Event Mixing

The Event Mixing Framework is still under development !

Requirements for Event Mixing in ALICE have been discussed over the ALICE Analysis Task Force mailing list. A summary of the requirements has been presented on 22/11/2007  (link to indico) .

The Event Mixing Framework (EMF) will be provided as an optional add-on to the existing Analysis Framework. The essential new component is the Event Pool. It contains the list of events which are close in a user defined space and for a given metric. Close events are grouped into bins. The event list corresponding to one bin can be attached as an TEntryList to a TChain  of files containing AOD Events. Another new component is the AliMultiAODInputHandler deriving from AliInputEventHandler. It implements a circular event buffer which is loaded from events provided by the event loop steered by the AliAnalysisManager. The AliAnalysisManager steers also the loop over bins on the Event Pool. The illustration below shows a  component view and the principle intercommunication.


The full class diagram is shown in the next Figure. The user mixing task should derive from AliAnalysisTaskME (ME = Multi Event). The user can require the access to the event buffer in the sliding window mode (one AODEvent is updated per UserExec-call) or in the refresh mode (fresh buffer for each UserExec-call).

The sequence diagram for the processing of one bin in the EventPool is shown below.


Current status of implementation:
  • AliVEventPool [ done]
    • Implemenation based on THnSparse [ awaiting commit
    • Test implementation with on-the-flight generation of bins in multiplicity (AliEventPoolOTF) [ done]
  • AliMultiAODAnalysisManager [ done]
  • AliAnalysisTask [ done]
  • AliAnalysisManager event steering using AliVEventPool [ testing]