| 1. |
- Aksyutina, Y., et al.
(författare)
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Structure of the unbound nucleus Be-13: One-neutron knockout reaction data from Be-14 analyzed in a holistic approach
- 2013
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 87:6
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Tidskriftsartikel (refereegranskat)abstract
- At the ALADIN-LAND setup at GSI the unbound nucleus Be-13 has been produced in one-neutron knockout reactions from a 304 MeV/nucleon relativistic beam of Be-14 ions impinging on a liquid hydrogen target. An analysis of the data including all available information about Be-13, and in particular recent data from a similar experiment performed at RIKEN, has been performed. A consistent description is reached. It is found that the excitation spectrum is dominated by s-waves at low energy, which solves problems from previous seemingly contradictory interpretations. A possible interference between two s-states in Be-13 is also discussed. The results indicate that the ground-state wave function of Be-14 is dominated by valence neutrons in the s-shell contributing with 60-75% of the total neutron knockout cross section.
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| 2. |
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| 3. |
- Bedaque, P., et al.
(författare)
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Quark mass variation constraints from Big Bang nucleosynthesis
- 2011
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 83:4
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Tidskriftsartikel (refereegranskat)abstract
- We study the impact on the primordial abundances of light elements created by a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way, we use lattice QCD data and a hierarchy of effective field theories. We find that the measured 4He abundances put a bound of -1%≲δmq/mq≲0.7% on a possible variation of quark masses. The effect of quark mass variations on the deuterium abundances can be largely compensated by changes of the baryon-to-photon ratio η. Including bounds on the variation of η coming from WMAP results and adding some additional assumptions further narrows the range of allowed values of δmq/mq.
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| 4. |
- Billnert, Robert, 1981, et al.
(författare)
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New prompt spectral gamma-ray data from the reaction Cf-252(sf) and its implication on present evaluated nuclear data files
- 2013
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 87:2
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Tidskriftsartikel (refereegranskat)abstract
- We present results from new spectral prompt gamma-ray measurements from the spontaneous fission of Cf-252. Apart from one recent experiment, about four decades have passed since the last dedicated experiments were reported in the literature. Hence, there was a need for a revision. We have measured prompt fission. rays with both cerium-doped LaBr3 and CeBr3 scintillation detectors, both of which exhibit excellent timing and good energy resolution. The emission yield was determined to be nu(gamma) = (8.30 +/- 0.08)/fission and nu(gamma) = (8.31 +/- 0.10)/fission, with the average energy of is an element of(gamma) = (0.80 +/- 0.01) MeV and is an element of(gamma) = (0.80 +/- 0.01) MeV and total energy of E-gamma,E-tot = (6.64 +/- 0.08) MeV and E-gamma,E-tot = (6.65 +/- 0.12) MeV, with the LaBr3 and CeBr3 detectors, respectively. Since the results from the two detectors are in excellent agreement and confirm the historical data, but not those in the present evaluated nuclear data files, we strongly recommend an update.
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| 5. |
- Burda, O., et al.
(författare)
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Resonance parameters of the first 1/2+ state in 9Be and astrophysical implications
- 2010
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 82:1
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Tidskriftsartikel (refereegranskat)abstract
- Spectra of the Be-9(e, e') reaction have been measured at the Superconducting Darmstadt Electron Linear Accelerator at an electron energy of E-0 = 73 MeV and scattering angles of 93 degrees and 141 degrees with high-energy resolution up to excitation energies of E-x = 8 MeV. The astrophysically relevant resonance parameters of the first excited 1/2(+) state of Be-9 have been extracted in a one-level approximation of R-matrix theory, resulting in resonance energy E-R = 1.748(6) MeV and width Gamma(R) = 274(8) keV, which are in good agreement with the latest Be-9(gamma, n) experiment but with considerably improved uncertainties. However, the reduced B(E1) transition strength deduced from an extrapolation of the (e, e') data to the photon point is smaller by a factor of two. Implications of the new results for possible production of C-12 in neutron-rich astrophysical scenarios are discussed.
