Forcing simulation of very short lived unstable nuclei

Physics Processes, Models and Cross Sections
1

Geant4 Version: V11.1.3
Operating System: Ubuntu 22.04.5 LTS
Compiler/Version: g++ 11.4.0
CMake Version: 3.22.1

Hello,

Is there a way to force the production of short lived unstable nuclei ?

Some mean time threshold parameter to set ?

I am looking for 16O states with a half life around 5 fs.

Thanks !

Romain

2

Hello @RomainBoffy ,

Could you be more specific about the “production” of your 16O? It is possible to use the state that you mention as your ion to be shot from the General Particle Source (GPS). Just use it with the correct parameters Z=8 A=16 Q=8 E=6917.1 keV

/gps/ion Z A Q E

Now, if what you want is to for the population of that state via Coulex or something else… that’s a complete different story.

/Pico

3

Hello @pico,

This production is made through hadronic process. Reaction of 2.7 MeV proton on Fluor.

This question is directly related to this previous post

4

Well,

I have never used biasing techiques myself but have a look at `examples/extended/biasing`. According to the README, This example illustrates how to bias process cross-sections which looks like what you might need.

It could be that you cannot biased the specific population of the state but if you can get better stats for your particular reaction that would be already good.

Please report back whether it worked for you.

Cheers,

/Pico

5

A small note about physics: in FTFP_BERT the isomer lifetime is limited to 1 nsec. So, you must tweak the generation physics not the decay process.