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Restore PRF for TRD2D clusters

Alexandru Bercuci requested to merge a.bercuci/cbmroot-mcbm:mcbm22-Unpack into master

MAJOR FIX for TRD2D unpacker

A random distribution of digi charges was observed for the TRD2D clusters. Although cluster timing and size was correct, the PRF was unusable and since, the position and energy reconstruction practically unusable.

C.Schiaua @schiaua_AT_nipne.ro discovered a feature of the ADC chips used on the FASPRO FEBs which produced this bug. The ADC reported asynchronous the digitized value. The bug was fixed by adding digi buffering until the proper signal is unpacked for each participating read-out channel.

Consequences :

  • the TRD2D position and energy resolution can be recovered (since run 1588) by rerunning the unpacker.
  • the full performances of the detector (especially for tracking) are now available

A view of data correlation in the TRD2D is here attached078_digiView in which, on the Q = f(pad_column) (3rd panel) the correct PRF can be seen for all clusters registered. The plot is taken from run 2365.

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