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Forum: Biasing and Scoring
Date: 06 Jan, 2015
From: Carlos Ayerbe Gayoso <Carlos Ayerbe Gayoso>

Dear GEANTers

this is a very simple question. I modified GB01 example to have protons of 1.2GeV over a carbon disk and biasing the production of pi+, mu+ and e+. Since is the first time I'm working wiht the biasing process, I just started quite naive.

I changed the gun to have protons of 1.2 GeV, instead of neutrons as was originally.

The detector is a carbon disk of 100mm radius and 5mm thickness.

In the main file, I started to modify the bias section with:

biasingPhysics->Bias("pi+"); biasingPhysics->Bias("mu+"); biasingPhysics->Bias("e+");

and something similar in the DetectorConstruction module: testMany->AddParticle...

Just for fun I used the GUI to see the result visually and compare the option ON or OFF, with only pi+ particles visible. The visual output was the same in both cases. In other words, biasing didn't change anything at all.

Then I figure out that neutrons were originally listed in the biaisng process, so I introduced the proton in the bias list

biasingPhysics->Bias("proton");

and it seems there is a change with the bias ON option comapred with previous runs (the OFF option seems to behave similar as before).

Is this the correct way? I mean, should the primary particle be listed in the bias? why?

Maybe everything is wrong since in the new one (with protons in the bias) I got the warnings:

-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : BIAS.GEN.14
      issued by : G4InteractionLawPhysical::SetPhysicalCrossSection(..)
Cross-section value passed is negative. It is set to zero !
*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------

Thank you very much for your feedback

Carlos Ayerbe

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1 None: Re: ExampleGB01 question   (Marc Verderi - 07 Jan, 2015)
(_ None: Re: ExampleGB01 question   (Carlos Ayerbe Gayoso - 07 Jan, 2015)
(_ Idea: Re: ExampleGB01 question   (Tom Roberts - 07 Jan, 2015)
(_ None: Re: ExampleGB01 question   (Carlos Ayerbe Gayoso - 08 Jan, 2015)
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