Welcome to the “Computer- Praktikum”!jwagner/WS1011/Uebung/... · 2010-10-20 · Computer-Praktikum WS 2010/2011 Why is particle physics interesting? How can subatomic particles

Computerpraktikum zu “Teilchenphysik für Fortgeschrittene” 1

Computer-Praktikum WS 2010/2011

Welcome to the “Computer-Praktikum”!

Thorsten Chwalek Jan LückJyothsna KomaragiriThomas PeifferJeannine Wagner-Kuhr


Computer-Praktikum WS 2010/2011

● Why is particle physics interesting?

● How can subatomic particles like quarks be “seen” at all?

● How does a typical analysis in particle physics look like?

● What are particle physicists doing the whole day long?

The aim of this “Computer-Praktikum” is to answer questions like:

… and to make you familiar with the tools which are used in particle physics analyses

… and of course to raise your interest in particle physics!


Standard Model

● There are six fundamental quarks and...

● six fundamental leptons (three charged and three neutrinos)

● Forces are mediated by bosons

● Very successful model, … but:

There are still some unanswered questions:Where do the masses come from? What is dark matter? What is dark energy? Why do neutrinos have masses? Why is there only matter but no antimatter in the universe? ...


Standard Model

● There are six fundamental quarks and...

● six fundamental leptons (three charged and three neutrinos)

● Forces are mediated by bosons

● Very successful model, … but:

There are still some unanswered questions:Where do the masses come from? What is dark matter? What is dark energy? Why do neutrinos have masses? Why is there only matter but no antimatter in the universe? ...

Particle physicists try to answer these fundamental questions!


Particle Physics: Experiments

● We collide protons with (anti) protons or electrons with positrons

● Today's most powerful colliders: Tevatron at Fermilab (~ 2 TeV) , LHC at CERN (7 TeV)

● In these collisions of well-known particles new or very rare particles can be produced

● Huge detectors are built around the collision points

● CDF II at Tevatron and CMS at LHC

Tevatron Collider, Fermilab (Chicago) LHC, Cern (Genva)

CDF II detector at Tevatron

CMS detector at LHC


Particle Physics: Experiments

● E=mc2 → in each collision new particles are produced

● Higher center of mass energies mean: heavier particles can be produced

● Their energy, momentum and direction of motion can be measured with detectors

● All information of one event is stored for the offline analysis


Ingredients for a Measurement

Detector

Collects information on all occurring collisions

ExperimentExperiment

Data


Particle Physics: Theory

● For many SM processes, detailed theory calculations have been performed by theorists

● The hard interaction can be formulated in terms of Feynman diagrams

● One can simulate the quantum mechanical structure of nature with Monte Carlo methods and generate millions of events

● In addition the detector response can be simulated → simulated events in the same format as real collision data!



Detector



Collision-Data

TheoryTheory

Simulated Data

Monte Carlo &Detector Simulation

Calculations


Data Analysis: Computer Tools

● Real collision data and simulated date have the same format

● Can be analyzed with the same analysis tools

● Based on C++ and Root

● Select events, reconstruct quantities (mass, momentum, angular distributuions,...) and fill histograms



Detector



Collision-Data

TheoryTheory

Simulated Data


Calculations

Analysis tools: C++, Root, …Reconstruct momenta, masses, angular distributions, … and fill histograms→ simulated data and collision data have the same format: the same tools can be used for both!

ToolsTools


Compare Experiment and Theory

Interpret and analyze histograms:Compare theory predictions with experimental data!

Data (Experiment)

Simulation(Theory)

Of course this is not so easy and trivial:We also make use of Neural Networks, Unfolding techniques, Fitting algorithms, Statistical tools to calculate significances,...



Detector



Collision-Data

TheoryTheory

Simulated Data


Calculations


Compare Measurement with Theory Predictions

ToolsTools

Publication


What we will cover in our tutorials

Detector



Collision-Data

TheoryTheory

Simulated Data


Calculations


Compare Measurement with Theory Predictions

ToolsTools

Publication


Program of the Tutorials

● Introduction: Linux and C++ today

● Tools: Root 28.10.2010

● Detector Simulation: Geant 4.11. and 11.11.2010

● Monte Carlo Generator: Madgraph 18.11 and 25.11.2010

● Analysis: D-Mesons 2.12. and 9.12.2010

● Analysis: Top-Quarks 16.12.2010, 13.1., 20.1., 27.1.2011

● Visit KIT Campus north 3.2.2011

● Presentations on selected topics (by you!) 10.2.2011


Presentations

● Arrange yourself in 4 (or 5) groups● Prepare a short presentation on your topic in

the last tutorial (10.2.2011)● The four topics are:

● Geant● Madgraph● D-Mesons● Top-Quarks (maybe here 2 groups)


Information

● All information, useful links, and of course the exercise sheets can be found on this webpage:

http://www-ekp.physik.uni-karlsruhe.de/~jwagner/WS1011/Uebung/

And now: Enjoy the tutorials!

For event more info: there is also a lecture “Moderne Methoden der Datenanalyse” by Prof. Quast and Prof. Feindt

Documents

Welcome to the “Computer- Praktikum”!jwagner/WS1011/Uebung/... · 2010-10-20 · Computer-Praktikum WS 2010/2011 Why is particle physics interesting? How can subatomic particles