STAR Computing Documentation
StStrangeMuDstMaker: the Player
Offline Software using ROOT in STAR	Maintained by Peter G. Jones
	Last modified Tue Dec 12 04:59:19 2000

StStrangeMuDstMaker

The Player

Description
Modes of operation
Run-time options
Applying cuts
Example usage

Overview of the Player

The StStrangeMuDstPlayer is basically a compiled version of the macro $STAR/StRoot/macros/analysis/makeStrangeMuDst.C. On one level, it simply improves performance by putting as much processing as possible into compiled code. On another, it provides added functionality, such as enabling the user to Filter (select candidates) from an existing MuDst, or simultaneously Make and Filter a new MuDst, applying stricter selection cuts while creating the MuDst. These and other options, such as providing a simple switch to select whether or not to write all branches to a single file or multiple files, hide almost all of the inner workings of the StStrangeMuDstMaker. The macros required to run the player are extremely simple by comparison, since the event loop is now part of the compiled code.

Player modes

StStrangeMuDstPlayer comprises three modes of operation and several selectable options. The three modes of operation are provided by the following member functions.

  Make(const Int_t NEvents, StFile *input, Char_t *output);
  Filter(const Int_t NEvents, StFile *input, Char_t *output);
  Play(const Int_t NEvents, StFile *input, Char_t *output);

Make() creates a new MuDst, Filter() creates a new MuDst from an existing MuDst and Play() combines the previous two steps to create a new MuDst from a subset of the candidates stored on the original DST. Each mode requires the same three input arguments, which are self explanatory.

Run-time options

Before invoking Make(), Filter() or Play() any of the following options may be selected.

  void DoFileSplit(Bool_t val = kTRUE); // write branches to separate files
  void DoMC(Bool_t val = kTRUE);        // process MC information
  void DoT0Abort(Bool_t val = kTRUE);   // abort events with a T0 jitter
  void DoTopMapFix(Bool_t val = kTRUE); // apply fix to the topology map
  void DoReadDST(Bool_t val = kTRUE);   // read .dst.root files

By default, all options are off. The default input format is .event.root files.

Applying cuts

Additionally, in Filter() or Play() mode the following cuts can be defined.

  void SetEvPrimTracks(unsigned int);
  void SetEvPrimVertexZ(Float_t);
  void SetV0DecayLength(Float_t);
  void SetV0DcaDaughtersToPrimVertex(Float_t);
  void SetV0DcaToPrimVertex(Float_t);
  void SetXiDcaDaughters(Float_t);
  void SetXiDcaV0Daughters(Float_t);
  void SetXiDcaToPrimVertex(Float_t);
  void SetXiDcaV0ToPrimVertex(Float_t);
  void SetXiDcaBachelorToPrimVertex(Float_t);

Candidates are selected if:

  EvPrimTracks > cut                 The following affect all events
 |EvPrimVertexZ| < cut
  V0DecayLength > cut                The following affect V0 candidates only
  V0DcaDaughterstoPrimVertex > cut
  V0DcaToPrimVertex < cut
  XiDcaDaughters < cut               The following affect Xi candidates only
  XiDcaV0Daughters < cut
  XiDcaToPrimVertex < cut
  XiDcaV0ToPrimVertex > cut
  XiDcaBachelorToPrimVertex > cut

By default, cuts are made. Here is a list of their values.

  evPrimTracks = 0;
  evPrimVertexZ = 100.;
  v0DecayLength = 2.0;
  v0DcaDaughtersToPrimVertex = 0.7;
  v0DcaToPrimVertex = 0.8;
  xiDcaDaughters = 0.7;
  xiDcaV0Daughters = 0.7;
  xiDcaToPrimVertex = 0.7;
  xiDcaV0ToPrimVertex = 0.;
  xiDcaBachelorToPrimVertex = 0.;

These cuts have been applied to all our common MuDsts. Clearly, not all possible cuts are implemented at this level. If you would like to see something added, please let me know.

Example usage

Below is an example of creating a MuDst, while filtering out candidates which do not pass the default cuts outlined above. In addition events which exhibit T0 jitter are aborted and the output is split across several files - one for each branch (i.e. V0, Xi and Kink). Note that the player processes all branches by default. This is not currently switchable.

  // Set output file
  Char_t *output = "evMuDst_P00hi_1244_T0Abort.root";

  // Set input file(s)
  StFile *input = new StFile();
  input->AddFile("/star/rcf/data03/reco/P00hi/2000/08/*1244*.dst.root");

  // Set number of events to analyse
  const Int_t Nevents = 1000000;
  
  // Create player
  StrangeMuDstPlayer player;
  player.DoT0Abort();                 // Filter out T0 jitter events
  player.DoFileSplit();               // Save branches to the separate files
  player.DoReadDST();                 // Setup to read .dst.root files
  player.Play(Nevents,input,output);