From: Peter H. L. Christiansen (pchristi@nbi.dk)
Date: Wed Jun 18 2003 - 04:09:27 EDT
Hi Kris I think that you suggestion to include a fP member which is the mommentum from your global fit and replace the T1 projection (I guess) of phi and theta with your global fit values sound very good. We should just make sure that we get meaningful values even without your refit module, so phi and theta should be said from the Ffs track in the Fs track and the momemntum should be initialised to something (0=no global fit?). Cheers Peter On Tue, 17 Jun 2003 hagel@comp.tamu.edu wrote: > Hello, > Interested parties probably read my message regarding the global track fitting > that I have implemented. More details on that will emerge. I have run into a > problem, however. I made Bdst files thinking I was using that information and > then things did not make sense when I began to use them, so I started digging in > the code (again). Here is what I find for the Bdst tracks unless I > misunderstand something. > > 1. theta, phi and vertices for BdstTrack are actually the theta, phi and vertex > of the BrFfsTrack extracted from the BrFsTrack and the information from the > BrFsTrack (as well as the information from the BrBfsTrack) is ignored/thrown > away. That seems strange to me as I had read the code generating the BrFsTracks > to be an attempt to have the "global picture" which is made up of the compendium > of information from the BrFfsTracks and the BrBfsTracks. That is where I set > the theta and phi that come out of that procedure. > > 2. There is no momentum information in the BdstTrack. The only momentum saved > is in the momentum information from the BdstFsTrack::fD2, fD3 and fD4. And > there is no possibility to save information from a global track ie the momentum > that you think is the best for the track. I had niavely set the momentum of the > BrFsTrack to be the momentum that comes out of the fitting procedure only to see > it thrown away by the BdstModule::FillTrack. > > I would like some comments on this. I do realize that almost all (if not all) > of the information necessary to fit the tracks is saved in the BdstFsTrack. But > if one waits until after the Bdst step to generate the fit tracks, the > possibility of using a perhaps better momentum to calculate pid or anything else > that one would use momentum for is precluded. So at least for my personal copy, > I am going to add a BdstTrack:: momentum and I will fill the theta and phi with > the values I get out of the fit. After I have comments I will weigh what to do > "officially" > > Regards > > Kris > > ------------------------------------------------- > This mail sent through IMP: http://horde.org/imp/ > -- :-) --------------------------- )-: Peter H L Christiansen @ NBI EMAIL : pchristi@nbi.dk OFFICE : Tb1@NBI (353 25269) HOME : Frimestervej 22, 1. tv PHONE : 35824930/40840492 :-D --------------------------- \-:
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