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The decay of the extremely neutron-deficient isotope 45Fe has been studied by using a new type of gaseous detector in which a technique of optical imaging is used to record tracks of charged particles. The two-proton radioactivity and the $ \beta$ -decay channels were clearly identified. For the first time, the angular and energy correlations between two protons emitted from the 45Fe ground state were measured. The obtained results were confronted with predictions of a three-body model. [ABSTRACT FROM AUTHOR]

The single-particle structure and shell gap of 100Sn as inferred from previous in-beam γ-ray spectroscopy has been confirmed in recent studies of seniority and spin-gap isomers by γγ, βγ, β pγ, pγ and 2 pγ spectroscopy. The results for 94, 95Ag, 98Cd and its N = 50 isotones 96Pd and 94Ru stress the importance of large-scale shell model calculations employing realistic interactions for the isomerism, np- nh excitations, seniority mixing and E2 polarisation of the 100Sn core. The strong monopole interaction of the Δ l = 0, 1 spin/isospin-flip partners π g 9/2- ν g 7/2 along the N = 50 isotones and the π f 5/2- ν g 9/2 pair of nucleons along the Z = 28 Ni isotopes are decisive for the evolution of the shell structure towards 100Sn and 78Ni. It can be traced back to the tensor force in the effective nucleon-nucleon interaction and provides a straightforward explanation for new shells in neutron-rich light nuclei, implying qualitative predictions for new N = 32, 34 subshells in Ca isotopes, persistence of the 78Ni proton and neutron shell gaps and non-equivalence of the g 9/2 valence mirror Ni isotopes and N = 50 isotones. This is corroborated by recent experimental data on 56, 58Cr and 70-76Ni. The implication of monopole driven shell evolution for apparent spin-orbit splitting towards N ≫ Z and structure along the astrophysical r-path between N = 50 and N = 82 is discussed. [ABSTRACT FROM AUTHOR]

Recent progress in experimental decay studies in the region of the doubly magic nucleus 78Ni is discussed. In particular new data on low-energy excitations in nickel isotopes has been obtained in experiments employing fragmentation reactions. The experimental data are confronted with different shell-model calculations. The position of the 2+ energy levels and behavior of 8+ isomers in even-even 70-76Ni isotopes has been interpreted. [ABSTRACT FROM AUTHOR]

The single-particle structure and shell gap of 100Sn is inferred from prompt in-beam and delayed γ-ray spectroscopy of seniority and spin-gap isomers. Recent results in 94, 95Ag and 98Cd stress the importance of large-scale shell model calculations employing realistic interactions for the isomerism, np- nh excitations and E2 polarisation of the 100Sn core. The strong monopole interaction of the Δ l = 0 spin-flip partners π g9/2- ν g7/2 in N = 51 isotones below 100Sn is echoed in the Δ l = 1 π f5/2- ν g9/2 pair of nucleons, which is decisive for the persistence of the N = 50 shell gap in 78Ni. This is corroborated by recent experimental data on 70, 76Ni, 78Zn. The importance of monopole driven shell evolution for the appearance of new shell closures in neutron-rich nuclei and implications for r-process abundances near the N = 82 shell is discussed. [ABSTRACT FROM AUTHOR]

A decay spectroscopy study of the neutron-rich cobalt isotopes has been performed using fragmentation of a86Kr36+ beam and the new LISE2000 spectrometer at GANIL. For71Co and73Co, the ß-delayed ? radiation has been observed for the first time, and the half-lives were found to be 79(5) ms and 41(4) ms, respectively. Features of the decay are discussed qualitatively in terms of nuclear models. [ABSTRACT FROM AUTHOR]

Decay-spectroscopy study of the67mFe isomer has been performed at GANIL. This isomer is found to have an energy of 387 keV and a half-life of 75(21) μs. An intermediate excited state is introduced at 367 keV. The results are interpreted in terms of various nuclear models, and a deformed shape is inferred for67Fe. [ABSTRACT FROM AUTHOR]

Decays of five 45Fe atoms have been observed at the fragment separator of GSI. Whereas one event is consistent with the β-decay of 45Fe accompanied by the emission of a 10 MeV proton, four decays are consistent with the emission of particle(s) of total energy 1.1±0.1 MeV. This observation represents the first evidence for two-proton ground-state radioactivity, a decay mode predicted for 45Fe. The time distribution of the observed decay events corresponds to a half-life of 3.2+2.6 -1.0 ms. [ABSTRACT FROM AUTHOR]

