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Sökning: LAR1:lu > Chalmers tekniska högskola > Tengblad O

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1.
  • Altstadt, S.G., et al. (författare)
  • B-13,B-14(n,gamma) via Coulomb Dissociation for Nucleosynthesis towards the r-Process
  • 2014
  • Ingår i: Nuclear Data Sheets. - : Elsevier BV. - 1095-9904 .- 0090-3752. ; 120, s. 197-200
  • Konferensbidrag (refereegranskat)abstract
    • Radioactive beams of 14,15B produced by fragmentation of a primary 40Ar beam were directed onto a Pb target to investigate the neutron breakup within the Coulomb field. The experiment was performed at the LAND/R3B setup. Preliminary results for the Coulomb dissociation cross sections as well as for the astrophysically interesting inverse reactions, 13,14B(n,γ), are presented.
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2.
  • Atar, L., et al. (författare)
  • Quasifree (p, 2p) Reactions on Oxygen Isotopes: Observation of Isospin Independence of the Reduced Single-Particle Strength
  • 2018
  • Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 120:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Quasifree one-proton knockout reactions have been employed in inverse kinematics for a systematic study of the structure of stable and exotic oxygen isotopes at the R3B/LAND setup with incident beam energies in the range of 300-450 MeV/u. The oxygen isotopic chain offers a large variation of separation energies that allows for a quantitative understanding of single-particle strength with changing isospin asymmetry. Quasifree knockout reactions provide a complementary approach to intermediate-energy one-nucleon removal reactions. Inclusive cross sections for quasifree knockout reactions of the type OA(p,2p)NA-1 have been determined and compared to calculations based on the eikonal reaction theory. The reduction factors for the single-particle strength with respect to the independent-particle model were obtained and compared to state-of-the-art ab initio predictions. The results do not show any significant dependence on proton-neutron asymmetry.
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3.
  • Axelsson, L., et al. (författare)
  • Study of the unbound nucleus 11N by elastic resonance scattering
  • 1996
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813 .- 2469-9985 .- 2469-9993. ; 54:4, s. 1511-1514
  • Tidskriftsartikel (refereegranskat)abstract
    • Resonances in the unbound nucleus 11N have been studied, using the resonance scattering reaction 10C+p. The data give evidence for three states above the 10C+p threshold with energies 1.30, 2.04, and 3.72 MeV. These states can be interpreted, in a potential-model analysis, as the ground state and the first two excited states with spin-parity 1 / 2+, 1 / 2-, and 5 / 2+ arising from the shell-model orbitals 1s1 / 2, 0p1 / 2, and 0d5 / 2. A narrow state superposed on a broad structure found at higher energy could be interpreted as the mirror state of the 3 / 2- in 11Be shifted down in energy. This shift would suggest a large radius of the potential.
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4.
  • Boillos, J. M., et al. (författare)
  • Isotopic cross sections of fragmentation residues produced by light projectiles on carbon near
  • 2022
  • Ingår i: Physical Review C. - 2469-9993 .- 2469-9985. ; 105:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We measured 135 cross sections of residual nuclei produced in fragmentation reactions of C12, N14, and O13−16,20,22 projectiles impinging on a carbon target at kinetic energies of near 400A MeV, most of them for the first time, with the RB3/LAND setup at the GSI facility in Darmstadt (Germany). The use of this state-of-the-art experimental setup in combination with the inverse kinematics technique gave the full identification in atomic and mass numbers of fragmentation residues with a high precision. The cross sections of these residues were determined with uncertainties below 20% for most of the cases. These data are compared to other previous measurements with stable isotopes and are also used to benchmark different model calculations.
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5.
  • Cabanelas, P., et al. (författare)
  • Commissioning of the CALIFA Barrel Calorimeter of the R 3 B Experiment at FAIR
  • 2020
  • Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1667:1
  • Konferensbidrag (refereegranskat)abstract
    • CALIFA is the high efficiency and energy resolution calorimeter for the R3B experiment at FAIR, intended for detecting high energy charged particles and γ-rays in inverse kinematics direct reactions. It surrounds the reaction target in a segmented configuration of Barrel and Forward End-Cap pieces. The CALIFA Barrel consists of 1952 detection units made of CsI(Tl) long-shaped scintillator crystals, and it is being commissioned during the Phase0 experiments at FAIR. The first setup for the CALIFA Barrel commissioning is presented here. Results of detector performance with γ-rays are obtained, and show that the system fulfills the design requirements.
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6.
