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Precise antineutrino measurements are very sensitive to proper background characterization. We present an improved measurement of the $^{13}\mathrm{C}(\ensuremath{\alpha},n)^{16}\mathrm{O}$ reaction cross section which constitutes significant background for large $\overline{\ensuremath{\nu}}$ detectors. We greatly improve the precision and accuracy by utilizing a setup that is sensitive to the neutron energies while making measurements of the excited state transitions via secondary $\ensuremath{\gamma}$-ray detection. Our results shows a 54% reduction in the background contributions from the $^{16}\mathrm{O}({3}^{\ensuremath{-}},6.13\text{ }\mathrm{MeV})$ state used in the KamLAND analysis.

The thermonuclear ^{30}P(p,γ)^{31}S reaction rate is critical for modeling the final elemental and isotopic abundances of ONe nova nucleosynthesis, which affect the calibration of proposed nova thermometers and the identification of presolar nova grains, respectively. Unfortunately, the rate of this reaction is essentially unconstrained experimentally, because the strengths of key ^{31}S proton capture resonance states are not known, largely due to uncertainties in their spins and parities. Using the β decay of ^{31}Cl, we have observed the β-delayed γ decay of a ^{31}S state at E_{x}=6390.2(7) keV, with a ^{30}P(p,γ)^{31}S resonance energy of E_{r}=259.3(8) keV, in the middle of the ^{30}P(p,γ)^{31}S Gamow window for peak nova temperatures. This state exhibits isospin mixing with the nearby isobaric analog state at E_{x}=6279.0(6) keV, giving it an unambiguous spin and parity of 3/2^{+} and making it an important l=0 resonance for proton capture on ^{30}P.

The Galactic 1.809-MeV $\ensuremath{\gamma}$-ray signature from the $\ensuremath{\beta}$ decay of $^{26g}\mathrm{Al}$ is a dominant target of $\ensuremath{\gamma}$-ray astronomy, of which a significant component is understood to originate from massive stars. The $^{26g}\mathrm{Al}(p,\ensuremath{\gamma})^{27}\mathrm{Si}$ reaction is a major destruction pathway for $^{26g}\mathrm{Al}$ at stellar temperatures, but the reaction rate is poorly constrained due to uncertainties in the strengths of low-lying resonances in $^{27}\mathrm{Si}$. The $^{26g}\mathrm{Al}(d,p)^{27}\mathrm{Al}$ reaction has been employed in inverse kinematics to determine the spectroscopic factors, and hence resonance strengths, of proton resonances in $^{27}\mathrm{Si}$ via mirror symmetry. The strength of the 127-keV resonance is found to be a factor of 4 higher than the previously adopted upper limit, and the upper limit for the 68-keV resonance has been reduced by an order of magnitude, considerably constraining the $^{26g}\mathrm{Al}$ destruction rate at stellar temperatures.

Classical novae are expected to contribute to the 1809-keV Galactic $\ensuremath{\gamma}$-ray emission by producing its precursor $^{26}\mathrm{Al}$, but the yield depends on the thermonuclear rate of the unmeasured $^{25}\mathrm{Al}(p,\ensuremath{\gamma})^{26}\mathrm{Si}$ reaction. Using the $\ensuremath{\beta}$ decay of $^{26}\mathrm{P}$ to populate the key ${J}^{\ensuremath{\pi}}={3}^{+}$ resonance in this reaction, we report the first evidence for the observation of its exit channel via a $1741.6\ifmmode\pm\else\textpm\fi{}0.6(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.3(\mathrm{syst})\text{ }\text{ }\mathrm{keV}$ primary $\ensuremath{\gamma}$ ray, where the uncertainties are statistical and systematic, respectively. By combining the measured $\ensuremath{\gamma}$-ray energy and intensity with other experimental data on $^{26}\mathrm{Si}$, we find the center-of-mass energy and strength of the resonance to be ${E}_{r}=414.9\ifmmode\pm\else\textpm\fi{}0.6(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.3(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.6(\mathrm{lit}.)\text{ }\text{ }\mathrm{keV}$ and $\ensuremath{\omega}\ensuremath{\gamma}=23\ifmmode\pm\else\textpm\fi{}6(\mathrm{stat}{)}_{\ensuremath{-}10}^{+11}(\mathrm{lit}.)\text{ }\text{ }\mathrm{meV}$, respectively, where the last uncertainties are from adopted literature data. We use hydrodynamic nova simulations to model $^{26}\mathrm{Al}$ production showing that these measurements effectively eliminate the dominant experimental nuclear-physics uncertainty and we estimate that novae may contribute up to 30% of the Galactic $^{26}\mathrm{Al}$.

Recent calculations suggest that the rate of neutron capture by 130Sn has a significant impact on late-time nucleosynthesis in the r-process. Direct capture into low-lying bound states is expected to be significant in neutron capture near the N=82 closed shell, so r- process reaction rates may be strongly impacted by the properties of neutron single particle states in this region. In order to investigate these properties, the (d, p) reaction has been studied in inverse kinematics using a 630 MeV beam of 130Sn (4.8 MeV/u) and a (CD2)n target. An array of Si strip detectors, including SIDAR and an early implementation of the ORRUBA, was used to detect reaction products. Results for the 130Sn(d, p)131Sn reaction are found to be very similar to those from the previously reported 132Sn(d, p)133Sn reaction. Direct-semidirect (n, ) cross section calculations, based for the first time on experimental data, are presented. The uncertainties in these cross sections are thus reduced by orders of magnitude from previous estimates.

The best examples of halo nuclei, exotic systems with a diffuse nuclear cloud surrounding a tightly-bound core, are found in the light, neutron-rich region, where the halo neutrons experience only weak binding and a weak, or no, potential barrier. Modern direct reaction measurement techniques provide powerful probes of the structure of exotic nuclei. Despite more than four decades of these studies on the benchmark one-neutron halo nucleus Be-11, the spectroscopic factors for the two bound states remain poorly constrained. In the present work, the Be-10(d,p) reaction has been used in inverse kinematics at four beam energies to study the structure of Be-11. The spectroscopic factors extracted using the adiabatic model, were found to be consistent across the four measurements, and were largely insensitive to the optical potential used. The extracted spectroscopic factor for a neutron in a nlj = 2s1/2 state coupled to the ground state of Be-10 is 0.71(5). For the first excited state at 0.32 MeV, a spectroscopic factor of 0.62(4) is found for the halo neutron in a 1p1/2 state., 5 pages, 4 figures

The rate of the (17)F(p,gamma)(18)Ne reaction is important in various astrophysical events. A previous (17)F(p,p)(17)F measurement identified a 3;{+} state providing the strongest resonance contribution, but the resonance strength was unknown. We have directly measured the (17)F(p,gamma)(18)Ne reaction using a mixed beam of (17)F and (17)O at ORNL. The resonance strength for the 3;{+} resonance in (18)Ne was found to be omegagamma = 33 +/- 14(stat) +/-1 7(syst) meV, corresponding to a gamma width of Gamma_{gamma} = 56 +/- 24(stat) +/- 30(syst) meV. An upper limit on the direct capture of S(E)