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| 6. |
- Caesar, C., et al.
(författare)
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Beyond the neutron drip line: The unbound oxygen isotopes O-25 and O-26
- 2013
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993 .- 0556-2813. ; 88:3
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Tidskriftsartikel (refereegranskat)abstract
- The very neutron-rich oxygen isotopes O-25 and O-26 are investigated experimentally and theoretically. The unbound states are populated in an experiment performed at the R3B-LAND setup at GSI via proton-knockout reactions from F-26 and F-27 at relativistic energies around 442 and 414 MeV/nucleon, respectively. From the kinematically complete measurement of the decay into O-24 plus one or two neutrons, the O-25 ground-state energy and width are determined, and upper limits for the O-26 ground-state energy and lifetime are extracted. In addition, the results provide indications for an excited state in O-26 at around 4 MeV. The experimental findings are compared to theoretical shell-model calculations based on chiral two- and three-nucleon (3N) forces, including for the first time residual 3N forces, which are shown to be amplified as valence neutrons are added.
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| 7. |
- Drut, J. E., et al.
(författare)
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Exact-exchange density functional theory for neutron drops
- 2011
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 84:1
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Tidskriftsartikel (refereegranskat)abstract
- We compute the ground-state properties of finite systems of neutrons in an external harmonic trap, interacting via the Minnesota potential, using the "exact-exchange" form of orbital-dependent density functional theory. We compare our results with Hartree-Fock calculations and find very close agreement. Within the context of the interaction studied, we conclude that this simple orbital-dependent functional brings conventional nuclear density functional theory to the level of Hartree-Fock in an ab initio fashion. Our work is a first step toward higher order ab initio nuclear functionals based on realistic nucleon-nucleon interactions.
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| 8. |
- Elvers, M., et al.
(författare)
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Investigation of octupole vibrational states in 150Nd via inelastic proton scattering (p,p 'gamma)
- 2011
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 84:5
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Tidskriftsartikel (refereegranskat)abstract
- Octupole vibrational states were studied in the nucleus (150)Nd via inelastic proton scattering with 10.9-MeV protons, which are an excellent probe to excite natural parity states. For the first time in (150)Nd, both the scattered protons and the gamma rays were detected in coincidence, giving the possibility to measure branching ratios in detail. Using the coincidence technique, the B(E1) ratios of the decaying transitions for 10 octupole vibrational states and other negative-parity states to the yrast band were determined and compared to the Alaga rule. The positive and negative-parity states revealed by this experiment are compared with interacting boson approximation calculations performed in the spdf boson space. The calculations are found to be in good agreement with the experimental data, for both positive and negative-parity states.
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| 9. |
- Ershov, S. N., et al.
(författare)
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Binding energy constraint on matter radius and soft dipole excitations of C-22
- 2012
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 86:3
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Tidskriftsartikel (refereegranskat)abstract
- An unusually large value of the C-22 matter radius has recently been extracted from measured reaction cross sections. The giant size can be explained by a very loose binding that is, however, not known experimentally yet. Within the three-body cluster model we have explored the sensitivity of the s-motion-dominated C-22 geometry to the two-neutron separation energy. A low energy of a few tens of keV is required to reach the alleged experimental lower value of the matter radius, while the experimental mean radius requires an extremely tiny binding. The dependence of the C-22 charge radius on the two-neutron separation energy is also presented. The soft dipole mode in C-22 is shown to be strongly affected by the loose binding and should be studied in the process of Coulomb fragmentation.
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| 10. |
- Ershov, S. N., et al.
(författare)
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Modified variable phase method for the solution of coupled radial Schrodinger equations
- 2011
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 84:6
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Tidskriftsartikel (refereegranskat)abstract
- A modified variable phase method for the numerical solution of coupled radial Schrodinger equations, which maintains linear independence for different sets of solution vectors, is suggested. The modification involves rearrangement of coupled equations to avoid the usual numerical instabilities associated with components of the wave function in their classically forbidden regions. The modified method is applied to nuclear structure calculations of halo nuclei within the hyperspherical harmonics approach.
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