122206593
Observation of Octupole Structures in Radon and Radium Isotopes and Their Contrasting Behavior at High Spin
Multinucleon transfer reactions have been used, for the first time, to populate high-spin bands of alternating parity states in {sup 218,220,222}Rn and {sup 222,224,226}Ra. The behavior of the angular momentum alignment with rotational frequency for the Rn isotopes is very different when compared with Ra and Th isotopes with N{approx}134, indicating a transition from octupole vibrational to stable octupole deformation. Throughout the measured spin range the values of {vert_bar}D{sub 0}/Q{sub 0}{vert_bar} remain constant for {sup 222}Ra and {sup 226}Ra and have a very small value for {sup 224}Ra, suggesting that the charge and mass distributions are not affected appreciably by rotations. {copyright} {ital 1997} {ital The American Physical Society}
118027838
Structure of Co-65,Co-67 studied through the beta decay of Fe-65,Fe-67 and a deep-inelastic reaction
The neutron-rich isotopes {sup 65,67}Fe and {sup 65}Co have been produced at the LISOL facility, Louvain-La-Neuve, in the proton-induced fission of {sup 238}U. Beams of these isotopes have been extracted with high selectivity by means of resonant laser ionization combined with mass separation. Yrast and near-yrast levels of {sup 65}Co have also been populated in the {sup 64}Ni+{sup 238}U reaction at Argonne National Laboratory. The level structure of {sup 65}Co could be investigated by combining all the information from both the {sup 65}Fe and {sup 65}Co{beta} decay and the deep-inelastic reaction. The {sup 65}Fe, {sup 65}Co, and {sup 67}Fe decay schemes and the {sup 65}Co yrast structure are fully established. The {sup 65,67}Co level structures can be interpreted as resulting from the coexistence of core-coupled states with levels based on a low-energy proton-intruder configuration.
7752926
Possible dynamic effects in the particle decay of 59Cu compound nuclei.
The slopes of the energy spectra of {ital p}, {ital d}, {ital t}, and {alpha} particles emitted from {sup 59}Cu nuclei formed in the reaction of {sup 32}S+{sup 27}Al at a bombarding energy of 150 MeV are described by statistical-model calculations in which the deformation is frozen during the first two steps of the deexcitation chain. The resultant fits to the high-energy portions of the spectra are comparable to those previously obtained by modifying the spin dependence of the level density, suggesting that dynamic effects may be important in evaporation from light nuclei.
40623384
Yrast isomers in exotic N=81 nucleus 151Yb studied using a fragment mass analyzer.
38753635
Shapes of 59Cu nuclei at moderate excitation energies and spin.
Continuum {gamma}-ray spectra from the decay of {sup 59}Cu formed at excitation energies of 54 and 74 MeV and angular momenta up to 40{h bar} have been measured and analyzed. The parameters of the giant dipole resonance have been extracted using the statistical model. The giant dipole resonance parameters for the lower excitation energy agree well with published data for spherical {sup 63}Cu nuclei. At the higher excitation, the giant dipole resonance strength distribution is not described by a single Lorentzian fit in disagreement with the findings for {sup 63}Cu at the same excitation energy. This seems to be correlated with the onset of spin driven deformations as recently evidenced from the shapes of evaporative particle spectra.
9087855
Gamma ray studies of neutron-rich sdf shell nuclei produced in heavy ion collisions.
Reanalysis of [ital ichproductsofbinaryreactio] [ital nsof]$[sup 34]S, [sup 36]S, and [sup 37]Cl beams on [sup 160]Gd targets. Gates set on known [ital amma]$[ital raysin]$[ital A][similar to]160 products selected individual react ion channels and identified coincident [ital amma]$[ital raysin]$[ital A][similar to]36 partner products. Transfers of protons from projectile to target and of neutrons from target to projectile were generally favored, leading to excited neutron-rich light nuclei, including some difficult to reach by other means. Notable results include the observation of [ital amma]$[ital raycascadesup][sup [ital t][ital h][ital e]][ital high] [ital e] [ital stknownyraststatesinfour]$[ital N]=20 isotones. In two [ital N]=19 nuclei, [sup 33]Si and [sup 34]P, the two [ital N]=22 nuclei, [sup 38]S and [sup 39]Cl, previously unknown yrast states were identified.
34406165
Standard model with compactified spatial dimensions
We analyze the structure of the standard model coupled to gravity with spatial dimensions compactified on a three-torus. We find that there are no stable one-dimensional vacua at zero temperature, although there does exist an unstable vacuum for a particular set of Dirac neutrino masses.
119437909
A Survey of Open Clusters in the u'g'r'i'z' Filter System. 3. Results for the Cluster NGC 188
The authors continue the series of papers describing the results of a photometric survey of open star clusters, primarily in the southern hemisphere, taken in the u'g'r'i'z' filter system. The entire observed sample covered more than 100 clusters, but here they present data only on NGC 188, which is one of the oldest open clusters known in the Milky Way. They fit the Padova theoretical isochrones to the data. Assuming a solar metallicity for NGC 188, they find a distance of 1700 {+-} 100 pc, an age of 7.5 {+-} 0.7 Gyr, and a reddening E(B-V) of 0.025 {+-} 0.005. This yields a distance modulus of 11.23 {+-} 0.14.
118501625
Standard model vacua for two-dimensional compactifications
We examine the structure of lower-dimensional standard model vacua for two-dimensional compactifications (on a 2D torus and on a 2D sphere). In the case of the torus we find a new standard model vacuum for a large range of neutrino masses consistent with experiment. Quantum effects play a crucial role in the existence of this vacuum. For the compactification on a sphere the classical terms dominate the effective potential for large radii and a stable vacuum is achieved only by introducing a large magnetic flux. We argue that there are no two-dimensional standard model vacua for compactifications on a surface of genus greater than one.
118615935
Supersymmetric dark matter sectors
We investigate the properties of a dark matter sector where supersymmetry is a good symmetry. In this context we find that the stability of the dark matter candidate is possible even when R-parity is broken in the visible sector. In order to illustrate the idea we investigate a simple scenario where the dark matter candidate is the lightest scalar field in the dark sector which annihilates mainly into two sfermions when these channels are available. We study the relic density constraints and the predictions for the dark matter detection experiments.