Particle Accelerators and Detectors

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 1937. This accelerator was used in the development of the first atomic bomb. http://en.wikipedia.org/wiki/Image:P3280014.JPG

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: http://www.facstaff.bucknell.edu/mvigeant/univ_270_03/Jaime/History.html

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 http://www.exploratorium.edu/origins/cern/tools/linac.html

8. Linear Accelerator – Example 1(Cathode Ray Tube) • The cathode ray tube is a linear accelerator found in many TVs, computer monitors, etc. http://science.howstuffworks.com/atom-smasher2.htm

9. Linear Accelerator - Example 2(Stanford Linear Accelerator) http://en.wikipedia.org/wiki/Image:LINAC.jpg

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 www.fnal.gov

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”):http://www-bd.fnal.gov/public/index.html

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 http://www.fnal.gov/pub/about/tour/index.html

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 http://www.fnal.gov/pub/now/live_events/index.html

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 http://www.fnal.gov/pub/about/whatis/picturebook/descriptions/00_635.html

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 • Check out www.particleadventure.org for more information http://www2.slac.stanford.edu/vvc/theory/fundamental.html