  • Diaz Fernandez, Paloma, 1983, et al. (författare)
  • Quasifree (p, pN) scattering of light neutron-rich nuclei near N=14
  • 2018
  • Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 97:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: For many years, quasifree scattering reactions in direct kinematics have been extensively used to study the structure of stable nuclei, demonstrating the potential of this approach. The (RB)-B-3 collaboration has performed a pilot experiment to study quasifree scattering reactions in inverse kinematics for a stable C-12 beam. The results from that experiment constitute the first quasifree scattering results in inverse and complete kinematics. This technique has lately been extended to exotic beams to investigate the evolution of shell structure, which has attracted much interest due to changes in shell structure if the number of protons or neutrons is varied. Purpose: In this work we investigate for the first time the quasifree scattering reactions (p, pn) and (p, 2p) simultaneously for the same projectile in inverse and complete kinematics for radioactive beams with the aim to study the evolution of single-particle properties from N = 14 to N = 15. Method: The structure of the projectiles O-23, O-22, and N-21 has been studied simultaneously via (p, pn) and (p, 2p) quasifree knockout reactions in complete inverse kinematics, allowing the investigation of proton and neutron structure at the same time. The experimental data were collected at the (RB)-B-3-LAND setup at GSI at beam energies of around 400 MeV/u. Two key observables have been studied to shed light on the structure of those nuclei: the inclusive cross sections and the corresponding momentum distributions. Conclusions: The knockout reactions (p, pn) and (p, 2p) with radioactive beams in inverse kinematics have provided important and complementary information for the study of shell evolution and structure. For the (p, pn) channels, indications of a change in the structure of these nuclei moving from N = 14 to N = 15 have been observed, i.e., from the 0d(5/2) shell to the 1s(1/2). This supports previous observations of a subshell closure at N = 14 for neutron-rich oxygen isotopes and its weakening for the nitrogen isotopes.
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7.
  • Gobel, K., et al. (författare)
  • Coulomb dissociation of 16O into 4He and 12C
  • 2020
  • Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1668:1
  • Konferensbidrag (refereegranskat)abstract
    • We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(a,?)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-To-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors' active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision.
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8.
  • Graña-González, A., et al. (författare)
  • Quasi-free (p,2p) reactions in inverse kinematics for studying the fission yield dependence on temperature
  • 2023
  • Ingår i: FAIR next generation scientists - 7th Edition Workshop : FAIRness2022 - FAIRness2022. - 1824-8039. ; 419
  • Konferensbidrag (refereegranskat)abstract
    • Despite the recent experimental and theoretical progress in the investigation of the nuclear fission process, a complete description still represents a challenge in nuclear physics because it is a very complex dynamical process, whose description involves the coupling between intrinsic and collective degrees of freedom, as well as different quantum-mechanical phenomena. To improve on the existing data on nuclear fission, we produce fission reactions of heavy nuclei in inverse kinematics by using quasi-free (p,2p) scattering, which induce fission through particle-hole excitations that can range from few to ten's of MeV. The measurement of the four-momenta of the two outgoing protons allows to reconstruct the excitation energy of the fissioning compound nucleus and therefore to study the evolution of the fission yields with temperature. The realization of this kind of experiment requires a complex experimental setup, providing full isotopic identification of both fission fragments and an accurate measurement of the momenta of the two outgoing protons. This was realized recently at the GSI/FAIR facility and here some preliminary results are presented.
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9.
  • Heil, M., et al. (författare)
  • A new Time-of-flight detector for the R 3 B setup
  • 2022
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 58:12
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the design, prototype developments and test results of the new time-of-flight detector (ToFD) which is part of the R3B experimental setup at GSI and FAIR, Darmstadt, Germany. The ToFD detector is able to detect heavy-ion residues of all charges at relativistic energies with a relative energy precision σΔE/ ΔE of up to 1% and a time precision of up to 14 ps (sigma). Together with an elaborate particle-tracking system, the full identification of relativistic ions from hydrogen up to uranium in mass and nuclear charge is possible.
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10.
  • Heine, M., et al. (författare)
  • Determination of the neutron-capture rate of C-17 for r-process nucleosynthesis
  • 2017
  • Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 95:1, s. Article no 014613 -
  • Tidskriftsartikel (refereegranskat)abstract
    • With the (RB)-B-3-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of C-18 at a projectile energy around 425A MeV on a lead target, which are needed to determine the radiative neutron-capture cross sections of C-17 into the ground state of C-18. Those data have been used to constrain theoretical calculations for transitions populating excited states in C-18. This allowed to derive the astrophysical cross section sigma(n gamma)*. accounting for the thermal population of C-17 target states in astrophysical scenarios. The experimentally verified capture rate is significantly lower than those of previously obtained Hauser-Feshbach estimations at temperatures T-9
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