilsson@radfys.gu.se" target="_blank">jenny.nilsson@radfys.gu.se</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div dir="auto">
<div>Hello, </div>
<div>Yes I know. But if, for example, the absorption length is 300
cm then all optical photons will not travel 300 cm before being
absorbed, the beam intensity will be 1/e after one absorption length. <br>
<br>
What I'm interested in is when in the calculations is the distance an
optical photon travels determined. Is the distance sampled from a
probability distribution before the actual transport begins? </div>
<div><br>
</div>
<div>Best regards</div>
<div>Jenny </div>
<br>
</div>
</blockquote>
</div>
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