CERN School of Computing 2006  21 August - 1 September 2006 in Helsinki, Finland

Programme Overview

Grid Track

Software Track

Physics Comp. Track

Schedule

Lecturers

Lecturer Bios

CSC-Live

Rudi Frühwirth, HEPHY Vienna
Andreas Pfeiffer, CERN
 

The track will introduce the fundamental concepts of Physics Computing and will then address the central aspects of simulation and visualization, including the simulation of the experimental setup to optimize detectors, to test and improve the reconstruction software, and to gain a detailed understanding  of the data.

The first series of lectures gives an overview of the software and hardware components required for the processing of the experimental data, from the source - the detector - to the physics analysis. The emphasis is on the concepts, but some implementation details are discussed as well. The key concept is data reduction, both in terms of rate and in terms of information density. The various algorithms used for data reduction, both online and offline, are described. The flow of the real data is the main topic, but the need for and the production of simulated data is discussed as well.

The second series of lectures gives an introduction to the domain of simulating high energy physics experiments with practical examples taken from the CERN/LHC based CMS experiment. The lectures focus on event simulation based on the GEANT4 toolkit.  GEANT4 is a toolkit for simulating the passage of particles through matter. It includes a complete range of functionality including tracking, geometry, physics models, and hits. The physics processes offered cover a comprehensive range, including electromagnetic, hadronic and optical processes, a large set of long-lived particles, materials and elements, over a wide energy range starting, in some cases, from 250 eV and extending in others to the TeV energy range. It has been designed and constructed to expose the physics models utilised, to handle complex geometries, and to enable its easy adaptation for optimal use in different sets of applications.
Basic simulation requirements are explained, such as experimental setup in terms of geometry, materials, and external electromagnetic fields, principles of physics processes, selection and configuration of physics processes, run and event concepts, and extraction of hit information. It is shown how this requirements are met by applying GEANT4. The programming language used throughout the lecture series is C++.

The third lecture series focuses on on-line Data Acquisition Techniques.

Series

Type

Lecture

Description

Lecturer

General Introduction to Physics Computing

Lectures

Series

General Introduction to Physics Computing

The two lectures give an overview of the software and hardware components required for the processing of the experimental data, from the source - the detector - to the physics analysis. The emphasis is on the concepts, but some implementation details are discussed as well. The key concept is data reduction, both in terms of rate and in terms of information density. The various algorithms used for data reduction, both online and offline, are described. The flow of the real data is the main topic, but the need for and the production of simulated data is discussed as well.

Rudi Frühwirth

Lecture 1

Lecture 1: Event filtering

The first lecture deals with the multi-level event filters (triggers) that are used to select the physically interesting events and to bring down the event rate to an acceptable figure. Some examples of the hardware and software that is deployed by the LHC experiments are presented.

Rudi Frühwirth

Lecture 2

 Reconstruction and simulation

The second lecture describes the various stages of event reconstruction, including calibration and alignment. The emphasis is on algorithms and data structures. The need for large amounts of simulated data is explained. The lecture concludes with a brief resume of the principles of physics analysis and the tools that are currently employed.

Rudi Frühwirth

Experiment simulation

  Lectures

Lecture 1
Lecture 2
Lecture 3
Lecture 4

Experiment simulation

This series of lectures gives an introduction to the domain of simulating high energy physics experiments with practical examples taken from the CERN/LHC based CMS experiment.

The lectures focus on event simulation based on the GEANT4 toolkit.  GEANT4 is a toolkit for simulating the passage of particles through matter. It includes a complete range of functionality including tracking, geometry, physics models, and hits. The physics processes offered cover a comprehensive range, including electromagnetic, hadronic and optical processes, a large set of long-lived particles, materials and elements, over a wide energy range starting, in some cases, from 250 eV and extending in others to the TeV energy range. It has been designed and constructed to expose the physics models utilised, to handle complex geometries, and to enable its easy adaptation for optimal use in different sets of applications.

Basic simulation requirements are explained, such as experimental setup in terms of geometry, materials, and external electromagnetic fields, principles of physics processes, selection and configuration of physics processes, run and event concepts, and extraction of hit information. It is shown how this requirements are met by applying GEANT4. The programming language used throughout the lecture series is C++.

