The summit of Bragg Peak.
A particle physicist, when asked by me to explain the genesis of a particular innovation in radiation therapy, decided it was best to start at the beginning. In this instance, said beginning took place on a very busy chalkboard, filled with inscrutable equations and half-erased diagrams. Layer upon layer competed for attention. With a full and slightly unkempt head of gray hair, the man sketched a basic line graph, illustrating depth v. dose level.
The point isn’t this venerable man of science’s patience or enthusiasm, it was his immediate instinct to provide a visual and go to the board. Back in school already.
He walked me through a Bragg peak, the extraordinary phenomenon that renders proton therapy (as one example) so vastly superior to x-ray therapy. This is the basic drawing, though lacking the charm of a chalkboard where each inch of real estate is won by haphazardly erasing with the palm of one’s hand.