Teachers colloquium

194 views

Published on

Dheeraj Kumar Singh

Published in: Education, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
194
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
3
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Teachers colloquium

  1. 1. Beauty in the Universe
  2. 2. Innermost SpaceHigh Energy ParticlePhysics is a study of thesmallest pieces of matter.It investigates the deepestand most fundamentalaspects of nature.It investigates (among otherthings) the nature of theuniverse immediately afterthe Big Bang.It also explores physics attemperatures not commonfor the past 15 billion years(or so).
  3. 3. Helium NeonPeriodic Table All atoms are made of protons, neutrons and electrons u u u d d d Proton Neutron Electron Gluons hold quarks together Photons hold atoms together
  4. 4. u dWhile quarks have b tsimilar electric charge,they have vastly sdifferent masses (but czero size!)
  5. 5. e rs ve ni U Why three dimensions? m n tu What gives particles their ua Q mass? he Are there new forces and t symmetries that we don’t yet know? of s rie Are the forces and particles of which we do te know just different faces of a deeper,ys unifying principle?M
  6. 6. α=e2/ħc
  7. 7. Fermi National Accelerator Laboratory (a.k.a. Fermilab) • Begun in 1968 • First beam 1972 (200, then 400 GeV) • Upgrade 1983Jargon alert: 1 Giga Electron Volt(GeV) is 100,000 times more energy (900 GeV)than the particle beam in your TV. • Upgrade 2001If you made a beam the hard way, (980 GeV)it would take 1,000,000,000 batteries
  8. 8. → The Main Injector upgrade was completed in 1999. → The new accelerator increases the number of possible collisions per second by 10-20. → DØ and CDF have undertaken massiveExpected upgrades to utilize the increased Number Huge statistics of for precision physics collision rate. Events at low mass scales 1000 → Run II began March 2001 Formerly rare processes become high statistics 100 processes 10 Run II Increased reach for discovery physics at highest masses 1 Run I Increasing ‘Violence’ of Collision
  9. 9. How Do You Detect Collisions?• Use one of two large multi-purpose particle detectors at Fermilab (DØ and CDF).• They’re designed to record collisions of protons colliding with antiprotons at nearly the speed of light.• They’re basically cameras.• They let us look back in time.
  10. 10. Typical Detector • Weighs 5,000 tons (Now) • Can inspect 10,000,000 collisions/second • Will record 50 collisions/second • Records30’ approximately 10,000,000 bytes/ second • Will record 1015 (1,000,000,000,000,000) 30 bytes in the next ’ 50’ run (1 PetaByte).
  11. 11. Remarkable PhotosIn this collision, a top andanti-top quark were created,helping establish their existence This collision is the most violent ever recorded (and fully understood). It required that particles hit within 10-19 m or 1/10,000 the size of a proton
  12. 12. Modern Cosmology • Approximately 15 billion years ago, all of the matter in the universe was concentrated at a single point • A cataclysmic explosion (of biblical proportions perhaps?) called the Big Bang caused the matter to fly apart.• In the intervening years, the universe has been expanding, cooling as it goes.
  13. 13. Now(13.7 billion years)Stars form(1 billion years)Atoms form(380,000 years)Nuclei form(180 seconds)Nucleons form(10-10 seconds) 4x10-12Quarks differentiate seconds(10-34 seconds?)??? (Before that)
  14. 14. e rs ve ni U Why three dimensions? m n tu What gives particles their ua Q mass? he Are there new forces and Back to the t symmetries that we don’t yet know? of Mysteries s rie Are the forces and particles of which we do te know just different faces of a deeper,ys unifying principle?M
  15. 15. In 1964, Peter Higgs postulated a physics mechanism which gives all particles their mass. This mechanism is a field which permeates the universe. If this postulate is correct, then one of the signatures is a particle (called the Higgs Particle). Fermilab’s Leon Lederman co-authored a book on the subject called The God Particle. bottom topUndiscovered!
