# Presentation: 130134

## Harvey Mudd College Alumni  

**Keith Gollwitzer**
**Antiproton Source Department**
**Accelerator Division**
**Fermilab**
**6 October 2007**

## My Bio

- Grew up in San Jose
- Harvey Mudd 1986; Physics
- Senior Thesis: “Calibration of Microradian Tilts”
- University of California Irvine 1993
- “The Charmonium 1P1 State (hc) Produced in Antiproton-Proton Annihilations”
- Research/Work
- Simulations for proposed experiments SNO and LCD
- Three rounds of Fermilab’s Charmonium experiment
- Antihydrogen at Fermilab
- Antiproton production for the Tevatron Collider program

## Founding of Fermilab

- The National Accelerator Laboratory started in the 1960s and was finished in the early 1970s and renamed.
- Founding Director Robert Rathburn Wilson

- Harvey Mudd College Connection?

- 1986 Wright Prize Winner

## Wright Prize Winner Wilson

**Wright Prize Winner Wilson**

## Quick Fermilab History

- Originally, high energy Fixed Target Experiments
- Late 1970s-1980s built “Energy Doubler” / “Energy Saver” / Tevatron and Antiproton Source so can have collider program
- Can now run collider and fixed target programs at the same time
- Some discoveries: Bottom quark, Top quark; Tau neutrino

## Slide 6

## What is an Antiproton?

- Government issued Webster’s Dictionary:
- “The antiparticle of the proton”
- Antiparticle definition “subatomic particle having the same mass, average lifetime, spin, magnitude of magnetic moment but opposite direction, magnitude of electric charge but opposite sign, opposite intrinsic parity”
- What about “Antimatter”?
- “Matter made from antiparticles”
- What is a Pbar?
- Shortened name for Antiproton based upon symbol used in physics
- Over-line or bar above symbol means “anti”

## Protons and Antiprotons

- Protons
- Plentiful
- Get “free” protons by separating hydrogen components
- 13.6eV to ionize electron from proton
- Antiprotons
- Scarce in nature
- Created by cosmic rays interacting with the atmosphere.
- The original “Fixed Target” experiment
- Particle and Antiparticle when they met --- annihilate
- One big physics question is why there is so little antimatter
- Dan Brown......later

## Particle Collisions

- Originally studied Cosmic Ray Particles Cosmic rays are energetic
- No human control of energy, type, when
- Detection done at high altitudes
- Discovered many types of particles that are not everyday matter

- Accelerators allow control of collisions
- Allowed study of many new particles
- Some with masses greater than the initial particles

## Fermilab Collisions

- Fixed Target
- In the Fixed Target mode, 1⁄2 of the experiment is at rest.
- The other 1⁄2 is moving at high energy.
- There is a big “relativistic” penalty to be paid because of the conservation of momentum.
- Collider Mode
- In the Collider mode, two particles of equal mass and energy travel directly at each other.
- The total momentum of the system is zero, so there is no “relativistic” penalty to be paid.
- Most of the energy goes directly into making new particles.

## Particle Acceleration

- A charged particle will be accelerated by a voltage potential.
- Opposite charges attract.
- One **electron Volt (eV)** is the energy gained by an electron (or any particle of unit charge) when it is accelerated through a potential of 1 Volt.

## To Higher Energies

- Scientific Prefixes
- K (kilo) 1,000
- M (mega) 1,000,000
- G (giga) 1,000,000,000
- T (tera) 1,000,000,000,000
- TeVatron accelerates beam to nearly 1 trillion electron Volts
- Batteries are 1Volt per inch
- A trillion inches is 15.8 million miles .
- TeV proton velocity is 0.9999956c

## First Stage of the Acceleration

- Crockoft-Walton Accelerator
- Can be thought of as a 750,000V DC voltage source.
- The maximum voltage is limited by how much the air can “stand-off” before sparking.

## Second Stage of Acceleration

**Second Stage of Acceleration**

- A linear accelerator (LINAC)

## Drift Tube Linac

## Synchrotrons

- The Fermilab Linac is 130 meters long and reaches an energy of 400 MeV (1 million Volts per foot)
- To get to 980 billion volts, a Linac would have to be
- 200 miles long at 1 million Volts per foot
- What about using the Linac over and over?
- The drift tube spacing at the beginning of the Linac would be wrong for higher energy particles

- But a Synchrotron could be used!
- Dipoles are used to bend particles
- Quadrupoles are used to focus particles
- RF cavities are used to accelerate particles

## Dipole Magnets

- Dipole magnets are used to bend the particle’s path
- The magnet body confines or concentrates the magnetic field
- The pole faces shape the magnetic field

## Quadrupole Magnets

- Quadrupoles are needed for focusing particles
- Not all the particles are on the “perfect” orbit.
- If the particle is on the right orbit – don’t bend.
- If the particle is on the inside – bend to the outside.
- If the particle is on the outside – bend to the inside.

