What Are They Doing at Fermilab Lately? Don Lincoln Fermilab

What’s 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). It’s a lot of fun.

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

All particles have ‘anti-particles’, which have similar properties, but opposite electrical charge  Particles –u,c,t +2/3 –d,s,b -1/3 –e, ,  -1  Anti-particles –u,c,t -2/3 –d,s,b +1/3 –e, ,  +1

Now (15 billion years) Stars form (1 billion years) Atoms form (300,000 years) Nuclei form (180 seconds) Protons and neutrons form ( seconds) Quarks differentiate ( seconds?) ??? (Before that) Fermilab 4× seconds LHC Seconds

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

Fermilab Facts Named after Enrico Fermi, the famous Italian physicist who worked on the Manhattan Project. Current Director: Michael S. Witherell Fermilab encompasses 6800 acres, much of it used for prairie restoration and preserving open space in the western suburbs. Employees about 2000 people. Original cost $250,000,000. Approximately the same amount in upgrades over the last 30 years. Electric bill between $10,000,000 and $20,000,000 NO classified work is done here, ask all the questions and take all the pictures you want.

Fermilab’s Wilson Hall Saint-Pierre Cathedral in Beauvais, France 1272 A.D.

Why the Buffalo? Radiation Detector? Nah...that’s why we have graduate students....and they’re cheaper....

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  The Main Injector upgrade was completed in  The new accelerator increases the number of possible collisions per second by  DØ and CDF have undertaken massive upgrades to utilize the increased collision rate.  Run II began March 2001

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.

DØ Detector: Run II 30’ 50’ Weighs 5000 tons Can inspect 3,000,000 collisions/second Will record 50 collisions/second Records approximately 10,000,000 bytes/second Will record (1,000,000,000,000,000) bytes in the next run (1 PetaByte).

Remarkable Photos This collision is the most violent ever recorded. It required that particles hit within 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

Highlights from Run Limits set on the maximum size of quarks (it’s gotta be smaller than 1/1000 the size of a proton) Supported evidence that Standard Model works rather well (didn’t see anything too weird) Studied quark scattering, b quarks, W bosons Top quark discovery 1995

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. We’ve identified 50 top quark events and expect 50 more which look like top, but aren’t. Run II ×10

Top Quark Run I: The Summary The top quark was discovered in 1995 Mass known to 3% (the most accurately known quark mass) The mass of one top quark is 175 times as heavy as a proton (which contains three quarks) Why???

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. top bottom Undiscovered!

“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 don’t. What we see is consistent with being a Higgs Particle. But it could end up being nothing. It’s Fermilab’s turn.

Calorimeters Tracker Muon System Beamline Shielding Electronics protons antiprotons 66 feet In Run II (March 1, 2001), the Fermilab Tevatron will deliver times as many collisions per second as Run I. The DØ detector required an overhaul in order to cope.

Eight cylinders covered with scintillating fiber are read out with a novel light detector (VLPCs). VLPCs DØ Fiber Tracker See the Display!

1.25 m p pp DØ Silicon Tracker 800,000 distinct detector elements Very complex (fragile) Absolutely crucial for viewing the details of how particles behave near the collision. Particles that don’t come from the collision point serve as ‘flags’ of interesting physics.

DØ Muon System Muons provide a signature of many interesting physics events. Muons penetrate dense material for long distances. Thus muon detectors are outside the large amount of metal that makes the rest of the detector. The muon system consists of many different detector technologies, and is the physically largest system.

Data-Model Comparison

Run II: What are we going to find? I don’t know! Improve top quark mass and measure decay modes. Do Run I more accurately Supersymmetry, Higgs, Technicolor, particles smaller than quarks, something unexpected?

Why DØ?  Ask famous Hollywood Star And it stuck

Why DØ? The Real Reason AØ: The High Rise BØ: The Competition CØ: Future BTeV FØ: The RF EØ: This Space For Rent DØ: Fermilab’s Best Detector

DØ vs. Borg Coincidence? Or just another cool thing about DØ? f