Measurements of pulsed radiation-induced fiber fluorescence and darkening

Spectral temperature measurements were made of the DIAMOND FORTUNE event at the Nevada Test Site. A large core fiber was used to gather light from the fireball produced in a large diameter cavity. To correct these spectral data for radiation effects on the fiber, a Fiber Monitor consisting of another fiber optic cable identical to that used to gather fireball light (but made blind to it) was used to measure changes in the fiber optic spectral transmission during the event. The data on the Fiber Monitor show a narrow induced-light pulse, followed by a long (approximately equals 1.5 ms) decay fluorescence signal. Following these induced signals a reduction in the preshot transmitted signals, caused by fiber darkening, was measured. DIAMOND FORTUNE event data will be presented and compared with data obtained from the Sandia National Laboratories (SNL) Hermes III gamma simulator and the SNL SPR III pulsed neutron facility. The radiation-induced fiber darkening thus determined will be presented.