Martin Liendl

Exercises

Exercise 1
Exercise 2
Exercise 3
Exercise 4
Exercise 5
Exercise 6

Combined exercises on Experiment simulation and Data Analysis and Visualization

Depending on their study backgrounds and personal interests, students will have the possibility to work on various exercises split into two topic sets aligned to the two lecture series:

• One problem set is related to developing experiment simulation code based on GEANT4.

• The corresponding exercises will focus on detector description, physics processes selection and tuning, and data extraction from a running simulation. Basic knowledge of C++ is required to work on the provided code examples.

Martin Liendl

assisted by

Joanna Weng

Pre-requisite Knowledge

Introduction

The lecture gives an overview of the various aspects to be considered in the simulation of of a high energy physics experiment emphasizing their statistical character. The Monte Carlo method for tracking particles through bulk matter is examined in some detail. GEANT4 is introduced as a state of the art C++ simulation engine covering many of the requirements for experiment simulation.

Desirable pre-requisite

and references to further information

In order to benefit optimally from the lectures and the associated programming exercises, it is advisable to have some basic knowledge about the following topics :

• Probability theory: definition of probability, discrete and continuous random variables, probability density and cumulative distribution, sampling from of a distribution

  • Really, only elementary knowledge is required!

  • Suggestion of links: wikipedia(probability), mathworld(probability), particle data group

• data analysis: mean and variance of a data set, histograms

  • Mean values and variances will be computed in the exercises, histograms will be our elementary analysis tools.

  • Suggestion of links: same as above, wikipedia(histograms)

• Object-oriented software development: UML class diagrams to represent classes, inheritance (is a – relationship, polymorphism, abstract classes), associations between classes (has a – relationship)

  • The design of GEANT4 is object-oriented. To understand its object model and its extensibility, we need to know the basics of object orientation.

  • Suggestion of links: wkipedia(class diagrams)

• C++ programming language, some easy concepts of STL like vector<something>, map<key, value>

  • Code snippets during the lectures and all exercises require C++

  • Suggestion of links: wikibook(C++ Programming)

• Elementary knowledge of the usage of some Linux/Unix tools like a shell, cd, ls. Standard editors like (x)emacs, nedit.. Knowledge about the GNU C++ compiler, make and debugging C++ on LIinux is an advantage.

  • All exercises consist of writing, building, and executing C++ simulation programs using the GEANT4 tool kit.

  • If possible, we will try to set up the examples using an IDE like Source navigator or KDevelop, but this is not sure yet.

• Elementary knowledge of some minimal features of the data

  analysis tool ROOT.  In the exercises, data will be stored in ROOT files.

  Data analysis will be done using the ROOT histograming and plotting capabilities. The following minimal features of ROOT will be used:

  ROOT macros, histograms, TTrees + TTree-browser, TFile.

  For students not familiar with ROOT at all, some introductory

  examples/tutorials will be provided during the exercises.

  Links: http://root.cern.ch

On-line Data Acquisition

Lectures

Lecture 1

A general introduction to data acquisition systems will be given by focusing on the four LHC experiments. The principle data flow, the qualitative/quantitative requirements and the architecture of these data acquisition systems will be discussed. Their relations with the other on-line systems for triggering, high-level filtering, and control will be explained.

Klaus Schossmaier

Lecture 2

Lecture 3

A case study of the ALICE data acquisition system will be presented. The chosen technologies will be discussed and the software framework (called DATE) including the add-on software for performance monitoring and data quality monitoring will be introduced. Also some simulation results will be shown.

Prerequisite Knowledge

Desirable prerequisite

and references to further information

A good knowledge of programming languages, Linux operating system, and computing technologies is considered as useful to benefit most from this series of lectures.

 References:

CERN  Summer Student  Lecture Programme - 2005

• Trigger and Data Acquisition Systems, by Paris Sphicas Part 1

• Trigger and Data Acquisition Systems, by Paris Sphicas Part 2

CERN  Summer Student  Lecture Programme - 2002

• Trigger and Data Acquisition Systems, by Clara Gaspar Part 1

• Trigger and Data Acquisition Systems, by Clara Gaspar Part 2

• Trigger and Data Acquisition Systems, by Clara Gaspar Part3

Additional  material will be available in the CSC handbook provided at the school.