The Big Bang Nucleosynthesis (BBN) theory allows to calculate the abundance of isotopes createdin the early universe. Interestingly, the primordial abundance of deuterium deduced from observations of pristine gas at high redshifts is more accurate with respect to the computed value because the BBN calculation is affected by the paucity of data for the deuterium-burning reaction D(p,g)3He. In fact, only a single dataset is currently available in the BBN energy range, in which the authors state systematic error of 9%. The concern for the D(p; g)3He cross section error is made worse by the fact that the theoretical and experimental values do not agree at the level of 20%. A new measurement is presently in progress at the LUNA (Laboratory for Underground Nuclear astrophysics) accelerator, operating deep underground at the Gran Sasso Laboratory, Italy. The main goal is the study of the D(p; g)3He cross section in the BBN energy range with accuracy. The LUNA measurement is described and preliminary results are discussed and compared with ab-initio calculations. The impact of this measurement in cosmology and particle physics is also highlighted. In particular, a precision measurement allows to derive the universal baryon density Wb with accuracy comparable to the one obtained by the PLANCK experiment. Finally, the accurate knowledge of the D(p; g)3He cross section increases the sensitivity to probe the existence of relativistic particles (e.g. sterile neutrinos, hot axions etc.) not foreseen in the standard model.

The Coulomb Dissociation (CD) cross sections of the stable isotopes 92,94,100Mo and of the unstable isotope 93Mo were measured at the LAND/R3B setup at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. Experimental data on these isotopes may help to explain the problem of the underproduction of 92,94Mo and 96,98Ru in the models of p-process nucleosynthesis. The CD cross sections obtained for the stable Mo isotopes are in good agreement with experiments performed with real photons, thus validating the method of Coulomb Dissociation. The result for the reaction 93Mo(g,n) is especially important since the corresponding cross section has not been measured before. A preliminary integral Coulomb Dissociation cross section of the 94Mo(g,n) reaction is presented. Further analysis will complete the experimental database for the (g,n) production chain of the p-isotopes of molybdenum.

The Coulomb Dissociation (CD) cross sections of the stable isotopes Mo-92,Mo-94,Mo-100 and of the unstable isotope Mo-93 were measured at the LAND/(RB)-B-3 setup at GSI Helmholtzzentrum fur Schwerionenforschung in Darmstadt, Germany. Experimental data on these isotopes may help to explain the problem of the underproduction of Mo-92,Mo-94 and Ru-96,Ru-98 in the models of p-process nucleosynthesis. The CD cross sections obtained for the stable Mo isotopes are in good agreement with experiments performed with real photons, thus validating the method of Coulomb Dissociation. The result for the reaction Mo-93(gamma,n) is especially important since the corresponding cross section has not been measured before. A preliminary integral Coulomb Dissociation cross section of the Mo-94(gamma,n) reaction is presented. Further analysis will complete the experimental database for the (gamma,n) production chain of the p-isotopes of molybdenum.

Recent observations of (6)Li in metal poor stars suggest a large production of this isotope during big bang nucleosynthesis (BBN). In standard BBN calculations, the (2)H(α,γ)(6)Li reaction dominates (6)Li production. This reaction has never been measured inside the BBN energy region because its cross section drops exponentially at low energy and because the electric dipole transition is strongly suppressed for the isoscalar particles (2)H and α at energies below the Coulomb barrier. Indirect measurements using the Coulomb dissociation of (6)Li only give upper limits owing to the dominance of nuclear breakup processes. Here, we report on the results of the first measurement of the (2)H(α,γ)(6)Li cross section at big bang energies. The experiment was performed deep underground at the LUNA 400 kV accelerator in Gran Sasso, Italy. The primordial (6)Li/(7)Li isotopic abundance ratio has been determined to be (1.5 ± 0.3) × 10(-5), from our experimental data and standard BBN theory. The much higher (6)Li/(7)Li values reported for halo stars will likely require a nonstandard physics explanation, as discussed in the literature.

