THRESHOLD BUBBLE-CHAMBER FOR MEASUREMENT OF KNOCK-ON DT NEUTRON TAILSFROM MAGNETIC AND INERTIAL CONFINEMENT EXPERIMENTS

We propose a new ''threshold'' bubble chamber detector for measurement of knock-on neutron tails. These energetic neutrons result from fusio n reactions involving energetic fuel ions created by alpha knock-on co llisions in tokamak and other magnetic confinement experiments, and by both alpha and neutron knock-on collisions in inertial confinement fu sion (ICF) experiments. The energy spectrum of these neutrons will yie ld information on the alpha population and energy distribution in toka maks, and on alpha target physics and rho R measurements in ICF experi ments. The bubble chamber should only detect neutrons with energies ab ove a selectable threshold energy controlled by the bubble chamber pre ssure. The bubble chamber threshold mechanism, detection efficiency, a nd proposed applications to the International Thermonuclear Experiment al Reactor and National Ignition Facility experiments will be discusse d. (C) 1997 American Institute of Physics.