Nuclear Physics Explained Nuclear radiation is everywhere. At this very moment, the byproducts of cosmic rays from the galaxy are raining down on you, neutrinos produced in the Sun are piercing your body in the trillions, and nuclear particles are emanating from everyday sources in your rocks, air, food, and water. They bombard from everywhere. Directions If you had a super-sensitive “Geiger counter” collecting all nuclear particles, it would beep without stopping. Yet despite this constant exposure, “radiation” is a word that evokes anxiety and even horror. There are sources of radiation to worry about, but real vigilance lies in understanding the physics of the atomic nucleus – the endlessly fascinating structure that defines the universe in which we live. Then, of course, there are nuclear weapons, which have certainly kept the fragile peace since the end of World War II intact, but also threaten civilization with unprecedented devastation. All of these insights, benefits and risks translate into an unimaginably small subatomic structure that was unknown a century ago. Covering the science, history, risks, applications and latest developments in the field, this course is your guide to a subject that is rarely presented at a level suitable for non-scientists. In these 24 half-hour lectures, Professor Laurence Weinstein of Old Dominion University first acquaints you directly with the sometimes disturbing ideas of nuclear physics, then takes you to the Thomas Jefferson National Accelerator Center to explain the wonders of nuclear research – the inspiring machines at the forefront of nuclear research – the machines he uses in his work. Then, the second part of the course – viewable separately but with your engagement with the key principles and methods in the first part – explores the many scientific and technological applications of nuclear physics, for example, understanding accelerators in the first part. This deepens your understanding of the basics. During the second half of these lectures, Dr. Weinstein shows how nuclear physicists think, analyzing problems in a quick, streamlined way, abandoning exact numbers in favor of integers, and anyone familiar with exponential symbols will find the mathematics in the course easy to study. Viewers want to find Dr. Weinstein’s presentation clear, enthusiastic, and full of humor. Additionally, the course is well illustrated with diagrams, charts, and computer animations, as well as laboratory demonstrations that bring the nuclear field to life.
Move over Three Mile Island: nuclear physics, an astonishingly productive discipline, covers diverse phenomena and applications:
- Particle physics and beyond: Giant instruments often called “atom smashers” are actually samples of atoms and other subatomic materials that reveal not only the basic building blocks of nature, but also how they are put together.
- Astrophysics and cosmology: Atomic physics not only explains how atoms work, but also explains how stars shine – and why they sometimes explode. It also gives information about the birth and evolution of the universe.
- Medical equipment and treatments: Nuclear processes enable a wide range of medical imaging equipment such as X-rays, CT scans, PET scans and MRIs, as well as treatments to kill cancer cells.
- Nuclear power: Energy from nuclear fission provides 20% of the electricity generated in the United States and a much larger share in countries such as France and Sweden.
For many, nuclear physics is inextricably linked to the reactor meltdowns at Three Mile Island in the United States, Chernobyl in the Soviet Union and Fukushima in Japan. Dr Weinstein examines these costly plant disasters that resulted in deaths from acute radiation in the case of Chernobyl, but otherwise had far less impact on public health than was believed at the time. He describes the unfortunate lessons and looks toward a new generation of reactors that could operate more safely, more cheaply and with less nuclear waste and risk of nuclear proliferation. He also explores the challenge of incorporating an even more powerful nuclear process: fusion.
Look inside the nucleus: The key to understanding nuclear physics is knowing what’s going on inside the nucleus. Here, Dr. Weinstein explains key concepts such as:
- Protons and neutrons: The nucleus or central core of an atom is composed of positively charged protons and neutral neutrons (except for hydrogen, which has one proton), held together by the short-range but very strong nuclear force. Surrounding the nucleus is a cloud of negatively charged electrons.
- Elements and Isotopes: Elements are 92 naturally occurring atoms, each with a unique number of protons. The number of neutrons can vary and these different forms of elements are called isotopes, which can be unstable. The element tin has 10 stable isotopes, uranium has none. There are over 3,000 confirmed isotopes, with even more being created all the time.
- Radioactivity: Unstable isotopes decay and release energetic alpha particles (helium nuclei), beta particles (electrons or positrons), or gamma rays (high-frequency light waves). These are the primary forms of nuclear radiation.
Dr. Weinstein goes into great depth about what binds protons and neutrons together, how they are both made up of different types of quarks, how the binding energy curve explains fission and fusion processes, other types of radioactive decay, and the enormous utility of both of these in this look. – The next chart of isotopes is called the Nuclides Table, which he presents in a colorful and easy-to-read chart. How do we know all this? Dr. Weinstein answers that question with a fascinating four-lecture tour of the Electron Linear Accelerator and Research Hall at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Center in Newport News, Virginia, which Dr. Weinstein knows inside and out. Gives. Later in the course, he’ll take you to Hampton University’s Proton Therapy Institute to see how nuclear physics therapy is used to precisely target cancer cells.
“Risks and rewards” Accuracy is important in medical radiation so that healthy cells are not damaged. This emphasizes the dangers of radioactivity as well as the benefits. Nuclear physics explains which types of radiation are dangerous and which are less dangerous, including:
- Radium: In the early 20th century, women who painted glowing numbers on watches ingested dangerous amounts of radium by brushing their lips against them. Wearing a watch with a radium dial poses little risk, but ingesting radium can be fatal.
- Radon: A radioactive gas, radon is a natural decay product of uranium and thorium in the Earth’s crust. It can be concentrated in mines and basements of certain geological regions, where it can be easily inhaled. Radon is the leading cause of lung cancer in non-smokers.
- “Dirty” bomb: A hypothetical “dirty” bomb uses conventional explosives to disperse radioactive material. Anyone exposed should leave the area, remove potentially contaminated clothing and shower, but the results would be more catastrophic than harmful.
- Bananas: Bananas are slightly radioactive, though not dangerously so, due to the amount of potassium they contain, which contains a small percentage of naturally occurring radioactive isotopes. The “banana equivalent dose” is a humorous way of measuring the radioactivity around us.
You’ll finish the course by seeing how radiation reveals a world hidden in space and time. For example, the ratios of different isotopes can be used to date everything from human artifacts to continental collisions. Gamma-ray and neutrino telescopes map the most energetic and distant events in the universe. And cosmic rays—which are continuous showers of radiation from space—can be used to analyze the structure of ancient buildings like the Great Pyramids. These examples and countless other applications demonstrate that nuclear physics is a versatile tool like no other.