Direct Measurement of the Fuel Density-Radius Product in Laser-Fusion Experiments

The first direct measurement of fuel density-radius product ρR in laser-fusion experiments is obtained by measuring the number of deuterium and tritium ions elastically scattered out of the fuel by 14-MeV fusion neutrons. They were recorded with the solid-state track detector CR-39. The energy spectrum of these particles is found to agree well with the theoretical result. This diagnostic was used in low- and high-compression experiments and gave measured ρR values of 1.3×{}10^-4 and 1.2×{}10^-3 g/cm², with an uncertainty of {~} 20%.