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Gas-filled capsules imploded with indirect drive on the National Ignition Facility have been employed as symmetry surrogates for cryogenic-layered ignition capsules and to explore interfacial mix. Plastic capsules containing deuterated layers and filled with tritium gas provide a direct mea-sure of mix of ablator into the gas fuel. Other plastic capsules have employed DT or D³He gas fill. We present the results of two-dimensional simulations of gas-filled capsule implosions with known degradation sources represented as in modeling of inertial confinement fusion ignition designs; these are time-dependent drive asymmetry, the capsule support tent, roughness at material interfa-ces, and prescribed gas-ablator interface mix. Unlike the case of cryogenic-layered implosions, many observables of gas-filled implosions are in reasonable agreement with predictions of these simulations. Yields of TT and DT neutrons as well as other x-ray and nuclear diagnostics are matched for CD-layered implosions. Yields of DT-filled capsules are over-predicted by factors of I.4-2, while D³He capsule yields are matched, as well as other metrics for both capsule types. [ABSTRACT FROM AUTHOR]

Low-spin single quasineutron levels in 153Gd and 157Gd have been studied following the 154Gd(p,d-ɣ)153Gd and 158Gd(p,d-ɣ)157Gd reactions. A combined Si telescope and high-purity germanium array was utilized, allowing d-ɣ and d-ɣ-ɣ coincidence measurements. Almost all of the established low-excitation-energy, low-spin structures were confirmed in both 153Gd and 157Gd. Several new levels and numerous new ɣ rays are observed in both nuclei, particularly for Ex≥1 MeV. Residual effects of a neutron subshell closure at N=64 are observed in the form of a large excitation energy gap in the single quasineutron level schemes. [ABSTRACT FROM AUTHOR]

A new experimental technique is presented using proton-y-y correlations from '"Mofd, pf5Mo reactions which allows for the model-independent extraction of the photon strength function at various excitation energies using primary y-ray decay from the quasicontinuum to individual low-lying levels. Detected particle energies provide the entrance excitation energies into the residual nucleus while y-ray transitions from low-lying levels specify the discrete states being fed. Results strongly support the existence of the previously reported low-energy enhancement in the photon strength function. [ABSTRACT FROM AUTHOR]

Background: The recent observation of a neutron-star merger finally confirmed one astrophysical location of the rapid neutron-capture process (r-process). Evidence of the production of A < 140 nuclei was seen, but there is still little detailed information about how those lighter elements are produced in such an environment. Many of the questions surrounding the A ≈ 80 nuclei are likely to be answered only when the nuclear physics involved in the production of r-process nuclei is well understood. Neutron-capture reactions are an important component of the r-process, and neutron-capture cross sections of r-process nuclei, which are very neutron rich, have large uncertainties. Purpose: Indirectly determine the neutron-capture cross section and reaction rate of 73 Zn (n, γ) 74 Zn. Methods: The nuclear level density (NLD) and γ -ray strength function (γ SF) of 74 Zn were determined following a total absorption spectroscopy (TAS) experiment focused on the ß decay of 74 Cu into 74 Zn performed at the National Superconducting Cyclotron Laboratory. The NLD and γ SF were used as inputs in a Hauser-Feshbach statistical model to calculate the neutron-capture cross section and reaction rate. Results: The NLD and γ SF of 74 Zn were experimentally constrained for the first time using ß -delayed γ rays measured with TAS and the ß -Oslo method. The NLD and γ SF were then used to constrain the neutron-capture cross section and reaction rate for the 73 Zn (n, γ) 74 Zn reaction. Conclusions: The uncertainty in the neutron-capture cross section and reaction rate of 73 Zn (n, γ) 74 Zn calculated in TALYS was reduced to under a factor of 2 from a factor of 5 in the cross section and a factor of 11 in the reaction rate using the experimentally obtained NLD and γ SF. [ABSTRACT FROM AUTHOR]

One of the greatest questions for modern physics to address is how elements heavier than iron are created in extreme astrophysical environments. A particularly challenging part of that question is the creation of the so-called p-nuclei, which are believed to be mainly produced in some types of supernovae. The lack of needed nuclear data presents an obstacle in nailing down the precise site and astrophysical conditions. In this work, we present for the first time measurements on the nuclear level density and average γ strength function of 92Mo. State-of-the-art p-process calculations systematically underestimate the observed solar abundance of this isotope. Our data provide stringent constraints on the 91Nb(p,γ)92Mo reaction rate, which is the last unmeasured reaction in the nucleosynthesis puzzle of 92Mo. Based on our results, we conclude that the 92Mo abundance anomaly is not due to the nuclear physics input to astrophysical model calculations. [ABSTRACT FROM AUTHOR]