In-flight Performance of the ISOMAX TOF

A state-of-the-art time-of-flight (TOF) system has been developed for the ISOMAX balloon-borne cosmic ray instrument. ISOMAX was built to measure the isotopic composition of the light elements in the cosmic rays, (3beryllium. In-flight performance of the TOF, during the first flight in August of 1998, and some isotopic results are presented. The uncorrected timing resolution for a single paddle was determined to be ~47 ps for helium and ~23 ps for carbon.