Re: Extended particle list in TGeant3

Dear Andreas,

I agree that external decayers for J/psi and other vector mesons is more correct as simple isotropic decay. Unfortunately, not all applications have their external decayer yet (besides aliroot).

As to decay definition in TGeant3.cxx v.1.34, in this and even in the head version, some misleading comments about J/psi and Upsilon decay do present, but actually they decay non-existing particles 113 and 114 into mu+mu-. It is this code which confused me.

Best regards,
Yuri.

Andreas Morsch wrote:

>Dear Yuri,
>the heavy flavor decay channels have been commented already some time ago.
>They are handled by the external decayer. I'm surprised that you find them
>in version 1.34.
>
>Cheers - Andreas.
>
>
>
>>Dear VMC developpers,
>>
>>The list of particles defined in TGeant3::DefineParticles() seems to
>>require some corrections. J/psi is defined as a particle 66:
>> Gspart(fNG3Particles++, "J/Psi", 3, 3.09688, 0., 0.);
>> fPDGCode[fNPDGCodes++]=443; // 66 = J/Psi
>>First, its lifetime (last paratemer) is set to 0 which causes fpe in
>>gtrak/gtneut.F:234.
>>Second, decay modes which were intended for J/psi, are defined for a
>>particle 113, not 66:
>>// --- jpsi ---
>> for (kz = 0; kz < 6; ++kz) {
>> bratio[kz] = 0.;
>> mode[kz] = 0;
>> }
>> ipa = 113;
>> bratio[0] = 50.;
>> bratio[1] = 50.;
>> mode[0] = 506;
>> mode[1] = 605;
>> Gsdk(ipa, bratio, mode);
>>I expect to have ipa=66 instead of ipa=66. The same concerns some other
>>particles (upsilon, phi) which are defined in TGeant3 beyond the
>>standard geant3.
>>
>>I use root 4.01/02, geant3 checked out CVS of late September 2004
>>(TGeant3 has cvs version 1.34), gcc 3.2.3.
>>
>>Best regards,
>>Yuri Kharlov.
>>
>>
>>
>>
>
>
>
Received on Wed Jan 05 2005 - 18:58:55 MET