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KRITIKA

RUN THROUGH OF OUR TASKS. KRITIKA. NATIONAL INSTITUTE OF TECHNOLOGY, GOA. ELEMENTARY PARTICLES. B asic building blocks of the universe from which all other particles are made . Elementary particles are normally treated as massless and have no substructure

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KRITIKA

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  1. RUN THROUGH OF OUR TASKS KRITIKA NATIONAL INSTITUTE OF TECHNOLOGY, GOA

  2. ELEMENTARY PARTICLES • Basic building blocks of the universe from which all other particles are made. • Elementary particles are normally treated as massless and have no substructure • Some of the elementary particles known are fermions, quarks, bosons, baryons, leptons, hadrons, mesons.

  3. Some outline on particles • Quarks- combine to form composite particles called hadrons. • Hadrons- Is a composite particle made of quarks and are categorised into two: • Baryons- made of three quarks (proton, neutron) • Mesons- made up of two quarks (pion) • Pion- A pion(short for pi meson) are the lightest mesons.

  4. DECAY MODE OF PARTICLES • An elementary particle becomes a different particle with less mass and an intermediate particle • The intermediate particle then transforms into other particles.

  5. CALORIMETER • Is an apparatus used to measure energy • Most particles enter the calorimeter and initiate a particle shower and the particles’ energy is deposited in the calorimeter, collected, and measured • We shall discuss about Electromagnetic Calorimeter and Hadron Calorimeter

  6. ELECTROMAGNETIC CALORIMETER • The Electromagnetic Calorimeter (ECAL) is designed to measure with high accuracy the energies of electrons and photons. • The ECAL is constructed from crystals of lead tungstate • Photodetectors are glued onto the back of each of the crystals to detect the scintillation light and convert it to an electrical signal that is amplified and sent for analysis.

  7. When an electron, positron, photon interacts with the material of the calorimeter it produces an em shower of low energy • The sum of ECALS signals belonging to the shower is proportional to the energy of the particle • The characteristic amount of matter traversed for these related interactions is called the radiation length X0.

  8. HADRON CALORIMETER • The Hadron Calorimeter (HCAL) measures the energy of hadrons, particles made of quarks and gluons • The HCAL is a sampling calorimeter meaning it finds a particles position, energy and arrival time using alternating layers of absorber & fluorescent scintillator materials • The total amount of light in the tower gives the energy of the particles

  9. Hadronicshower takes longer to develop than the electromagnetic shower • The shower can be parameterised by a nuclear interaction length • Interaction length is the mean free path of a particle before undergoing an interaction

  10. HADRON FORWARD CALORIMETER • Particles incident on HF will initiate showers leading to large neutron fluxes in the calorimeter absorber material • The amount of light observed by a detector positioned at one end depends on the velocity of the particle, on the incident angle, and on the distance between the particle trajectory and the center of the quartz fibre. • The HF calorimeter comprises –wedges of iron with quartz fibres embedded into them. • These emit Cerenkov light which is collected by an array of PhotoMultiplierTubes (PMTs).

  11. LUMINOSITY • Measure of how efficiently a particle accelerator produces collision events. • The number of events that an experiment observes is proportional to a quantity called the luminosity. • In CMS, the luminosity is measured using signals from the Hadronic Forward (HF) calorimeters.

  12. Methods of measuring luminosity • Online Methods: • Zero Counting Method-measure the average fraction of empty towers per bunch crossing in order to determine the relative luminosity • ETSum Method- exploits the linear relationship between the average transverse energy per tower and the luminosity • Offline Methods: • Luminosity value is stored every 23sec. • It serves as a cross check of online analysis • Better than online measurements

  13. DATA ACQUISITION (DAQ) • Is the process of sampling signals that measure real world physical conditions and converting the samples into digital numeric values. • A trigger is required that can select the potentially interesting events

  14. DAQ ARCHITECTURE

  15. LUMINOSITY DAQ

  16. LumiDAQ

  17. ROOT AND LXPLUS SERVER • Root- Object Oriented Program used to analyse data. • LXPLUS Server- Cluster of machines for interactive work. • Logging onto lxplus server using SSH command • SSH- Network protocol for remote command-line login between two computers • Copying files to and from lxplus server

  18. CURVE FITTING

  19. FUTURE SCOPE Have been given a task for getting deeper into the ET Sum Method and Occupancy Method for Luminosity Measurement and doing a comparative study of both using plots.

  20. THANK YOU

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