## Pre-Acc

- First stage of acceleration
- Start with Hydrogen Bottle
- Final Energy = 750KeV

## Linac

**Linac**

- Final Energy of 400MeV

## Booster Ring

- Final Energy of 8GeV
- Uses combined function magnets

## Main Injector Ring

- Final Energy of 150GeV
- 2 mile circumference
- Upper ring is the Recycler

## Tevatron Ring

- Final Energy of 980GeV
- 4 mile circumference
- Uses cryogenic superconducting dipoles

## Fixed Target Beam Lines

- Fixed Target program has
- run at 800GeV and
- currently at 120GeV

- Neutrino Program runs at two different energies 8GeV and 120GeV

## Antiproton Source

- 120GeV protons from Main Injector hit (fixed) production target.
- Antiproton Source beam lines and rings capture and collect 8GeV pbars
- 8GeV pbars are sent to the rest of accelerator complex to be injected into the Tevatron for the collider program

## The Antiproton Target Station

- Nickel Alloy
- with air cooling
- through the
- copper disks

## The Antiproton Target Station

## Stacking Cycle - Debuncher

- Every 2.2 seconds
- 8 x 1012  (8 trillion) 120GeV protons onto target
- Beam line transfers negatively charged 8GeV particles to the Debuncher
- Other particles decay or radiate away in a few turns
- Beam circulates every 1.6 microseconds
- 0.0000016 seconds

- 2 x 108  (200 million) 8GeV pbars circulate in the Debuncher
- Stochastic cooling reduces the phase space by a factor of ten
- Transfer all pbars to the Accumulator

## Stacking Cycle - Accumulator

- RF system decelerates from injection to deposition orbit
- Stochastic Cooling
- 2-4 GHz stacktail
- Pushes and compresses beam into the core
- 2-4 & 4-8 GHz core momentum
- Gathers beam from the stacktail
- 4-8 GHz transverse slotted waveguide pickups
- Increase particle density by factor of 5000
- Factor of 3-5 decrease in both transverse phase space dimensions

## Accumulation rate of 2 x 1011 (200 billion) pbars per hour
When reach 5 x 1011 (500 billion) pbars, transfer beam out of the Accumulator to the Main Injector into the Recycler Ring for storage until needed for the Tevatron collider program

Most number of antiprotons that have been on site at Fermilab at one time (Accumulator, Recycler and Tevatron)
6 x 1012  (6 trillion) pbars
10pg = 0.000 000 000 01grams
This last year produced 
825 trillion pbars (1.4ng)

- When reach 5 x 1011 (500 billion) pbars, transfer beam out of the Accumulator to the Main Injector into the Recycler Ring for storage until needed for the Tevatron collider program
- Most number of antiprotons that have been on site at Fermilab at one time (Accumulator, Recycler and Tevatron)
- 6 x 1012  (6 trillion) pbars
- 10pg = 0.000 000 000 01grams
- This last year produced
- 825 trillion pbars (1.4ng)

**Total Antiprotons at Fermilab**

## Dan Brown and Antiprotons

- Page of “Facts” in a book of fiction
- Fact: 0.5 grams of antiprotons mixed with 0.5 grams of protons would produce an explosion equivalent Hiroshima
- Fiction: Can easily produce, capture and transport that much antimatter
- Fact: Fermilab’s bottles are over 6 miles of rings and would take 80 million years
- It would cost a lot

## Using Antiprotons

- Antiprotons are collected in _Recycler Ring_ at 8GeV for a day
- Then antiprotons are sent in 36 batches to _Main Injector_ to be accelerated to 150GeV
- Antiprotons are transferred to the Tevatron which already has 36 proton batches
- Both beams are accelerated to 980GeV

## Tevatron Collider

- Two beams in one accelerator going in opposite directions!
- Electrostatic separators keep beams on different helical orbits during acceleration
- Bring beams into collisions by collapsing helix orbits at desired interaction points
- Middle of detectors

## Fun Numbers

- The maximum Tevatron intensity is 20 trillion particles
- 20 trillion particles “weighs” about 30 trillionths of a gram
- 20 trillion particles at 980GeV
- Has the same kinetic energy as a 200 lb. man traveling at 550 miles/hour
- Has the momentum equivalent to 1 oz. of mass traveling at 1 mile/hour
- Would deliver a radiation dose of 35,000 Rads. to a 200 lb. man
- 10,000x the acceptable yearly dose at Fermilab
- Several levels of safety to keep people out of enclosures when beam may be present.

## Safety

**Safety**

- You will be on tours in different areas
- Including into the Antiproton Source tunnel
- No smoking, eating or drinking in the tunnel enclosure
- Please be careful on the stairs and walking
- Edges of components and cables do stick out
-         Tunnel is hot – 90oF!

## Today

- Enjoy your time at Fermilab
-            Please take pictures
- Please ask questions
- Hope that you have learned a little about antiprotons, particle accelerators and what goes on at Fermilab