sPHENIX tracking discussion

["Frawley, Anthony" <afrawley AT fsu.edu>]

Hi All,

Sorry for the delay, but here are the minutes of last Friday's tracking meeting.

Tony

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Mike McCumber - HF tracking status
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Advanced to full proposal stage for large DR. Working on full proposal.

Mike described his progress on preparing the code base for HF tracking.
-- Close to being  able to throw Pythia events with B jets and study them.
-- Mike has been able to cut and paste Alan's code successfully.

Comments from Mike on realistic geometry for answering the ALD's charge:
Quick turnaround implies cylinder cell geometry
Need Kalman in place, several other things before going to more realistic geometry (staves, ladders, etc.)
We do need to agree on what to plug into the macros

Carlo Perez - TPC space charge report:
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Slide 3: There was a discussion about what is meant by a multiplicity of 450. Is this track multiplicity per event?
If so, it is too small - expect ~1200 tracks in central HIJING events
Carlos: ALICE and STAR tune this number to account for angle crossing effects, not just track multiplicity
It was pointed out that this should be an average over all collisions. Is it about right for a MB event?

How many events do we average over? Carlos: the number of events needed to get saturation. Not sure how many that is.
Fluctuations are not included yet.

Slide 6: This is a study of making the inner radius 20 cm, but tracking only outside 30 cm.
It was notyed that this would preclude putting a separate tracker at 20+ cm

Question: Do you have an expert in ALICE who you can talk to? Yes. Should informally ask them for comments.

There was a discussion of how to insert these results into tracking performance studies.
One could get the momentum resolution from delta_r running many events to get fluctuations due to variation in initial charge.
Maybe the first step in making things more realistic.
The delta_r we are getting is much smaller than ALICE. Comment: need to push on understanding whether you are using a realistic space charge.

Carlos agreed to discuss with Tom and Alan how to incorporate space charge distortion results into tracking performance studies.
Deciding on an algorithm for smearing hits in the TPC should be a quick job.

Mike noted that pattern recognition studies would need both space charge and pileup.

Carlos will report back on this before the next tracking meeting.

Rachid Nouicer - Integration of the silicon pixels into sPHENIX:
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Rachid reported on the final step (for now) in the integration study, adding the bus extender cables.

Skip to slide 19, the rest is history.

The extenders shown are what we presently have in the lab. Would have to go back to the company to discuss how much longer they could be.

Rachid will focus on the Si strip tracker now.
Working on how to make the stave rigid, configure HDI on stave (changed from Al to CFC this week), how to do wire bonding etc.

Next meeting will report status of that work.

TPC tracking discussion
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Mike does not have time available to make the needed TPC code changes himself, but could work with a new TPC expert.

Currently, the TPC tracking is with two perfect pixel layers, and has no space charge effects or pileup effects.

There is a possibility that we would need an intermediate tracking layer between pixels and TPC. Mike said he could push the MAPS cost and schedule estimates  to include an optional intermediate layer.

Mike will be at BNL on 16th next month, will be there for a month, could overlap with SB crew. Carlos - good Sourav volunteered to look at the TPC code in the next couple of days.

There will be a pre collaboration meeting heasvy flavor workfest in May.
Could maybe expand that to include a tracking workfest with breakout sessions.