Who/What/Where is TRIUMF ? TRIUMF is Canada's National Lab for - PowerPoint PPT Presentation

Who/What/Where is TRIUMF ? ● TRIUMF is Canada's National Lab for Particle and Nuclear Physics ● ~470 staff, ~220 Canadian Scientists, ~380 foreign scientists ● Joint venture of UBC, SFU, UVic, Alberta, Carleton, Toronto ● Collaborations with 14+ institutions in Canada, 36+ abroad ● Happen to be located on UBC campus Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

What do we do ? ● DON'T ... Make bombs Generate power Have an assembly line ● DO ... Stellar nuclear synthesis Fundamental Interactions Medical Physics Nuclear structure Material properties Applications of physics Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

WHY ? D' ou venons nous? Que sommes nous? D' ou allons nous ? Physicists ask - “ Why does the universe and everything in it exist, and why does it look the way it does” Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

This Hour has 13 Billion years 1.The Standard Model (briefly) 1. What is everything made of ? 2.Big Bang Cosmology (briefly-er) 1. History of the universe 3.Connection between 1) and 2) 4.Creation of the elements 5. (Where TRIUMF fits in) Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

“Fundamental particles” ● Idea of a fundamental particle age old ● started with Democritus (~400BC) ● “atom” means indivisible ● Search for the fundamental constituents of matter, and the fundamental rules governing their interaction is called Particle Physics ● Techniques have evolved drastically over time Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Evolution of the “fundamental particles” ● “fundamental” pa rticles are electrons and quarks . . . ● . . . which have no size ● Huh ? Then how is stuff “ s olid” Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Fundamental Forces Electromagnetic Force (not to scale) Helium (also binds molecules) ==> “ P hoton Exchange” Strong Force d u (also binds nuclei) d ==> “ Glu on” Ex change u Weak Force p (important for radioactive decay) ==> “ W, Z Boson” Exchange n Forces give matter its structure Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

How do we “see” p λ = 500 nm (0.00000005 m) λ λ = 0.000001 nm E = 2.5 eV E = 500 000 000 eV Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Why we build particle accelerators ● Idea #1 : to “ see ” so mething, must “touch” it with something smaller ● Idea #2 : in quantum mechanics, higher energy ==> smaller dimensions Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Tools of the trade “particle” Light Helium nucleus proton electron Energy [eV] ~1 ~1 000 000 ~500 000 000 ~100 000 000 000 size [ µ m] ~1 ~0.000 01 ~0.000 000 000 5 ~0.000 000 000 000 000 000 1 cell other nuclei protons, neutrons quarks “what” Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

The Standard Model (on a T-shirt) Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

The “other” force - Gravity ● Einstein's General Theory of Relativity ● G µν = 8 π T µν – λ g µν ● “geometrical” theory unlike Standard Model ● Friedmann (1922) said that GR predicts that universe is expanding ● Edwin Hubble (1929) observed that universe is expanding ● Hmmm , if universe is expanding, if we run clock backwards, then ... Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

The Big Bang ● Take all the energy in the universe, and start shrinking it into a smaller and smaller volume ● Average energy gets higher and higher ● (think compressing a bicycle pump) ● Eventually energy high enough to - ● Break apart atoms, then ● Break apart nuclei, then ● Break apart protons, then ● etc etc ... ● Eventually get to a point – The Big Bang Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

