| 1. |
- Wamers, F., et al.
(författare)
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Exclusive measurements of nuclear breakup reactions of 17Ne
- 2014
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 66
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Konferensbidrag (refereegranskat)abstract
- We have studied one-proton-removal reactions of about 500MeV/u 17Ne beams on a carbon target at the R3B/LAND setup at GSI by detecting beam-like 15O-p and determining their relative-energy distribution. We exclusively selected the removal of a 17Ne halo proton, and the Glauber-model analysis of the 16F momentum distribution resulted in an s2 contribution in the 17Ne ground state of about 40%. © Owned by the authors, published by EDP Sciences, 2014.
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| 2. |
- Aksouh, F., et al.
(författare)
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STUDY OF THE O-15(2p,gamma)Ne-17 CROSS SECTION BY COULOMB DISSOCIATION OF Ne-17 FOR THE rp PROCESS OF NUCLEOSYNTHESIS
- 2014
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Ingår i: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 45:2, s. 229-234
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Tidskriftsartikel (refereegranskat)abstract
- The O-15(2p, gamma)Ne-17 cross section has been studied by the inverse reaction, the Coulomb dissociation of Ne-17. The experiment has been performed at the GSI. The Ne-17 excitation energy prior to decay has been reconstructed by using the invariant-mass method. The preliminary differential and integral Coulomb dissociation cross sections (sigma(Coul)) have been extracted, which provide a photoabsorption (sigma(photo)) and a radiative capture cross section (sigma(cap)). Additionally, important information about the Ne-17 nuclear structure will be obtained. The analysis is in progress.
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| 3. |
- Kondo, Y., et al.
(författare)
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First observation of 28 O
- 2023
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 620:7976, s. 965-970
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Tidskriftsartikel (refereegranskat)abstract
- Subjecting a physical system to extreme conditions is one of the means often used to obtain a better understanding and deeper insight into its organization and structure. In the case of the atomic nucleus, one such approach is to investigate isotopes that have very different neutron-to-proton (N/Z) ratios than in stable nuclei. Light, neutron-rich isotopes exhibit the most asymmetric N/Z ratios and those lying beyond the limits of binding, which undergo spontaneous neutron emission and exist only as very short-lived resonances (about 10−21s), provide the most stringent tests of modern nuclear-structure theories. Here we report on the first observation of 28O and 27O through their decay into 24O and four and three neutrons, respectively. The 28O nucleus is of particular interest as, with the Z = 8 and N = 20 magic numbers1,2, it is expected in the standard shell-model picture of nuclear structure to be one of a relatively small number of so-called ‘doubly magic’ nuclei. Both 27O and 28O were found to exist as narrow, low-lying resonances and their decay energies are compared here to the results of sophisticated theoretical modelling, including a large-scale shell-model calculation and a newly developed statistical approach. In both cases, the underlying nuclear interactions were derived from effective field theories of quantum chromodynamics. Finally, it is shown that the cross-section for the production of 28O from a 29F beam is consistent with it not exhibiting a closed N = 20 shell structure.
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| 4. |
- Lindgren, S., et al.
(författare)
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Laser flip-chip mounting for passive alignment and high-frequency modulation
- 1996
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Ingår i: Optical Communication, 1996. ECOC ’96. 22nd European Conference on. ; , s. 103-106
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Konferensbidrag (refereegranskat)abstract
- We have developed a silicon motherboard for flip-chip mounting of lasers in a way that is compatible with high-frequency modulation (24 GHz) and which allows passive alignment of the lasers to single-mode fibres.
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| 5. |
- Marganiec, C., et al.
(författare)
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Coulomb breakup of 17Ne from the viewpoint of nuclear astrophysics
- 2013
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Ingår i: Proceedings of Science.
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Konferensbidrag (refereegranskat)abstract
- By the Coulomb breakup of 17Ne, the time-reversed reaction 15O(2p,γ)17Ne has been studied. This reaction might play an important role in the rp process, as a break-out reaction of the hot CNO cycle. The secondary 17Ne ion beam with an energy of 500 MeV/nucleon has been dissociated in a Pb target. The reaction products have been detected with the LAND-R3B experimental setup at GSI. The preliminary differential and integral Coulomb dissociation cross section sCoul has been determined, which then will be converted into a photo-absorption cross section sphot o, and a two-proton radiative capture cross section σcap. Additionally, information about the structure of the 17Ne, a potential two-proton halo nucleus, will be received. The analysis is in progress.
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| 6. |
- Marganiec, J., et al.
