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We report on the first experiment dedicated to the study of nuclear reactions on dopants in a cryogenic capsule at the National Ignition Facility (NIF). This was accomplished using bromine doping in the inner layers of the CH ablator of a capsule identical to that used in the NIF shot N140520. The capsule was doped with 3 × 1016 bromine atoms. The doped capsule shot, N170730, resulted in a DT yield that was 2.6 times lower than the undoped equivalent. The Radiochemical Analysis of Gaseous Samples (RAGS) system was used to collect and detect 79Kr atoms resulting from energetic deuteron and proton ion reactions on 79Br. RAGS was also used to detect 13N produced dominantly by knock-on deuteron reactions on the 12C in the ablator. High-energy reaction-in-flight neutrons were detected via the 209Bi(n,4n)206Bi reaction, using bismuth activation foils located 50 cm outside of the target capsule. The robustness of the RAGS signals suggests that the use of nuclear reactions on dopants as diagnostics is quite feasible. [ABSTRACT FROM AUTHOR]

We report the first measurement of the 10 B (α , n) 13 N reaction in a polar-direct-drive exploding pusher (PDXP) at the National Ignition Facility (NIF). This work is motivated by the need to develop alternative mix diagnostics, radiochemistry being the focus here. The target is composed of a 65/35 at. % deuterium–tritium (DT) fill surrounded by a roughly 30 μ m thick beryllium ablator. The inner portion of the beryllium ablator is doped with 10 at. % of 10B. Radiation-hydrodynamics calculations were performed in 1D to optimize both the remaining boron rho-R and the DT neutron yield. A charged-particle transport post-processor has been developed to study α-induced reactions on the ablator material. Results indicate a large 13N production from α-induced reactions on 10B, measurable by the radiochemical analysis of a gaseous samples system at the NIF. The PDXP target N201115-001 was successfully fielded on the NIF, and nitrogen from the 10 B (α , n) 13 N reaction was measured. The 13N production yield, as well as the DT neutron yield, was, however, lower than expected. Some of the reduced yields can be explained by the oblate shape, but the ratios of the various radiochemical signals are not commensurate with expectations based on a simple reduction of the 1D results. Preliminary 2D radiation-hydrodynamics computations are consistent with the experimental measurements, and work is ongoing to extend the radiochemistry analysis into higher dimensions. [ABSTRACT FROM AUTHOR]

For the first time, 41Ar produced by the (n,Y) reaction trom 40Ar in the beryllium shell ot a DT filled Inertial Confinement Fusion capsule has been measured. 41Ar is co-deposited with beryllium in the sputter deposition ot the capsule shell. Combined with a measurement ot the neutron yield, the radioactive 41Ar then quantifies the areal density of beryllium during the DT neutron production. The measured 1.15 ± 0.17 × 10+8 atoms of 41Ar are 2.5 times that from the best post-shot calculation, suggesting that the 41Ar and Be areal densities are correspondingly higher than those calculated. Possible explanations are that (1) the beryllium shell is compressed more than calculated, (2) beryllium has mixed into the cold DT ice, or more likely (3) less beryllium is ablated than calculated. Since only one DT filled beryllium capsule has been fielded at NIF, these results can be confirmed and expanded in the future. [ABSTRACT FROM AUTHOR]

Precisely-known fission yield distributions are needed to determine a fissioning isotope and the incident neutron energy in nuclear security applications. 14 MeV neutrons from DT fusion at the National Ignition Facility induce fission in depleted uranium contained in the target assembly hohlraum. The fission yields of Kr isotopes (85m, 87, 88, and 89) are measured relative to the cumulative yield of 88Kr and compared to previously tabulated values. The results from this experiment and England and Rider are in agreement, except for the 85mKr/88Kr ratio, which may be the result of incorrect nuclear data. [ABSTRACT FROM AUTHOR]

The high-fluence neutron spectrum produced by the National Ignition Facility (NIF) provides an opportunity to measure the activation of materials by fast-spectrum neutrons. A new large-volume gas-cell diagnostic has been designed and qualified to measure the activation of gaseous substances at the NIF. This in-chamber diagnostic is recoverable, reusable and has been successfully fielded. Data from the qualification of the diagnostic have been used to benchmark an Monte Carlo N-Particle Transport Code simulation describing the downscattered neutron spectrum seen by the gas cell. We present early results from the use of this diagnostic to measure the activation of natXe and discuss future work to study the strength of interactions between plasma and nuclei. [ABSTRACT FROM AUTHOR]

Collection of representative samples of debris following inertial confinement fusion implosions in order to diagnose implosion conditions and efficacy is a challenging endeavor because of the unique conditions within the target chamber such as unconverted laser light, intense pulse of x-rays, physical chunks of debris, and other ablative effects. We present collection of gas samples following an implosion for the first time. High collection fractions for noble gases were achieved. We also present collection of solid debris samples on flat plate collectors. Geometrical collection efficiencies for Au hohlraum material were achieved and collection of capsule debris (Be and Cu) was also observed. Asymmetric debris distributions were observed for Au and Be samples. Collection of Be capsule debris was higher for solid collectors viewing the capsule through the laser entrance hole in the hohlraum than for solid collectors viewing the capsule around the waist of the hohlraum. Collection of Au hohlraum material showed the opposite pattern: more Au debris was collected around the waist than through the laser entrance hole. The solid debris collectors were not optimized for minimal Cu backgrounds, which limited the conclusions about the symmetry of the Cu debris. The quality of the data limited conclusions on chemical fractionation effects within the burning, expanding, and then cooling plasma. [ABSTRACT FROM AUTHOR]

The Radiochemical Analysis of Gaseous Samples (RAGS) diagnostic apparatus was recently installed at the National Ignition Facility (NIF). Following a NIF shot, RAGS is used to pump the gas load from the NIF chamber for purification and isolation of the noble gases. After collection, the activated gaseous species are counted via gamma spectroscopy for measurement of the capsule areal density and fuel-ablator mix. Collection efficiency was determined by injecting a known amount of 135Xe into the NIF chamber, which was then collected with RAGS. Commissioning was performed with an exploding pusher capsule filled with isotopically enriched 124Xe and 126Xe added to the DT gas fill. Activated xenon species were recovered post-shot and counted via gamma spectroscopy. Results from the collection and commissioning tests are presented. The performance of RAGS allows us to establish a noble gas collection method for measurement of noble gas species produced via neutron and charged particle reactions in a NIF capsule. [ABSTRACT FROM AUTHOR]

Precisely-known fission yield distributions are needed to determine a fissioning isotope and the incident neutron energy in nuclear security applications. 14 MeV neutrons from DT fusion at the National Ignition Facility induce fission in depleted uranium contained in the target assembly hohlraum. The fission yields of Kr isotopes (85m, 87, 88, and 89) are measured relative to the cumulative yield of 88 Kr and compared to previously tabulated values. The results from this experiment and England and Rider are in agreement, except for the 85m Kr/ 88 Kr ratio, which may be the result of incorrect nuclear data.