The FINUDA Online Monitor Classes



The FINUDA Online Monitoring

and Event Display System

The FINUDA Online Monitor: Classes

The C++ classes developed for the FINUDA online monitor system and their relationship are described in the following.

The Global Run information, coming as a separate sub-buffer at the beginning of each run, is organized into an object of the TFndGenInfo class.


The Raw Data Tape events (RDT), written by the Global Event Builder (GEB) process, are organized into a header (TFndHHdr class) and a set of sub-event buffers, containing the information coming from separate detectors. The sub-event takes two different formats, corresponding to the gts, tof, lmd, stb (TFndRawEqp class) and the ism, osm detectors (TFndRawSil class), respectively. A TFndRawSlc class, describing the raw Slow Control buffer slc, will be developed.


The Raw Event contains the elementary information, still in encoded format. In order to monitor the detector performance, to start the event reconstruction and the event display, a re-organization of the RDT event must take place, leading to a more flexible data format, which we call HDT (Hit Data Tape), described by the TFndHdt class.

The HDT Event is a composite object, containing the Event Header (TFndHHdr class), the Trigger (TFndTrig), a set of integer values corresponding to the multiplicities of each detector, and a list of hits for each detector (TObjArray class). The elements of each list are described by the TFndHTof, TFndHSil, TFndHLmd, TFndHStb classes, corresponding to the Time of Flight, Silicon Detector, Drift Chambers and Straw Tubes elementary hits.

The bridge from the Raw to the HDT Event is the information contained into the Database, described by the TFndFeeMap class, which allows the correct mapping of an electronic channel number to a well identified detector channel (slab, strip, wire, tube).

  • TFndHdt: the HDT Event, built of objects represented by the following classes:

    • TFndHHdr: the event header (run & event number, event date & time);
    • TFndDate: date & time;
    • TFndTrig: the event trigger;
    • TObjArray of TFndHTof: the list of tof hits;
    • TObjArray of TFndHSil: the list of sil hits;
    • TObjArray of TFndHLmd: the list of lmd hits;
    • TObjArray of TFndHStb: the list of stb hits;


The Online Monitoring is provided by making use of ROOT shared memories, in which a producer stores and periodically updates a set of histograms. This task is performed, for different detectors, by the following set of classes:

  • TFndGtsMon: (Global Trigger Supervisor);
  • TFndTofMon: (Time of Flight);
  • TFndSilMon: (Silicon Detector);
  • TFndLmdMon: (Drift Chambers);
  • TFndStbMon: (Straw Tubes).


The shared memories are read by a consumer, which runs interactively and displays the histograms on operator request, through the ROOT Object Browser.

The Event Display is started by the creation of an object of the TFndDisplay class, from an interactive session. A clickable menu allows to access the FIRST or LAST event on the HDT file, and then to move around the file with the NEXT and PREVIOUS buttons.

The class allows either to scan a HDT file after an offline reconstruction or to access a HDT file which is at the same time being produced by a process receiving Raw Events from the GEB across the network, allowing to display events in online mode.

The operator can display a 2D Front, Side or Top view of the experimental set-up or a 3D view. On top of the experimental configuration, the hits are displayed, with different colours, depending on whether they were used or not to fit a track by the reconstruction code.

The implementation of a class describing reconstructed tracks will soon be added to the package.

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PC (update 27 Jan 99)