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99,101,103Ru were populated in (α,nγ) reactions. Half-lives in the sub-nanosecond range were measured by using the ROSPHERE γ ray array. Results for the first 3/2+ states in 99,101Ru and the first 7/2+ states in 99,101,103Ru were obtained and are discussed within the Rigid-Triaxial-Rotor-plus-Particle model. Calculated level energies are in good agreement with the experimental level scheme but the model fails in reproduction of some of the reduced transition probabilities. This is, most probably, due to wave function admixtures which are outside the model space. [ABSTRACT FROM AUTHOR]

Low-energy isomeric states of 86Y were populated in the reaction 73Ge + 16O at 57MeV and were investigated by means of delayed n $ \gamma$ and $ \gamma$ $ \gamma$ coincidences. A half-life of 70(7)ns was measured for the 5- state at 208keV, yielding an exceptionally small B( M1) value of 2.0(7)×10-5 W.u. and a B( E2) value of 0.34(+24 -13) W.u. For the other three known isomeric states at 218, 243, and 302keV, the half-lives extracted from the present experimental data are in very good agreement with previous measurements. Given the newly observed isomeric character of the 5- 208keV state, the re-analysis of earlier experimental data on the 302keV isomer led to a new spin-parity assignment, 6+, for this state. In addition, this re-evaluation provided two g -factors, -0.083(3) and +0.63(2) , for the 208 and 302keV states, respectively. The results are discussed in terms of spherical-shell model calculations performed with a truncated space of configurations built on the f5/2 , p3/2 , p1/2 , and g9/2 valence orbitals. Effective spin, orbital, and “tensor” g -factors were determined empirically for protons and neutrons in the considered configuration space. [ABSTRACT FROM AUTHOR]

We present a new study of the low-lying states in 124Te nucleus by γ-ray spectroscopy following 124Iβ+/ε decay. The β radioactive sources were produced in the 124Te(p, n)124I reaction induced by 11 MeV protons, delivered by the Bucharest FN Tandem Accelerator. The γ-rays were measured in a low background area with three large volume HPGe detectors. A total number of 276 milion double coincidence events were recorded in a six-day run. Most of the gamma line intensities previously measured were confirmed with improved accuracy and several gamma lines were obtained for the first time. Our results, combined with those from a recent (n, γ) study are compared with the predictions of the E(5) critical point symmetry model and numerical IBA-1 model calculations at the critical point of the U(5)–O(6) phase transition. [ABSTRACT FROM AUTHOR]

Gamma-ray coincidence techniques are used to determine new level structures in the N = 81 nucleus 139Ce, at low spins and excitation energies with the 139La(p, nγ) reaction at 5.0 and 6.0MeV incident energy, and at high spins with the 130Te(12C, 3nγ) reaction at 50.5MeV, respectively. Lifetime determinations are also made in the ( p, nγ) reaction with the centroid DSA method. The observed level structures are discussed by comparison with existing calculations and with those in the neighbouring nucleus 140Ce. [ABSTRACT FROM AUTHOR]

High-spin states in the 96Tc nucleus have been studied with the reactions 82Se(19F,5nγ) at 68 MeV and Zn(36S,αp xn) at 130 MeV. Two γ-ray cascades (irregular bandlike structures) have been observed up to an excitation energy of about 10 MeV and spin 21-22?. [ABSTRACT FROM AUTHOR]

The lifetimes of twelve low spin excited states in [SUP73]As, below 2 MeV excitation, have been measured with the DSA method in the 73Ge(p,n&gama;) reaction. The existing data (energy levels, electromagnetic moments, transition probabilities and branching ratios, one-nucleon transfer spectroscopic factors) are discussed in the frame of multi-shell interacting boson-fermion model calculations. A good agreement is obtained for a large number of levels. [ABSTRACT FROM AUTHOR]

The half-life of the yrast IΠ = 2+ state in the neutron-rich nucleus 188W has been measured using fast-timing techniques with the HPGe and LaBniCe array at the National Institute of Physics and Nuclear Engineering, Bucharest. The resulting value of t1/2 = 0.87(12) ns is equivalent to a reduced transition probability of B(E2;21 →01 +) = 85(12) W.u. for this transition. The B(E2;21 →01 +) is compared to neighboring tungsten isotopes and nuclei in the Hf, Os, and Pt isotopic chains. Woods-Saxon potential energy surface (PES ) calculations have been performed for nuclei in the tungsten isotopic chain and predict prolate deformed minima with rapidly increasing y softness for l84-192W and an oblate minimum for l94W. [ABSTRACT FROM AUTHOR]

