We have recently demonstrated significant improvements to the resolution and sensitivity of the NIF gamma imaging system by replacing the existing EJ262 plastic scintillator with the Ce-doped gadolinium garnet transparent ceramic scintillator GYGAG. Penumbral imaging of inelastic gammas emitted during inertial confinement fusion (ICF) experiments at NIF can be used to recover the time integrated spatial distribution of the remaining shell during the fusion burn, the technique is therefore a critical diagnostic for understanding the failure modes and quality of NIF implosions. In this work we discuss GEANT4 calculations of the relative sensitivities of GYGAG and EJ262 as well as rolled edge measurements made on NIF shot N221204 in December 2022, for the purpose of directly comparing the spatial resolution of each scintillator in-situ.
The flux of neutrons and charged particles produced from inertial confinement fusion experiments at the National Ignition Facility (NIF) induces measurable concentrations of nuclear reaction products in various target materials. The collection and radiochemical analysis of the post-shot debris can be utilized as an implosion diagnostic to obtain information regarding fuel areal density and ablator-fuel mixing. Furthermore, assessment of the debris from specially designed targets, material doped in capsules or mounted on the external surface of the target assembly, can support experiments relevant to nuclear forensic research. To collect the shot debris, we have deployed the Large Area Solid Radiochemistry Collector (LASR) at NIF. LASR uses a main collector plate that contains a large collection foil with an exposed 20 cm diameter surface located ∼50 cm from the NIF target. This covers ∼0.12 steradians, or about 1% of the total solid angle. We will describe the design, analysis, and operation of this experimental platform as well as the initial results. To speed up the design process 3-dimensional printing was utilized. Design analysis includes the dynamic loading of the NIF target vaporized mass, which was modeled using LS-DYNA.
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