[¦in·tər¦sek·tiŋ ′stȯr·ij ‚riŋz] (nucleonics) Proton storage rings, located at Geneva, Switzerland, in which counterrotating protons with energies of up to 31 gigaelectronvolts injected from a proton synchrotron are made to undergo nearly head-on collisions. Abbreviated ISR.AcronymsSeeISR