# Presentation: 816661

## 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

- Helium

- Neon

- 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

- 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

- Anti-Matter

## Slide 5

## 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
- 4×10-12 seconds
- LHC
- 10-13 Seconds

## Slide 7

## 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, France1272 A.D.

## Why the Buffalo?

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

## Slide 12

##   The Main Injector upgrade was completed in 1999.

**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.
- 			     ****  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’

- 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 1015  (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 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

## Highlights from 1992-1996 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 

- 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*.

- Undiscovered!

## “LEP observes significant Higgs

- “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.

## In Run II (March 1, 2001), the Fermilab

- Tevatron will deliver 10-20 times as
- many collisions per second as Run I.
- The DØ detector required an overhaul
- in order to cope.

## DØ Fiber Tracker

- covered with
- scintillating fiber
- are read out with
-     a novel light
-     detector (VLPCs).

- VLPCs

- See the Display!

## 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

- 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

## 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

## DØ vs. Borg

*Coincidence?  *
*	**	**	**Or just another cool thing about DØ? *

- f