class AtlTriggerTool: public AtlAnalysisTool

 Tool for computing trigger efficienies in MC events

 The tool counts events fulfilling certain trigger requirements
 given by the user and creates efficiency graphs as a function of
 Pt, Eta and Phi of the trigger object in question (jet, electron,
 muon).

 The tool is not affected by any other event selection which might
 be exisiting in the parent analysis.

 Example in MyTask.C :

    // Add trigger tool
    AtlTriggerTool *trigger = new AtlTriggerTool("trigger_tool",
                                                 "Trigger Efficiencies");
    SetToolCut("trigger_tool", "fTriggerSelection", "L2_e10_medium");
    fSelector->AddTool(trigger);

 (See class AtlAnalysisTool for a general description and usage of
 A++ analysis tools.)

 Note that the tools allows also for combined items (logical OR only), eg
 "item1 || item2 || item3"
 In this case the tool creates a sub-folder for the efficencies of
 each item and another folder forr the combined case.


 Author: Charlotte Santer <mailto: kind@mail.desy.de>
 Update: $Id: AtlTriggerTool.cxx,v 1.6 2013/08/22 12:53:20 stamm Exp $
 Copyright: 2010 (C) Charlotte Santer