HSF Reconstruction & Software Triggers WG: 4D reconstruction algorithms

Andreas Salzburger (CERN), Dorothea Vom Bruch (Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France), Jin Huang (Brookhaven National Lab)

Live minutes: https://codimd.web.cern.ch/Cz3jyTEgTS2l6FQUi1WzdA

HSF Reconstruction & Software Triggers WG
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HSF Reconstruction & Software Triggers WG: 4D reconstruction algorithms

URL: https://indico.cern.ch/event/1128087/

4D tracking at sPHENIX (TPC and silicon detectors) - Joe Osborn

Summary: sPHENIX @ RHIC start data taking in 2023. Hit occupancies of O(100; 000) are expected in the TPC readout window that is similar to the pileup occupancy expected at HL-LHC. Tracking combines vertex layers, timing layers, a time projection chamber (TPC) with 13 us drift time, and a micromegas tracker for TPC calibration. Timing information was used to translate TPC time to z and differentiating collisions pile up in a single vertexing/TPC time frame.


Graeme: ALICE readout including time frame to best use data from TPC.
Joe: sPHENIX readout a similar time window of about 67 crossing at a time. Challenges in separating crossing with in a time window is quite similar. One difference is ALICE stream 100% of data while sPHENIX only stream a fraction, which leads to difference in different structure in time window.
Graeme: would it be done for AuAu running?
Joe: still in discussion

Dorothea: Any other option for timing detector
Joe/Jin/Tony: driven by avaialbility of the ASIC of 100ns and group to build it, which is designed to tag beam bunch at RHIC

4D tracking at LHCb (Timespot project) - Nicola Neri

Summary: LHCb Time spread among PVs is about 180 ps. Time info
helpful to reduce hit combinations for track reco. Timespot: developing a silicon and diamond 3D tracker with fast timing (20 ps demonstrated) and 4D fast-tracking reco on FPGA. Tracking purity improves with hit
time resolution.


Jin: How alignment is introduced?
Nicola: alignment is loaded to the look up in track finding/fitting engine

Dorothea: Stub time -> collision time to constraint the fit and pattern reco?
Niclola: Good point. Not used yet

Jin: magnetic field in Velo region? Kalman filter for fitting?
Nicola: magnetic field in Velo can be neglected, fitting happens via engines (i.e. point in reference plane): weights are calculated using the distance from a point in the reference plane, positions of engines for different track parameters are stored in LUT

Graeme: VHDL programing or high level programing language, e.g. Sycl, used?
Nicola: balance between resource efficiency and programing access. On-going topic
Graeme: expecting improvements in high level language compiler

There are minutes attached to this event. Show them.
    • 3:30 PM 4:00 PM
      4D tracking at sPHENIX (TPC and silicon detectors) 30m
      Speaker: Joe Osborn (Oak Ridge National Laboratory)
    • 4:00 PM 4:30 PM
      4D tracking at LHCb (Timespot project) 30m
      Speaker: Nicola Neri (Università degli Studi e INFN Milano (IT))