History of the Universe, Part II TRIUMF Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Big Bang: the moment after ● A “ roughly-pretty-good-outline-of-an- -idea” about what happened ● t<10 -43 seconds: ● “quantum gravity” ??? ● 10 -43 <t<10 -35 seconds: ● As universe 'cooled', gravitation force separated from others ● ~10 -35 seconds : Inflation !! ● Universe enlarges unimaginably fast ● From much smaller than a proton to the size of a softball Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Hot Particle Soup ● 10 -35 <t<10 -5 seconds ● “somehow” fun damental particles are created ● Strong force separates from the others ● Then Weak force separates from Electromagnetic ● W, Z bosons created ● “Soup” of quarks, photons, gluons, W, Z, etc... ● Too energetic to stick together Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Whence Antimatter ? ● Q: if we started with equal matter and anti-matter, why didn't they just annihilate each other and leave just photons ? ● A: CP Violation i.e. Matter and anti-matter interact (very) slightly differently. ● Result in small excess of matter ● NOT TOTALLY UNDERSTOOD Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Primordial Nucleosynthesis ● 10 -5 <t<100 seconds: ● Most Anti-particles gone ● Quarks+gluons slow down enough to bind into protons, neutrons, mesons ● But no nuclei form since deuteron (p+n nucleus) unstable ● 100 s < t < 300,000 years ● Deuteron stable, light elements form ● But only up to 7 Li since no stable mass-8 nuclei ● p, D, 3 He, 4 He, 7 Li Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Cosmic Background Radiation ● At 300,000 years, nuclei capture electrons to become atoms ● T=3000K ● Universe now transparent to photons ● As universe expands, photon wavelength increases ● Energy decreases ● Expanding blob of gas ● Almost all hydrogen ● Not exactly uniformly distributed ● Slight density differences Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

STOP !!!Are you pulling my leg ? ● Predict that if T~3000K @ 13 billion years go THEN ~3K today ● Measurement - bang on ! ● Inflation predicts universe smooth and flat ● tiny CMB deviations --> smooth ● Also distribution of galaxies ● Pattern of deviations --> flat ● General relativity calculation Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Are you pulling my leg ? (part 2) ● W, Z bosons observed by experiments at CERN, SLAC ● A TRIUMF experiment helped determine key property of W ● CP violation detected in 1964 ● matter/anti-matter asymmetry ● TRIUMF helped build detector for latest-generation experiment studying this problem ● Predicted BBN element abundances agree with observation ● And CMB pattern supports the result Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

What happened next ? The Stars formed ● After ~1 billion years, inhomogeneities in gas clouds 'clump together' by mutual gravitation to common centre ● Eventually, speed up enough to initiate nuclear fusion reactions ● Reaction primarily creates more helium from the hydrogen ● Clusters, galaxies, etc. forming as well Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Red Giant phase ● Helium gradually builds up in core ● Eventually Helium core contracts, outer expands --> Red Giant ● Energy increases so that Helium can fuse to make Carbon and Oxygen 4 He + 4 He → 8 Be 4 He + 8 Be → 12 C (carbon) 4 He + 12 C → 16 O (oxygen) Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Heavier element synthesis ● For stars < 10 solar masses ● process stops at oxygen ● Becomes nebula+white dwarf ● H, He, C, and O ejected into space ● Star > 10 solar masses ● Enough energy for helium, carbon, oxygen, and silicon fusion ● Process stops with iron production ● Iron most tightly bound nucleus ● Get onion-like structure in star Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Stellar burning time scales Threshold Duration Fuel Major Products Temperature of stage (K) Hydrogen Helium 4 Million 7 x 10 6 years Helium Carbon, Oxygen 100 Million 5 x 10 5 years Oxygen, Neon, Sodium, Carbon 600 Million 600 years Magnesium Magnesium, Sulfur, Oxygen 1 Billion 6 months Phosphorous, Silicon Silicon Cobalt, Iron, Nickel 3 Billion 1 day Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Heavy Element Synthesis - supernova ● Stars > 10 solar masses ● No more fusion after iron produced ● No more energy to counteract gravitational collapse ● In seconds , major implosion followed by explosion – supernova ! ● Heaviest elements created ● “R-process” , “s-process” Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

What happens to ejected matter ? ● Matter ejected from nebula or supernova eventually recombine from gravitation attraction to form new stars ● Hydrogen, etc tends to collect in centre ● New star ! ● Heavier elements tend to the edges ● Planets ! ● Densest elements end up in ... men ? ● We are Star Dust ! Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006

Are you SURE ?? - Yes. ● Look at the solar surface, interstellar space to determine relative abundances ● Model stellar evolution and see if you can predict it ● Study meteorite grains older than solar system ● RESULT ? - very good agreement Marcello M. Pavan, TRIUMF, Sechelt Oct 27, 2006