FV0 Reconstyruction

FV0 reconstruction

Please note that this readme shows how the reconstruction is done at the moment. The current reconstruction is not necessarily done the way it should be. The algorithm is under review and subject to change.

The FV0 reconstruction workflow is

• O2/Detectors/FIT/FV0/workflow/src/fv0-reco-workflow.cxx

and the actual reconstruction happens in

• src/BaseRecoTask.cxx (include/FV0Reconstruction/BaseRecoTask.h)

Channel data reconstruction

Currently, there's no channel data filtering applied in the FV0 reconstruction. All digit channel data are propagated to RecPoints. The following conversions are made:

• Channel ID (uint8_t) -> Channel ID (int)
• CFD time (TDC units, int16_t) -> Time in ns (double)
  • Furthermore, if available and enabled, a time offset correction is applied. For FV0 it is not available nor enabled at the moment.
• Amplitude (ADC channels, int16_t) -> Ampltidue (ADC channels, double)
• Channel bits (uint8_t) -> Channel bits (int)

RecPoint reconstruction

The reconstructed RecPoints contain:

• BC information (o2::InteractionRecord)
• Channel data
• Three different times:
  • "TimeFirst": time of first signal (w/ charge > FV0DigParam::chargeThrForMeanTime)
  • "TimeGlobalMean": average of all signals passing some filtering (including CFD in gate)
  • "TimeSelectedMean": average of all signals passing a bit stricter filtering (includling CFD in gate)