(författare)
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Coulomb breakup of 17Ne from the viewpoint of nuclear astrophysics
- 2012
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Ingår i: Proceedings of Science. - Proceedings of Science : Sissa. - 1824-8039.
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Konferensbidrag (refereegranskat)abstract
- By the Coulomb breakup of 17Ne, the time-reversed reaction 15O(2p,γ)17Ne has been studied. This reaction might play an important role in the rp process, as a break-out reaction of the hot CNO cycle. The secondary 17Ne ion beam with an energy of 500 MeV/nucleon has been dissociated in a Pb target. The reaction products have been detected with the LAND-R3B experimental setup at GSI. The preliminary differential and integral Coulomb dissociation cross section sCoul has been determined, which then will be converted into a photo-absorption cross section sphoto, and a two-proton radiative capture cross section σcap. Additionally, information about the structure of the 17Ne, a potential two-proton halo nucleus, will be received. The analysis is in progress. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
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| 7. |
- Marganiec, J., et al.
(författare)
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Experimental study of the O-15(2p, gamma) Ne-17 cross section by Coulomb Dissociation for the rp process
- 2016
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 665:1
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Konferensbidrag (refereegranskat)abstract
- The time-reversed reaction O-15(2p, gamma) Ne-17 has been studied by the Coulomb dissociation technique. Secondary 17Ne ion beams at 500 AMeV have been produced by fragmentation reactions of Ne-20 in a beryllium production target and dissociated on a secondary Pb target. The incoming beam and the reaction products have been identified with the kinematically complete LAND-(RB)-B-3 experimental setup at GSI. The excitation energy prior to decay has been reconstructed by using the invariant-mass method. The preliminary differential and integral Coulomb Dissociation cross sections (sigma(Coul)) have been calculated, which provide a photoabsorption (sigma(photo)) and a radiative capture cross section (sigma(cap)). Additionally, important information about the nuclear structure of the Ne-17 nucleus will be obtained. The analysis is in progress.
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| 8. |
- Aksyutina, Yu, et al.
(författare)
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Lithium isotopes beyond the drip line
- 2008
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 666:5, s. 430-434
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Tidskriftsartikel (refereegranskat)abstract
- The unbound isotopes 10Li, 12Li and 13Li have been observed after nucleon-knockout reactions at relativistic energies with 11Li and 14Be beams impinging on a liquid hydrogen target. The channels , and were analysed in the ALADIN-LAND setup at GSI. The 10Li data confirm earlier findings, while the 12Li and 13Li nuclei were observed for the first time. The relative-energy spectrum shows that the ground state of 12Li can be described as a virtual s-state with a scattering length of -13.7(1.6) fm. A broad energy spectrum was found for the channel. Based on the assumption that the relative-energy spectrum is dominated by a correlated background presumably stemming from initial correlations in the 14Be ground-state, evidence for a 13Li resonance at 1.47(31) MeV above the threshold with a width around 2 MeV has been found.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Cortina-Gil, D., et al.
(författare)
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One-neutron knockout of O-23
- 2005
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 25, s. 343-346
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Konferensbidrag (refereegranskat)abstract
- Breakup reactions were used to study the ground-state configuration of the neutron-rich isotope O-23. The O-22 fragments produced in one-nucleon removal from O-23 at 938 MeV/nucleon in a carbon target were detected in coincidence with de-exciting gamma rays, allowing to discern between 220 ground-state and excited-states contributions. From the comparison of exclusive experimental momentum distributions for the one-neutron removal channel to theoretical momentum distributions calculated in an Eikonal model for the knockout process, and spin and parity assignment of I-pi = 1/2(+) was deduced for the 230 ground state. This result solved the existent experimental discrepancy.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Koszorús, Agota, et al.
(författare)
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Charge radii of exotic potassium isotopes challenge nuclear theory and the magic character of N = 32
- 2021
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2481 .- 1745-2473. ; 17:4, s. 439-443
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear charge radii are sensitive probes of different aspects of the nucleon–nucleon interaction and the bulk properties of nuclear matter, providing a stringent test and challenge for nuclear theory. Experimental evidence suggested a new magic neutron number at N = 32 (refs. 1–3) in the calcium region, whereas the unexpectedly large increases in the charge radii4,5 open new questions about the evolution of nuclear size in neutron-rich systems. By combining the collinear resonance ionization spectroscopy method with β-decay detection, we were able to extend charge radii measurements of potassium isotopes beyond N = 32. Here we provide a charge radius measurement of 52K. It does not show a signature of magic behaviour at N = 32 in potassium. The results are interpreted with two state-of-the-art nuclear theories. The coupled cluster theory reproduces the odd–even variations in charge radii but not the notable increase beyond N = 28. This rise is well captured by Fayans nuclear density functional theory, which, however, overestimates the odd–even staggering effect in charge radii. These findings highlight our limited understanding of the nuclear size of neutron-rich systems, and expose problems that are present in some of the best current models of nuclear theory.
