Nuclear Radiation Measurement Using Cerenkov Light Generated in a Light Guide

Cerenkov light pulses were generated in one end of 100-m lengths of multi-fiber cable and a single strand of graded index fibers by a 50-ps burst of 18-MeV electrons. Pulse dispersion in this length was between 3.5 and 2.9 ns for the cabled fibers and 4.1 ns in the single fiber. By narrow band optical filtering, the dispersion was reduced to values between 610 and 246 ps in the cable and 400 ps for the single fiber. Cerenkov sensitivity was measured for two of the fibers and found to be 6 × 1013 photons/sec and 6 × 1012 photons/ sec for 50 ps electron bursts of 10 A/cm2 and 6 A/cm2 respectively. In terms of time response and sensitivity it appears feasible to design a nuclear explosive diagnostic system utilizing Cerenkov radiation generated in and transmitted by cables of graded index fibers.