Recently, we have made changes to the StJetMaker and StSpinPool Directories, which will allow the user to determine the underlying event using two different methods. 1) A Regional Determination and 2) an Off-Axis Cone. These two methods were created by two different people so there are some inherent differences in the code methods, but they both work without interfering with the one another. This blog has two main purposes 1) describe to STAR Jet analyzers how to run their code, 2) decribe in detail how the codes work.  

So there are two new macros ready for use and stored on CVS located at StRoot/StJetMaker/macros:

RunJetFinder2009pro_ue.C ( example of the regional usasge) 
RunJetFinder2012pro.C (example of using the off-axis cone usage)

IMPORTANT: The following must now be included if you want to run you macros:

gSystem->Load("StUeEvent");

So even if you did't want to determine the underlying event (not sure why you wouldn't), this line must be included. 

RunJetFinder2009pro_ue.C 

This code implements the StUEMaker2009 class, which inherits from the standard StMaker.  The text mark-up of this code is found at the following: 

StUEMaker2009.h 
StUEMaker2009.cxx 

Some lines of code relevant to the regional analysis: 

•  anapars12_away = anapars12; // Away Region for Tracks and Towers
•  anapars12_away->setTrackRegion(new StjTrackRegion(120.0,-120.0,1.0));
•  anapars12_away->setTowerRegion(new StjTowerRegion(120.0,-120.0,1.0));
•  uemaker->addBranch("away",anapars12_away,"AntiKtR060NHits12"); <-- Adds the uebranch to the ueTree

This allows the users to define regions based on phi and eta. The code above for example has  |phi| > 120 and |eta| <  1.0. 

RunJetFinder2012pro.C 

This code implements the new StJetMaker2012 class, which is inherited from the StJetMaker2009 class. You can find a text mark-up of the new class at the following: 

StJetMaker2012.h 
StJetMaker2012.cxx 

Some lines of relevant code in the above macro are the following:

• StOffAxisConesPars *off060 = new StOffAxisConesPars(0.6); <-- Allows for changing the cone radius parameter of the off axis cone. 
• jetmaker->addUeBranch("OffAxisConesR060", off060); <-- Adds the uebranch. 

Jet Area for both: 

For the UE correction in both methods the Jet area is needed and is now stored in the jet trees. Please examine the following lines of code: 

StFastJetAreaPars *JetAreaPars = new StFastJetAreaPars;
 JetAreaPars->setGhostArea(0.04); <-- This line is not need as the default is 0.04, but can be changed to have finer (< 0.04) or coaser (> 0.04) area calculations. Be mindful of the computation time. 
AntiKtR060Pars->setJetArea(JetAreaPars); 

To-Do:
Provide embedding based macros on CVS <-- Macro exsists (currently cleaning up and including systematics example). 

Cross-checks needs to be performed to ensure the amount of underlying event energy  by the different methods are consistent.

Particle and Parton Level code needs to be re-examined since the leading jet match is far too constringent.   

If you use the code, look at it. Devils are in the details and you may want to change or add functionality that currently exists. Comments and suggestions are welcomed.