sPHENIX MAPS tracker discussion

[Hideki Okawa <Hideki.Okawa AT cern.ch>]

Dear all,

 

Below are the minutes from yesterday's biweekly meeting.

They are also attached to the indico:

https://indico.bnl.gov/event/9218/

 

Regards,

Jin & Hideki

 

###

 

August 31, 7PM ET

 

Participants: Guannan Xie, Hideki Okawa, Jin Huang, Ming Liu, Sanghoon Lim, Sourav Tarafdar, Weihu Ma, Yasser C. Morales, Yuanjing Ji, Zhaozhong Shi

 

Introduction - convenors

 

-       BUP is submitted today (8/31). An important point is the streaming readout (10% for pp, pA).

 

Ming: Will we have the multiplicity trigger during the pp collisions?

Jin: That would rely on INTT. ECAL tower counting is possible for the early data, but it will suffer from the noise later on.

 

Zhaozhong: Is 10 GeV the upper pT limit for p.9? (RAA & v2 measurements in the small collision systems)

Jin: We can actually go higher for a few more bins.

 

D0 program in pp collisions – Guannan Xie (LBNL)

 

p.3

Jin: DCA should be considered from the initial prompt. We should be careful, since the non-prompt ones are also in the samples.

 

Jin: In pp, the correlated background will become important. How is it done in STAR?

Guannan: I don’t have a clear answer for now.

 

p.4

Jin: DCA resolution will be good in AuAu collisions. We should check the performance in pp as well.

 

p.5

Jin: MC should be pure Gaussian. Are the secondary vertices included?

Guannan: Currently using the maximum matched vertices. Will update the plots.

 

p.6 Vertex resolution saturates against track multiplicity.

Yasser: Is this DCA?

Guannan: p4 is DCA. This one is the vertex resolution.

Jin: The values seem large. Do these include secondary vertices? Sanghoon, how was it before?

Sanghoon: The resolution did drop against track multiplicity, but saturated around 15~20 microns after a certain multiplicity. We should get the correct values with the single vertex mode.

Jin: Let’s follow up offline. The default is the iterative vertex fitting. Let’s look for the optimal condition.

 

p.9

Jin: Poor vertex resolution. Surprising. Let’s check with Sanghoon. Vertices can be refined and refitted offline.

 

Hideki: What is the situation with the full simulation samples? Which ones are used here?

Jin: Test samples produced in Jan this year are used in this talk.

 

 

B_s updates – Zhaozhong Shi (MIT)

 

p.2

Jin: We should implement this simulation code in the sPHENIX framework.

 

p.4:

Zhaozhong: These plots are still with a single vertex.

Jin: You can start from B_s->J/psi phi, since this process has the same vertex.

 

p.5

Jin: Please switch to the log scale for the right plot. What is the BG here?

Zhaozhong: Inputs taken from AuAu (centrality 40-80%)

 

p.6

Hideki: You should improve the x-axis numbers.

Zhaozhong: I will reduce the number of ticks.

Jin: We should look at the relative differences and not the absolute ones.

 

p.10

Jin: The lepton efficiency can be taken from the Upsilon group.

 

Yuanjing, Jin: Applying initial track selection cut dramatically reduces down the combinatorial tracks need to be considered for the B_s background computation. Please try to use the B_s signal to define the cut.

Jin: One worry for B_s background simulation is that the B_s signal is so rare. To simulate enough background events under the B_s and for S/B to be not too bad, we may need to simulate many more background collisions than the case of D0 or Lc.