DefaultReconstructedParticleMaker

Reconstructed Particles are Atlfast physics output entities which correspond to the following physics user analysis objects

• Electrons
• Muons
• Photons

DefaultReconstructedParticleMaker Overview

The DefaultReconstructedParticleMaker 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

1. Retrieve the relevant Monte Carlo HepMC::Particles from the TES
2. Smear the momentum of the particle according to desired parameterisations
3. Create a ReconstructedParticle from the smeared momentum
4. Apply acceptance cuts to the particle
5. Store particles to the TES

DefaultReconstructedParticleMaker has a number of helper classes which it uses
to perform these tasks, all of which are shown in the DefaultReconstructedParticleMaker class diagram.

• TesIO - used to extract HepMC::Particles and store ReconstructedParticles to the TES
• Smearer class - used to smear Monte Carlo four momenta according to correct parameterisation

User Requirements Satisfied

The design fulfills requirements of Sec 3.1.1. of the ARD.

DefaultReconstructedParticleMaker

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.

• Luminosity - LHC luminosity (high/low)
• ParticleType - Determines which kind of maker this is (electron/muon/photon)
• mcMinimumPt - Acceptance cut value
• mcMaximumEta - Acceptance cut value
• MinimumPt - Acceptance cut value
• MaximumEta - Acceptance cut value
• DoSmearing - Flag to determine whether to do smearing or not
• MC_eventLocation - location in TES of input MCParticles
• OutputLocation - location in TES of output ReconstructedParticles
• MuonSmearKey - Chooses muon smearing attributes from an integer range
• RandSeed - Used by the smearer

Initialisation

The initialise method is called once at the beginning of the job. It creates the algorithm's helper classes. It is here that the GetMC and Store objects are instantiated.
DefaultReconstructedParticleMaker has an ISmearer pointer, thus allowing any type of smearer
which honours this interface to be instantiated during the execution of the Algorithm's initialise method.
At present there are three types of Smearer available to this Algorithm; one for Electrons, one for Muons and one for Photons. The correct smearer is chosen by the ParticleType jobOptions property.

The initialisation process is shown in the
DefaultReconstructedParticleMaker initialisation sequence diagram.

Execution

The execute method is performed once per event and carries out the main operation of the algorithm.
The execution process is shown in the
DefaultReconstructedParticleMaker execution sequence diagram

Class Diagram