Search

A study of the shape transition from spherical to axially deformed nuclei in the even Ce isotopes using the nucleon-pair approximation of the shell model is reported. As long as the structure of the dominant collective pairs is determined using a microscopic framework appropriate to deformed nuclei, the model is able to produce a shape transition. The resulting transition is too rapid, however, with nuclei that should be transitional being fairly well deformed. The possibility of using several pairs with each angular momentum to improve the description of the transitional region is discussed. [ABSTRACT FROM AUTHOR]

The interacting boson model (IBM) of Arima and Iachello is applied to calculate nuclear charge radii and electric monopole transitions of even-even nuclei in the rare-earth region. Consistent operators are used for the two observables. In addition, a relation between summed M1 strength and ρ(E0) values is pointed out. [ABSTRACT FROM AUTHOR]

Radiative and electroweak penguin decays of B mesons are a sensitive probe of new physics beyond the Standard Model. We study the inclusive and exclusive radiative and electroweak penguin decays of B meson and also search an exotic particle seen by the HyperCP experiment. The measurements are based on a large data sample of 605 fb-1 containing 657 millions BB pairs collected at the Υ(4S) with the Belle detector at the KEKB energy asymmetric e+e- collider. [ABSTRACT FROM AUTHOR]

Recent advances in the study of pd radiative capture in a wide range of center-of-mass energy below and above deuteron breakup threshold are here presented and discussed. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Fragmentation of [sup 208]Pb has been used to populate very neutron-rich nuclei in the transitional region with A∼190–200. The isomeric states of these nuclei have been studied using γ-ray spectroscopy. After fragmentation, the nuclei of interest were separated, identified and finally implanted in an aluminum plate surrounded by a γ-spectroscopy set-up. This experiment has proven the ability of such a technique to populate medium to high spin states and γ-ray transitions have been observed for the first time in a number of neutron-rich nuclei in this region, including [sup 190]W, [sup 195]Os, [sup 197]Ir, [sup 202]Pt. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The excited states in 127I were investigated via in-beam gamma-ray spectroscopy techniques. The excited states were populated in reaction 124Sn (7Li, 4nγ) 127I at beam energy of 33 MeV. Multipolarities and linear polarization measurements were carried out for several transitions belonging to the negative parity band based on the πh11/2[550] 1/2-Nilsson state. The spin and parity have been confirmed for several states. A very weak E2 transitions of 683.7 keV was observed populating the Iπ = 27/2- state at 3958 keV. The Iπ = 27/2- state mainly populated via strong M1 transition of 409.5 keV. These observations indicate a change in the configuration of the Iπ = 29/2- state of this band. [ABSTRACT FROM AUTHOR]

Both from theoretical and experimental sides, the existence of cluster structure in light nuclei has been studied for a few decades and the appearance has been confirmed. To confirm the properties of these states is important also from the astrophysical view point. We investigate the properties of the structure of 12C above the α cluster threshold. Here, we apply orthogonality condition model (OCM), where the model space is given by SU(3) and its symplectic (sp) configuration. This enables us to treat both strong and weak coupling configuration. We show that sp-quanta is important to understand the mechanism of the appearance of large E0 strength. We also show that the other transition properties have good correspondence with experiments. [ABSTRACT FROM AUTHOR]

We perform amplitude analyses of the decays χc1→ηπ+π- and χc1→η′π+π-, where the χc1 is produced in the radiative process ψ(2S)→γχc1. Using a data sample of 2.59×107 ψ7 decays collected by the CLEO-c detector, we find evidence for an exotic, JPC = 1-+, η′π amplitude. When interpreted as a resonance, this amplitude has parameters consistent with the π1 (1600) state quoted elsewhere. In addition, we make the first direct observation of the decay a0(980) → η′π and also compare the spectra of ππ pairs recoiling against the η and η′. [ABSTRACT FROM AUTHOR]

The direct transition from ortho-positronium to para-positronium with high-power sub-THz radiation has been observed with 5.1 σ significance. The observed transition rate is consistent with the theoretical calculation. A sub-THz gyrotron is used as the light source, and a quasi-optical Fabry-Perot cavity is utilized to accumulate the radiation. This is the first observation of the positronium hyperfine splitting (Ps-HFS), which leads to the first direct measurement of Ps-HFS with a target accuracy of 100 ppm in several years. [ABSTRACT FROM AUTHOR]

Beta decays of N=126 isotones are studied by shell model calculations by including both the Gamow-Teller (GT) and first-forbidden (FF) transitions. The half-lives of the isotones are found to be reduced considerably by the the contributions from the FF transitions, and short compared to the standard half-lives usually used for the nucleosynthesis network calculations. Possible implications of the short half-lives of the waiting point nuclei on the r-process nucleosynthesis during the supernova explosions are discussed. [ABSTRACT FROM AUTHOR]