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The structure of nuclei around the neutron-rich nucleus 132Sn is of particular interest due to the vicinity of the Z = 50 and N = 82 shell closures and the r-process nucleosynthetic path. Four states in 131Sn with a strong single-particle-like component have previously been studied via the (d,p) reaction, with limited excitation energy resolution. The 130Sn(9Be,8Be)131Sn and 130Sn(13C,12C)131Sn single-neutron transfer reactions were performed in inverse kinematics at the Holifield Radioactive Ion Beam Facility using particle-gamma coincidence spectroscopy. The uncertainties in the energies of the single-particle-like states have been reduced by more than an order of magnitude using the energies of gamma rays. The previous tentative Jpi values have been confirmed. Decays from high-spin states in 131Sn have been observed following transfer on the isomeric component of the 130Sn beam. The improved energies and confirmed spin-parities of the p-wave states important to the r-process lead to direct-semidirect cross-sections for neutron capture on the ground state of 130Sn at 30 keV that are in agreement with previous analyses. A similar assessment of the impact of neutron-transfer on the isomer would require significant nuclear structure and reaction theory input. There are few measurements of transfer reaction on isomers, and this is the first on an isomer in the 132Sn region., Comment: 7 pages, 4 figures

Precise antineutrino measurements are very sensitive to proper background characterization. We present an improved measurement of the ^{13}C(α,n)^{16}O reaction cross section which constitutes significant background for large ν[over ¯] 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 γ-ray detection. Our results shows a 54% reduction in the background contributions from the ^{16}O(3^{-},6.13 MeV) state used in the KamLAND analysis.

The astrophysical $S$-factor for the radiative proton capture reaction on $^7$Be ($S_{17}$) at low energies is affected by the $s$-wave scattering lengths. We report the measurement of elastic and inelastic scattering cross sections for the $^7$Be+p system in the center-of-mass energy range 0.474 - 2.740 MeV and center-of-mass angular range of 70$^\circ$- 150$^\circ$. A radioactive $^7$Be beam produced at Oak Ridge National Laboratory's (ORNL) Holifield Radioactive Ion Beam Facility was accelerated and bombarded a thin polypropylene (CH$_{2}$)$_\text n$ target. Scattered ions were detected in the segmented Silicon Detector Array. Using an $\textit{R}$-matrix analysis of ORNL and Louvain-la-Neuve cross section data, the $s$-wave scattering lengths for channel spins 1 and 2 were determined to be 17.34$^{+1.11}_{-1.33}$ and -3.18$^{+0.55}_{-0.50}$ fm, respectively. The uncertainty in the $s$-wave scattering lengths reported in this work is smaller by a factor of 5-8 compared to the previous measurement, which may reduce the overall uncertainty in $S_{17}$ at zero energy. The level structure of $^8$B is discussed based upon the results from this work. Evidence for the existence of 0$^+$ and 2$^+$ levels in $^8$B at 1.9 and 2.21 MeV, respectively, is observed.

The $^{15}$O($\alpha$,$\gamma$)$^{19}$Ne reaction is responsible for breakout from the hot CNO cycle in Type I x-ray bursts. Understanding the properties of resonances between $E_x = 4$ and 5 MeV in $^{19}$Ne is crucial in the calculation of this reaction rate. The spins and parities of these states are well known, with the exception of the 4.14- and 4.20-MeV states, which have adopted spin-parities of 9/2$^-$ and 7/2$^-$, respectively. Gamma-ray transitions from these states were studied using triton-$\gamma$-$\gamma$ coincidences from the $^{19}$F($^{3}$He,$t\gamma$)$^{19}$Ne reaction measured with GODDESS (Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies) at Argonne National Laboratory. The observed transitions from the 4.14- and 4.20-MeV states provide strong evidence that the $J^\pi$ values are actually 7/2$^-$ and 9/2$^-$, respectively. These assignments are consistent with the values in the $^{19}$F mirror nucleus and in contrast to previously accepted assignments.

