MODELS OF PARTICLE-DETECTION IN REGIONS OF SPACE-TIME

We investigate two models of measuring devices designed to detect a no nrelativistic free particle in a given region of space-time. These mod els predict different probabilities for a free quantum particle to ent er a space-time region R; therefore, this notion is device dependent. The first model is of a von Neumann coupling, which we present as a co ntrast to the second model. The second model is shown to be related to probabilities defined through partitions of configuration-space paths in a path integral. This study thus provides insight into the physica l situations to which such definitions of probabilities are appropriat e.