Problem 2135

Summary:	No internal conversion and x rays produced in the decay of 137Cs
Product:	Examples/Extended	Reporter:	Johan Nyberg <johan.nyberg>
Component:	radioactivedecay/rdecay02	Assignee:	Laurent Desorgher <laurent.desorgher>
Status:	RESOLVED FIXED
Severity:	major
Priority:	P4
Version:	10.5
Hardware:	PC
OS:	Linux
Attachments:	Geant4 macro file to use with rdecay02

Description Johan Nyberg 2019-02-14 23:23:56 CET

Created attachment 543 [details]
Geant4 macro file to use with rdecay02

Hello, 

I am trying to produce a simulated gamma-spectrum from the decay of 137Cs with the attached macro file. As far as I can see from the results, the internal conversion is not included in the simulation. I get 94% gamma rays with an energy of 662 keV. According to NUDAT2 (ENSDF) it should be 85%. Also, I could not see any produced conversion electrons for example at 624 keV nor any K x rays at ~32 keV.

I posted this problem on the Geant4 User Forum 

http://hypernews.slac.stanford.edu/HyperNews/geant4/get/emprocess/1522.html

I got this reply by Michel Maire to my post:

"You are right : internal conversion is not active, despite of what is printed on  output (Radioactive decay parameters table). It becomes evident on some examples of rdecay01. This behaviour is new and unexpected. May I suggest you to open a bug report."

Sincerely,

Johan Nyberg

Comment 1 Laurent Desorgher 2019-02-15 07:15:04 CET

Dear Johan,

Indeed there is a problem with the internal conversion in Geant4.10.5.
The issue is due to a wrong much too low maximum  limit vale of the so called alpha internal conversion coefficient. It has been corrected and will be available with the next patch.
Before the release of the next patch you can correct your self the Geant4 code by  replacing in line 58 of the class G4LevelReader.cc

fAlphaMax = (G4float)1.e-15;
by
fAlphaMax = (G4float)1.e15; 
or even higher.

You can find the file G4LevelReader.cc
on geant4/source/processes/hadronic/models/de_excitation/management/src

Best regards


Laurent