EventHeadMaker

Purpose

Create an event header object and store it to the TES.
EventHeader is a place where variables pertaining to the entire event, such as missing transverse momentum, are kept. The complete list of these variable is given in the EventHeaderMaker class diagram.

EventHeaderMaker Detail

The EventHeaderMaker is an Athena-Algorithm which is created at the start of a job and executed once per event.
The following three public methods are executed by Athena, and are needed to honour the IAlgorithm interface

initialise() - create helper classes and declare any jobOptions properties
execute() - perform the algorithm's function once per event
finalise() - perform any end of job tasks

EventHeaderMaker stores numbers of isolated electron, isolated muon, non-isolated muon and jet to find the numbers of each for the event.
The number of jets by flavor is stored. The missing momentum is calulated by summing the p_t of:

isolated electrons
isolated photons
isolated muons abd non-isolated muons
jets
clusters
cells

and subtracting the p_t of:

clusters associated with electrons
clusters associated with photons
clusters associated with jets
clusters associated with jets
reconstructed particles associated with jets
cells associated with clusters

The escaped momentum (missing momentum calculated from the generator four-vectors) is calulated by summing the pt of neutrinos, and muons out of acceptance (|eta| >2.5 or pt<6.0 GeV.) EventHeaderManager also retreives the Monte Carlo generator process number, and keeps track of the event number. Both these items are due to become ATHENA responsabilities, and removed from Atlfast.

User Requirements Satisfied

The design fulfills requirements 3.1.6 of the ARD.

jobOptions Properties

jobOptions properties are steering parameters which can be set by the user in the jobOptions file.
They are declared in the constructor and initialised to Default Values
The options for this algorithm are

ElectronLocation - TES location
PhotonLocation - TES location
Isolated Muon Location - TES location
Non-Isolated Muon Location - TES location
Jet Location - TES location
Cell Location - TES location
Cluster Location - TES location
MC Truth Location - TES location
OutputLocation - TES location
Beam Energy - Missing Mom
Do Smearing - Cell Smearer
RconeB - Cell Smearer
RconeF - Cell Smearer
BarrelForwardEta - Cell Smearer
RandSeed - Cell Smearer

Initialisation

The initialise method is called once at the beginning of the job. It is here that the helper classes are instantiated.
JetSmearer is instatiated. To be used to smear cells used in missing pt caluslation.

Execution

See above.

Class Diagram

The various classes discussed above are shown in the class diagram.
EventHeaderMaker class diagram