Commissioning the new pulse dilation Gas Cherenkov Detector at the National Ignition Facility

An effort to enhance the threshold contrast index of gas Cherenkov detectors

“…Those GCDs have also been successfully applied for diagnosing bang time, reaction history and ablator areal density measurements in the OMEGA laser-based inertial confinement fusion facility (ICF) and the national ignition facility (NIF). However, the measurement results are not yet completely satisfactory because there appear to be some unexpected tailing phenomena on the falling edge of the waveforms [12][13][14][15]. The primary cause is that the actual performance of the energy threshold response of current GCDs is not ideal so that the interference from secondary gamma rays in GCDs is not cleanly excluded.…”

“…Because the energy of fusion gamma rays is higher than that of most secondary gamma rays (less than 12 MeV generally), it is a very natural choice to exclude interference from secondary gamma rays if considering the energy threshold response characteristic of the Cherenkov mechanism. Therefore, gas Cherenkov detectors (GCDs) with 12 MeV threshold have been designed for detecting fusion gamma rays, and some super GCDs with higher Cherenkov sensitivity or lower Cherenkov threshold energy have also been widely studied and developed in the past few decades [4][5][6][7][8][9][10][11][12][13][14][15]. Those GCDs have also been successfully applied for diagnosing bang time, reaction history and ablator areal density measurements in the OMEGA laser-based inertial confinement fusion facility (ICF) and the national ignition facility (NIF).…”