[Gate-users] difference between User Mode and arbitrary mode

[STRYDHORST Jared]

If I understand correctly, the difference between arbitrary and user histogram is that in user mode, the energies are uniformly distributed between the upper and lower edges of each bin. In arbitrary mode, the the energy distribution is interpolated between the points.

I think if you want to use the G4 mechanism for creating an energy histogram, before entering the points, you have to call "/gate/source/[source_name]/gps/histname arb" if you want to use the arbitrary energy spectrum, or "/gate/source/[source_name]/gps/histname energy" if you want to use the user energy histogram (consistent naming conventions were not a high priority here). You could also use the command "/gate/source/[source_name]/gps/hist/type" command to do the same thing. (GATE has helpfully created duplicates of the same commands with slightly different names (and perhaps an additional option or two) at different levels of the command hierarchy which is not at all confusing.) If you don't call this command first before entering histogram points, I think it will modify the bias of the x-position random generator.

Likewise, you can enter the points using either "/gate/source/[source_name]/gps/histpoint" or "/gate/source/[source_name]/gps/hist/point".

If you use the arbitrary spectrum, you then have to set the interpolation method. Again, you have your choice of commands. "/gate/source/[source_name]/gps/arbint" or "/gate/source/[source_name]/gps/hist/inter". Followed by "Lin" or "Log" or whatever.

And finally the energy distribution type has to be set to either User or Arb, as desired. You do this with either "/gate/source/[source_name]/gps/ene/type" or "/gate/source/[source_name]/gps/energytype". The latter command however allows for a longer list of options than the former, including something called UserSpectrum. This UserSpectrum type duplicates, more or less, the functionality of both the Arb and User options (although it only does linear interpolation and not log or exponential or spline interpolation for the arbitrary spectrum.)

Use of the UserSpectrum is documented here: http://wiki.opengatecollaboration.org/index.php/Users_Guide_V7.2:Source#Defining_the_energy This is probably an easier approach than using the G4 mechanism.


Jared STRYDHORST

Laboratoire Imagerie Moléculaire In Vivo (IMIV)
UMR 1023 Inserm/CEA/Université Paris Sud - ERL 9218 CNRS
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<mailto:karima.ait-aissa at cea.fr>
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De : gate-users-bounces at lists.opengatecollaboration.org [gate-users-bounces at lists.opengatecollaboration.org] de la part de NEGRE Pauline [pauline.negre at irsn.fr]
Envoyé : jeudi 3 mars 2016 18:29
À : gate-users at lists.opengatecollaboration.org
Objet : [Gate-users] difference between User Mode and arbitrary mode

Hi everyone !

I’m looking for details about the user mode and the arbitrary mode on the section “define the source” on Gate.
In fact, I am working on a Ra spectrum and I am using “gps/histpoint” to create an histogram macro of the energies. I enter on the first column  the energy in MeV and on the second column the weight. I use for the moment the user mode, but I’m not sure it’s the good one. Secondly,  When I run the simulation, I can see when the Parent ID = 0, the first KinE (MeV) is never one of my energy I entered.  Could you enlighten me about this question?
Thank you.
Pauline N.
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