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Question exrdm example (radioactive decay) 

Keywords: radioactive decay, exrdm example
Forum: Documentation and Examples
Date: 06 Mar, 2006
From: Victor <>


I am trying to run GEANT4 simulations where I would like to construct a radioactive sample to model a beta-decay. As a sample of the code I have used "exrdm" example. I have a few questions about this example. First of all, in the top of the file called "exrdm.out" one could see the usual output of the GEANT4. Namely, one could see the tag of the GEANT4's version with the day when this version was released. For the mentioned example the tag corresponds to the latest version of the GEANT4 (geant4-08-00-pathch-01), however the release day corresponds to the 27-July-2004. Therefore, I would like to know was this example compiled and run with the latest GEANT4 code and with the latest data library.

Secondly, I have found a part of the code (file called that I do not understand properly. This is a part where initial conditions of the particle that have been created during radioactive decay are stored. The initial information (particle name, energy, weight and time) is stored for any particle that is not a nucleus. If someone would like to simulate a beta-decay with GEANT4 one of the particles that would be created by Radioactive Decay process is neutrino, and neutrino is not a nucleus, and its initial information is stored as well. That could create a problem if one is interested in the emission spectra from radioactive nuclei that would be consisting i.e. from beta and gamma particles. For example, if we can choose decay of Co60 in the initial spectra that would be created by exrdm program we will not find a characteristic shape of the beta-spectra.

Thirdly, if in the command file called "" in the top of the file as an additional command I will add line "/control/saveHistory" as an output from GEANT4 I will get a file called G4History.macro. This file contains records of all commands that were sent to GEANT4. I am confused with the next line: /gps/pos/center 0. 0. -25 This line does not contain a dimension of the length for the center position, which seems a little bit suspicious. Originally in the code (file called general purpose source is set to the center of the World, which is half of the detector length (fDetectorLength = 5.0 * cm). So, I would expect that when I simulate 1GeV proton beam on the NaI target ( example) I should see an initial Z-position of the proton from the track information to be -25 mm. Nevertheless, the output from GEANT4 shows center of the source as -250 mm.

I am not an expert in GEANT4 and I would be appreciated any help from GEANT community. Regards, Victor Golovko. March 6, 2006

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1 None: Re: exrdm example (radioactive decay)   (Fan Lei - 07 Mar, 2006)
(_ None: Re: exrdm example (radioactive decay)   (Victor - 07 Mar, 2006)
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