Modifying half-life of No252 in rdecay01 example

Physics Processes, Models and Cross Sections
1

Geant4 Version: 11.2.1
Operating System: macOS Sonoma 14.4.1
Compiler/Version: C++98
CMake Version: 3.29.2

I am having issues altering the half-lives of nuclear excited states in Geant. I think the best way to illustrate my issue is through the rdecay01 example in 11.2.1. If I run the No252.mac file with no modifications, I get the appropriate mean life listed in the terminal output of the macro. However, this mean life (3.52 s) does not change even when I edit the UserData/UserEvapData_z102.a252 file, stored in the rdecay01 directory, to increase the half-life of the ground state. The terminal still gives the same mean life of 3.52 s. This is a general issue I am having with Geant, both with v11.2.1 and older versions. I seem unable to control the half-life of metastable states by editing the photon evaporation files. Are there any solutions here?

2

@MarkMurdy

Hello,

Have you defined the decay file in the macro you used “No252.mac”.
In case not defined, please add it in macro;

 /grdm/setRadioactiveDecayFile path2/filename

#OR 

 /grdm/setPhotoEvaporationFile path2/filename

VRS

3

I am using that line, with the exception that the most recent version of Geant uses /process/had/rdm/ instead of /grdm/. I am referring to the following line in the rdecay01 example that comes with Geant:

/process/had/rdm/setPhotoEvaporationFile 102 252 ../UserData/UserEvapData_z102.a252

When I try updating the UserEvapData_z102.a252 file, it has no effect on the code output.

The complete script is here:

# macro for rdecay01
#
# to read user's data file
#
/control/cout/ignoreThreadsExcept 0
#
# Set a very high time threshold to allow all decays to happen
/process/had/rdm/thresholdForVeryLongDecayTime 1.0e+60 year
#
/process/had/rdm/setPhotoEvaporationFile 102 252 ../UserData/UserEvapData_z102.a252
#
/gun/particle ion
/gun/ion 102 252 0 3.2070e+02 
#
/run/beamOn 100000
4

RadioactiveDecay process needs not only RadioactiveDecay and PhotonEvaporation datasets, but also G4ENSDFSTATE.
In particular, timeLife of isotopes are read from G4ENSDFSTATE and there is no way for a user to change it, unless to modify directly G4ENSDFSTATE.

5

So there is no way via macros to update the lifetimes of metastable states. We just need to directly modify the source files in G4ENSDFSTATE?

6

I my knowledge, yes.
You can ask details or confirmation directly to Alberto.Ribon@cern.ch or luis.sarmiento_pico@hep.lu.se or Vladimir.Ivantchenko@cern.ch

7

maybe you can use some code like this:

G4ParticleDefinition *fParticle = fIonTable->GetIon(71, 176, 0.0 * keV);
fParticle->SetPDGLifeTime(1 * s);