The neutron-rich isotope 136Sb has been produced following the relativistic projectile fission of 238U in an experiment performed at the Fragment Separator at GSI, Darmstadt. Delayed γ-ray spectroscopy of the fission products has been performed after isotope separation. A new isomeric state in 136Sb has been populated, and its lifetime measured as T1/2 = 565(50) ns. Realistic and empirical shell-model calculations have been performed and are compared to the experimental observables. [ABSTRACT FROM AUTHOR]

We report results from a pioneering experiment to measure the g factors of isomeric states of neutron-rich nuclei around [sup 68]Ni, far from the valley of β stability. For the first time, the timedependent perturbed angular distribution method was applied in combination with the heavy-ion-γ correlation technique to study g factors of spin-aligned isomers produced in a projectile fragmentation reaction and mass-separated. Some technical aspects are discussed and illustrated with preliminary results. [ABSTRACT FROM AUTHOR]

The β-decay of the Tz = - 2 nucleus 36Ca was studied at the LISE3 magnetic spectrometer at GANIL. Two new proton-emitting states have been detected and the other nine known βp and βγ transitions have been remeasured with improved resolution. A simulation with the GEANT code has been applied to this experimental setup. A comparison with shell model calculations is given. [ABSTRACT FROM AUTHOR]

Decay studies of very neutron-deficient nuclei ranging from 39Ti to 49Ni have been performed during a projectile fragmentation experiment at the GANIL/LISE3 separator. For all nuclei studied in this work, 39, 40Ti, 42, 43Cr, 46Mn, 45, 46, 47Fe and 49Ni, half-lives and decay spectra have been measured. In a few cases, γ coincidence measurements helped to successfully identify the initial and final states of transitions. In these cases, partial decay scheme are proposed. For the most exotic isotopes, 39Ti, 42Cr, 45Fe and 49Ni, which are candidates for two-proton radioactivity from the ground state, no clear evidence of this process is seen in our spectra and we conclude rather on a delayed particle decay. [ABSTRACT FROM AUTHOR]

The ß-decay ofTi andCa have been studied at the LISE3 spectrometer at GANIL. The decay schemes were deduced from the observed ß-delayed proton and γ emission ofTi andCa into the ground and first excited states ofCa andAr, respectively. The Gamow-Teller strength function B(GT) of theTi ß-decay extracted from the ß-decay branching ratios and the precisely measuredTi half-life, provides for the first time an experimental calibration of the neutrino detection efficiency for the ICARUS solar neutrino detector. [ABSTRACT FROM AUTHOR]

The β-decay properties of ground-state and isomer of 103In were investigated by means of γ-ray spectroscopy. The half-lives of 103gIn and 103mIn were determined to be 60 ± 1 s and 34 ± 2 s, respectively. Out of 149 γ transitions ascribed to the decay of 103gIn, 104 have been placed in a decay scheme including 55 excited states of 103gCd. The main part of the resulting distribution of the Gamow-Teller strength B(GT) is associated with the feeding of 103Cd levels at excitation energies around 3 MeV. This observation can be interpreted as a sign of dominant feeding of three-quasiparticle states in 103Cd, which correspond to the 1+(πg9/2−1, vg7/2)⊗πg9/2 shell-model configuration spread over many levels. The sum of the B(GT) values deduced from the present γ-ray data amounts to 0. 34, which provides a lower limit to the total Gamow-Teller strength. The B(GT) distribution for 103In decay is compared to the corresponding experimental results for 105,107,109In and to theoretical predictions for 99,101In. The latter were calculated by using an advanced spherical shell model. The β-branching ratio for the 103mIn decay is estimated and compared with the relevant values for the neighbouring indium isotopes including 101In whose half-life was determined to be 14. 9 ± 1.2 s. [ABSTRACT FROM AUTHOR]

Evidence for the proton decay of 144Tm was found in an experiment at the Recoil Mass Spectrometer at Oak Ridge National Laboratory. The 144Tm events were found in the weak p5n channel of the fusion reaction using a 58Ni beam at 340 MeV on a 92Mo target. The observed proton decay energies are 1.70 MeV and 1.43 MeV and the half-life ∼ 1.9μs. The decay properties suggest proton emission from the dominant π h11/2 part of the wave function and from the small π f7/2 admixture coupled to a quadrupole vibration. [ABSTRACT FROM AUTHOR]

