ION-TEMPERATURE MEASUREMENT OF INDIRECTLY DRIVEN IMPLOSIONS USING A GEOMETRY-COMPENSATED NEUTRON TIME-OF-FLIGHT DETECTOR

A geometry-compensated neutron time-of-flight detector has been constructed and used on Nova to measure ion temperatures from indirectly driven implosions with yields between 2.5 and 5×109 DD neutrons. The detector, which has an estimated respond time of 250 ps, was located 150 cm from the targets. Due to the long decay time of the scintillator, the time-of-flight signal must be unfolded from the measured detector signal. Several methods for determining the width of the neutron energy spectrum from the data have been developed and give similar results. Scattered x rays continue to be a problem for low yield shots, but should be brought under control with adequate shielding. © 1995 American Institute of Physics.