Masterclass 2011 MINERVA Masterclass ‘Discover the Cosmos’ Teachers’ Workshop 29 th February 2012 Hardeep Bansil

Masterclass 2011 Introduction to MINERVA  A masterclass tool for students to learn about the ATLAS Experiment at CERN  Motivates identification of individual particles and events from the signatures seen in the ATLAS detector  Based on the ATLAS event display - Atlantis  Project is a joint venture between the Rutherford Appleton Laboratory (RAL) and the University of Birmingham Masterclass INvolving Event Recognition Visualised with Atlantis

Masterclass 2011 Aims of the exercise  Identify the particles detected by ATLAS detector with the Atlantis Event Display (electrons, muons, neutrinos)  Classify different types of Events (“particles produced in one collision”)  W  e  W   Z  ee  Z   Background from jet production (which might look like W or Z event)  All the above events are ‘well-known’ processes, studied in great detail

Masterclass 2011 How to detect particles in a detector Tracking detector −Measure charge and momentum of charged particles in magnetic field (produced by solenoid) Electromagnetic calorimeter −Measure energy of electrons, positrons and photons Hadronic calorimeter −Measure energy of hadrons (particles containing quarks), such as protons, neutrons, pions, etc. Muon detector −Measure charge and momentum of muons Neutrinos are only detected indirectly via ‘missing energy’ not recorded in the calorimeters Electron Photon Proton or π + Neutrino (not seen) Neutron Muon

Masterclass 2011 GUI Load and cycle through events Control what gets displayed in Canvas Get more details in event

Masterclass 2011 Canvas View event as seen in ATLAS detector in a number of ways Use all views to get the complete picture!

Masterclass 2011 Side view of the detector (R-z projection) Particles in all regions of detector are shown

Masterclass 2011 End-on view of the detector (x-y projection) Warning: Only particles reconstructed in central region shown here (otherwise the particles in the forward would cover the view)!

Masterclass Lego plot (‘rolled out’ calorimeters) Shows energy seen by all regions of the calorimeters as towers

Masterclass 2011 Electron identification Electron deposits its energy in electromagnetic calorimeter Note, what you see here are the energy deposits. Length gives magnitude, but everything is within this calorimeter! Track in tracking detector in front of shower in calorimeter No ‘trace’ in other detectors (electron stops in electromagnetic calorimeter)

Masterclass 2011 Example: W  e Electron track in tracking detector has high “side- ways” or transverse momentum (p T >10GeV) To see this yourself, Electron identification Electron track in tracking detector has high transverse momentum (p T >10GeV) To see this yourself, click on ‘hand’

Masterclass 2011 Example: W  e Electron track in tracking detector has high “side- ways” or transverse momentum (p T >10GeV) To see this yourself, Example: W  e Electron track in tracking detector has high “side- ways” or transverse momentum (p T >10GeV) To see this yourself, click on ‘pick’ Electron identification Electron track in tracking detector has high transverse momentum (p T >10GeV) To see this yourself, click on ‘hand’ move the pointer to the track and click on it

Masterclass 2011 Example: W  e Electron track in tracking detector has high “side- ways” or transverse momentum (p T >10GeV) To see this yourself, click on ‘hand’ move the pointer to the track and click on it Selected track becomes grey Electron identification Electron track in tracking detector has high transverse momentum (p T >10GeV) To see this yourself, click on ‘hand’ move the pointer to the track and click on it Selected track becomes grey p T is shown here

Masterclass 2011 Neutrino identification Characteristics: Neutrino measured indirectly via large missing transverse energy (E T miss > 10GeV) -Red dashed line in end- on view -Note the thickness corresponds to the magnitude of E T miss ( -Not shown if value very small) E T miss value also shown on Lego Plot

Masterclass 2011 Muon identification Track in muon detector Track in tracking detector Extremely small activity in calorimeters Muon has high track transverse momentum (p T >10GeV)

Masterclass 2011 Jet Background Characteristics: Does not contain W  e, W , Z  ee, Z  Typically bundles of particles (jets) are produced Energy deposited in the electro-magnetic and hadronic calorimeter Several tracks belonging to a jet are found in tracking director Missing Energy is usually small or zero

Masterclass 2011 Exercise: Let’s start!  The first event you have to analyse is already displayed  Study each event and classify it into 5 different categories  W  e, W , Z  ee, Z , background  Only one category per event!  There are some additional sheets to help you next to your computer  If you don’t manage to classify all events do not worry!  Have a play with Atlantis  Enjoy and feel free to ask questions!

Masterclass 2011 Exercise: Almost done!  Now capable of identifying different types of events  W  e, W , Z  ee, Z , background  Only worked with a small sample of events  Many more W’s are produced compared to Z events  Note: in reality there many more background events than W or Z events compared to this sample  Thank you for taking part!  Make use of the links available in the handouts (next slide)  Feedback welcome!

19 MINERVA Masterclass Resources Main Minerva website Access to handouts/instruction sheets (also linked from Minerva page under ‘Masterclass resources’) ATLAS Experiment public website Learning with The Particle Adventure (Good introduction to particle physics)