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In a recent experiment performed at Triumf using the Dragon 0° spectrometer and its associated BGO array, the complete γ-decay of the radiative capture channel below the Coulomb barrier has been measured for the first time. This measurement has been performed at two energies Ec.m. = 6.6 and 7.2 MeV. A selective contribution of the entrance spins 2+ and 3- has been evidenced which is consistent with existing results above the barrier. [ABSTRACT FROM AUTHOR]

For the first time, the excited states in the extremely neutron-deficient nucleus 180Pb have been observed in an in-beam γ-ray measurement employing the recoil-decay tagging technique. Deduced level energies follow the trend of prolate intruder band level energies derived from heavier lead isotopes and reflect the persistence of magicity of the closed Z = 82 proton shell when approaching the proton drip line. [ABSTRACT FROM AUTHOR]

We have studied the β-decay of 23Al with a novel detector setup at the focal plane of the MARS separator at the Texas A&M University to resolve existing controversies about the proton intensities of the IAS in 23Mg and to determine the absolute proton branching ratios by combining our results to the latest γ-decay data. Experimental technique, results and the relevance for nova nucleosynthesis are discussed. [ABSTRACT FROM AUTHOR]

The 12C(16O,γ)28Si radiative capture reaction has been studied at energies close to the Coulomb barrier at Triumf (Vancouver) using the Dragon spectrometer and its associated BGO array. It has been observed that the γ decay flux proceeds mainly via states around 10–11 MeV and via the direct feeding of the 28Si 31- (6879 keV) and 42+ (6888 keV) deformed states. A discussion is presented about this selective feeding as well as perspectives for the use of novel detection systems for the study of light heavy-ion radiative capture reactions. [ABSTRACT FROM AUTHOR]

It has been proposed to associate the narrow (Γ=170 keV) and high spin (Jπ=36+) resonance in the 24Mg + 24Mg reaction at Ec.m= 45.7 MeV with a hyperdeformed molecular state in 48Cr. Such a description has important consequences for the resonance decay into the favoured inelastic channels. Through fragment-γ coincidence measurements performed ON and OFF resonance using the PRISMA-CLARA array, we have established that the 24Mg states selectively populated are the 2+ and 4+ members of the ground state band. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The heavy-ion radiative capture reactions 12C(12C,γ)24Mg and 12C(16O,γ)28Si have been performed on and off resonance at TRIUMF using the Dragon separator and its associated BGO array. The decay of the studied narrow resonances has been shown to proceed predominantly through quasi-bound doorway states which cluster and deformed configurations would have a large overlap with the entry resonance states. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

High-spin states in 3674Kr38 were studied using the 40Ca(40Ca,α2p)74Kr fusion evaporation reaction at a beam energy of 165 MeV with GAMMASPHERE and MICROBALL and at a beam energy of 185 MeV with EUROBALL and ISIS multi-detector arrays. Lifetimes of the high-spin states for the ground-state band and the favoured negative-parity band have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments show a marginal decrease as a function of spin, suggesting that the rotational bands do not terminate at the maximum spin Imax. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The quasi-continuum of γ rays from the feeding and decay of superdeformed and normal bands in the nucleus 152Dy have been extracted in 1 - and 2 - dimensional spectra. The Eγ-Eγ correlations in the latter reveals strong ridges associated with superdeformed and normal states in this nucleus. The entry distributions for normal and superdeformed bands were also extracted. A Monte Carlo model was developed that simultaneously describes all the quasi-continuum and ridge spectra as well as the feeding intensity of the superdeformed bands. Through the calculation of the continuum of γ rays at finite temperature, the rotational damping widths in the normal and superdeformed wells were extracted. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Composite chiral bands, corresponding to the πg9/2v(h11/2)2 quasiparticle configuration, have been observed in 103Rh and 105Rh. The behaviour of these bands is compared with that of the chiral bands with a πg9/2vh11/2 quasiparticle configuration observed in the odd-odd 102Rh and 104Rh nuclei. This comparison shows in a model independent way that the energy separation pattern of the chiral partner bands depends strongly on the properties of the triaxial core whilst the dependence on the valence quasiparticle coupling and on the Fermi level is weaker. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The narrow (Γ=170 keV) and high spin (Jπ=36+) resonance in the 24Mg + 24Mg reaction at ECM= 45.7 MeV has been associated with a hyperdeformed molecular state in 48Cr. Such a description has important consequences for the resonance decay into the favored inelastic channels. Through fragment-γ coincidence measurements performed ON and OFF resonance using the PRISMA-CLARA array, we have identified the 24Mg states selectively populated: the 2+ and 4+ members of the ground state band. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Both the quasi-continuum of γ rays as well as the ridges from the feeding (and decay) of superdeformed and normal bands have been extracted in the nucleus 152Dy. A model has been developed that simultaneously describes all these spectra as well as the feeding intensity of the superdeformed bands. Through the calculation of the continuum of γ rays at finite temperature, the rotational damping width in the normal and superdeformed wells are extracted. This is the first time the rotational damping width in a superdeformed well has been measured in the A∼150 mass region. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

