N. V. Zamfir

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We report on a gamma-ray coincidence analysis using a mixed array of hyperpure germanium and cerium-doped lanthanum tri-bromide (LaBr3:Ce) scintillation detectors to study nuclear electromagnetic transition rates in the pico-to-nanosecond time regime in 33,34P and 33S following fusion-evaporation reactions between an 18O beam and an isotopically enriched(More)
Nuclei below the Z = 50 magic shell gap with A∼100 show a wide variety of structural phenomena. These include excellent examples of vibrational collectivity at low-spins, which give way to more rotational-like excitations with increasing angular momentum. In this paper we present recent results from an experiment performed at Yale to study the yrast(More)
Recently, a set of nine nonmagic nuclei with anomalous values of the B(E2) ratio B 4/2 ≡ B(E2; 4 + 1 → 2 + 1)/B(E2; 2 + 1 → 0 + 1) < 1 were identified. Such values are outside the range allowed by current collective models. In the present work, the B(E2; 4 + 1 → 2 + 1) values for two of these nuclei, 98 Ru and 180 Pt, were re-measured to determine if the(More)
Shape/phase transitions in atomic nuclei have first been discovered in the framework of the Interacting Boson Approximation (IBA) model. Critical point symmetries appropriate for nuclei at the transition points have been introduced as special solutions of the Bohr Hamiltonian, stirring the introduction of additional new solutions describing wide ranges of(More)
The parameter independent (up to overall scale factors) predictions of the X(5)-β 2 , X(5)-β 4 , and X(3) models, which are variants of the X(5) critical point symmetry developed within the framework of the geometric collective model, are compared to two-parameter calculations in the framework of the interacting boson approximation (IBA) model. The results(More)
Lifetime measurements of yrast levels in 162 Yb and 166 Hf were performed using the recoil distance Doppler-shift method in coincidence mode. Excited states in 162 Yb and 166 Hf were populated via the reactions 116 Cd(50 Ti, 4n) and 122 Sn(48 Ti, 4n), respectively. The resulting B(E2) values are compared with the X(5) critical point model predictions and(More)
Evidence is presented to show that a group of nuclei, spanning a range of structures, corresponds to a previously proposed isolated region of regular behavior between vibrational and rotational structures that was never before observed empirically. Nuclei predicted to show such regular spectra correspond to Hamiltonian parameters that lie amidst those(More)
The nature and evolution of collectivity and coherence in nuclei is one of the most fundamental issues in nuclear structure and its evolution with N and Z. Despite many experiments, the nature of nuclear vibrational modes in deformed nuclei and the nature of nuclear phase/shape transitions are not at all understood. We discuss new experiments on phonon and(More)
The study of spherical-deformed ground–state phase transitions in finite nuclei as a function of N and Z is hindered by the discrete values of the nucleon number. A resolution of the integer nucleon number problem, and evidence relating to phase transitions in finite nuclei, are discussed from the experimental point of view and interpreted within the(More)
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