The Large Hadron Collider By Chongjia Wang, Akiyoshi Koide, Jack Mawhinney
Background Information 1.CERN 2.Standard Model 3.Hadron
CERN
Standard Model The Standard Model is the theory describing three of the four known fundamental forces, as well as classifying all known elementary particles.
Hadron
● A particle made from quarks and antiquarks ● Held together by the strong nuclear force ● Example: proton(the particle in LHC), neutron
Cool Facts
● 111 nations involved in designing, building and testing equipment and software ● The total cost of building the LHC was approximately £3.74 billion (4,675,878,900.00$ ) ● Runs for a circumference of 27 km (16.5 mi) ● Can recreate conditions that existed moments after the big bang ● May create a tiny black hole
The design: Particle acceleration ● First step is stripping hydrogen (protium) atoms of electrons ● chain of 4 accelerators (Linac 2, PSB, PS, SPS) ● Injects bunches into LHC in opposite directions
The design: Particle acceleration ● Radiofrequency cavities accelerate particles in tight bunches ● Magnetic fields keep particles in circular motion ● Ultrahigh vacuum inside the beam pipe, largest in the world
Luminosity ● Luminosity (m⁻²s⁻¹): ﱣpotential collisions per given cross section (σ) per second ● Integrated Luminosity: gives collisions occurring per cross section over a given period, measured in inverse femtobarns (1/Area)
Nevents/sec = Luminosity · Cross Section
The Design: Particle collision ● Collide at four locations around the accelerator ring, corresponding to the four particle detectors (ATLAS, CMS, ALICE, LHCb) ● Semiconductor detectors to measure trajectories of charged particles ● Calorimeters measure energies of particles ● Data then analysed and compared to current theories on particle physics
Applications of Relativity ● Particles moving very close to the speed of light γ ≈ 7460 β ≈ 0.999999991 ● Particles would observe large effects of time dilation and length contraction ● Small changes in velocity have large changes in energy
E = γmc²
Synchrotron Radiation â—? Radially accelerated charges produce electromagnetic radiation â—? Limits the amount of energy electrons can have in a circular accelerator
Main Result: Higgs Boson “THE GOD PARTICLE”
Fills in standard model, unifies electromagnetic and weak force
Higgs
Electroweak theory causes some particles to come out with 0 mass. This is a problem for W/Z bosons
Problems Hierarchy Problem
Matter-Antimatter asymmetry
The Hierarchy Problem
To Explain Gravity vs Weak forces
Black Holes for Supersymmet ric Particles
Matter-Antimatter Asymmetry Problem
Answers?
What the LHCb has found (March 2019) For the first time! Asymmetry observed as CP violation in particle D0 Meson (Charm quarks)
CP symmetry = laws of physics apply same to particle and antiparticle Standard Model produces CP violation (Different behaviors)
Without dark matter, galaxies should tear themselves apart
To Recap: Hierarchy problem:
Matter Antimatter Asymmetry:
Supersymmetric particles
CP violation (particle antiparticle behavior) observed
Gravitons Black Hole decay to find elementary particles
Dark Matter could hopefully be observed in LHC collisions
^^^Hope to find with LHC
^^^Also hope with LHC
Bibliography “Large Hadron Collider.” Science and Technology Facilities Council, UK Research and Innovation, 18 Feb. 2019, stfc.ukri.org/research/particle-physics-and-particle-astrophysics/large-hadron-collider/. Plettner, Thomas, et al. “The Impact of Einstein’s Theory of Special Relativity on Particle Accelerators.” Stanford, 2005, web.stanford.edu/~rlbyer/PDF_AllPubs/2005/407.pdf. “Synchrotron Radiation.” Hyperphysics, hyperphysics.phy-astr.gsu.edu/hbase/Particles/synchrotron.html. “LHC: How Fast Do These Protons Go?” Journal Batard, journal.batard.info/post/2008/09/12/lhc-how-fast-do-theseprotons-go. Vidal, Xabier, and Ramon Manzano. “Cross Section.” Taking a Closer Look at the LHC, www.lhccloser.es/taking_a_closer_look_at_lhc/0.cross_section.
Bibliography Institute of Physics. “Particle Detection.” Institute of Physics, www.iop.org/resources/topic/archive/cern/index.html. “Accelerators.” CERN, 2019, home.cern/science/accelerators. Siegel, Ethan. “Five Years After The Higgs, What Else Has The LHC Found?” Forbes, Forbes Magazine, 11 Apr. 2018, www.forbes.com/sites/startswithabang/2018/04/11/five-years-after-the-higgs-what-else-has-the-lhcfound/#1e576fec552c. Diamante, Litizia. “Key Plans for the next Two Years of the LHC.” CERN, 10 Dec. 2018, home.cern/news/news/accelerators/key-plans-next-two-years-lhc. Adams, Todd. “10 Years of Large Hadron Collider Discoveries.” EarthSky, 16 Sept. 2018, earthsky.org/humanworld/large-hadron-collider-lhc-discoveries.