1. Particle Accelerators and Detectors
World’s Largest ‘Microscopes’

2. Contents What is a Particle Accelerator? An Early Accelerator
Modern Linear and Circular Accelerators
Particle Detectors
Examples of Accelerators and Detectors
Accelerators and Detectors as Giant Microscopes

3. What is a Particle Accelerator?
Any device that accelerates charged particles to very high speeds using electric and/or magnetic fields
The picture to the right shows an early particle accelerator from This accelerator was used in the development of the first atomic bomb.

4. An Early Accelerator
In 1929, Ernest Lawrence developed the first circular accelerator
This cyclotron was only 4 inches in diameter, and contained two D-shaped magnets separated by a small gap
An oscillating voltage created an electric field across the small gap, which accelerated the particles as they went around the accelerator

5. An Early Accelerator, cont.
Here is picture of Lawrence’s cyclotron:

6. Today’s Accelerators
Modern accelerators fall into two basic categories:
Linear Accelerators
Circular Accelerators

7. Linear Accelerators
In linear accelerators, particles are accelerated in a straight line, often with a target at one to create a collision
The size of linear accelerators varies greatly
A cathode ray tube is small enough to fit inside of a television
Stanford’s linear accelerator is two miles long

8. Linear Accelerator – Example 1 (Cathode Ray Tube)
The cathode ray tube is a linear accelerator found in many TVs, computer monitors, etc.

9. Linear Accelerator - Example 2 (Stanford Linear Accelerator)

10. Circular Accelerators
Circular accelerators propel particles along a circular path using electromagnets until the particles reach desired speeds/energies
Particles are accelerated in one direction around the accelerator, while anti-particles are accelerated in the opposite direction

11. Circular Accelerators, cont.
Circular accelerators are able to bring particles up to very high speeds (energies) by allowing each particle to be accelerated for a longer period of time—around the accelerator.
The distance around a circular accelerator can be quite large
Fermilab’s Tevatron (Near Chicago, USA) - 4 miles (6.44 km)
CERN’s LHC (Near Geneva, Switzerland) – 16.8 miles (27 km)

12. Fermilab Accelerators
The protons and anti-protons at Fermilab go through a series of accelerators in order to accelerate them to 1 TeV (just 200 miles per hour slower than the speed of light)
At Fermilab, protons are accelerated in one direction around the ring; anti-protons are accelerated in the opposite direction
The series of accelerators at Fermilab is illustrated by an animation located at this website (be sure to press “play”):

13. Collisions
The particle and anti-particle beams are focused and directed at particular sites around the ring in order to collide with one another
These collisions are designed to occur within detectors, which are able to analyze the many events (particles created, etc.) that result from the collisions of the particles and anti-particles

14. Particle Detectors
The large detectors are able to trace and characterize the particles that result from the collisions
The picture to the right shows the 5,000-ton CDF Collider Detector at Fermilab
400,000 proton-antiproton collisions occur each second in this detector

15. Particle Detectors, cont.
By analyzing the nature and type of particles resulting from the collisions, scientists are able to learn much about matter at a more fundamental level

16. CERN Accelerators and Detectors
The diagram to the right shows the accelerators and detectors at CERN near Geneva, Switzerland
The LHC is the largest circular accelerator at CERN and is to begin operation in 2007
CMS and ATLAS are two of the five examples of detectors approved at CERN for the LHC

17. Fermilab Accelerators and Detectors
The most powerful accelerator (the Tevatron) in the US is at Fermilab
The diagram to the right shows the series of accelerators (including the Main Injector and Tevatron) and detectors (including CDF and DZERO) at Fermilab

18. Accelerators and Detectors as Giant Microscopes
Together, particle accelerators and detectors have helped scientists discover very small building blocks of matter
For instance, scientists now think that protons within atoms are made up of even smaller particles known as quarks
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