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| 21. |
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| 22. |
- Meister, Mikael, 1969, et al.
(författare)
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High-energy breakup of 8B
- 2003
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Ingår i: Nucl. Phys. A. ; 718, s. 431-433
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Konferensbidrag (refereegranskat)
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| 23. |
- Petri, M., et al.
(författare)
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Structure of C-16: Testing shell model and ab initio approaches
- 2012
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 86:4, s. Art. no. 044329-
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in C-16 were populated via the Be-9(N-17,C-16+gamma)X one-proton knockout reaction. The lifetime of the 2(1)(+) state in C-16 was measured using the recoil distance method. The extracted lifetime of tau(+)(21) = 11.4(-0.9)(+0.8)(stat) +/- 0.7(syst(B rho))(-1.5)(+0.0)(syst(feeding)) ps yields a deduced B(E2;2(1)(+) -> 0(1)(+)) = 4.21(-0.26)(+0.34)(stat)(-0.24)(+0.28)(syst(B rho))(-0.00)(+0.64)(syst(feeding)) e(2)fm(4) value in good agreement with a previous measurement. The one-proton knockout cross section is used to extract the proton amplitude of the C-16 2(1)(+) state, which confirms the neutron dominant character of this state. Gamma-ray branching ratios between the 2(2)(+) state and the 2(1)(+) and ground states were also determined. The results are compared with p-sd shell model and no-core shell model (with NN and NN + NNN) calculations. The inclusion of three-body forces are essential in order for the no-core shell model calculations to reproduce the experimental findings on the gamma-ray branching ratios.
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| 24. |
- Acharya, B., et al.
(författare)
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Uncertainty quantification for proton-proton fusion in chiral effective field theory
- 2016
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 760, s. 584-589
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Tidskriftsartikel (refereegranskat)abstract
- We compute the S-factor of the proton-proton (pp) fusion reaction using chiral effective field theory (chi EFT) up to next-to-next-to-leading order (NNLO) and perform a rigorous uncertainty analysis of the results. We quantify the uncertainties due to (i) the computational method used to compute the pp cross section in momentum space, (ii) the statistical uncertainties in the low-energy coupling constants of chi EFT, (iii) the systematic uncertainty due to the chi EFT cutoff, and (iv) systematic variations in the database used to calibrate the nucleon-nucleon interaction. We also examine the robustness of the polynomial extrapolation procedure, which is commonly used to extract the threshold S-factor and its energy-derivatives. By performing a statistical analysis of the polynomial fit of the energy-dependent S-factor at several different energy intervals, we eliminate a systematic uncertainty that can arise from the choice of the fit interval in our calculations. In addition, we explore the statistical correlations between the S-factor and few-nucleon observables such as the binding energies and point-proton radii of H-2,H-3 and He-3 as well as the D-state probability and quadrupole moment of H-2, and the beta-decay of 3H. We find that, with the state-of-the-art optimization of the nuclear Hamiltonian, the statistical uncertainty in the threshold S-factor cannot be reduced beyond 0.7%.
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| 25. |
- Aksyutina, Yuliya, 1983, et al.
(författare)
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Properties of the 7He ground state from 8He neutron knockout
- 2009
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 679:3, s. 191-196
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Tidskriftsartikel (refereegranskat)abstract
- The unbound nucleus 7He, produced in neutron-knockout reactions with a 240 MeV/u 8He beam in a liquid-hydrogen target, has been studied in an experiment at the ALADIN-LAND setup at GSI. From an R-matrix analysis the resonance parameters for 7He as well as the spectroscopic factor for the 6He(0+) + n configuration in its ground-state have been obtained. The spectroscopic factor is 0.61 confirming that 7He is not a pure single-particle state. An analysis of 5He data from neutron-knockout reactions of 6He in a carbon target reveals the presence of an s-wave component at low energies in the α+n relative energy spectrum. A possible low-lying exited state in 7He observed in neutron knockout data from 8He in a carbon target and tentatively interpreted as a Iπ=1/2− state, could not be observed in the present experiment. Possible explanations of the shape difference between the 7He resonance obtained in the two knockout reactions are discussed in terms of target-dependence or different reaction mechanisms at relativistic energies.
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| 26. |
- Bergmann, U. C., et al.
