C. A. Ur

Structure of 52,54Ti and shell closures in neutron-rich nuclei above 48Ca

Abstract The level structure of 5422Ti32 has been explored for the first time by combining β-decay measurements from fragmentation products with prompt γ-ray spectroscopy following deep inelastic reactions. The latter technique was also instrumental in tracing 52Ti30 to higher spin. The data provide new tests of effective interactions for full pf-shell calculations in neutron-rich nuclei above 48Ca. The data indicate the presence of a significant subshell gap at N=32 and comparisons between theory and experiment suggest an additional shell closure at N=34 in Ca and Ti isotopes.

Triaxial Superdeformed Bands in

Abstract In a search for exotic structures in odd-odd 164 Lu, performed as one of the first Euroball experiments eight new, presumably triaxial, superdeformed bands were found. For the first time, evidence is presented for superdeformation in an odd-odd Lu isotope for which theory predicts large triaxiality. The data are compared to expectations from calculations with the code “Ultimate Cranker”. Two of the bands are connected to normal-deformed structures and the E1 strength of the decay-out appears to be enhanced over single particle expectations, possibly due to octupole correlations.

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The Germanium Detector Array (GERDA) in the search for neutrinoless ββ decays of 76Ge at LNGS will operate bare germanium diodes enriched in 76Ge in an (optional active) cryogenic fluid shield to investigate neutrinoless ββ decay with a sensitivity of T1/2 > 2 × 1026 yr after an exposure of 100 kg yr. Recent progress includes the installation of the first underground infrastructures at Gran Sasso, the completion of the enrichment of 37.5 kg of germanium material for detector construction, prototyping of low-mass detector support and contacts, and front-end and DAQ electronics, as well as the preparation for construction of the cryogenic vessel and water tank.

Lu and Enhanced E1 Decay-Out Strength

The isotopes 159–163Dy have been investigated using the incomplete fusion reactions 7Li → 158,160Gd at beam energies of 8 MeV/u. The γ-rays were detected in the GASP spectrometer in coincidence with the fast charged particles detected in the ISIS silicon ball. The level schemes of all five isotopes could be amply extended. The most important result was the observation of both the ground state and Stockholm bands in 162Dy up to high spin covering the band crossing region. The crossing in this nucleus is shifted to a higher frequency in comparison to the lighter Dy isotopes. The interaction strength between the two bands could be determined with high precision and with this result, a full oscillation of the interaction strength from one node to the next within an isotopic chain could be observed for the first time.

Status of the Germanium Detector Array (GERDA) in the search of neutrinoless ββ decays of 76Ge at LNGS

Abstract: The high energy γ-rays from the fusion-evaporation reaction 101 MeV 19F +181Ta have been measured in coincidence with different γ-ray fold windows or discrete γ-rays in final residual nuclei. The line-shape analysis of the high energy γ-ray spectra confirms the large deformation of the 200Pb nuclei at high angular momenta. Coincidences with discrete γ-transitions evidence a strong correlation between γ-rays in the Giant Dipole Resonance region (Eγ≥ 8 MeV) and final evaporation residues.

Investigations of 159-163Dy using Incomplete Fusion Reactions

The stable nucleus

Inclusive and exclusive measurements of high energy γ-rays in the 101 MeV 19F +181Ta fusion reaction

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Determination ofγ-ray widths inN15using nuclear resonance fluorescence

N is the mirror of

Determination of

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O, the bottleneck in the hydrogen burning CNO cycle. Most of the