Excited states in 129I were populated with the 124Sn(7Li,2n) reaction at 23 MeV. In-beam measurements of γ-ray coincidences were performed with an array of eight HPGe detectors and five LaBr3(Ce) scintillation detectors. Based on the γγ coincidence data, a positive parity band structure built on the 7/2+ ground state was established and the nπg7/2 configuration at oblate deformation was assigned to it. The results are compared to interacting Boson-Fermion model (IBFM) and total Routhian surface (TRS) calculations. [ABSTRACT FROM AUTHOR]

The half-life of the 2305-keV, I&pgr; = 4(-) intruder state in 34P has been measured as t1/2 = 2.0(1) ns using &ggr;-ray coincidence, fast-timing techniques with the Bucharest HPGe and LaBr3:Ce detector array. Excited states in 34P were populated using the 18O(180, pn)34P fusion-evaporation reaction at a beam energy of 36 MeV. Reduced transition probabilities have been calculated for different values of the M2/E3 mixing ratio, &dgr;E3/M2, and compared with shell-model estimates. For small values of the mixing ratio, the B(M2) value was found to be consistent with similar transitions associated with the occupation of neutron f7/2 configurations in this mass region. [ABSTRACT FROM AUTHOR]

The knowledge of excited states in the odd-odd 150Pm, completely unknown until recently, is important both for understanding double &bgr; decay of 150Nd and for nuclear structure studies in mass regions with a quantum phase transition. A large number of excited states have been determined for the first time in this nucleus by measuring spectra of the 152Sm(d,&agr;) direct reaction at 25 MeV with the Munich Q3D spectrograph and by &ggr;-ray spectroscopy with the (p, ny) reaction at 7.1 MeV at the Bucharest tandem accelerator. Some of these levels correspond to peaks recently observed with the (3He,r) reaction at 140 MeV/u. [ABSTRACT FROM AUTHOR]

The cross sections of the 115Sn(α,γ)119Te, 115Sn(α,n)118Te, and 116Sn(α,n)119Te reactions (both on ground and isomeric states) have been measured at effective center-of-mass energies from 9.3 to 14.8 MeV. During a first experiment, enriched self-supporting 115Sn (51.2%) + 116Sn (24.4%) foils were bombarded with an α beam delivered by the Bucharest IFIN-HH Tandem Accelerator. In a second experiment, a highly enriched 116Sn target was irradiated in order to disentangle the experimental cross section contributions due to 115Sn(α,γ)119Te and 115Sn(α,n)118Te reactions obtained in the first measurement. The beam-induced activity was measured with two large volume HPGe detectors in close geometry. The experimental results were compared with theoretical predictions obtained in the framework of the statistical model. [ABSTRACT FROM AUTHOR]

γ rays were measured at several angles in both singles and coincidence modes in the 115Sn(α,nγ)118Te reaction at 15 MeV on a thick target. Multipolarities and mixing ratios were determined from the γ-ray angular distribution analysis. Lifetimes of 11 low- and medium-spin excited states in 118Te were determined from a Monte Carlo Doppler-shift attenuation method analysis of the Doppler broadened line shapes of γ rays deexciting the levels. The results are discussed in comparison with the predictions of the interacting boson model. [ABSTRACT FROM AUTHOR]

Abstract: The nuclei 85Y and 86Y were studied in two series of experiments conducted by using the heavy-ion reactions 76Ge(14N, 4n)86Y and 52Cr(37Cl, 2pxn)85,86Y. The analysis of double and triple coincidences of γ rays along with the investigation of angular distributions led to the extension of the level schemes of the 85Y and 86Y nuclei to spins and excitation energies higher than observed in previous experiments. In addition, a few new levels with low spins and excitation energies were identified in both nuclei. In order to better understand the nuclear structure of these isotopes, shell-model calculations were carried out considering a valence space formed by the proton and neutron orbitals , , , and . [Copyright &y& Elsevier]

Abstract: 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 18O implanted tantalum target. Energies from decay gamma-rays associated with the reaction residues were measured in event-by-event coincidence mode, with the measured time difference information between the pairs of gamma-rays in each event also recorded using the ultra-fast coincidence timing technique. The experiment used the good full-energy peak resolution of the LaBr3:Ce detectors coupled with their excellent timing responses in order to determine the excited state lifetime associated with the lowest lying, cross-shell, “intruder” state previously reported in the N=19 isotone 34P. The extracted lifetime is consistent with a mainly single-particle M2 multipolarity associated with a single particle transition. [Copyright &y& Elsevier]