A series of experiments to study the properties of transfermium nuclei have been performed at the Department of Physics of the University of Jyväskylä. The experiments are carried out by a large group of collaborating institutes. These studies have been rendered possible by the coupling of various state-of-the-art detector systems to the RITU gas-filled recoil separator. In-beam conversion-electron and gamma-ray measurements have been made using the SACRED silicon and JuroGam germanium-detector arrays, respectively. The introduction of the GREAT spectrometer and TDR data acquisition system have greatly improved the quality of the data obtained at RITU. A brief overview of the instrumentation used and highlights from recent experiments are presented. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The heavy ion radiative capture reaction 12C(12C,γ) has been investigated around a beam energy of 16 MeV. The total cross-section has been measured with the Fragment Mass Analyser at Argonne National Laboratory and found to be somewhat larger than has previously been measured. A subsequent measurement with the Gammasphere array has shown that a considerable proportion of this extra cross-section relates to a highly non-statistical decay through high-lying states in 24Mg. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Evidence for chirality in nuclei has been found in N ∼ 75 isotopes in the A ∼ 130 mass region. This phenomenon is a signature of triaxiality in nuclei and there is a clear need to study other regions of the Segre chart to see if further examples can be found. Potential Energy Surface (PES) calculations suggest that the N ∼ 57–63, Z ∼ 43–45 region is another promising island of triaxiality. The present experimental study with the Euroball γ-ray array, using the reaction 96Zr(13C, p2n) at 51 MeV is aimed to search for chirality in 106Rh. Channel selection of 106Rh was done using the charged-particle array DIAMANT. The yrast level scheme, studied previously in fusion-fission work, has been confirmed and extended in the present study. In addition, a new strongly coupled band, lying at an excitation energy of ∼ 300 keV above the yrast band, has been found. The two structures show the characteristic properties of the chiral phenomenon. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The excitation energy, spin and parity of the yrast superdeformed (SD) band in 152Dy have been established. The excitation energy of the lowest observed level in this band is found to be 10,644 keV with an assigned spin and parity of 24+. In addition, nine transitions of dipole character have been identified, which connect the excited superdeformed band 6 in 152Dy to the yrast SD band. The excitation energy of the lowest level in the excited SD band 6 is 14,239 keV. The spin and parity of this state has been determined to be either 29- or 31-. The measured properties of SD band 6 are consistent with an interpretation in terms of a rotational band built on an octupole vibration. A comparison with an RPA calculation by Nakatsukasa et al. suggests that the spin of the lowest SD band 6 level is 31-. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The N = Z nucleus [sup 70]Br has been investigated using a variety of reactions, beam energies and experimental techniques. A rather complete decay scheme has emerged, with low-lying configurations of fp-shell parentage based on the J = 0 groundstate and g-shell parentage based on the J = 9 β-decaying isomer, which is placed at 2293 keV. Comparison with other odd-odd nuclei shows a surprisingly low-level density in the first MeV of excitation energy. [ABSTRACT FROM AUTHOR]

