Interactions Kihyeon Cho September 6, 2004

People have long asked, What is world made of? and What holds it together?

In Ancient time What is world made of? water fire earth air

What is World Made of?

Standard Model t, b, c are heavier than other quarks - heavy flavor quarks W, Z, top are stand out from the rest.

Matter Hadron (Quark) - size –Baryon (qqq): proton, neutron –Meson (q qbar): pion, kaon Lepton – no size –Point particle

How to know any of this? (Testing Theory) Example –Light bulb (Source) –Tennis ball (target) –Eye (detector)

Accelerators solve two problems: –High energy gives small wavelength to detect small particles. (Lambda = h /p ) –The high energy create the massive particles that the physicist want to study.(E=mc^2) How to detect?

Accelerator design Shapes –Linacs (SLAC) –Synchrotrons (Fermilab) Collision types –Fixed target (E687, FOCUS) –Colliding beams (CDF, Belle, BTeV) => CM = 1TeV+1TeV => 2TeV

High Energy Experiment

Fixed target vs Colliding beams (total energy) 2 -(total momentum) 2 = invariant in all frames of reference Assume that 800GeV(E beam ) proton collides in a fixed target(proton). Center of mom. frame Laboraroty frame Total energy: E CM E beam +m p Total momentum: 0 P beam Invariant: E CM 2 (E beam +m p ) 2 -P beam 2 E = [ 2(m p 2 +E beam m p ) ] 1/2 = 38.8GeV We are enough to 19.4GeV+19.4GeV proton beams in collider !!! Question: What’s the advantage of a fixed target experiment?

The Fermi National Accelerator Laboratory

Where is Fermilab? 20 mile west of Chicago U.S.A Fermilab

Fermi National Accelerator Laboratory Highest Energy Accelerator in the World Energy Frontier: CDF, D0 Search for New Physics (Higgs, SUSY, quark composites,… Precision Frontier: charm, kaon, neutrino physics (FOCUS, KTeV, NUMI/MINOS,BOONE,…etc. Connection to Cosmology: Sloan Digital sky survey, Pierre Auger,… Largest HEP Laboratory in USA 2200 employees 2300 users (researchers from univ.) Budget is >$300 million

Overview of Fermilab Main Injector and Recycler  p source Booster CDF D0 Fixed Target Experiment

Tevatron Run 1 ( ) Protons H source (18 KeV) → Cockcroft Walton accelerator (750 KeV) → Linac (400 MeV) → Booster (8 GeV) → Main Ring (150 GeV) → Tevatron (900 GeV) Antiprotons Main Ring (120 GeV) → Antiproton Source (Ni) → Debuncher (8 GeV) Accumulator (8 GeV) → Main Ring (150 GeV) → Tevatron (900 GeV)

Tevatron Run II (2001 – 2007) Main Injector (150 GeV proton storage ring) replaces Main Ring Pbar improved –Cooling system –a new permanent magnet recycler Increased number of p and pbar bunches (6  36  100 )

What holds it together? (The four interactions)

Masses of Fundamental Particles t, b, c are heavier than other quarks - heavy flavor quarks W, Z, top are stand out from the rest.

Electromagnetic interactions w/ atoms

WeakElectromagn etic Strong Range 1/Mw Infinitive 1F=1/m  Typical Lifetime(sec) 10^-12 or longer 10^-20~ 10^-16 10^-23 Typical Cross section(mb) 10^-1110^-310 Typical Coupling  10^-610^-21 Summary of interactions

References B.G Cheon ’ s Summer School (2002) S.H Yang ’ s Colloquium (2001) PDG home page (