Re: [ROOT] Problem with TGenPhaseSpace

From: Rene Brun (Rene.Brun@cern.ch)
Date: Thu Sep 26 2002 - 11:39:48 MEST


Hi Elin,

I have forwarded your mail to Valerio Filipini who implemented this class.
Meanwhile, could you send a script showing the problem?

Rene Brun

On Thu, 26 Sep 2002, [iso-8859-1] Elin Lundström wrote:

> Hello. 
> I have a problem with a macro that I have written.
> It performs a deutron-deuton reaction which produces two pi0:s and one helium-4. It uses the TGenPhaseSpace class and generates the reaction for 100 000 events. It plots distributions of the obtained data and the results seem correct. But if I change the order of the final state particles, I get systematic errors of about 6% between the distributions. The distributions have the same shape but less reactions get detected if the order of the particles is pi0, pi0, He4 then if it is He4, pi0,pi0. 
> Is the TheGenPhaseSpace::SetDecay function sensitive to the order of particles in the mass array parameter or should I continue to look for mistakes in my code? 
> 
> Thanks in advance
> /Elin
> 
> 
> 



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