[Frost] About MVRT bank

[Eugene Pasyuk]

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