The radiative capture reaction involving heavy ions is a relatively unexplored reaction mechanism which affords the possibility of gaining insights into molecular structure in nuclei and exotic, highly-deformed nuclear shapes. The [sup 12] C([sup 12]C,γ) reaction has been studied using an unconventional application of gamma-ray spectroscopy using the Gammasphere array. A resonance for this reaction has been located for E[sub beam]=15.8 MeV. Favored population of the K=2 rotational band in [sup 24]Mg as well as particular states around 10 MeV in excitation is observed. Using a Monte Carlo simulation of the previously uncharacterised high energy efficiency of Gammasphere, we set a lower limit on the cross-section for the species of decays observed of lµb. [ABSTRACT FROM AUTHOR]

The excitation energy, spin and parity of the yrast superdeformed band 1 in [sup 152]Dy have been established. The evidence comes mainly from the measured properties of a 4011 keV single-step transition connecting the yrast superdeformed level fed by the 693 keV transition to the 27[sup -] yrast state. Four additional, weaker, linking γ rays have been placed as well. The excitation energy of the lowest superdeformed band 1 member is 10,644 keV and its spin and parity are determined to be 24[sup +]. A further nine transitions of dipole character have been identified, which connect the excited superdeformed band 6 in [sup 152]Dy to the yrast SD band 1. The excitation energy of the lowest level in the excited SD band 1 is 14,239 keV. The lowest state in band 6 has been determined to be of negative parity and odd spin (29[sup -] or 31[sup -]). The measured properties of band 6 are consistent with an interpretation in terms of an octupole vibrational band. A comparison with an RPA calculation by Nakatsukasa et al. suggests that the spin of the lowest SD band 6 level is 31[sup -]. [ABSTRACT FROM AUTHOR]

With the coupling of large γ-ray arrays to recoil mass spectrometers, in-beam gamma-ray studies can be performed on nuclei lying at the very edges of stability. We have recently performed in-beam experiments using Gammasphere coupled to the FMA to measure excited states in proton unbound Au isotopes and neighboring Hg isotopes. These studies have allowed us to characterize the evolution of nuclear shapes as one approaches the proton drip line. In two of the isotopes studied, namely, [sup 175]Au and [sup 179]Hg, structures built on three distinct shapes at low excitation energy have been observed. [ABSTRACT FROM AUTHOR]

High-energy γ rays emitted in the symmetric reaction [sup 90]Zr + [sup 89]Y have been measured at the Argonne National Laboratory using the LEPPEX array coupled to the Fragment Mass Analyzer (FMA). The high-energy γ-ray spectra emitted by the giant dipole resonance built on excited states and associated with the evaporation of 0, 1 and 2 nucleons have been measured. The statistical model analysis indicates that the radiative-fusion process, namely the 0 particle emission channel, can be well described as a compound nucleus decay channel. In addition, the analysis of the highenergy γ-ray spectra associated with the different evaporation channels provides the first evidence that shell effects still play a role in determining the nuclear shapes of [sup 179]Au in the temperature interval 0.5-1 MeV. [ABSTRACT FROM AUTHOR]

A Recoil-Beta Tagging (RBT) experiment was recently performed at the accelerator laboratory at the University of Jyväskylä in order to identify T = 1 excited states in the medium-heavy N = Z = 33 nucleus 66As. The fusion-evaporation reaction 28Si(40Ca,pn)66As was employed at a beam energy of 75 MeV. The experiment was carried out utilising the JUROGAM II γ-ray spectrometer in conjunction with the gas-filled recoil separator RITU and the GREAT focal plane spectrometer system. The half-lives and ordering of the two known isomeric states in 66As have been determined. In addition, several new prompt γ-ray transitions from excited states both bypassing and decaying to the isomeric states in 66As have been observed. [ABSTRACT FROM AUTHOR]

For the first time, excitated states in very neutron-deficient odd-mass nucleus 185Pb have been observed in an in-beam γ-ray measurement. The present data provide evidence for a strong-coupling of an odd-neutron hole to the even-mass prolate core in the light Pb isotopes. [ABSTRACT FROM AUTHOR]

High-spin states in the nucleus 102Ru have been studied through the 96Zr(13C,α3n) reaction using the EUROBALL IV γ-ray spectrometer accompanied by the DIAMANT array for the detection of charged particles. All previously known bands have been extended to higher spins and additional bands have been found. Comparing the experimental Routhians and aligned angular momenta to the predictions of Woods-Saxon TRS calculations, vh11/2(d5/2,g7/2) configurations have been assigned to the observed negative-parity bands. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]