Problem 674

Summary:	radioactive decay is extremely slow for heavy isotopes
Product:	Geant4	Reporter:	marie.di.marco
Component:	processes/hadronic/models	Assignee:	flei
Status:	RESOLVED INVALID
Severity:	normal
Priority:	P2
Version:	6.2
Hardware:	All
OS:	All

Description marie.di.marco 2004-09-29 10:02:34 CEST

The problem is the following: I start with 39Ar atoms and let them decay by
using the G4RadioactiveDecay class. For 39Ar this is not a problem, but for
more complicate things like 222Rn and daughters, the processing speed drops
down by more than a factor 1000. I wonder where this unacceptable loss of
speed comes from. It should be possible to make the radioactive decay almost
as fast as the other physical processes. In fact I cannot use the
G4RadioactiveDecay, because it is impossible to get enough statistics.

Of course it never can be excluded that I made a mistake in writing my
code, but a colleague of mine here at MPIK has observed the same effect
independently, and I have heard of other cases as well, so it seems to be a
general problem.

Comment 1 Hans-Peter.Wellisch 2005-02-22 04:01:59 CET

Hi Fan,

  was this already chreaed out in 7.0?

Many greetings,

Hans-Peter.

Comment 2 flei 2005-02-24 05:28:59 CET

In version ealier than 7.0, one needs should use the fast beta decay mode if
speed is a concern. This is controlled by the command "/grdm/fBeta true".
Since 7.0 a new faster beta decay algorithm is used and there is no more
accurate/fast modes.