On the Analysis of Intermediate-Energy Coulomb Excitation Experiments

In a recent publication (Bertulani et al., PLB 650 (2007) 233 and arXiv:0704.0060v2) the validity of analysis methods used for intermediate-energy Coulomb excitation experiments was called into question. Applying a refined theory large corrections of results in the literature seemed needed. We show that this is not the case and that the large deviations observed are due to the use of the wrong experimental parameters. We furthermore show that an approximate expression derived by Bertulani et al. is in fact equivalent to the theory of Winther and Alder (NPA 319 (1979) 518), an analysis method often used in the literature.Comment: 10 pages, 1 figure, submitted to PL

Rotational level structure of sodium isotopes inside the "island of inversion"

The neutron-rich nuclei 33,34,35Na were studied via in-beam γ-ray spectroscopy following nucleon removal reactions from a 36Mg secondary beam at ~220 MeV/u. Excited states of 34,35Na are reported for the first time. A third transition was observed for 33Na in addition to the known 7/2+ 1 → 5/2+ 1 → 3/2+ g.s. cascade and is suggested to be the 9/2+ 1 → 7/2+ 1 transition. Similarly, a 7/2+ 1 → 5/2+ 1 → 3/2+ g.s. cascade is proposed for the decay pattern observed for 35Na. The transition energy ratios are close to expectation values for K = 3/2 rotational bands in the strong coupling limit. Comparisons to large-scale shell model calculations in the sd-p f model space support the spin-parity assignments. © The Author(s) 2014.published_or_final_versio

Structure of 136Sn and the Z = 50 magicity

The first 2+ excited state in the neutron-rich tin isotope 136Sn has been identified at 682(13) keV by measuring γ -rays in coincidence with the one proton removal channel from 137Sb. This value is higher than those known for heavier even-even N = 86 isotones, indicating the Z = 50 shell closure. It compares well to the first 2+ excited state of the lighter tin isotope 134Sn, which may suggest that the seniority scheme also holds for 136Sn. Our result confirms the trend of lower 2+ excitation energies of even-even tin isotopes beyond N = 82 compared to the known values in between the two doubly magic nuclei 100Sn and 132Sn. © The Author(s) 2014.published_or_final_versio

Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon

A search for new isotopes using in-flight fission of a 345 MeV/nucleon 238U beam has been carried out at the RI Beam Factory at the RIKEN Nishina Center. Fission fragments were analyzed and identified by using the superconducting in-flight separator BigRIPS. We observed 45 new neutron-rich isotopes: 71Mn, 73,74Fe, 76Co, 79Ni, 81,82Cu, 84,85Zn, 87Ga, 90Ge, 95Se, 98Br, 101Kr, 103Rb, 106,107Sr, 108,109Y, 111,112Zr, 114,115Nb, 115,116,117Mo, 119,120Tc, 121,122,123,124Ru, 123,124,125,126Rh, 127,128Pd, 133Cd, 138Sn, 140Sb, 143Te, 145I, 148Xe, and 152Ba

Investigating nuclear shell structure in the vicinity of 78Ni: Low-lying excited states in the neutron-rich isotopes 80,82Zn

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Coulomb dissociation of O-16 into He-4 and C-12

We measured the Coulomb dissociation of O-16 into He-4 and C-12 within the FAIR Phase-0 program at GSI Helmholtzzentrum fur Schwerionenforschung Darmstadt, Germany. From this we will extract the photon dissociation cross section O-16(alpha,gamma)C-12, which is the time reversed reaction to C-12(alpha,gamma)O-16. With this indirect method, we aim to improve on the accuracy of the experimental data at lower energies than measured so far. The expected low cross section for the Coulomb dissociation reaction and close magnetic rigidity of beam and fragments demand a high precision measurement. Hence, new detector systems were built and radical changes to the (RB)-B-3 setup were necessary to cope with the high-intensity O-16 beam. All tracking detectors were designed to let the unreacted O-16 ions pass, while detecting the C-12 and He-4

World new facilities for radioactive isotope beams

The use of unstable nuclei in the form of energetic beams for nuclear physics studies is now entering into a new era. “New-generation” facilities are either in operation, under construction or being planned. They are designed to provide radioactive isotope (RI) beams with very high intensities over a wide range of nuclides. These facilities are expected to provide opportunities to study nuclear structure, astrophysical nuclear processes and nuclear matter with large proton-neutron imbalance in grate detail. This article reports on the current status of such new-generation RI-beam facilities around the world