Developing Student Fluency, Not Just Familiarity

In this section, Professor Michael Short describes he emphasizes developing fluency in basic nuclear physics, content that nuclear engineers must “know like instinct”.

This is the kind of stuff that, without batting an eye, you should know, just as you know gravity is 9.8 meters per second squared.

— Michael Short

22.01 Introduction to Nuclear Engineering and Ionizing Radiation, more than any other course in the department, is the one that every nuclear scientist and engineer has to know like instinct. This is the kind of stuff that, without batting an eye, you should know, just as you know gravity is 9.8 meters per second squared. You should know relative half-lives. You should understand binding energy. You should be able to make relative judgements of radioactivity, and make them quickly.

Students must develop fluency in basic nuclear physics. Not just familiarity, but fluency. If you are not fluent in it, you will have difficulty with the material to come. So we have fewer overall topics than some classes, and we spend longer on them.

There are three main parts of the course. Month one is getting to know E = mc2 and radioactive decay, and the basic kinematics of what happens when a particle elastically collides with another one. Month two is how radiation interacts with matter: How is energy transferred? How does a photon interact? How does a neutron interact? How does an electron interact? Why are they different? And not only what are the formulas for their interactions, strength, and energies, but where do the formulas come from? We do derivations there.

Finally, month three is kind of a hodgepodge of nuclear medicine, biological and chemical effects, and then some societal and policy aspects, like models for dose versus cancer risk, or acute effects of radiation poisoning. If you want to understand why certain types of radiation are more damaging to biological tissue, you go right to their stopping power, which is their differential energy transfer and their range in matter (like our bodies). Then you can understand why alpha particles, the heavy helium nuclei, are so dangerous when you ingest them, but harmless outside the body. Whereas neutrons, no matter where they are, will do damage.