LA@CERN WP3 :LA@CERN Educational and Outreach Portal 6/25/2018 C.Kourkoumelis,UoA C. Kourkoumelis, UoA

Home rage of the Portal Three cloned pages Data Base search 6/25/2018 C.Kourkoumelis,UoA

Here the different scenaria and missions from WP2 will be added 6/25/2018 C.Kourkoumelis,UoA

6/25/2018 C.Kourkoumelis,UoA

Will be developed later 6/25/2018 C.Kourkoumelis,UoA

H Y P A T I A HYbrid Pupil’s Analysis Tool for Interactions in Atlas already two versions (Simplified and Full) 6/25/2018 C.Kourkoumelis,UoA

Several parts of HYPATIA: (increasing difficulty and involvement time) Background info: HEP, detector description.. 0th) Get acquainted with event display (ATLANTIS) 1st) Look at single particles, identify electrons, muons, match them in different detector parts, .. 2nd) Combine tracks to measure (masses..) of known particles W,Z’s 3rd) Combine tracks to discover new particles ----------------------------- 4th) Go in depth to detector, reconstruction, triggers etc 6/25/2018 C.Kourkoumelis,UoA

HYPATIA 6/25/2018 C.Kourkoumelis,UoA

Part I – Working with Single tracks (for schools) All you need is the Track Window where all the single track information is stored. You can choose different kinds of tracks with the different tabs or put cuts on the tracks using the "cuts tab" of the Parameters Window. Look at single particles (learn the different detector parts, the matching between different detectors, the methods to identify different kinds of particles) In the download file area, there should be some example xml files of few (5-10) SINGLE muons, electrons, pions, neutrinos. One can load these events and look at the detector signatures. Then look at the different kinds of tracks (Muon or Inner Detector tracks, simulated tracks) provided by the different tabs on the Track parameter window. What about the sign of particles? (Explain how to recognize)                Part I (exercises) 1)Provide a file of mixed muons and electrons and ask the student to identify them looking at the different detector signatures. 2)Investigate the effect of the cut button. What happens if you increase the p threshold? Expalin why? 3) Associate the Inner Detector tracks with the Muon tracks in the case of muons. 6/25/2018 C.Kourkoumelis,UoA

Part II – Working with combinations of tracks and reconstructing the Z and W particles (schools and universities) Combine tracks to observe and measure known particles. You are provided with a specialized window called Invariant Mass Window. You can pick and insert to this window several tracks from the previous window Copy the track(s) you wish to make combinations (never more than four tracks/event) using the "Insert track" button. You can also delete tracks with the "Delete track" button and replace them with others. One track: (Use it for the W→ν (neutrino) lepton decays) Insert one track from the Track window to this window. The invariant mass of this track and the missing Et will be automatically calculated and appear under column mνl . Two tracks: (Use them for the Z→lepton-lepton decays) The invariant mass of the inserted two tacks (muons, electrons, one of each etc.) will be calculated automatically and appear under column mll. Part II (exercises) Calculate the invariant mass of two tracks using the analytic formula (or eventually of 3 or 4 particles). This can be done copying the momentum information in an excel file. Check the results with the numbers calculated in the invariant mass window. Examples of these could be Z’s (and eventually Higgs if we have them but wait for the 3rd part!).So by using selection possibilities you should be able to isolate the e’s or muons which are their decay products in an event picture and then calculate their invariant mass. Check with the masses given in the PDG tables. For reconstructing the mass of the Z do you choose tracks with same or opposite sign? Explain your choice. Do you use muon-muon, muon-electron,electron-electron events? Try the different combinations. What is the sum of charges for the two track combinations which you are using? Make histograms of reconstructed Z mass and W transverse mass.What is the Z width? Is the mass which you determine close to the nominal one? Look at the Particle Data Booklet or in tables hanging in your school or in the Web to see what the mass and width of the Z and W is supposed to be. How are the Z and W connected?? 6/25/2018 C.Kourkoumelis,UoA

Part III – Discover the Higgs particle (universities,science centers?) The easiest decays of the Higgs to look for, are those to four muons, four electrons or two muons plus two electrons. For this purpose use the Invariant mass Window but insert four tracks .You should pick and insert to this window the four tracks which you think they belong to a possible Higgs decay. Then the four particle invariant mass will be calculated in the mllll column. Load enough events and histogram the four track masses mllll. If you do not "like" the invariant mass of a particular combination of four tracks you can replace from one to four tracks with another(s). The window will automatically give you the new invariant mass under the relevant column. If the Higgs exists and if you have picked up the right tracks then you will see an accumulation of events around a specific mass, which is hopefully the Higgs mass!!! Part III (exercises) 1)Make separately the invariant masses of four muons, four electrons and two muon-two electron combinations. Do you observe any difference? What is the sum of all charges of the four tracks? 2)Look also at the two track combinations (which?).What is the sum of the sign of the two particles? Why? Do you see any sign of the previously reconstructed Z particle? 3)(Lastly and more complicated: reconstruct tt events. First try to reconstruct the two W’s from their bW decays. They could also learn about b’s and the signature of their semileptonic decays). Higgs histogram 6/25/2018 C.Kourkoumelis,UoA