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The stable Cd isotopes have long been used as paradigms for spherical vibrational motion. Extensive investigations with in-beam γ spectroscopy have resulted in very-well-established level schemes, including many lifetimes or lifetime limits. A programme has been initiated to complement these studies with very-high-statistics β decay using the 8π spectrometer at the TRIUMF radioactive beam facility. The decays of 112In and 112Ag have been studied with an emphasis on the observation of, or the placement of stringent limits on, low-energy branches between potential multi-phonon levels. A lack of suitable 0+ or 2+ three-phonon candidates has been revealed. Further, the sum of the B(E2) strength from spin 0+ and 2+ states up to 3 MeV in excitation energy to the assigned two-phonon levels falls far short of the harmonic-vibrational expectations. This lack of strength points to the failing of collective models based on vibrational phonon structures. [ABSTRACT FROM AUTHOR]

The TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer (TIGRESS) is a state-of-the-art γ-ray spectrometer being constructed at the ISAC-II radioactive ion beam facility at TRIUMF. TIGRESS will be comprised of twelve 32-fold segmented high-purity germanium (HPGe) clover-type γ-ray detectors, with BGO/CsI(Tl) Compton-suppression shields, and is currently operational at ISAC-II in an early-implementation configuration of six detectors. Results have been obtained for the first experiments performed using TIGRESS, which examined the A = 20, 21, and 29 isotopes of Na by Coulomb excitation. [ABSTRACT FROM AUTHOR]

Fusion-fission reactions were induced by bombarding a thick 27Al target with 178Hf projectiles at a laboratory energy of 1150 MeV using the ATLAS accelerator at Argonne National Laboratory. The subsequent γ-ray decays were measured using the GAMMASPHERE germanium detector array. The beam was pulsed at two different ON/OFF cycles of 82.5/825 ns and 25/75 μs in order to observe the γ rays from the decay of isomeric states. In 121Sb 2721+Δ keV, Iπ=(25/2+) and 2434 keV, Iπ=19/2- states have measured half-lives of T1/2=200(30) μs and 8.2(2) ns respectively. The 2614+Δ keV, Iπ=(27/2+) and 2486 keV, Iπ=19/2+ states in 123Sb have measured half-lives of T1/2=52(3) μs and 7.9(4) ns respectively. The positive parity isomers in these nuclei correspond to a πd5/2 or πg7/2 configuration, in 121Sb and 123Sb respectively, coupled to aligned (h11/2)2 neutrons. The Iπ=19/2- isomeric state in 121Sb is proposed to have a νh11/2 x νd3/2 x πd5/2 configuration. A previously unobserved isomer has been identified in 99Mo at an energy of 3010 keV, decaying with T1/2=18(5) ns. This state is interpreted as an energetically favoured 3 quasi-particle alignment of ν (d5/2) x π(gg7/2) x π(g9/2 configuration which is observed systematically in the even-Z N=57 isotones. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]2 configuration which is observed systematically in the even-Z N=57 isotones. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

A measurement of the ground state β-decay branching ratio of 62Ga has been made as part of a program of high-precision superallowed Fermi β decay studies at the ISAC radioactive beam facility. The experiment was conducted by detecting γ rays and β particles from the decay of 62Ga using the 8π γ-ray spectrometer and the SCEPTAR plastic scintillator array. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The 8π spectrometer at TRIUMF-ISAC consists of 20 Compton-suppressed germanium detectors and various auxiliary devices. The Ge array, once used for studies of nuclei at high angular momentum, has been transformed into the world’s most powerful device dedicated to radioactive-decay studies. Many improvements in the spectrometer have been made, including a high-throughput data acquisition system, installation of a moving tape collector, incorporation of an array of 20 plastic scintillators for β-particle tagging, 5 Si(Li) detectors for conversion electrons, and 10 BaF2 detectors for fast-lifetime measurements. Experiments can be performed where data from all detectors are collected simultaneously, resulting in a very detailed view of the nucleus through radioactive decay. A number of experimental programmes have been launched that take advantage of the versatility of the spectrometer, and the intense beams available at TRIUMF-ISAC. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The intrinsic quadrupole moment Q[sub 0] of superdeformed rotational bands in A∼150 nuclei depends on the associated single-particle configuration. We have derived an empirical formula based on the additivity of effective quadrupole moments of single-particle orbitals that describes existing measurements from [sup 142]Sm to [sup 152]Dy. To further test the formula, the predicted Q[sub 0] moments for two superdeformed bands in [sup 146]Gd of 14.05 eb were confronted with a new measurement yielding 13.9±0.4 eb and 13.9±0.3 eb respectively. This excellent agreement provides empirical evidence of extreme single-particle behavior in highly deformed, collective systems. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The common feature to all superdeformed bands is the way they abrupty terminate when the nucleus suddenly changes shape. In most cases, it is extremely hard to tell how the nucleus then decays to its normally deformed groundstate, and this is why only very scarce information is available for superdeformed states. After a brief introduction on superdeformation, I will show, with a few examples, what is the status of our knowledge about the decay from superdeformed states. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In response to new opportunities presented by re-accelerated beams from the ISAC-II facility at TRIUMF, a plunger-type Recoil Distance Method device, the TIGRESS Integrated Plunger, is under construction to be used with the TIGRESS segmented germanium array. An experimental program aimed in nuclear structure measurements along the N=Z line is planned. Lifetime measurements in the shape-coexistence region near N∼Z∼36 are anticipated to provide information of significance to Vud matrix element evaluation from superallowed beta-decay measurements. [ABSTRACT FROM AUTHOR]