|Message: Geant vs EGS Dose-dept Disagreement||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
I've been doing some simple dose simulations with GEANT, but my results disagreed when compared with a similar EGSnrc simulation. I was looking at a monoenergetic photon beam (~100 keV) going through water with a layer of another material (tungsten, for instance). For instance: 3 cm water, followed by 2 cm tungsten, then 5 cm water. The geant sim shows less initial energy deposit (I'm using the eDep scorer on a cubic mesh) than the EGS sim.
Initially I was using the Livermore physics list, and saw no difference when switching to Penelope. When I switched to EmStandardPhysics I saw my dose-depth profile become more similar to EGS in the tungsten (but the backscatter disappears). No visible difference was seen in just water. I have my cuts set to 1 nm/ 100 eV. I've attached a plot comparing the 3 physics models in Geant.
Is the problem here EGSnrc, Geant, or me? I assumed that the EmLivermore package was better for the photoelectric effect (and similar low energy studies I'm doing) and that it was sufficient on its own. Should I be using EMStandard instead/in addition? Is Geant (Livermore) getting the physics "right" and EGSnrc has it "wrong"?
I'm hoping there is a simple explanation. Thank you in advance.
|Inline Depth:||Outline Depth:||Add message:|