Masterclass 20081 Introduction to hands-on Exercise Aim of the exercise  Identify electrons, muons, neutrinos in the ATLAS detector  Types of Events

Download Masterclass 20081 Introduction to hands-on Exercise Aim of the exercise  Identify electrons, muons, neutrinos in the ATLAS detector  Types of Events

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<ul><li><p>Introduction to hands-on ExerciseAim of the exerciseIdentify electrons, muons, neutrinos in the ATLAS detectorTypes of Events (particles produced in one collision)WeWZeeZBackground from jet production (which might look like W or Z event) All the above events are well-known processesin addition we added one event from a yet undiscovered particle, Higgs, we hope to find soonHeeee, Hmmm, or Heem There will be a surprise prize for those who identifies this event !!!To do the exercise we use the Atlantis visualisation programAs we dont have data yet, we will use simulations</p></li><li><p>How does a collider work?</p></li><li><p>How to detect particles in a detectorTracking detectorMeasure charge and momentum of charged particles in magnetic fieldElectro-magnetic calorimeterMeasure energy of electrons, positrons and photonsHadronic calorimeterMeasure energy of hadrons (particles containing quarks), such as protons, neutrons, pions, etc.Muon detectorMeasure charge and momentum of muonsNeutrinos are only detected indirectly via missing energy not recorded in the calorimeters</p></li><li><p>Detail we cannot measure the whole event energy because energy is lost in very forward region (beam-pipe) better measurement: side-way component typically interesting collisions contain particles with big side-ways energies</p></li><li><p>Example: WeElectron track in tracking detector has high side-ways or transverse momentum (pT&gt;10GeV)To see this yourself,</p></li><li><p>Example: We Electron deposits large side-ways energy (ET) in electro-magnetic calorimeter (ET&gt;10GeV)To see this yourself,</p></li><li><p>Example: WeCharacteristics: Electron with high side-way energy- We now know how to identify them!Example: WeCharacteristics: Electron with high side-way energy- We now know how to identify them! Neutrino measured indirectly via large missing side-way or transverse energy (ETmiss &gt; 10GeV)</p></li><li><p>Example: WCharacteristics:</p></li><li><p>Muon identification</p></li><li><p>Example: WCharacteristics: Large missing side-ways energy (ETmiss &gt; 10 GeV) 1 muon with high track side-way momentum (pT&gt;10GeV)</p></li><li><p>Example: ZeeCharacteristics:2 electrons in the eventExample: Zee</p></li><li><p>Example: ZCharacteristics:2 muons in the eventExample: ZCharacteristics:2 muons in the event</p></li><li><p>Example: backgroundCharacteristics: Does not contain We, W, Zee, ZExample: backgroundCharacteristics: Does not contain We, W, Zee, Z Typically bundles of particles (jets) are produced</p></li><li><p>Remember: Sometimes its not so obvious if its a jet or an electron Electron stops in electro-magnetic calorimeter, so has ONLY electro-magnetic component Jet goes also in hadronic calorimeter, so has electro-magnetic AND hadronic component </p></li><li><p>Exercise: lets start!The first event you have to analyse is already displayedStudy each event and classify it into 5 different categoriesWe, W, Zee, Z, backgroundThere are some additional sheets to help you next to your computerWhen you decide what type it is, tick the corresponding box (,,)Only one tick per event! Go to the next event using Nextclassify tick next Once you have analysed 20 events youre done! Calculate the totals and tell me your resultslook at the detector displays or hunt for the Higgs If you dont manage to classify all events do not worry!just stop where you are at the end and do the final count Dont forget there is also one Higgs event (Hmmm, Heeee or Heem) in the whole sample and theres a prize waiting. At the end we will do the final summary and look at the ratio We/W, Zee/Z and the ratio W/Z production together</p></li></ul>