The setup of cut is not work

Physics Lists
1

The cut is set in the main program, the code is:
physicsList->SetCutValue(0.*mm,“e-”);
physicsList->SetCutValue(0.*mm,“e+”);
physicsList->SetCutValue(0.mm,“gamma”);
physicsList->SetCutValue(0.001mm,“proton”);

but it is not work.

2

I’m sorry, but we’ll need more information than this - what is not working, and what did you want to happen?

3

@bmorgan, when setting the cut in main program like this:
physicsList->SetCutValue(0.*mm,“e-”);
physicsList->SetCutValue(0.*mm,“e+”);
physicsList->SetCutValue(0.mm,“gamma”);
physicsList->SetCutValue(0.001mm,“proton”);

and this
physicsList->SetCutValue(1e6mm,“e-”);
physicsList->SetCutValue(1e6mm,“e+”);
physicsList->SetCutValue(1e6mm,“gamma”);
physicsList->SetCutValue(1e6mm,“proton”);

the projection cost almost the same times.

but set the cut in G4VUserPhysicsList, the former setup cost time 10^3 times more than the latter.

4

Thanks! Hopefully one of the physics experts can answer this.

5

Hi,

I have a question, Why would you set a cut equal to zero? if you use Geant4-DNA physics models, particles are tracked down to few eV, interaction by interaction. If you use condensed history approach models, to have a cut equal to zero does not make sense because, depending on the physics models used, the low energy limit of the physics models can be 1 keV, 250 eV (livermore when applying recommended limit) , 100 eV (penelope) or 10 eV (livermore). You will also have to set the /cuts/setLowEdge “energy limit” .

Cheers
Susanna

6

Separate from the OP, we do this for “protons” in my experiment (CDMS), because we are specifically interested in nulcear recoils. By setting the cut to zero, we ensure that the recoiling nucleus always appears in our output with the amount of energy it picked up (e.g., from a neutron scatter). We can then apply our own detector-response models to that energy.

For EM interactions, I agree with you that a zero-cut doesn’t make a lot of sense, because the subsequent application of physics models will be “out of bounds.”

7

I set the particle range cut to 0*mm for convinience, because i do not know the default mininal range cut in every physicsList, but i want to the result most precisely for particle range cut. so i let Geant4 to select the mininal particle range cut.

8

Thank you @mkelsey ! I get it (for protons) :slight_smile: