[Frost] About MVRT bank

[Sungkyun Park]

Thanks Eugene,
I understand.

I will add more cuts in my code.
  1. compare the vertex position between GPID.vertex and MVRT.vertex
  2. compare the sc_time with st_time
  3. check MVRT.chi2
  4. compare mass_ref of the each particle.

I have one more question about vertex.
Do I use the MVRT vertex information as the input parameter of ELoss Correction?
Until now, I used the GPID vertex information.
If so, Do I need to use the MVRT vertex information when I need to use the vertex?
Thanks very much.

Best Wishes

Sung


----- Original Message -----
From: Eugene Pasyuk <pasyuk at jlab.org>
Date: Wednesday, April 21, 2010 10:05 pm
Subject: Re: About MVRT bank
To: Sungkyun Park <sp06k at fsu.edu>
Cc: FROST <frost at jlab.org>

> Hi Sung,
> 
> You found very good example of accidental tracks.
> First of all, as you noticed the vertexes are different. This is an 
> indication that they may have nothing to do with each other.
> Furthemore, if you look at the timing information you see that for 
> the 
> "proton" ST time is way off, it is even larger than  SC time.
> Also you see that mass_ref is not good for it. All together makes 
> it a 
> bad track. chi2 for the fitted vertex in MVRT bank is also 
> terrible, 45!
> When you select multi-track events you have to make sure that they 
> all 
> belong to the same interaction, apply cuts on vertex time and 
> vertex 
> position differences. Also check that they have good pid status 
> (mass_ref amand they matched to the same photon).
> 
> -Eugene
> 
> 
> 
> On 4/21/10 2:29 PM, Sungkyun Park wrote:
> > Hi Eugene,
> >
> > In today meeting, you said that I need to use the vertex 
> information in MVRT bank.
> > Until now, I use the vertex in GPID bank.
> >
> > I have a question about MVRT bank.
> >
> > In my code, the part to get the vertex information of the proton 
> is the following:
> > 	
> >          if( GPID[row].pid == 14 ){
> >            
> My_pro_vertex.SetXYZ(GPID[row].x,GPID[row].y,GPID[row].z);>         
> }
> >
> > 1. Do the MVRT bank not have any information for the particle ID?
> >
> > In the event with a proton and pi-,
> > the GPID vertex for proton is   x: -0.000       y: 0.019        
> z: 2.180   ,
> > the GPID vertex for pi- is  x: 0.000        y: 2.320        z: -
> 9.450    , and
> > the MVRT vertex is  x: 3.328  y: 1.341  z: 2.930
> > 2. I do not understand why this event has two GPID vertexes and 
> one MVRT vertex.
> > Who is this MVRT vertex the vertex for? How do I use the MVRT 
> vertex in this case.
> >
> > The following is the outputs of the GPID and MVRT bank in the 
> event with a proton and a pi-
> > ------------------------------------------------------------------
> -------------------------------------------------------
> > Group:  GPID    Sector: 1       Nhits:  2       Next ind:       0
> > pid:     14
> >     vert->        x: 0.000        y: 2.320        z: -9.450
> >     p->           E: 1.106        px: 0.151       py: 0.010       
> pz: 0.565
> >     q:   1       trkid:   1      sec:   1        paddle:  16
> >     dedx: 33.069 beta: 0.529
> >     sc_stat:   0 sc_time: 40.619         sc_len: 526.997
> >     st_stat:   1 st_time: 57.143         st_len: 34.069
> >     mass: 0.882  mass_ref:   2   betam: 0.553
> >     epho: 0.726  tpho: 8.749     tagrid:   2     ngrf:   1       
> ppid:  14
> > pid:      9
> >     vert->        x: -0.000       y: 0.019        z: 2.180
> >     p->           E: 0.311        px: -0.270      py: -0.023      
> pz: -0.064
> >     q:  -1       trkid:   2      sec:   4        paddle:  41
> >     dedx: 11.189 beta: 0.894
> >     sc_stat:   2 sc_time: 24.078         sc_len: 414.331
> >     st_stat:   1 st_time:  9.746         st_len: 10.415
> >     mass: 0.130  mass_ref:   0   betam: 0.906
> >     epho: 0.726  tpho: 8.749     tagrid:   2     ngrf:   1       
> ppid:   9
> >
> > Group:  MVRT    Sector: 1       Nhits:  1       Next ind:       0
> > v_id:      6  ntrk:      2  x: 3.328  y: 1.341  z: 2.930  chi2: 
> 45.419  cxx: 0.003  cxy: -0.001  cxz: 0.001  cyy: 0.027  cyz: -
> 0.001  czz: 0.002  stat:      0
> >
> > Best Wishes
> > Sung
>