. The production of the stable isotope 6 Li in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological 6 Li plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of 7 Li abundances and would point to a predominantly primordial origin of 6 Li , contrary to the results of standard Big Bang nucleosynthesis calculations. Therefore, the nuclear physics underlying Big Bang 6 Li production must be revisited. The main production channel for 6 Li in the Big Bang is the 2 H(α,γ) 6 Li reaction. The present work reports on neutron-induced effects in a high-purity germanium detector that were encountered in a new study of this reaction. In the experiment, an α-beam from the underground accelerator LUNA in Gran Sasso, Italy, and a windowless deuterium gas target are used. A low neutron flux is induced by energetic deuterons from elastic scattering and, subsequently, the 2 H(d,n) 3 He reaction. Due to the ultra-low laboratory neutron background at LUNA, the effect of this weak flux of 2-3MeV neutrons on well-shielded high-purity germanium detectors has been studied in detail. Data have been taken at 280 and 400keV α-beam energy and for comparison also using an americium-beryllium neutron source.

The N-14(p,gamma)O-15 reaction is the slowest process of the CN cycle, and thus it is of high astrophysical interest since it regulates the total rate of energy and neutrinos production through the cycle. The N-14+p ground state capture is strongly influenced by a sub-threshold resonance corresponding to the 6.79 MeV state in O-15. The width of this resonance is a major source of uncertainty in the extrapolation of the reaction cross section in the Gamow energy window.Preliminary results of a new Doppler Shift Attenuation measurement of the lifetime of the 6.79 MeV state in O-15 are discussed. The level of interest was populated via the H-2(N-14,n)O-15 reaction in inverse kinematics at 32 MeV beam energy. The gamma-rays emitted in the decay of the 6.79 MeV level to the ground state were detected with the AGATA Demonstrator array of high-purity germanium detectors. The sensitivity of the shape of the peak in the gamma-ray energy spectrum to the level lifetime is investigated comparing the experimental peaks with detailed Monte Carlo simulations of the reaction mechanisms and the gamma-ray emission and detection. Nuclear levels in N-15 (also populated in the N-14+H-2 reaction) for which the lifetimes are known in the literature provided a test of the analysis technique.

The preliminary results of a new direct measurement of the lifetime of the first excited 3/2(+) state in O-15 are discussed. An accurate evaluation of this lifetime is of paramount importance for the determination of the cross section of the N-14(p,gamma)O-15 reaction, the slowest one in the CNO cycle, at the energies of the solar Gamow peak. The H-2(N-14,O-15)n reaction in inverse kinematics at 32 MeV beam energy (XTU Tandem, LNL) was used to populate the level of interest, which decays via a 6.79 MeV E1 gamma-ray transition to the ground state. Gamma rays were detected with 4 triple clusters of HPGe detectors of the AGATA Demonstrator array. The energy resolution and position sensitivity of this state-of-the-art gamma-ray spectrometer have been exploited to investigate the Doppler Shift Attenuation effect on the lineshape of the gamma-ray peak in the energy spectrum. The deconvolution of the lifetime effects from those due to the kinematics of the emitting nuclei has been performed using detailed Monte Carlo simulations of the gamma emission and detection. CDCC-CRC calculations for the nucleon transfer process have been used for this purpose and preliminary results are shown.

Photo-dissociation reactions play an important role in p-process nucleosynthesis, which takes place in supernova explosions. Theoretical calculations of isotopic abundances of the p-nuclei require a vast reaction network linking thousands of isotopes, where most of the reaction rates must be derived from the Hauser-Feshbach statistical model. However, as many rates as possible need to be determined experimentally, in order to provide a reliable reference for the calculations. Measuring reaction rates on Mo isotopes is important to explain the problem of the significant underproduction of Mo and Ru in all existing models of p-process nucleosynthesis. Another aspect of the project is to verify the accuracy of the Coulomb dissociation method by comparing our data with experiments performed with real photons at S-DALINAC (TU Darmstadt) and ELBE (FZD) [1].

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The gamma-ray strength function is an important input quantity for the determination of the photoreaction rate and the neutron capture rate for astrophysics as well as for nuclear technologies. To test model predictions, the photoabsorption cross section of La-139 up to the neutron-separation energy was measured using bremsstrahlung produced at the electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf with an electron beam of 11.5 MeV kinetic energy. The experimental data were analyzed by applying Monte Carlo simulations of gamma-ray cascades to obtain the intensities of the ground-state transitions and their branching ratios. We found a significant enhancement of electric dipole strength in the energy range from 6 to 10 MeV that may be related with a pygmy dipole resonance. The present data are combined with photoneutron cross sections for La-139 and compared with results of calculations on the basis of a quasiparticle-random-phase approximation using an instantaneous-shape sampling.

