부산대학교 도서관

When particles move about randomly in the presence of traps, how long does it take for them to be captured? Well, it depends on the average speed of the particles and the dimensions and distribution of the traps. For example, when neutrons are generated in nuclear fission reactions, they must be captured by other fissionable nuclei in order to sustain a chain reaction. But we learn in introductory physics that these energetic neutrons are traveling at enormous speeds and must be slowed to increase the time that they spend in the vicinity of the nuclei. While the capture of "thermal" particles into lower energy states is an important physical process, it is difficult to simulate macroscopically. For example, where do you get a collection of macroscopic objects that have the means to sustain random motion? Enter Squiggle Balls[TM]--inexpensive spherical cat toys that use a battery-powered motor and asymmetric rotor to roll and tumble happily about. Put a few on a bounded, elevated platform with several circular holes, and you have an ideal macroscopic system for exploring the world of capture.