Re: [ROOT] small requests for TParticle, TParticlePDG and TMCParticle

From: Costas Andreopoulos (
Date: Thu Nov 18 2004 - 19:57:09 MET

Hello all,

Thanks for the numerous replies.

> <Pasha/>
> 	A nucleus is a very different object and an 
> 	attempt to extend definition of a particle to accomodate for a 
> 	definition of a nucleus will sooner or later break - ths is why
> 	we're using different words for them (a particle and a nucleus).

Whether they are different or not depends on the level of 'abstraction':

In the guts of my generator - during the actual calculations - of course
I use different classes for a particle and a nucleus because it is just
non-sense to ask a neutrino what is the binding energy of its most loose
nucleon... I agree.

But, in my output 'STDHEP'-like record a nucleus is *not* such a
different thing from a particle: There, all that is needed to be 
known for a nucleus  is some "particle" code, the 4-momentum, 
and links to mother / daughter - "particles".

Since, as Rene pointed out, TDatabasePDG can be extended and, 
as Robert pointed out, there are some ready-to-use PDG extensions
for nuclei, I think my question is answered.

> <Robert/>
> our additions to the pdg table can be found at:
> which adds quite a number of Ions using the PDG extension of giving

> as this will double up the decay list of things in the original pdg
> table (giving 200% decay branching probabilities :-).  To get around

Thanks! - I did not realize we already had that in our offline system.

I will copy that and I will use a similar trick to merge the standard
ROOT file with the extensions when I am building the generator.

> this MINOS concatenates the two text files by an external process (our
> SRT build processing) and then reads the resultant file via a globally
> accessible routine LoadMinosPDG() , c.f.:

yes, for this, I do something similar. 
ROOT's only TDatabasePDG instance is accessed through GENIE's only
PDGLibrary instance

TDatabasePDG * pdg = PDGLibrary::Instance() -> GetDBase();

which, the first time it hands over the TDatabasePDG instance, 
searches in some list of paths to find the pdg-table and loads 
it to the TDatabasePDG.


Dr. Constantinos Andreopoulos, CCLRC - Rutherford Lab.

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