Detection of nuclear-decay γ rays provides a sensitive thermometer of nova nucleosynthesis. The most intense γ-ray flux is thought to be annihilation radiation from the β^{+} decay of ^{18}F, which is destroyed prior to decay by the ^{18}F(p,α)^{15}O reaction. Estimates of ^{18}F production had been uncertain, however, because key near-threshold levels in the compound nucleus, ^{19}Ne, had yet to be identified. We report the first measurement of the ^{19}F(^{3}He,tγ)^{19}Ne reaction, in which the placement of two long-sought 3/2^{+} levels is suggested via triton-γ-γ coincidences. The precise determination of their resonance energies reduces the upper limit of the rate by a factor of 1.5-17 at nova temperatures and reduces the average uncertainty on the nova detection probability by a factor of 2.1.

The neutron-capture reaction plays a critical role in the synthesis of the elements in stars and is important for societal applications including nuclear power generation and stockpile-stewardship science. However, it is difficult-if not impossible-to directly measure neutron capture cross sections for the exotic, short-lived nuclei that participate in these processes. In this Letter we demonstrate a new technique which can be used to indirectly determine neutron-capture cross sections for exotic systems. This technique makes use of the (d,p) transfer reaction, which has long been used as a tool to study the structure of nuclei. Recent advances in reaction theory, together with data collected using this reaction, enable the determination of neutron-capture cross sections for short-lived nuclei. A benchmark study of the ^{95}Mo(d,p) reaction is presented, which illustrates the approach and provides guidance for future applications of the method with short-lived isotopes produced at rare isotope accelerators.

Knowledge of the 3He(3He,2p)4He reaction is important for understanding stellar burning and solar neutrino production. Previous measurements have found a surprisingly large rise in the cross section at low energies that could be due to a low-energy resonance in the 3He + 3He (6Be) system or electron screening. In the 6Be nucleus, however, no excited states have been observed above the first 2+ state at Ex = 1.67 MeV up to 23 MeV, even though several are expected. The 2H(7Be,3H)6Be reaction has been studied for the first time to search for resonances in the 6Be nucleus that may affect our understanding of the 3He(3He,2p)4He reaction. A 100-MeV radioactive 7Be beam from the Holifield Radioactive Ion Beam Facility (HRIBF) was used to bombard CD2 targets, and tritons were detected by using the silicon detector array (SIDAR). A combination of reaction mechanisms appears to be necessary to explain the observed triton energy spectrum.

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.

International audience; The Galactic 1.809-MeV γ-ray signature from the β decay of $^{26g}$Al is a dominant target of γ-rayastronomy, of which a significant component is understood to originate from massive stars. The$^{26g}$Al(p; γ)$^{27}$Si reaction is a major destruction pathway for $^{26g}$Al at stellar temperatures, but the reactionrate is poorly constrained due to uncertainties in the strengths of low-lying resonances in $^{27}$Si. The$^{26g}$Al(d; p)$^{27}$Al reaction has been employed in inverse kinematics to determine the spectroscopic factors,and hence resonance strengths, of proton resonances in $^{27}$Si via mirror symmetry. The strength of the127-keV resonance is found to be a factor of 4 higher than the previously adopted upper limit, and the upperlimit for the 68-keV resonance has been reduced by an order of magnitude, considerably constraining the$^{26g}$Al destruction rate at stellar temperatures.

Initial measurements are presented of the (d,p) reactions on neutron-rich N = 50 isotones along the r-process path of nucleosynthesis with radioactive ion beams of 82Ge and 84Se. Prospects for measurements with unstable 130,132Sn beams are discussed.

Neutron-capture reactions on neutron-rich nuclei are important to understand r-process nucleosynthesis, as well as applied needs such as stewardship science and nuclear energy. Because of the short half-lives of these species, it is not possible to measure these reactions directly with neutron beams on unstable targets. The (d,pγ) reaction with radioactive ion beams has been proposed as a surrogate reaction for (n,γ). Experiments to develop (d,pγ) techniques with radioactive ion beams and to demonstrate the efficacy of the (d,pγ) reaction as a surrogate for (n,γ) are discussed.

