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Ali Izadi Rad Sharif University of Technology, Tehran, IRAN

Towards τ reconstruction at the High Luminosity LHC with a High Granularity Endcap Calorimeter for CMS. Ali Izadi Rad Sharif University of Technology, Tehran, IRAN Supervisors: M. Mannelli , P.Silva (CERN-CMG). CERN Summer Student Lectures 14 August 2014.

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Ali Izadi Rad Sharif University of Technology, Tehran, IRAN

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  1. Towards τ reconstruction at the High Luminosity LHC with a High Granularity Endcap Calorimeter for CMS Ali Izadi Rad Sharif University of Technology, Tehran, IRAN Supervisors: M. Mannelli , P.Silva (CERN-CMG) CERN Summer Student Lectures 14 August 2014

  2. A.Izadi Rad, SUT 2/13 Outline What is HL-LHC What is High Granularity Endcap Calorimeter of CMS Whyτ reconstruction ? Howτ reconstruction?

  3. A.Izadi Rad, SUT 3/13 Future of LHC Good News! You Are Here !! I will be 30 years old!

  4. A.Izadi Rad, SUT 4/13 The High Granularity Calorimeter Good News! Why ?? • In the HL-LHC we expect to have an average pileup of 140while so far we had ~20 pileup.This means that the energy flow and the occupancy of the detector willincrease drastically. The endcap detectors must be upgradedotherwise they won't be able to:  - sustain the radiation damage  - distinguish a hard collision from the superposition of pileup eventsIn this context a high granularity calorimeter can help has the • occupancy is reduced because the energy flow is divided by • more cells, one is able to distinguish single particles.Given the calorimeter architecture is new, reconstruction • algorithms must be adapted, Refer to yesterday talk of Alena For the first time a calorimeter is able to behave as a "tracker".

  5. A.Izadi Rad, SUT 5/13 Higgs physics prospects at the HL-LHC The measurement of the Higgs self coupling will become feasible at higher energy and integrated luminosity • In July 2012, ATLAS and CMS discovered a SM Higgs-like particle using ~25 fb-1 of 7+8 TeVpp data • The nature of this particle not yet fully established : spin, CP, couplings will benefit from high luminosity

  6. A.Izadi Rad, SUT 6/13 Main branches of Higgs decays

  7. A.Izadi Rad, SUT 7/13

  8. A.Izadi Rad, SUT 8/13 Towards τ reconstruction The most abundant particles found after a τ lepton decay are π±, π0, K± and K0. To reconstruct a τ lepton we naturally start by studying how pions are reconstructed.

  9. A.Izadi Rad, SUT 9/13 π0 reconstruction • Neutral pions decay mostly to two photons. As the decay products interact electromagnetically it is detected in the electromagnetic calorimeter. Due to interaction • with the tracker material we may observe several electromagnetic showers developing in parallel.

  10. A.Izadi Rad, SUT 10/13

  11. Exploring the shower structure A.Izadi Rad, SUT 11/13 • By looking at the structure of energy deposit in the Calorimeter we can study • how collimated is the shower • How many particles it contains • An Hough transform can be used for this purpose. The total accumulated in the maximum of the Hough transform can help us to distinguish between single and multiparticle showers. As shown in the Figures single photons are expected to produce collimated, high energy showers while neutral pions tend to produce multiple-core showers of lower energy. We are exploring these properties for particle identification.

  12. A.Izadi Rad, SUT 12/13 π± reconstruction • π± are charged hadrons which interact mostly in the hadronic calorimeter. In the electromagnetic calorimeter they are expected to leave low energy ionization deposits. • Showers are expected to be wider with respect to π0.

  13. A.Izadi Rad, SUT 13/13 Thank you 

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