PAPAS (PArametrized PArticle Simulation)

UNDER Development and Testing

Introduction

PAPAS (PArametrized PArticle Simulation) provides simulation and reconstruction reconstruction algorithm which is designed to allow users to test the performance of detector design. The approach is fast simulation/ reconstruction. Users must provide simple C++ classes to define key detector parameters eg tracker acceptance and calorimeter radius and length. An implementation of the CMS detector is provided as a starting point.

PAPAS propagates stable generated particles through a simple detector model.

In the tracker, charged particles may be detected as tracks, taking into account the acceptance, efficiency, and momentum resolution of this detector.

In the calorimeters, particles are detected as energy deposits. The energy deposits are modelled by taking into account the following detector properties: energy resolution, acceptance, energy thresholds and characteristic size. The latter is defined as the distance between two clusters below which the two clusters cannot be resolved and are considered as a single cluster.

A particle flow algorithm then runs over the simulated tracks and clusters to identify and reconstruct charged hadrons, photons, and neutral hadrons. These particles can then be used as an input to higher-level algorithms like jet clustering, or directly in the analysis.

TIP Electrons and muons are passed through PAPAS without any modification, and the user is responsible for applying is own efficiency and resolution models. The hadronic decay products of tau leptons are simulated just like other hadrons and photons.

A CMS-like detector model is provided as an example.

Installing

Required software

If you're working on lxplus, all the necessary software has been preinstalled for you and you can just proceed with installing the fcc-physics package.

The other supported operating systems are ubuntu 14, macos X, and slc6 (other than lxplus nodes).

You need to install:

• The FCC packages needed to produce and read events in the FCC event data model (EDM):

• podio (add link to tutorial): a package allowing to define event data models and to manipulate EDM events.
• fcc-edm (add link to tutorial): definition of the FCC EDM, based on podio

• You may also find it useful to have

• pythia8 (add link)

Installing the Papas package

Before installing and everytime you want to use this software on lxplus, set up your environment:

source init.sh

On other systems make sure you have PODIO, FFCEDM and ROOT environment variables set up.

Compilation

mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX=../install ../
make -j 4
make install
cd ..

DOxygen Documentation

   make doc

Tests

Rudimentary tests that run a simple example and run unit tests can be run with

    cd build
    make test

Running examples

Examples can be found in the examples directory

To run example_simple:

1. create a Pythia example.root file eg by following:-

https://twiki.cern.ch/twiki/bin/view/FCC/FccSoftwareHeppy

2. Then run Papas on this file

   example_simple example.root

This should produce text outputs and also jgp display files.

You should get a printout like:

    Generated Stable Particles
    Particle :p206     :17179869390: pdgid =    22, status =   1, q =  0, pt =   0.9, e =   0.9, eta = -0.13, theta = -0.13, phi =  0.08, mass =  0.00
    Particle :p202     :17179869386: pdgid =   211, status =   1, q =  1, pt =   1.0, e =   1.0, eta = -0.21, theta = -0.21, phi = -2.72, mass =  0.14
    Particle :p201     :17179869385: pdgid =    22, status =   1, q =  0, pt =   0.3, e =   0.3, eta = -0.44, theta = -0.43, phi =  0.69, mass =  0.00
    ...
    Particle :p88      :17179869272: pdgid =  -211, status =   1, q = -1, pt =   0.8, e =   0.8, eta =  0.10, theta =  0.10, phi = -2.56, mass =  0.14

    Reconstructed Particles
    Particle :r678     :21474837158: pdgid =   211, status =   1, q =  1, pt =   0.6, e =   0.6, eta = -0.24, theta = -0.24, phi = -2.94, mass =  0.14
    Particle :r677     :21474837157: pdgid =  -211, status =   1, q = -1, pt =   0.8, e =   0.9, eta =  0.30, theta =  0.29, phi = -2.44, mass =  0.14
    Particle :r676     :21474837156: pdgid =   211, status =   1, q =  1, pt =   1.0, e =   1.0, eta = -0.21, theta = -0.21, phi = -2.72, mass =  0.14
    ...
    Particle :r631     :21474837111: pdgid =    22, status =   1, q =  0, pt =  16.1, e =  16.5, eta = -0.23, theta = -0.23, phi = -0.01, mass =  0.00

jpg files like:

#todo set up the correct output (temporary example just for now)

The example will also produce an output root file containing the reconstructed particles

          simpleeg.root

For Mac Xcode project use

´´´ mkdir xbuild cd xbuild cmake -G Xcode ../ make ´´´

NB for now will be necessary to set in edit screen/ run.

DYLD_LIBRARY_PATH=Users/alice/local/root/lib:/Users/alice/fccwork/fcc-edm/install/lib:/Users/alice/fccwork/podio/install/lib:/Users/alice/local/lib