Single-neutron states in (133)Sn and (209)Pb, which are analogous to single-electron states outside of closed atomic shells in alkali metals, were populated by the ((9)Be, (8)Be) one-neutron transfer reaction in inverse kinematics using particle-γ coincidence spectroscopy. In addition, the s(1/2) single-neutron hole-state candidate in (131)Sn was populated by ((9)Be, (10)Be). Doubly closed-shell (132)Sn (radioactive) and (208)Pb (stable) beams were used at sub-Coulomb barrier energies of 3 MeV per nucleon. Level energies, γ-ray transitions, absolute cross sections, spectroscopic factors, asymptotic normalization coefficients, and excited-state lifetimes are reported and compared with shell-model expectations. The results include a new transition and precise level energy for the 3p(1/2) candidate in (133)Sn, new absolute cross sections for the 1h(9/2) candidate in (133)Sn and 3s(1/2) candidate in (131)Sn, and new lifetimes for excited states in (133)Sn and (209)Pb. This is the first report on excited-state lifetimes of (133)Sn, which allow for a unique test of the nuclear shell model and (132)Sn double-shell closure.

Two generalized transfer reaction techniques have been used to exploit these beams in regions of the nuclear chart around N = 50 and N = 82. The first employs large silicon detector arrays to measure protons emitted from the (d,p) reaction in inverse kinematics [2 6]. The second uses HYBALL to detect the charged particles emitted from ( 9 Be, 8 Be), and ( 13 C, 12 C) reactions with gamma rays measured in coincidence in CLARION [6 7].

Classical novae are expected to contribute to the 1809-keV Galactic γ-ray emission by producing its precursor 26Al, but the yield depends on the thermonuclear rate of the unmeasured 25Al(p,γ)26Si reaction. Using the β decay of 26P to populate the key J(π)=3(+) resonance in this reaction, we report the first evidence for the observation of its exit channel via a 1741.6±0.6(stat)±0.3(syst) keV primary γ ray, where the uncertainties are statistical and systematic, respectively. By combining the measured γ-ray energy and intensity with other experimental data on 26Si, we find the center-of-mass energy and strength of the resonance to be E(r)=414.9±0.6(stat)±0.3(syst)±0.6(lit.) keV and ωγ=23±6(stat)(-10)(+11)(lit.) meV, respectively, where the last uncertainties are from adopted literature data. We use hydrodynamic nova simulations to model 26Al 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 26Al.

The coincident detection of particles and gamma rays allows the study of the structure of exotic nuclei via inverse kinematics reactions using radioactive ion beams and thick targets. We report on the status of the project to couple the highresolution charged-particle detector ORRUBA to Gammasphere, a high-efficiency, high-resolution gamma ray detector.

The study of nuclei far from stability elucidates the evolution of nuclear shell structure, and also affects estimates of heavy element nucleosynthesis in supernova explosions. Measurement of transfer reactions in inverse kinematics with radioactive ion beams is a powerful technique for these types of studies. Rare isotope beams often have relatively low intensities, and this places difficult requirements on the detection systems for reaction products. The detectors must provide large solid angle coverage in the laboratory along with good position and energy resolution. The Super ORRUBA detector array has been developed for such measurements and is comprised of 18 double-sided, nonresistive silicon strip detectors. This configuration features low thresholds and improved resolution over detectors employing charge division. As a first implementation of this system, the 80Ge(d,p)81Ge neutron transfer reaction in inverse kinematics was measured at HRIBF at ORNL, to determine the properties of levels in 81Ge.

