Slide 1

f Don Lincoln, Fermilab f Recreating the Universe 3,000,000 Times a Second Don Lincoln Fermilab f Slide 2 f Don Lincoln, Fermilab f Hubble Telescope This image is taken of galaxies that are billions of light-years away. Light takes a very long time to travel to Earth. Consequently, this photograph is of the conditions that existed billions of years ago, just a billion years or so after the big bang. Astronomers have thus created a time machine of sorts. Slide 3 f Don Lincoln, Fermilab f Slide 4 Familiar Cosmology 1In the beginning God created the heaven and the earth. 2And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters. Slide 5 f Don Lincoln, Fermilab f 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. Slide 6 f Don Lincoln, Fermilab f Big Bang Theory White Sox Version Slide 7 f Don Lincoln, Fermilab f Consequences of the Big Bang If the universe did come into existence through a cataclysmic explosion, there should be some evidence. Three forms which I will discuss are: The universe should be expanding The universe should have a measurable temperature. The mix of the elements should be known. Slide 8 f Don Lincoln, Fermilab f Doppler Effect The Doppler effect says that things moving away from you look redder than they would if they werent moving. Things moving towards you look more blue. YouSource Slide 9 f Don Lincoln, Fermilab f Edwin Hubble Using the Doppler effect, Edwin Hubble discovered that objects that were further away move away faster (and, hence, were redder) than nearer objects. This discovery showed that the universe was expanding and still provides one of the best measurements of the age of the universe. 1929 Galaxies Modern Supernova Slide 10 f Don Lincoln, Fermilab f Black Body Radiator Universe A black body radiator is one which absorbs all light which is incident on it. Such a body can also emit light, if sufficiently hot. Since the universe is the remnant of a hot explosion, it should thus have a temperature and an afterglow. ? ? ? ? Slide 11 f Don Lincoln, Fermilab f Afterglow From the Big Bang Slide 12 f Don Lincoln, Fermilab f Afterglow From the Big Bang In 1964, while working at Bell Labs, Penzias and Wilson discovered a radio hiss that they couldnt make go away. They had (by accident!) discovered the remnant echo of the Big Bang The universe was shown to have a temperature of 2.726K (-450 F) Slide 13 f Don Lincoln, Fermilab f COsmic Background Explorer In 1992, COBE announced a measurement that showed that the background radiation was not quite uniform (although nearly so) This measurement records information approximately 300,000 years after the Big Bang Slide 14 f Don Lincoln, Fermilab f Goldilocks Effect These three plots show three different effects, each 10% less than the one larger than it. You can see how seeing a small effect first requires removing the bigger one. Full, 10%, and 1% 10% and 1% 1% Full only 10% only Slide 15 f Don Lincoln, Fermilab f COBE 0 K4 K2.724 K2.732 K2.7279 K2.7281 K2.72799 K2.72801 K Gross Temperature Profile Motion Dipole Galactic Plane COBE Results Slide 16 f Don Lincoln, Fermilab f Helium Abundance in the Universe At the late time (as we shall see) of 3 minutes in the history of the universe, atomic nuclei were created. Big Bang theory predicts that the relative abundances of hydrogen and helium were: Hydrogen 76% Helium 24% Lithium 1 part per 10 10 Due to nuclear fusion in stars since the Big Bang, current abundances: Hydrogen 73% Helium 26% Everything else 1% Slide 17 f Don Lincoln, Fermilab f Summary of Cosmologic Measurements The Big Bang theory is consistent with observations. Specifically Hubble Telescope can view the universe ~1,000,000,000 years after the Big Bang The COBE satellite can view the universe ~300,000 years after the Big Bang The Hydrogen/Helium ratio can view the universe ~3 minutes after the Big Bang To which a particle physicist replies. Slide 18 f Don Lincoln, Fermilab f Thats cute Slide 19 f Don Lincoln, Fermilab f No.really..its cute Slide 20 f Don Lincoln, Fermilab f Whats so interesting about that? All the interesting stuff is over by three minutes. The universe was in a retirement home by then. Slide 21 f Don Lincoln, Fermilab f The really interesting question is: What happened when the universe was young and hot? Slide 22 f Don Lincoln, Fermilab f Whats the Point? High Energy Particle Physics is a study of the smallest pieces of matter. It investigates (among other things) the nature of the universe immediately after the Big Bang. It also explores physics at temperatures not common for the past 15 billion years (or so). Its a lot of fun. Slide 23 f Don Lincoln, Fermilab f Periodic Table All atoms are made of protons, neutrons and electrons HeliumNeon u d u u d d Proton Neutron Electron Gluons hold quarks together Photons hold atoms together Slide 24 f Don Lincoln, Fermilab f Slide 25 Now (15 billion years) Stars form (1 