(författare)
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Analysis of decay data from neutron-rich nuclei
- 2001
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Ingår i: European Physical Journal A. - 1434-601X .- 1434-6001. ; 11:3, s. 279-284
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Tidskriftsartikel (refereegranskat)abstract
- The beta -decays of the neutron-rich nuclei Be-12 and Ne-29 have been studied. The statistical correlations between the almost identical half-lives of Be-12 and its daughter B-12 are analysed for a large sample of Be-12 decay data. Stringent mutual bounds are obtained on the parameter set, leading to a precise determination of the Be-12 half-life of 21.50 +/- 0.04 ms. From a simultaneous detection of beta -particles and neutrons from the decay of Ne-29 the neutron emission probability, P-n, is determined to 17 +/- 5%. No indication of two-neutron emission is seen from this nucleus. An upper limit of 2.2% (90% confidence level) is established for P-2n.
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| 27. |
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| 28. |
- Escher, J., et al.
(författare)
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Surrogate reactions: the Weisskopf-Ewing approximation and its limitations
- 2008
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Ingår i: Proceedings of the International Conference on Nuclear Data for Science and Technology, April 22-27, 2007, Nice, France, editors O.Bersillon, F.Gunsing, E.Bauge, R.Jacqmin, and S.Leray, EDP Sciences. - Les Ulis, France : EDP Sciences. ; , s. 325-329
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Konferensbidrag (refereegranskat)abstract
- A brief description of the Surrogate reaction method, an indirect approach for determining compound-nuclear reaction cross sections, is presented. The Weisskopf-Ewing limit, an approximation scheme that is typically employed in the analysis of Surrogate experiments, is considered and its validity and limitations are discussed.
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| 29. |
- Johansson, Håkan T, 1977, et al.
(författare)
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The unbound isotopes He-9,He-10
- 2010
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Ingår i: Nuclear Physics A. - Elsevier : Elsevier BV. - 0375-9474 .- 1873-1554. ; 842:1-4, s. 15-32
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Tidskriftsartikel (refereegranskat)abstract
- The unbound nuclei He-9 and He-10 have been produced in proton-knockout reactions from a 280 MeV/u Li-11 beam impinging on a liquid hydrogen target at the ALADIN-LAND setup at GSI. Information on their nuclear structure has been obtained from the relative-energy spectra, He-8 + n and He-8 + 2n, employing reaction models incorporating the structure of Li-11. The (8H)e + n relative-energy spectrum is dominated by a strong peak-like structure at low energy, which may be interpreted within the effective-range approximation as the result of an s-wave interaction with a neutron scattering length of -3.17(66) fm. This spectrum also shows evidence for resonance states at 1.33(8) MeV and at 2.4 MeV above the He-8 + n threshold. It is argued that the s-state might not be the He-9 ground state. For He-8 + n + n, the analysis of the relative-energy spectrum gives two alternative possibilities for an interpretation: either a narrow resonance at 1.42(10) MeV (Gamma = 1.11(76) MeV) superimposed on a correlated background, or two overlapping resonances, a ground state at 1.54(11) MeV (Gamma = 1.91(41) MeV) together with an excited state at 3.99(26) MeV (Gamma = 1.64(89) MeV). The two possible interpretations are discussed. (C) 2010 Elsevier B.V. All rights reserved.
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| 30. |
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| 31. |
- Kirsten, Franz, 1983, et al.
(författare)
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A repeating fast radio burst source in a globular cluster
- 2022
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 602:7898, s. 585-589
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Tidskriftsartikel (refereegranskat)abstract
- Fast radio bursts (FRBs) are flashes of unknown physical origin1. The majority of FRBs have been seen only once, although some are known to generate multiple flashes2,3. Many models invoke magnetically powered neutron stars (magnetars) as the source of the emission4,5. Recently, the discovery6 of another repeater (FRB 20200120E) was announced, in the direction of the nearby galaxy M81, with four potential counterparts at other wavelengths6. Here we report observations that localized the FRB to a globular cluster associated with M81, where it is 2 parsecs away from the optical centre of the cluster. Globular clusters host old stellar populations, challenging FRB models that invoke young magnetars formed in a core-collapse supernova. We propose instead that FRB 20200120E originates from a highly magnetized neutron star formed either through the accretion-induced collapse of a white dwarf, or the merger of compact stars in a binary system7. Compact binaries are efficiently formed inside globular clusters, so a model invoking them could also be responsible for the observed bursts.
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| 32. |
- Lindfors, L, et al.