The (d, p) reaction was measured with the radioactive ion beams of 126Sn and 128Sn in inverse kinematics at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory, utilizing the Super ORRUBA silicon detector array. Angular distributions of reaction protons were measured for several states in 127Sn and 129Sn to determine angular momentum transfers and deduce spectroscopic factors. Such information is critical for calculating direct (n,γ) cross sections for the r-process as well as for constraining shell model parameters in the A≈130 region. Combined with previous experiments on 130Sn and 132Sn, these results will provide a complete set of (d, p) reaction data on even tin isotopes between stable 124Sn and doubly-magic 132Sn.

The astrophysical rapid neutron-capture process (r-process) is believed to have produced approximately half of the nuclear species more massive than Fe. Unfortunately, almost nothing is known about the structure of the majority of the extremely neutron-rich nuclei involved in the reaction flow. At exotic beam facilities such as the Holifield Radioactive Ion Beam Facility (HRIBF), measurements with accelerated beams of fission fragments have provided some of the first spectroscopic information on many r-process nuclei. The new SuperORRUBA (Oak Ridge Rutgers University Barrel Array) detector has been constructed at the HRIBF to study such nuclei, and first results are presented.

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 28Si(p,3 He)26Al reaction was utilized for the first time to study the levels in 26Al, using a proton beam from the Holifield Radioactive Ion Beam Facility. Five previously unreported states in 26Al are observed and discussed, including Distorted Wave Born Approximation analysis. Proton-decay branching ratios consistent with previous studies and theoretical expectations were found by detecting decay protons from highly excited 26Al states in coincidence with the 3He particles.

Galactic 26Al is the first radioactive nucleus to be positively identified by -ray astronomy with detection of the 1.809 MeV ray associated with its decay. This nucleus is destroyed in astrophysical environments in the 26Al(p, )27Si and inelastic 26Al+p scattering reactions where properties of 27Si levels determine reaction rates. To investigate these properties, elastic and inelastic 26Al+p scattering reactions were measured between Ec.m. = 0.5 1.5 MeV at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). A candidate for a new resonance in the 26Al(p, )27Si reaction was identified. Upper limits were also set on the strengths of postulated resonances and on the cross section of the inelastic reaction, but there is little effect on current reaction rate calculations.

Recent calculations suggest that the rate of neutron capture by (130)Sn 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 (130)Sn (4.8 MeV/u) and a (CD(2))(n) target. An array of Si strip detectors, including the Silicon Detector Array and an early implementation of the Oak Ridge Rutgers University Barrel Array, was used to detect reaction products. Results for the (130)Sn(d, p)(131)Sn reaction are found to be very similar to those from the previously reported (132)Sn(d, p)(133)Sn reaction. Direct-semidirect (n,γ) 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.

A good understanding of the level structure of ${}^{19}\mathrm{Ne}$ around the proton threshold is critical to estimating the destruction of long-lived ${}^{18}\mathrm{F}$ in novae. Here we report the properties of levels in ${}^{19}\mathrm{Ne}$ in the excitation energy range of 6.9 $\ensuremath{\leqslant}$ ${E}_{x}$ $\ensuremath{\leqslant}$ 8.4 MeV studied via the proton-transfer ${}^{18}\mathrm{F}(d,n){\mathrm{Ne}}^{*}$ reaction at the Holifield Radioactive Ion Beam Facility. The populated ${}^{19}\mathrm{Ne}$ levels decay by breakup into $p+{}^{18}\mathrm{F}$ and $\ensuremath{\alpha}+{}^{15}\mathrm{O}$ particles. The results presented in this manuscript are those of levels that are simultaneously observed from the breakup into both channels. An $s$-wave state is observed at 1468 keV above the proton threshold, which is a potential candidate for a predicted broad ${J}^{\ensuremath{\pi}}$ $=$ 1/2${}^{+}$ state. The proton and $\ensuremath{\alpha}$ partial widths are deduced to be ${\ensuremath{\Gamma}}_{p}$ $=$ 228 $\ifmmode\pm\else\textpm\fi{}$ 50 keV and ${\ensuremath{\Gamma}}_{\ensuremath{\alpha}}$ $=$ 130 $\ifmmode\pm\else\textpm\fi{}$ 30 keV for this state.

