Problem 1068

Summary: K40 beta- decay description
Product: Geant4 Reporter: mauro taiuti <taiuti>
Component: processes/hadronic/models/radioactive_decayAssignee: dennis.herbert.wright
Status: RESOLVED FIXED    
Severity: trivial CC: John.Apostolakis, Koichi.Murakami
Priority: P5    
Version: 9.2   
Hardware: All   
OS: All   

Description mauro taiuti 2009-05-26 10:19:14 CEST 
As you probably already know the K40 beta decay is not correctly described. The generated electron energy spectrum corresponds to a Fermi transition corrected for the effect of the nuclear electric field but the K40 beta- decay is a type-3 forbidden transition and the energy distribution is harder compared to the Fermi distribution. I am suggesting that the correct spectrum can be generated simply adding in the G4RadioactiveDecay.cc file after

f = std::sqrt(g*g-1)*(ee-g)*(ee-g)*g;

for the beta- channel, the following instruction

if (theParentNucleus.GetParticleName() == "K40[0.0]") f *= (pow((g*g-1),3)+pow((ee-g),6)+7*(g*g-1)*pow((ee-g),2)*(g*g-1+pow((ee-g),2)));

You will find a discussion of this improvement in the attached note

Best regards
Prof. Mauro Taiuti
Physics Department
University of Genova
Italy
Comment 1 John Apostolakis 2009-10-22 09:24:19 CEST 
Thank you for the feedback and proposed improvement.

We will try to respond within a short time.

J.A.
Comment 2 dennis.herbert.wright 2011-05-10 17:48:32 CEST 
Your suggested code was implemented in radioactive decay.