[Frost] About MVRT bank

[Eugene Pasyuk]

Hi Sung,

For you first point, NO. You don't compare between GPID and MVRT. Ypou 
compare z-vertexes in GPID for protons an pions.

2 and 3 will be unnecessary if you require mass_ref=0 for all particles 
you are interested in and they all have the same tagrid.

So, for pi+pi-p events you do:
1. mass_ref=0 for all particles you need.
2. targrid is the same for all particles
3. check if difference between z-vertexes of particles you need is less 
than some number.

This would be the initial criteria for the good event.

You use GPID vertex to find that tracks are coming from the same vertex. 
Once you know that this is the case, you use MVRT vertex for everything 
else.

-Eugene

On 4/22/10 1:16 PM, Sungkyun Park wrote:
> 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
>>
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