Single-neutron excitations in neutron-rich tin isotopes have been studied with (d,p) reactions in inverse kinematics with accelerated beams of 124,126,128,130,132Sn. Reaction protons were measured with silicon strip detectors from ORRUBA. For the heavier isotopes, f and p single neutron configurations from across the N=82 gap dominate the spectra. Heavy-ion induced neutron transfer reactions have recently been measured with particle-gamma-ray coincidences. Measures of direct neutron capture can be obtained from the spectroscopic factors for p states. Plans to deduce the statistical component of neutron-capture cross sections are discussed.

Simultaneous measurement of the proton-transfer {sup 18}F(d, n){sup 19}Ne and neutron-transfer {sup 18}F(d, p){sup 19}F reactions were performed with a {sup 18}F radioactive beam at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The experiments clarify the nuclear structure of {sup 19}Ne near the proton threshold, which is relevant for understanding the rates of proton-induced reactions on {sup 18}F in novae. Analogs for several states in the mirror nucleus {sup 19}F have not yet been identified in {sup 19}Ne, indicating that the level structure of {sup 19}Ne in this region is incomplete. We observed 15 levels in {sup 19}Ne from the {sup 18}F(d, n){sup 19}Ne measurement and 18 levels in {sup 19}F from the {sup 18}F(d, p){sup 19}F measurement. Angular distributions were extracted for all strongly populated states and compared to distorted-wave Born approximation calculations. The angular distributions for all the known states in the two nuclei determined in this work are consistent with their previously assigned spins and parities. The spectroscopic factors determined for these levels in the two nuclei are reported.

Big Bang nucleosynthesis calculations, constrained by the Wilkinson Microwave Anisotropy Probe results, produce {sup 7}Li abundances almost a factor of four larger than those extrapolated from observations. Since primordial {sup 7}Li is believed to be mostly produced by the beta decay of {sup 7}Be, one proposed solution to this discrepancy is a resonant enhancement of the {sup 7}Be(d,p)2{alpha} reaction rate through the 5/2{sup +} 16.7-MeV state in {sup 9}B. The {sup 2}H({sup 7}Be,d){sup 7}Be reaction was used to search for such a resonance; none was observed. An upper limit on the width of the proposed resonance was deduced.

The ${}^{18}\mathrm{F}(p,\ensuremath{\alpha}){}^{15}\mathrm{O}$ reaction is the predominant destruction mechanism in novae of the radionuclide $^{18}\mathrm{F}$, a target of $\ensuremath{\gamma}$-ray observatories. Thus, its rate is important for understanding $^{18}\mathrm{F}$ production in novae. We have studied resonances in the ${}^{18}\mathrm{F}+p$ system by making a measurement of a proton-transfer reaction ${}^{18}\mathrm{F}(d,n)$. We have observed 15 $^{19}\mathrm{Ne}$ levels, 5 of which are below the proton threshold, including a subthreshold state, which has significant ${l}_{p}=0$ strength. Our data provide a direct determination of the spectroscopic strength of these states and new constraints on their spins and parities, thereby resolving a controversy, which involves the 8- and 38-keV resonances. The ${}^{18}\mathrm{F}(p,\ensuremath{\alpha}){}^{15}\mathrm{O}$ reaction rate is reevaluated, which takes the subthreshold resonance and other new information determined in this experiment into account.

Low-energy resonances in 31P(p, α 28Si and 35Cl(p, α)32S were studied directly in order to gain a better understanding of reaction cycling in the Si-Ar region in novae. New resonance strengths at E c.m. = 600 and 622 keV in 31P(p, α)28Si were measured (ωγ p, α = (2.2#x00B1;0.7) × 10−2 eV and ωγ p, α = (0.99±0.08) eV, respectively) as well as the E c.m. = 610 keV resonance in 35Cl(p, α)32S [ωγ p, α = (1.2±0.2) × 10−2 eV], the lowest energy that any resonance in this reaction has been observed, directly or indirectly. The strengths of these resonances were found to be lower than previously determined, resulting in even weaker cycling in the Si-Ar region.