billion years) Atoms form (300,000 years) Nuclei form (180 seconds) Protons and neutrons form (10 -10 seconds) Quarks differentiate (10 -34 seconds?) ??? (Before that) Fermilab 410 -12 seconds LHC 10 -13 Seconds Slide 26 f Don Lincoln, Fermilab f The Big Question How do you get something as hot as it was during the Big Bang? Smash stuff together!! Hot! Slide 27 f Don Lincoln, Fermilab f Fermi National Accelerator Laboratory The highest energy particle accelerator in the world. Slide 28 f Don Lincoln, Fermilab f Fermi National Accelerator Laboratory (a.k.a. Fermilab) Begun in 1968 First beam 1972 (200, then 400 GeV) Upgrade 1983 (900 GeV) Upgrade 2001 (950 GeV) Jargon alert: 1 Giga Electron Volt (GeV) is 100,000 times more energy than the particle beam in your TV. If you made a beam the hard way, it would take 1,000,000,000 batteries Slide 29 f Don Lincoln, Fermilab f Slide 30 How Do You Detect Collisions? Use one of two large multi-purpose particle detectors at Fermilab (D and CDF). Theyre designed to record collisions of protons colliding with antiprotons at nearly the speed of light. Theyre basically cameras. They let us look back in time. Slide 31 f Don Lincoln, Fermilab f D Detector: Run II Weighs 5000 tons Can inspect 3,000,000 collisions/second Will record 50 collisions/second Records approximately 10,000,000 bytes/second Will record 10 15 (1,000,000,000,000,000) bytes in the next run (1 PetaByte). 30 50 Slide 32 f Don Lincoln, Fermilab f Slide 33 Remarkable Photos This collision is the most violent ever recorded. It required that particles hit within 10 -19 m or 1/10,000 the size of a proton In this collision, a top and anti-top quark were created, helping establish their existence Slide 34 f Don Lincoln, Fermilab f Highlights from 1992-1996 Run Limits set on the maximum size of quarks (its gotta be smaller than 1/1000 the size of a proton) Supported evidence that Standard Model works rather well (didnt see anything too weird) Studied quark scattering, b quarks, W bosons Top quark discovery 1995 Slide 35 f Don Lincoln, Fermilab f The Needle in the Haystack: Run I There are 2,000,000,000,000,000 possible collisions per second. There are 300,000 actual collisions per second, each of them scanned. We write 4 per second to tape. For each top quark making collision, there are 10,000,000,000 other types of collisions. Even though we are very picky about the collisions we record, we have 65,000,000 on tape. Only 500 are top quark events. Weve identified 50 top quark events and expect 50 more which look like top, but arent. Run II 10 Slide 36 f Don Lincoln, Fermilab f What Do Top Quarks Look Like? Top quarks are the heaviest particle known. Each one has the mass of an entire gold atom (while remaining among the smallest objects known). Slide 37 f Don Lincoln, Fermilab f Increasing Violence of Collision Expected Number of Events Run II Run I Increased reach for discovery physics at highest masses Huge statistics for precision physics at low mass scales Formerly rare processes become high statistics processes 1 10 100 1000 The Main Injector upgrade was completed in 1999. The new accelerator increases the number of possible collisions per second by 10-20. D and CDF have undertaken massive upgrades to utilize the increased collision rate. Run II began March 2001 Slide 38 f Don Lincoln, Fermilab f Run II: What are we going to find? I dont know! Improve top quark mass and measure decay modes. Do Run I more accurately Supersymmetry, Higgs, Technicolor, particles smaller than quarks, something unexpected? Slide 39 f Don Lincoln, Fermilab f 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). Fermilabs Leon Lederman co-authored a book on the subject called The God Particle. top bottom Undiscovered! Slide 40 f Don Lincoln, Fermilab f LEP observes significant Higgs candidates for a mass of 115 GeV with a statistical significance of 2.7 and compatible with the expected rate and distribution of search channels. Chris Tully, Fermilab Colloquium 13-Dec-2000 Non-Expert Translation: Maybe we see something, maybe we dont. What we see is consistent with being a Higgs Particle. But it could end up being nothing. Its Fermilabs turn. Slide 41 f Don Lincoln, Fermilab f Data-Model Comparison Slide 42 f Don Lincoln, Fermilab f Data-Model Comparison Slide 43 f Don Lincoln, Fermilab f At Fermilab, we collide elementary particles at unprecedented energies, routinely recreating the conditions fractions of a second after the Big Bang. In the spring of 2001, we have resumed operations after a five year upgrade. We will push our understanding of the universe even further back in time. Its gonna be cool! Slide 44 f Don Lincoln, Fermilab f The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!), but That's funny... -- Isaac Asimov Slide 45 f Don Lincoln, Fermilab f E = m c 2 Energy is Matter Matter is Energy Lots of energy makes lots of matter and vice versa!!!!!!