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Introduction to Particle Physics

Introduction to Particle Physics. Isabel Baransky. Sophomore at Columbia University's Engineering School (SEAS) Majoring in Applied Physics Minoring in Music Volunteer at multiple teaching organizations Peace by P.E.A.C.E Peer Health Exchange Let's Get Ready, Manhattan! Columbia Splash.

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Introduction to Particle Physics

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  1. Introduction to Particle Physics Isabel Baransky

  2. Sophomore at Columbia University's Engineering School (SEAS) Majoring in Applied Physics Minoring in Music Volunteer at multiple teaching organizations Peace by P.E.A.C.E Peer Health Exchange Let's Get Ready, Manhattan! Columbia Splash About Me

  3. Atoms Subatomic Particles

  4. leptons Elementary Particles

  5. Leptons: Electron Electron Positron: Anti Particle • One of the building blocks of mass • Has a spin of ½, forcing it into the Pauli Exclusion Principle • Negative charge • Identical in mass but has a positive charge • If an electron and positron encounter, they will annihilate each other and produce two gamma rays (photons)

  6. When matter and antimatter ‘touch’, they immediately annihilate each other For instance, electron and positron, or proton and antiproton Two gamma rays are produced At the beginning of the Big Bang, anti matter and matter was produced For reasons unknown, matter “won” and now is the primary source of mass in the universe Annhiliation: Matter and Antimatter

  7. Partner to Electron: Neutrino Neutrino • Sibling of the electron • Neutral charge and almost zero mass • Makes it incredibly difficult to detect • Produced in radioactive decay of nuclei • Neutron turns into a proton by emitting a neutrino and an electron (beta decay) • “Fossil relic” from the Big Bang • Help reveal how fast the universe is expanding • Neutrinos constantly created in the core of the sun

  8. About 400 billion neutrinos from the Sun pass through each one of us each second About 50 billion neutrinos from the ground (radioactive elements such as uranium) hit us each second We emit about 400 neutrinos per second (yes, we are slightly radioactive1) A neutrino can fly through a light-year of lead without hitting anything Very difficult to detect as a result Beta decay and Neutrinos

  9. Leptons: Muon and Tau Muon Tau • Half life is 2.2 microseconds • Very massive • Measuring the flux of muons of cosmic ray origin at different heights above the earth is an important time dilation experiment in relativity. • Muons make up more than half of the cosmic radiation at sea level • 3490 times more massive than the electron • 17 times more massive than the muon • Very unstable • Half life of 2.96*10^-13 seconds

  10. Quarks Elementary Particles

  11. There are six quarks, but physicists usually talk about them in terms of three pairs: up/down, charm/strange top/bottom. For each of these quarks, there is a corresponding antiquark Quarks have the unusual characteristic of having afractionalelectric charge Quarks also carry another type of charge called color charge Quarks and Charge

  12. Quarks: Color Force Color Force Over Distances • The force between quarks • Dictated by gluons • Replacement for the strong force • Strong force only works in baryons • Six colors: three for quarks and three for anti quarks • Force does not decrease with distance • In fact, postulated to increase with distance • The quarks are like free particles within the confining boundary of the color force • Only experience the strong confining force when they begin to get too far apart

  13. baryons Subatomic Particles

  14. Particles made of Quarks Protons Neutrons • Charge of positive one • Slightly less massive than a neutron • Therefore more stable • Half life of 10^32 years • Composed of two up quarks and one down quark • Held together in the nucleus with neutrons by the strong force • Neutral charge • Composed of two down quarks and an up quark • .2% more massive than a proton, making it more unstable • A free neutron has a half life of approximately 10.3 minutes • Decay of the neutron converts a down quark to an up quark using the weak force

  15. Electromagnetic Force Fundamental Force

  16. A combination of the electric and magnetic force, unified under one theory It is an exchange force Carrier particle is the photon, a massless particle Works over infinite distances Follows the same inverse square law as gravity More powerful than gravity, but over long distances it averages to 0 Electromagnetic Force and Photons

  17. Photons • A particle representing a quantum of light or electromagnetic radiation • Completely massless • The infinite range of the electromagnetic force is due to the rest mass of the photon • Has finite momentum • Creates an issue because it has no mass • Can exert a force

  18. Gravity Fundamental Force

  19. Weakest of the four fundamental forces Has the most influence over long distances Carrier particle is hypothesized to be the graviton Graviton is massless, similar to the photon Infinite distance of influence Gravity and Gravitons

  20. Weak Force Fundamental Force

  21. Dictated by the exchange of W and Z bosons Weak force changes one flavor of quark into another Vital for hydrogen burning in the core of the sun and for heavy nuclei build up W and Z bosons are incredibly masssive, which means the weak force only works over very short distances (.1% of a proton) Interacts with both quarks and leptons Weak Force and the W Boson

  22. Strong Force Fundamental Force

  23. Strong Force and Gluons • The strong force holds the particles in the nucleus together • The strong force between nucleons may be considered to be a residual color force • Basic exchange particle is the gluon which mediates the forces between quarks

  24. Dark Matter Particle Physics Standpoint

  25. Introduction to Dark Matter • In 1933, Fritz Zwicky measured the mass of the Coma cluster of galaxies, one of the nearest clusters of galaxies outside of our local group • Zwicky’stechnique was to measure the relative velocities of the galaxies in this cluster from their Doppler shift, use the virial theorem to infer the gravitational potential in which these galaxies were moving, and compute the mass that must generate the potential. • He found this mass to be 400 times the mass of the visible stars in galaxies in the cluster. • The observation was soon confirmed by similar measurements of the Virgo cluster

  26. Types of Dark Matter Hot Dark Matter Cold Dark Matter • Speeds close to the speed of light • The very high speed of the particles would initially prevent the formation of a structure smaller than the supercluster of galaxies dividing up in galaxy cluster then in galaxies, then in smaller structures • The best candidate to constitute the hot dark matter is the neutrino • More massive and therefore slower than hot dark matter • The particles will go on a smaller distance and thus will erase the density's fluctuations on extents smaller than in the case of hot dark matter • The ordinary matter would then gather to form galaxies (starting from gas clouds and smaller structures), which themselves will gather in cluster, then supercluster • The candidates for cold dark matter are WIMP

  27. Dark matter is based on the idea of the WIMP (weakly interacting massive particle) A WIMP is a particle that is massive but stable Can also be produced in pairs with a possible anti particle Very low probability of interacting with matter General Overview

  28. An experiment called XENON100 has been running deep underground at the Gran Sasso Laboratory in Italy. There, a vat filled with 137 pounds of liquid, ultra-pure xenon is protected by the 5,000 feet of ground above it, as well as layers of copper, polyethylene, lead and water, in an attempt to shield it from anything but WIMPS. Detecting WIMPs

  29. After collecting data for 13 months, scientists reported only two events that could have been collisions between WIMP particles and the xenon liquid. However, these two events could also have been caused by impacts from background particles, such as cosmic rays from space, that managed to bypass the detector's shields.

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