|Message: Re: How to define the flux of particles?||Not Logged In (login)|
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Hello Lee, I would recommend the use of the GPS module in G4 for setting up the primary generator. To establish a particle source you need to define: 1. the particle source surface - the surface on which the primaries are generated 2. the angular distribution of the primaries - in space this is usually omni-directional 3. the energy spectrum The surface for generating the particle sources is in the most simple, a sphere that encapsulates the model. The angular distribution of radiation in space is generally assumed to be isotropic or omni-directional. There are deviations from this, e.g. at low altitudes in the South Atlantic Anomaly, during the rising phase of a solar proton event, or astronomical events such as gamma ray bursts. For radiation belts, solar proton event and cosmic ray analyses, though, the omni-directional assumption is usually valid. So, the omni-directional assumption requires a cosine-law to ensure a correct angular distribution. If it is radiation belt or solar protons that you are trying to simulate, then I'd recommend the SPENVIS system (http://www.spenvis.oma.be/) and it's mulassis model implementation to generate the energy spectrum GPS macro calls. Mulassis is a 1D general purpose Geant4 application. It will also provide you with examples on setting up the GPS parameters. Then there is the issue of tuning all of the above to ensure each event produces the data you require. This can be achieved through the biasing of the angles, energies, etc. Regards, Hugh ----- H. Evans ESA/ESTEC/TEC-EES Postbus 299 2200 AG Noordwijk The Netherlands Phone:+31 (0)71 565-5109 Fax: +31 (0)71 565-4999 Lee Xuesheng <email@example.com> wrote on 07/03/2006 08:54:08: > *** Discussion title: Space Applications > Email replies to firstname.lastname@example.org must include: > In-Reply-To: <"/space_app/16"@geant4-hn.slac.stanford.edu> > Subject: ...change this to be about your reply. > > When using the geant4 in application for Space Radiation,how can I > define the flux of particles(e- or gamma)? thanks
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