In nuclear network calculations especially the p-nucleus 92Mo is frequently underproduced. Since experimental data of the photodisintegration of 92Mo so far do not exist, it was necessary to measure the reaction yields with the photoactivation method using the brems-strahlung facility ELBE at FZ Dresden-Rossendorf. Also the reaction 100Mo(γ,n) could be tested while irradiating Mo samples of natural composition. The photon fluence was measured with nuclear resonance fluorescence (NRF) of strong and well-known transitions in 11B. As a normalization standard the photoactivation reaction 197Au(γ,n) was used. For the 65 s half-life of 91mMo a fast pneumatic delivery was used. The photoactivation yields of the (γ,p) and (γ,n) reactions are compared to yield integrals of the bremsstrahlung spectral shape folded with the cross sections derived from Hauser-Feshbach nuclear model calculations using the TALYS program and cross sections from earlier experiments.

R. Schwengner,1 R. Massarczyk,1,2 B. A. Brown,3 R. Beyer,1 F. Dönau,1 M. Erhard,1,* E. Grosse,1,2 A. R. Junghans,1 K. Kosev,1 C. Nair,1,† G. Rusev,1,‡ K. D. Schilling,1 and A. Wagner1 1Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, D-01314 Dresden, Germany 2Institut für Kernund Teilchenphysik, Technische Universität Dresden, D-01062 Dresden, Germany 3National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA (Received 9 March 2010; revised manuscript received 6 April 2010; published 21 May 2010)

The dipole response of the doubly magic nuclide $^{208}\mathrm{Pb}$ was studied in photon-scattering experiments at the electron linear accelerator ELBE with bremsstrahlung produced at kinetic electron energies of 9.0 and 15.0 MeV. The present $(\ensuremath{\gamma},{\ensuremath{\gamma}}^{\ensuremath{'}})$ data combined with $(\ensuremath{\gamma},n)$ data from the literature are compared with results of shell-model calculations and calculations using a quasiparticle random-phase approximation. The shell-model calculations including (2p-2h) excitations describe the experimental $E1$ strength well and reproduce the spreading of the giant dipole resonance by applying a small smearing width only.

Photoactivation measurements on Sm-144 have been performed with bremsstrahlung endpoint energies from 10.0 to 15.5 MeV at the bremsstrahlung facility of the superconducting electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf. The measured activation yield for the Sm-144(gamma,n) reaction is compared with the calculated yield using cross sections from previous photoneutron experiments. The activation yields measured for all disintegration channels Sm-144(gamma,n), (gamma,p), and (gamma,alpha) are compared to the yield calculated by using Hauser-Feshbach statistical models. A new parametrization of the photon strength function is presented and the yield simulated by using the modified photon strength parameters is compared to the experimental data.

The 14 N(p,γ) 15 O reaction is the slowest reaction of the carbon-nitrogen-oxygen cycle of hydrogen burning in stars. As a consequence, it determines the rate of the cycle. The 15 N(p,αγ) 12 C reaction is frequently used in inverse kinematics for hydrogen depth profiling in materials. The 14 N(p,γ) 15 O and 15 N(p,αγ) 12 C reactions have been studied simultaneously, using titanium nitride targets of natural isotopic composition and a proton beam. The strengths of the resonances at Ep = 1058 keV in 14 N(p,γ) 15 O and at E p = 897 and 430 keV in 15 N(p,αγ) 12 C have been determined with improved precision, relative to the well-known resonance at E p = 278 keV in 14 N(p,γ) 15 O. The new recommended values are ωγ = 0.353 ± 0.018, 362 ± 20, and 21.9 ± 1.0 eV for their respective strengths. In addition, the branching ratios for the decay of the E p = 1058 keV resonance in 14 N(p,γ) 15 O have been redetermined. The data reported here should facilitate future studies of off-resonant capture in the 14 N(p,γ) 15 O reaction that are needed for an improved R-matrix extrapolation of the cross section. In addition, the data on the 430 keV resonance in 15 N(p,αγ) 12 C may be useful for hydrogen depth profiling.