Several resonances in $^{25}\mathrm{Al}$($p,\ensuremath{\gamma}$)$^{26}\mathrm{Si}$ have been studied via the $^{28}\mathrm{Si}$($p,t$)$^{26}\mathrm{Si}$ reaction. Triton energies and angular distributions were measured using a segmented annular detector array. An additional silicon detector array was used to simultaneously detect the coincident protons emitted from the decay of states in $^{26}\mathrm{Si}$ above the proton threshold in order to determine branching ratios. A resonance at $5927\ifmmode\pm\else\textpm\fi{}4$ keV has been experimentally confirmed as the first $\ensuremath{\ell}=0$ state above the proton threshold, with a proton branching ratio consistent with one.

The level structure of 22Na has been studied at the Holifield Radioactive Ion Beam Facility in Oak Ridge National Laboratory using the 24Mg(p,3He)22Na reaction. 41 and 41.5 MeV proton beams were generated by 25 MV tandem accelerator and bombarded isotopically enriched 24Mg targets. Angular distributions of recoiling 3He particles were extracted by using a segmented annular silicon strip detector array. Spins and parities for ten levels were constrained through a distorted wave Born approximation analysis of angular distributions including three above the proton threshold at 6.739 MeV.

Atomic nuclei have a shell structure where nuclei with 'magic numbers' of neutrons and protons are analogous to the noble gases in atomic physics. Only ten nuclei with the standard magic numbers of both neutrons and protons have so far been observed. The nuclear shell model is founded on the precept that neutrons and protons can move as independent particles in orbitals with discrete quantum numbers, subject to a mean field generated by all the other nucleons. Knowledge of the properties of single-particle states outside nuclear shell closures in exotic nuclei is important for a fundamental understanding of nuclear structure and nucleosynthesis (for example the r-process, which is responsible for the production of about half of the heavy elements). However, as a result of their short lifetimes, there is a paucity of knowledge about the nature of single-particle states outside exotic doubly magic nuclei. Here we measure the single-particle character of the levels in 133Sn that lie outside the double shell closure present at the short-lived nucleus 132Sn. We use an inverse kinematics technique that involves the transfer of a single nucleon to the nucleus. The purity of the measured single-particle states clearly illustrates the magic nature of 132Sn., 19 pages, 5 figures and 4 tables

We directly measure the {sup 17}F(p,{gamma}){sup 18}Ne resonant reaction using a mixed beam of {sup 17}F and {sup 17}O at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory (ORNL). The astrophysically important 3{sup +} resonance at {approx}600 keV above the proton threshold in {sup 18}Ne is found to have a partial width {Gamma}{sub {gamma}} = 56 {+-} 24(stat) {+-} 30(sys) meV, in reasonable agreement with the theoretically predicted width. A 2{sigma} upper limit on the direct capture of S(E) = 65 keV b is determined at an energy of 800 keV. Experimental techniques and astrophysical implications are discussed.

The transfer of neutrons onto 24Ne has been measured using a reaccelerated radioactive beam of 24Ne to study the (d,p) reaction in inverse kinematics. The unusual raising of the first 3/2+ level in 25Ne and its significance in terms of the migration of the neutron magic number from N=20 to N=16 is put on a firm footing by confirmation of this state's identity. The raised 3/2+ level is observed simultaneously with the intruder negative parity 7/2- and 3/2- levels, providing evidence for the reduction in the N=20 gap. The coincident gamma-ray decays allowed the assignment of spins as well as the transferred orbital angular momentum. The excitation energy of the 3/2+ state shows that the established USD shell model breaks down well within the sd model space and requires a revised treatment of the proton-neutron monopole interaction.