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We discuss a phenomenological shell model analysis of the structure of 48 , 49 , 50 Ca. Based on simple arguments, we propose wavefunctions fit to the available data on spectroscopic factors derived from direct one neutron addition and removal reactions. These empirical wavefunctions are then used to calculate properties of low-lying states in 49 , 50 , 51 Ca, which are consistent with available experimental data. Our analysis appears to capture the main ingredients at play in the low-lying properties of these nuclei and emphasize the prominent role of pairing correlations. We also present predictions that could motivate further work. [ABSTRACT FROM AUTHOR]

Experimental transition probabilities between states of the ground-state alternating-parity bands of 144Ba and their theoretical analysis are presented. Lifetimes of states in 144Ba have been measured using the recoil distance method following spontaneous fission of 252Cf. The experiment was performed at the Lawrence Berkeley National Laboratory employing the Gammasphere array and the New Yale Plunger Device. The experimental data show a significantly larger value of the E2 transition probability between the negative-parity states compared to the positive-parity ones. It is shown that this effect can be explained by a higher weight of the deformed component in the wave functions of the odd- I states. In the framework of the cluster approach it is explained by a higher weight of the alpha-cluster component in the wave function of the negative-parity states compared to the positive-parity ones. In the framework of the traditional collective model with the quadrupole and octupole degrees of freedom the same effect is explained by a higher value of the quadrupole deformation at the minima of the potential energy as a function of β20 and β30 compared to its value at the top of the barrier separating two physically equivalent minima, having opposite signs of the octupole deformation. Additionally, the dependence on parity of the E2 transition probability is analyzed qualitatively in nuclei with a minimum at β30 = 0 in the collective potential energy and compared to experimental data for 148Nd. [ABSTRACT FROM AUTHOR]

A multi-nucleon transfer reaction using an 850 MeV 136Xe beam incident on a 198Pt target was used to populate high-spin states in 184W, 14 nucleons from the target. A 4-quasiparticle isomer with t1/2 =188±38 ns has been observed for the first time and its de-excitation through collective and intrinsic structures studied. The results are compared with predictions of blocked BCS Nilsson calculations. Observation of this metastable state completes the tungsten 4-quasiparticle isomer systematics from A 176 to 186. Mapping out the most yrast 4-quasiparticle isomers in these even-even tungsten isotopes suggests the existence of a highly favoured state in 188W, within reach of current experimental set-ups. [ABSTRACT FROM AUTHOR]

High-spin states in 202Pb and 203Pb have been investigated by in-beam γ-ray spectroscopy following the reaction 198Pt(9Be,xn). A search for magnetic rotational bands in these isotopes confirmed one of the two bands previously assigned to 202Pb and revealed a new band in this isotope. No evidence for magnetic rotation has been found in 203Pb. [ABSTRACT FROM AUTHOR]

Eighteen previously unknown γ-ray transitions were identified in the Tz = - 1/2 nucleus 51Fe following the fusion-evaporation reaction 32S(28Si,2α1 n)51Fe. The level scheme reaches the fully aligned Iπ = 27/2- terminating state of the five holes in the f7/2 shell. The 17/2- state was found to be isomeric, and the lifetime was measured to be 2.87 ns. The mirror symmetry of 51Fe and 51Mn is discussed, and the level scheme of 51Fe is compared to shell-model calculations. [ABSTRACT FROM AUTHOR]

High–spin states in 200Hg have been investigated by in–beam γ–ray spectroscopy following the reaction 198Pt(9Be,α3n). The α–emission channel leading to 200Hg is strongly enhanced which may be explained by an incomplete fusion reaction with pre–equilibrium emission of the α particle. The level scheme is extended to higher spins and new band crossings are observed. The band structures are compared to the lighter Hg isotopes with even mass number. [ABSTRACT FROM AUTHOR]

Average transition quadrupole moments in the yrast triaxial superdeformed bands of 163Lu, 164Lu and 165Lu were determined in a Doppler-shift attenuation-method experiment. Fractional Doppler shifts were determined in γ-ray coincidence spectra measured with the Gammasphere array. The transition quadrupole moments derived from these data show a decrease from 163Lu to 165Lu which is not predicted by total-energy surface calculations. [ABSTRACT FROM AUTHOR]

High-spin states have been studied in 72Kr and 72Br using the 40Ca + 40Ca and 36Ar + 40Ca reactions at 164 and 145 MeV, respectively. The properties and configurations of the high-spin bands observed have been interpreted using unpaired cranked Nilsson-Strutinsky (CNS), and for 72Kr, paired cranked relativistic Hartree-Bogoliubov (CRHB) calculations. In 72Kr a new band has been identified that has the properties expected for the doubly aligned S-band configuration. In 72Br the previously known bands have been extended to higher spin. This has lead to a re-interpretation of the configurations. [ABSTRACT FROM AUTHOR]