  16. 16. Higgs: AnAnalogy
  17. 17. Hunting for HiggsFor technical reasons, we look for Higgs bosons in association with a W or Z boson. b jet In the region where the Higgs boson is expected, we expect itelectron to decay nearly- exclusively into b- quarksneutrino(MET) H → bb
  18. 18. Symmetries Translational Rotational
  19. 19. More Complex Symmetries In a uniform gravitational field, a ball’s motion is independent of vertical translation. The origin from where potential energy is chosen is ∆h irrelevant. 1 2 mv = mg∆h 2The equations of motion are“symmetric under vertical orhorizontal translations.” v = 2 g∆h
  20. 20. Complex Familiar Symmetries y r r2 r1 x 1 q1q12 2qqV= 4πε o | r1 − r2 | r
  21. 21. Complex Familiar Symmetries yTranslations: r x → x + ∆x y → y + ∆y r2 r1 r2 x r1 1 q1q2V= 4πε o | r1 − r2 |
  22. 22. Complex Familiar Symmetries yReflections: r x → -x y → -y r2 x r1 x 1 q1q2V= 4πε o | r1 − r2 | y
  23. 23. Complex Familiar Symmetries yRotations: r φ → −φ r2 r1 x 1 q1q2V= 4πε o | r1 − r2 |
  24. 24. Complex Familiar Symmetries yCharge Flip: r q→−q r2 r1 x 1 q1q2 1 (−q1 )(− q2 )V= = =V 4πε o | r1 − r2 | 4πε o | r1 − r2 |
  25. 25. Complex Familiar Symmetries y rBottom Line:Electromagnetic force r2exhibits a symmetryunder: r1TranslationRotationReflection xCharge Congugation 1 q1q 1 (−q1 )(− q2 )V=(and many others) 2 = =V 4πε o | r1 − r2 | 4πε o | r1 − r2 |
  26. 26. Fermions and Bosons Fermions: matter particles ½ integer spin Bosons: force particles integer spin
  27. 27. Unfamiliar SymmetriesOne possible symmetry that is not yet observed is theinterchange of fermions (spin ½ particles) and bosons(integral spin particles) Known equation Equation = Fermions + Bosons Interchanged equation (pink ⇔ green) Equation = Fermions + Bosons
  28. 28. Unfamiliar SymmetriesOne possible symmetry that is not yet observed is theinterchange of fermions (spin ½ particles) and bosons(integral spin particles) Fermions + Bosons + Known equation Equation = Fermions + Bosons Interchanged equation (pink ⇔ green) + Fermions + Bosons This New=Symmetry+is called Equation Fermions Bosons SuperSymmetry (SUSY)
  29. 29. SUSY Consequence• SUSY quark “squark”• SUSY lepton “slepton”• SUSY boson “bosino”
  30. 30. The Golden Tri-lepton SuperSymmetry Signature muonsThis is the easiest toobserve signature forSUSY. electronNo excess yet observed. neutrino
  31. 31. The Conundrum of Gravity• Why is gravity so much weaker (~10-35×) the other forces? – Completely unknown• One possibility is that gravity can access more dimensions than the other forces
  32. 32. The Dimensionality of Space Affects a Force’s Strength Qencl  • Gauss Law = ∫ E ⋅ dA εo 1 Qencl 1 Qencl E= E= 2πε o r 4πε o r 2 2D 3D
  33. 33. Are More Dimensions Tenable?• Newton’s Law of Gravity Gm1m2 F= 2 r• Clearly indicates a 3D space structure. Or does it?
  34. 34. Nature of Higher Dimensions• What if the additional dimensions had a different shape?• What if the additional dimensions were small?
  35. 35. Access to Additional Dimensions• What if gravity alone had access to the additional dimensions?
  36. 36. Access to Additional Dimensions• What if gravity alone had access to the additional dimensions?
  37. 37. A Model with “n” Dimensions.• Gravity communicating with these extra dimensions could produce an unexpectedly large number of electron or photon pairs.• Thus, analysis of the production rate of electrons and photon provides sensitivity to these extra dimensions.• Large energies are required to produce such pairs. p e q q’ G p e
  38. 38. Once again there are interesting events! (way out on the mass tail.) ee pair γγ pairelectrons photons
  39. 39. Data-Model Comparison
  40. 40. Data-Model Comparison
  41. 41. Summary• Particle physics allows us to study some of the deepest mysteries of reality.• We know a whole bunch of stuff. Send students.• The things we don’t know, we’re studying like mad.• The mysteries mentioned here are unsolved. We need help.
  42. 42. www-d0.fnal.gov/~lucifer/PowerPoint/Teacher_Colloquium.ppt
  43. 43. Available at Amazon, BarnesandNoble.com + local book stores

×