sPHENIX tracking discussion

["Yasuyuki Akiba" <akiba AT rcf.rhic.bnl.gov>]

Dear Mike,

 

Thank you for the prompt reply and clarification.

 

So where is the DCA distribution from the evaluator?

 

If at least 1 noise hit is picked up, this should cause a large DCA for the track. So the DCA distribution should have a grass of wide DCA tail of 5% of all tracks.

 

Sincerely yours,

              Y. Akiba

 

From: michael.p.mccumber AT gmail.com [mailto:michael.p.mccumber AT gmail.com] On Behalf Of Michael P. McCumber
Sent: Friday, August 12, 2016 8:42 AM
To: Yasuyuki Akiba <akiba AT rcf.rhic.bnl.gov>
Cc: sphenix-tracking-l AT lists.bnl.gov
Subject: Re: [Sphenix-tracking-l] sPHENIX tracking meeting 9:00 am Friday August 12

 

Hello Yasuyuki,

 

The inner purity plot does indicate that 5% of the time a noise hit is picked up in the inner 3 layers. However the "vertex residual" plot is a collision vertex reconstruction resolution, it is not a plot of the track DCA distribution.

 

Mike

--

Michael P. McCumber, PhD
Los Alamos National Laboratory
505-709-8161

 

On Fri, Aug 12, 2016 at 4:33 AM, Yasuyuki Akiba <akiba AT rcf.rhic.bnl.gov> wrote:

Dear Mike,

 

I looked your slides posted in the CDS agenda and have a question.

 

In slide 5, you have

What is the meaning of “inner finding efficiency” and “inner purity”? What is the exact definition?

From the word “inner”, I suppose this is plot is for 3 layers of MAPs.

So I guess “exact match efficiency (purity)” means the efficiency (purity) that the TPC track is associated with the correct hits in all of the 3 MAPs layers. Is this correct?

 

If this is correct, I have a related question n the vertex residual.

 

According to the inner purity plot, the probability of exact match is about 95%. This means 5% of the tracks are wrongly associated to at least 1 hits. Then these 5% track should have “wrong DCA” measurement. But there is no grasses of the DCA distribution. This is very strange.

 

I suspect that this could be artifact due to that all tracks are coming from DCA=0. There is no track that has a real large DCA. Since all track segment in the 3 layers of MAPs is a straight line coming from the event vertex, their DCA values is very close to zero. So, even if a TPC track is associated with a wrong hit in one or more of MAPs layer, the DCA can be still zero.

 

Sincerely yours,

              Y. Akiba

 

 

 

From: sphenix-tracking-l-bounces AT lists.bnl.gov [mailto:sphenix-tracking-l-bounces AT lists.bnl.gov] On Behalf Of Frawley, Anthony
Sent: Wednesday, August 10, 2016 7:45 PM
To: sphenix-tracking-l AT lists.bnl.gov
Subject: [Sphenix-tracking-l] sPHENIX tracking meeting 9:00 am Friday August 12

 

Hi All,

We will have an sPHENIX tracking meeting on Friday, August 12 at 9:00 am ET. The agenda page is:

 

https://indico.bnl.gov/conferenceDisplay.py?confId=2325

 

The focus of the meeting will be progress and plans for the tracking review.

 

Best regards

Tony

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