(författare)
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Amorphous drug nanosuspensions. 2. Experimental determination of bulk monomer concentrations
- 2006
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 22:3, s. 911-916
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Tidskriftsartikel (refereegranskat)abstract
- A simple turbidimetric method was developed to measure the bulk concentration of drug in nanosuspensions. The bulk concentrations measured were in the range from 1 mu M to 1 mM. The accuracy of the method was checked by determination of the bulk concentration of crystalline nanosuspensions, i.e., the crystalline solubility, which compared favorably to solubilities measured by a conventional method. Results obtained for amorphous nanosuspensions agreed with predictions using a theory describing the relative solubility between a supercooled liquid and a crystal. Further, it was found that the bulk concentration in Ostwald ripening inhibited amorphous nanosuspensions and could be lowered by incorporation of higher amounts of the inhibitor, in agreement with predictions using the Bragg-Williams theory of nonideal solutions.
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| 33. |
- Orce, J. N., et al.
(författare)
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Reorientation-effect measurement of the (2+ 1 Eˆ22+ 1) matrix element in 10Be
- 2012
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 86:4
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Tidskriftsartikel (refereegranskat)abstract
- The highly-efficient and segmented TIGRESS gamma-ray spectrometer at TRIUMF has been used to perform a reorientation-effect Coulomb-excitation study of the 2(1)(+) state at 3.368 MeV in Be-10. This is the first Coulomb-excitation measurement that enables one to obtain information on diagonal matrix elements for such a high-lying first excited state from gamma-ray data. With the availability of accurate lifetime data, a value of -0.110 +/- 0.087 eb is determined for the diagonal matrix element, which assuming the rotor model, leads to a negative spectroscopic quadrupole moment of Q(S)(2(1)(+)) = -0.083 +/- 0.066 eb. This result is in agreement with both no-core shell-model calculations performed in this work with the CD-Bonn 2000 two-nucleon potential and large shell-model spaces, and Green's function Monte Carlo predictions with two-plus three-nucleon potentials.
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| 34. |
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| 35. |
- Reifarth, R., et al.
(författare)
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The [sup 14]C(n,gamma) cross section between 10 keV and 1 MeV
- 2008
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Ingår i: Physical Review C (Nuclear Physics). ; 77:1, s. 015804-
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Tidskriftsartikel (refereegranskat)abstract
- The neutron capture cross section of 14C is of relevance for several nucleosynthesis scenarios such as inhomogeneous Big Bang models, neutron induced CNO cycles, and neutrino driven wind models for the r process. The 14C(n,gamma) reaction is also important for the validation of the Coulomb dissociation method, where the (n,gamma) cross section can be indirectly obtained via the time-reversed process. So far, the example of 14C is the only case with neutrons where both, direct measurement and indirect Coulomb dissociation, have been applied. Unfortunately, the interpretation is obscured by discrepancies between several experiments and theory. Therefore, we report on new direct measurements of the 14C(n,gamma) reaction with neutron energies ranging from 20 to 800 keV.
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| 36. |
- Simon, H., et al.
(författare)
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Systematic investigation of the drip-line nuclei 11Li and 14Be and their unbound subsystems 10Li and 13Be
- 2007
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 791:3-4, s. 267-
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Tidskriftsartikel (refereegranskat)abstract
- Fragmentation reactions in a carbon target with beams of 11Li and 14Be at relativistic energies have been studied in a kinematically complete experiment at the ALADIN-LAND setup at GSI. Excited states in 11Li and 14Be were obtained from the data in the inelastic channel. The measured cross sections with the core nucleus in the final state show that in the 14Be case core polarization plays an important role. In the one-neutron knockout channels the measured angular correlations between fragment and neutron are asymmetric, which demonstrates the presence of states with different parities in the 11Li and 14Be ground states. For 10Li a low-lying virtual s-state, a p-state and evidence for a d-state could be extracted from the data, while the 12Be+n system shows resonances with more complicated structure.
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| 37. |
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| 38. |
- Voss, P., et al.
(författare)
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Excited-state transition-rate measurements in C-18
- 2012
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 86:1
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in C-18 were populated by the one-proton knockout reaction of an intermediate energy radioactive N-19 beam. The lifetime of the first 2(+) state was measured with the Koln/NSCL plunger via the recoil distance method to be tau (2(1)(+)) = 22.4 +/- 0.9(stat)(-2.2)(+3.3)(syst) ps, which corresponds to a reduced quadrupole transition strength of B(E2; 2(1)(+) -> 0(1)(+)) = 3.64(-0.14)(+ 0.15)(stat)(-0.47)(+0.40)(syst) e(2)fm(4). In addition, an upper limit on the lifetime of a higher-lying state feeding the 2(1)(+) state was measured to be tau
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