1. HCP: Particle Physics Module, Lecture 5
Plan for today:
Discuss several historical examples of the benefits of basic
physics research to society

2. Benefits of Fundamental (Basic) Physics Research to Society
About $4.0 billion is spent each year by the United States on what is
considered fundamental physics research
This is compared to the total U.S. federal government budget of
~ $2.8 trillion
How does this investment by the taxpayers in basic physics research
benefit society?
To answer this question, we will consider several past examples
from the AIP (American Institute of Physics) “Physics Success
Stories”

3. Why should the United States pursue basic physics research?
One answer comes from Robert Wilson, founding director of the Fermilab
Accelerator in Illinois:
But, if that were the only reason why isn’t the annual physics research budget ($4.0 billion)
more like the National Endowment for the Arts budget ($130 million)?

5. Invention of semiconductor transistor
(Bell Labs, 1947) was essential here.

6. Invention of the Semiconductor Transistor – Bell Labs 1947
Basic physics research in the quantum physics of solids was essential
to the development of the semiconductor transistor.

7. Why are Semiconductor Transistors so Important?
Transistors can be used to make voltage controlled switches. This is
essential ingredient to the digital switching logic (0 and 1) that makes
all computers work.

8. Integrated Circuits
The development of integrated circuits made desktop computers
possible – millions of transistors on a thumbnail sized chip of silicon.

9. Integrated Circuits

11. MASER: “Microwave Amplification
by Stimulated Emission of Radiation”
LASER: “Light Amplification

13. How A Laser Works – the three minute version
Research on the quantum mechanics of atoms and radiation eventually
led to the development of the LASER: “Light Amplification by
Stimulated Emission of Radiation”

20. World Energy Consumption
Within ~ 300 years supplies of fossil fuels will run out:
One possible alternative: Nuclear fusion (same process that powers
the stars):
deuterium
(from heavy water)
electrical
power generation

21. There are 2 billion people in
China and India who would
like to have the same standard
of living as the U.S.

23. Nuclear Power – electrical energy from nuclear fission
Based on a controlled chain reaction:
Example:
These neutrons can initiate
further reactions  chain reaction
Neutrons are emitted with kinetic energy:
neutrons slow down  heat is generated  water is heated up
 steam is created  turbine turns  generator  electricity

24. Proliferation Issue Natural uranium is 0.72% 235U and 99.28% 238U
Only 235U is useful for fission because it can be fissioned by “slow”
neutrons.
Reactor grade uranium: ~3% 235U
Weapons grade uranium: ~ 90% 235U
OR “breed” useful fissionable material (239Pu) from the more abundant
238U:

27. Magnetic Resonance Imaging (MRI)
Also called nuclear magnetic resonance (NMR). Came from fundamental
research into the magnetism of atomic nuclei.
Makes use of the magnetism of the proton:
When radio waves (no tissue damage) of
proper frequency are applied, the proton
“magnets” flip to the opposite direction
Magnetic field direction

28. Example of a MRI facility

29. PET (positron emission tomography)
Uses radioactive (short-lived) nuclei created in low energy particle
accelerators
Medical use: Tag glucose with radioactive form of fluorine (18F)
Then you can follow and track where the glucose is used in the body!
PET setup:  
BGO
BGO  
BGO = photon (x-ray) detector
 Timing difference between the emitted photons  spatial positions
 spatial profile of glucose usage  tomography!

30. Equipment needed at a PET facility
Cyclotron (type of accelerator)
Used to produce the radioactive nuclei:
18F
Patient inserted into cavity
surrounded by BGO  detectors 

31. Example of PET scans FDG = 2-fluoro – 2 deoxy – D - glucose
Huntington disease brain
Decreased metabolic activity in basal ganglia
Responsible for some body motor functions
basal ganglia
Normal brain
Note: the dark areas in each picture
are areas of high metabolic activity;
ie. places where glucose is being
consumed
basal ganglia