|Message: Re: Generating a Beam with a given Energy Probability Distribution||Not Logged In (login)|
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Indeed for special sources one might need to write come C++ code.
I have the impression, though, that the General Particle Source (GPS), combined with the radioactive decay physics, can already give you a ready-to-use solution.
GPS provides many options for spatial, angular and energy distribution of the source. In your case, you probably just need to specify a source of Sr90 ions, at rest (unless you have a radioactive beam facility), with the position distribution given by your actual source shape (maybe a Point as a first approximation, but many options are available).
You can find an example of how to use the GPS in the advanced example
For a detailed description of all GPS options, see http://reat.space.qinetiq.com/gps/new_gps_sum_files/gps_sum.htm (you can reach this link from the Geant4 User Support pages)
The Radioactive Decay process will give you the decay of the Sr90 with the correct spectrum for the secondary particles.
You might be interested in particular in the "fast beta generation option" fBeta of the radioactive decay process, to reduce CPU time.
You can find an example of how to use the radioactive decay physics in the example
In your case, I would start from a script such as the following one:
/gps/ion 38 90
/gps/ene/mono 0.0 MeV
/gps/pos/centre 0. 0. 0. cm
You can then switch on the tracking verbosity
to see wheather the decay actually happens, and start a few events
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Giovanni Santin Space Environments and Effects Analysis ESA - ESTEC - TEC-EES Keplerlaan 1, 2200 AG Noordwijk, Netherlands e-mail: email@example.com Tel: +31 71 565 6267 Fax: +31 71 565 4999
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