The evolution of the π h11/2ν h11/2 and π h11/2ν s1/2 isomeric configurations was studied for the N = 77 isotones near the proton drip line. The decays of metastable levels in 140Eu, 142Tb , and 144Ho were measured by means of X-, gamma- and conversion electron spectroscopy at the Recoil Mass Spectrometer at Oak Ridge. The sequence of isomeric levels in 140Eu was experimentally determined. The half-life of the π h11/2ν h11/2 state in 142Tb was remeasured to be 25(1) μs. The spins and parities of 5- and 8+ for the π h11/2ν s1/2 and π h11/2ν h11/2142Tb isomers, respectively, were established from measured multipolarities. No evidence for the expected 1+ ground state was found in the 144Ho decay data. [ABSTRACT FROM AUTHOR]

The very neutron-deficient isotope 50Ni was produced in fragmentation reactions between a 650 A MeV 58Ni beam and a 9Be target. For the first time the decay of this nucleus was investigated, leading to the determination of the half-life as 12+3 -2 ms and the branching ratio for β-delayed proton emission of (70 ± 20)%. [ABSTRACT FROM AUTHOR]

In an experiment at the SISSI/LISE3 facility of GANIL, the most proton-rich zinc isotopes 55,56Zn have been observed for the first time. The experiment was performed using a high-intensity 58Ni beam at 74.5 MeV/nucleon impinging on a nickel target. The identification of 55,56Zn opens the way to 54Zn, a good candidate for two-proton radioactivity according to theoretical predictions. [ABSTRACT FROM AUTHOR]

An experiment was performed at the National Superconducting Cyclotron Laboratory at Michigan State University to investigate β decay of very neutron-rich cobalt isotopes. Beta-delayed neutron emission from 71-74Co has been observed for the first time. Preliminary results are reported. [ABSTRACT FROM AUTHOR]

Measurement of fine structure in proton emission allows one to deduce the composition of the parent and daughter state’s wavefunction populated by proton emission. This paper presents new experimental data on the fine-structure decay of 146Tm, and a new interpretation of its decay properties. [ABSTRACT FROM AUTHOR]

A technique to enhance the purity of accelerated radioactive ion beams for decay studies is presented. The technique requires a 3MeV/nucleon beam and a transmission ionization chamber. The gas pressure in the multi-anode ionization chamber is adjusted so that high- Z components of the beam are ranged out in the gas transmitting the more exotic, low- Z components to the measuring station. Initial tests with a radioactive 120Ag and 120In mixed beam indicate at least a factor of 5 relative enhancement of the 120Ag decay transitions. [ABSTRACT FROM AUTHOR]

In the experiment performed at the LISE2000 spectrometer at GANIL neutron-rich nickel isotopes were studied by microsecond isomer spectroscopy. Evidence for an isomer in 76Ni is found, consistently with the shell model prediction of an 8+ state of v(g9/2)² structure. [ABSTRACT FROM AUTHOR]

We report the results from the first experiment to measure gyromagnetic factors of μs isomers in neutron-rich nuclei produced by intermediate-energy projectile-fragmentation reactions. The Time Dependent Perturbed Angular Distribution (TDPAD) method was applied in combination with the heavy-ion-gamma correlation technique. The nuclides in the vicinity of 68Ni were produced and spin-oriented following the fragmentation of a 76Ge, 61.4 MeV/u beam at GANIL. The results obtained, |g|(69mCu) = 0.225(25) and |g|(67mNi) = 0.125(6) provide another indication of the importance of proton excitation across the Z = 28 shell gap for the description of these states. [ABSTRACT FROM AUTHOR]

The neutron deficient nucleusPd was identified and studied for the first time by in-beam spectroscopy. An I=(14) isomer with t=0.8 (2) μs was observed in a recoil catcher setup inside the multi-detector γ-array OSIRIS. Filter detectors for neutrons and charged particles were used to identify the (2p2n) exit channel of the reactionNi+Ca, populated with only 0.06% of the total evaporation residue cross section. The structure of the isomer is discussed within the frame work of shell model calculations in the (p,g) model space with emphasis on the g T=0, I=1,9 'pairing' two-body matrix elements. [ABSTRACT FROM AUTHOR]

By using aCa beam of the UNILAC accelerator the new isotopesAg andAg were produced throughNi(Ca,p3n) andNi(Ca,p2n) reactions, respectively, and identified by detecting β-delayed protons from mass-separated sources.Ag represents the heaviest N=Z nucleus with known decay properties. The β-decay half-lives ofAg andAg were determined to be 0.42±0.05 s and 2.0±0.1 s, respectively. The measured β-decay properties are compared with model predictions. [ABSTRACT FROM AUTHOR]