sPHENIX tracking discussion

[Thomas K Hemmick <tkhemmick AT gmail.com>]

Hi guys

Just an FYI.  I think that the TPC and the MVTX can run in a streaming mode without triggers applied.  This is what we plan for the TPC in the lab, thereby eliminating the need for a trigger.  It will not do the calorimeters, but the calorimeter alignment is less of an issue than the tracking.

Tom

On Fri, Jul 2, 2021 at 6:26 PM Anthony Frawley via sPHENIX-tracking-l <sphenix-tracking-l AT lists.bnl.gov> wrote:

Here are some notes on the discussion we had at the meeting last Monday on alignment of tracking detectors. Sorry for the delay, I have been on vacation.

We expect to do alignment with cosmics (prior to beam) and with low luminosity collisions after we have beam.

Cosmics

-----------

It was noted that John Haggerty has expressed doubt that a cosmics trigger (using scintillator slats) is feasible on the time scale available. We should take that up again with John.

Can the MVTX produce a trigger signal?

In the event of no trigger being available, it was suggested that we might be able to record data at 15 KHz and use a software trigger (similar to the level 2 triggers in PHENIX) in the event builder to select cosmic candidates to reconstruct. We would not get very many cosmic tracks, but even a small sample would be helpful.

De-aligned detector:

----------------------------

Discussed whether to de-align the detector elements in GEANT or after the fact by moving hits. There was a strong sentiment to do it in GEANT when we build the detector model. The reco geometry has to be separate from the G4 geometry.

We will need to discuss with the detector subgroups how and who ....

Alignment software:

---------------------------

The standard is to use Millipede - packages exist.

The LHC experiments have C++ versions. Open source?

The procedure will be similar to that for SC distortions - have to aggregate over many events.

Ask LANL group re FVTX alignment - Hugo will ask

Alignment databases:

-----------------------------

Chris: The conditions database contains just files. Put the geometry into a file, maybe an xml file with locations?

Applying alignment corrections:

-------------------------------------------

We will use the Acts geometry context feature, which is associated with surfaces.

We will get the Acts experts to give us a talk on how they intend to do alignment.

Joe will ping them.

Check alignment how often?

After turning field off and on

Temperature changes?

Caroline Reidl requested a status report to the commissioning task force - we settled on July 21

We will definitely have to find people to work on this.

We agreed to meet on Tuesday morning next week, due to the holiday on Monday.

Cheers

Tony

_______________________________________________
sPHENIX-tracking-l mailing list
sPHENIX-tracking-l AT lists.bnl.gov
https://lists.bnl.gov/mailman/listinfo/sphenix-tracking-l