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    Low-energy dipole strength in Sn-112,Sn-120
    (AMER PHYSICAL SOC, 2014) Oezel-Tashenov, B.; Enders, J.; Lenske, H.; Krumbholz, A. M.; Litvinova, E.; von Neumann-Cosel, P.; Tsoneva, N.
    The Sn-112,Sn-120(gamma, gamma') reactions below the neutron separation energies have been studied at the superconducting Darmstadt electron linear accelerator S-DALINAC for different endpoint energies of the incident bremsstrahlung spectrum. Dipole strength distributions are extracted for Sn-112 up to 9.5 MeV and for Sn-120 up to 9.1 MeV. A concentration of dipole excitations is observed between 5 and 8 MeV in both nuclei. Missing strength due to unobserved decays to excited states is estimated in a statistical model. A fluctuation analysis is applied to the photon scattering spectra to extract the amount of the unresolved strength hidden in the background due to fragmentation. The strength distributions are discussed within different model approaches such as the quasiparticle-phonon model and the relativistic time blocking approximation, allowing for an inclusion of complex configurations beyond the initial particle-hole states. While a satisfactory description of the fragmentation can be achieved for sufficiently large model spaces, the predicted centroids and total electric dipole strengths for stable tin isotopes strongly depend on the assumptions about the underlying mean field.
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    Scintillating fiber detectors for the HypHI project at GSI
    (ELSEVIER SCIENCE BV, 2009) Nakajima, D.; Oezel-Tashenov, B.; Bianchin, S.; Borodina, O.; Bozkurt, V.; Gokuzum, B.; Fukuda, T.
    The construction and properties of three sets of two-dimensional scintillating fiber detector arrays for tracking of charged particles used in the HypHI Phase 0 experiment at GSI will be reported in this paper. The position resolutions and the detection efficiency of detectors have been obtained for each layer of detectors by using Li-6 primary beams and particles with Z = 1 produced by fragment reactions of Xe-136 projectiles on the hydrogen target. Besides, the response of energy deposition of charged particles in the first detector set placed right behind the target has been studied by using light projectile fragments with Z = 1, 2 and 3 produced by Ni-58 and C-12 beams. Extracted resolutions for energy deposition and position as well as the detection efficiency fulfill the requirements of the HypHl Phase 0 experiment. (C) 2009 Elsevier B.V. All rights reserved.
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    Summary of the HypHI Phase 0 experiment and future plans with FRS at GSI (FAIR Phase 0)
    (ELSEVIER SCIENCE BV, 2016) Saito, T. R.; Rappold, C.; Bertini, O.; Bianchin, S.; Bozkurt, V.; Geissel, H.; Oezel-Tashenov, B.
    Results of the HypHI Phase 0 experiment with the reaction of Li-6+C-12 at 2 A GeV are summarised. Invariant mass distributions as well as,the lifetime measurements for H-3(Lambda) and H-4(Lambda) are discussed. The lifetime values for both the hypernuclei are respectively observed to be 18(-32)(+42) ps and 140(-33)(+48) ps, being significantly shorter than those of the Lambda-hyperon. Statistical analyses of existing lifetime data for H-3(Lambda) up to 2014 confirm a significantly short lifetime of H-3(Lambda), which is not explained by present models. Observed hypernuclear production cross section values for H-3(Lambda) and H-4(Lambda) are also summarised. In addition, observed signals for the final states of d + pi(-) and t + pi(-) are discussed. All the discussions on the results of the HypHI Phase 0 experiment in this article are based on [1-4]. We also present a new proposed experiment with the FRS (FRagment Separator) at GSI (FAIR Phase 0) to improve the precision of the hypernuclear spectroscopy with peripheral heavy ion induced reactions. (C) 2016 Elsevier B.V. All rights reserved.