KRITIKANATIONAL INSTITUTE OF TECHNOLOGY, GOA

RUN THROUGH OF OUR TASKS

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.

ELEMENTARY 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.

Some outline on particles

An elementary particle becomes a different particle with less mass and an intermediate particle

The intermediate particle then transforms into other particles.

DECAY MODE OF PARTICLES

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

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.

ELECTROMAGNETIC CALORIMETER

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.

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

HADRON CALORIMETER

Hadronic shower 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

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 PhotoMultiplier Tubes (PMTs).

HADRON FORWARD CALORIMETER

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.

LUMINOSITY

Online Methods: Zero Counting Method- measure the average fraction of

empty towers per bunch crossing in order to determine the relative luminosity

ET Sum 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

Methods of measuring luminosity

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

DATA ACQUISITION (DAQ)

DAQ ARCHITECTURE

LUMINOSITY DAQ

LumiDAQ

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

ROOT AND LXPLUS SERVER

CURVE FITTING

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.

FUTURE SCOPE

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