[Halld-offline] geant particle ids

[Kei Moriya]

Hi Beni,

Thanks for putting in the requested changes.
I ran over 1M events newly generated, and got the
following statistics from hd_dump:

Number of EtaPrime   : 31719
Number of omega      : 232782
Number of phiMeson   : 11300
Number of Lambda     : 50773
Number of Sigma      : 16421
Number of Xi         : 68
Number of OmegaMinus : 0
(For the above, I'm just grep-ing for particle names,
so if there are events with multiple omegas or
Lambda/AntiLambda pairs, they are counted multiple times)

It does seem that the code is now able to tag
eta', phi, omega events as advertised, and there are no rho
meson events tagged as such.

One thing I want to ask about is your statement:
 > At this point I would like to make a comment. Generally it is not a good
 > idea to let
 > geant decay particles it is not designed for that. Phythia however is
 > exactly desinged
 > to do that.

Could you clarify what the advantage is of having pythia
doing the decays over geant? Is it angular correlations, polarizations,
etc?  Do you know if there is any polarization information
contained in the pythia output, and does pythia decay the particles
based on these correlations?

I'll have more updates at the offline meeting tomorrow.

Thanks,
	Kei

On 9/17/13 9:06 AM, Beni Zihlmann wrote:
> Hi All,
>
> Upon request:
> I committed changes to bggen, hdgeant and particleType.h in order for the
> use to be able to let omega, phi, eta', and the three rhos decay in geant.
> the pid number are:
>
> Geant  Pythia
> -------------------------------------
>    33       223    ! omega(783)
>    34       331    ! eta prime
>    35       333    ! PHI
>    42      113    ! rho0
>    43      213    ! rho+
>    44      -213   ! rho-
>
>
> If you use bggen with the current pythia-geant.map translation table
> omega, phi and eta' are decayed by geant and their pids will appear in
> DMCThrown as well as their decay products with the appropriate association.
>
>
> At this point I would like to make a comment. Generally it is not a good
> idea to let
> geant decay particles it is not designed for that. Phythia however is
> exactly desinged
> to do that. What we should do in the future, maybe when we move to
> geant4 is to
> change the code in DANA to take the full pythia output and create the
> proper relation
> between daughter and parent particles for the user such that the user
> does not have
> to do it him/her- self.
>
>
> cheers,
> Beni
> _______________________________________________
> Halld-offline mailing list
> Halld-offline at jlab.org
> https://mailman.jlab.org/mailman/listinfo/halld-offline
>