The completely unknown spectrum of excited states of the odd-odd nucleus Pa-230 was studied employing the one-neutron transfer reaction Pa-231(d, t)Pa-230 at a beam energy of 22 MeV. The excitation energy and the cross section were measured for, in total, 81 states below 1.4 MeV. Level assignments of these states are based on a semiempirical model and comparison with theoretical predictions, based on distorted-wave Born approximation (DWBA) calculations for the cross sections. For 12 rotational bands the band-head energy and the rotational parameter are determined. The K quantum numbers and the Nilsson configurations are established. Empirical values for the Gallagher-Moszkowski splittings and for Newby shifts are obtained. DOI: 10.1103/PhysRevC.87.044322

Excited states of the odd-odd isotope Pa-230 have been identified by means of the one-neutron transfer reaction Pa-231((d) over right arrow ,t)Pa-230 at a beam energy of 22 MeV. The ground state of Pa-230 is assigned to be a 2(-) state. A sequence of four rotational states is measured on top of the ground state up to spin values of 6h. The band head of the first excited rotational band has an excitation energy of 48 key, the corresponding rotational band is observed up to a spin value of 5h. Based on the distribution of the strength among the low-lying states, the Nilsson configuration 1/2[530](p) + 3/2[631](n) is considered the most probable configuration of the ground state, leaving 1/2[530](p) - 5/2[633](n) for the second excited band. The energy difference between the band heads of these two bands is compared to similar states in other N = 139 isotones, especially the directly neighboring odd-mass isotone Th-229. Here the two neutron orbitals 5/2[633](n) and 3/2[631](n) cause an extremely low-lying isomeric state. (C) 2012 Elsevier B.V. All rights reserved.

The reaction U-234((d) over right arrow, t)U-233 was measured at the Munich Q3D magnetic spectrometer with a polarized deuteron beam. The beam energy was 22 MeV, and a vector polarization of the deuterons of 80% was achieved. Angular distributions of the reaction cross section and analyzing power at seven angles between 5 degrees and 35 degrees were analyzed. Spin and parity assignments for 33 states were determined by comparison with results from distorted wave Born approximation (DWBA) calculations. Based on these assignments and energy systematics, the observed states were sorted into rotational bands. The Nilsson configurations of the bands are identified by examining the population strengths within each band. Two rotational bands with Nilsson configurations 1/2[501] and 3/2[501] could be identified for the first time.

The ground state properties of 31Mg indicate a change of nuclear shape at N=19 with a deformed Jπ=1/2+ intruder state as a ground state, implying that 31Mg is part of the “island of inversion”. The collective properties of excited states were the subject of a Coulomb excitation experiment at REX-ISOLDE, CERN, employing a radioactive 31Mg beam. De-excitation γ-rays were detected by the MINIBALL γ-spectrometer in coincidence with scattered particles in a segmented Si-detector. The level scheme of 31Mg was extended. Spin and parity assignment of the 945 keV state yielded 5/2+ and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of 30,31,32Mg establishes that for the N=19 magnesium isotope not only the ground state but also excited states are largely dominated by a deformed pf intruder configuration.

Post-accelerated isomerically purified radioactive beams, available at the CERN On-Line Isotope Mass Separator facility using the resonant ionization laser technique, have been used to study the Coulomb excitation of the I-pi = 3(-) state in Cu-70 (Z = 29, N = 41). While first results using a I-pi = 6(-) beam were reported previously, the present complementary experiment allows us to complete the study of the multiplet of states (3(-), 4(-), 5(-), 6(-)) arising from the pi 2p(3)/(2)nu 1g(9/2) configuration. Besides the known gamma-ray transition deexciting the 4(-) state, a ground-state. ray of 511(3) keV was observed for the first time and was unambiguously associated with the 5(-) state deexcitation. This observation fixes the energy, spin, and parity of this state, completing the low-energy level scheme of Cu-70. B(E2) values for all possible E2 transitions within the multiplet were determined. A comparison with large-scale shell model calculations using different interactions and valence spaces shows the importance of proton excitation across the Z = 28 shell gap and the role of the 2d(5/2) neutron orbital.

We report on one- and two-neutron transfer reactions to study the single-particle properties of nuclei at the border of the "island of inversion". The (d,p)- and (t,p)-reactions in inverse kinematics on the neutron-rich isotope Mg-30, delivered as radioactive beam by the REX-ISOLDE facility, have been investigated. The outgoing protons have been detected and identified by a newly built array of Si detectors. The gamma-decay of excited states has been detected in coincidence by the MINIBALL array. First results for Mg-31 and from the search for the second, spherical, 0(+) state in Mg-32 are presented.