Search results for "hell"
showing 10 items of 1035 documents
Shell structure and shape coexistence in195Pb
1995
Pb-195 was investigated utilizing the reactions Dy-164(S-36, 5n)Pb-195 and Dy-164(S-34, 3n)Pb-195 at beam energies of 170 and 160MeV respectively. Two new dipole bands which feed into the yrast 25/2(+) state, were found in Pb-195. The connection between the bands and the spherical states was established and thus spins and energies of the involved collective states were determined. The deformation is understood as mainly due to excitations of protons across the Z = 82 shell gap. The observed backbends are interpreted as alignment of i(13/2) neutrons.
Evolution of collectivity in the78Ni region: Coulomb excitation of74Ni at intermediate energies.
2014
The study of the collective properties of nuclear excitations far from stability provides information about the shell structure at extreme conditions. Spectroscopic ob- servables such as the energy or the transition probabilities of the lowest states, in nuclei with large neutron excess, allow to probe the density and isospin dependence of the ef- fective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Emblematic is the case of the evolution of the Ni isotopic chain where several features showed up moving from the most neutron rich stable isotope ( 64 Ni) towards the 78 Ni nucleus where the large neu…
Discovery of shell-like radio-structure in SN1993J
1995
The radio-luminous supernova SN 1993J in M81 offers an unprecedented opportunity to study with high linear resolution the details of the growth of a supernova radio structure by means of the VLBI technique.
Mass measurements of $^{56-57}$Cr and the question of shell reincarnation at N = 32
2005
Binding energies determined with high accuracy provide smooth derivatives of the mass surface for analysis of shell and pairing effects. Measurements with the Penning trap mass spectrometer ISOLTRAP at CERN-ISOLDE were made for $^{56-57}$Cr for which an accuracy of 4 $\times 10^{-8}$ was achieved. Analysis of the mass surface for the supposed new N = 32 shell closure rather indicates a sub-shell closure, but of a different nature than known cases such as $^{94}$Sr.
Unified description of structure and reactions: implementing the Nuclear Field Theory program
2015
The modern theory of the atomic nucleus results from the merging of the liquid drop (Niels Bohr and Fritz Kalckar) and of the shell model (Marie Goeppert Meyer and Axel Jensen), which contributed the concepts of collective excitations and of independent-particle motion respectively. The unification of these apparently contradictory views in terms of the particle-vibration (rotation) coupling (Aage Bohr and Ben Mottelson) has allowed for an ever increasingly complete, accurate and detailed description of the nuclear structure, Nuclear Field Theory (NFT, developed by the Copenhagen-Buenos Aires collaboration) providing a powerful quantal embodiment. In keeping with the fact that reactions are…
Level structure of 99Nb
1998
The β decay of 97Sr to 97Y has been investigated using ion-guide on-line mass separation and a 10 Ge-detector array to record γ−γ coincidences to a detection limit well below that of former studies. Similarities are found in the β-decay patterns of 99Zr and of its isotone 97Sr and also in the γ-ray decay rates and branchings of the corresponding levels in their respective daughters 99Nb and 97Y. This indicates a persisting influence of the d5/2 neutron shell closure for 99Nb. The level structure of 99Nb and the β-feeding pattern are discussed in the frame of the interacting boson-fermion plus broken pair model and the microscopic quasiparticle phonon model.
Thin plastic shell x-ray optics: an update
2003
We present new results from a program to develop large area X-ray telescopes that are made from thin plastic shells. We use multi-shell cylindrical lenses in a point-to-point configuration to form full aperture images of the small focal spot in a an X-ray tube on a microchannel plate detector. The image data are analyzed to yield radial profiles and encircled energy curves. The derived parameters can be extrapolated to the case of a telescope that is a conical approximation to Wolter 1 optics. The plastic shells can be coated with suitable mono- or multilayers that allow for a wideband coverage of X-ray energies. Our current program is focused on the development of a large area, hard X-ray …
Superheavy element flerovium (element 114) is a volatile metal.
2014
The electron shell structure of superheavy elements, i.e., elements with atomic number Z ≥ 104, is influenced by strong relativistic effects caused by the high Z. Early atomic calculations on element 112 (copernicium, Cn) and element 114 (flerovium, Fl) having closed and quasi-closed electron shell configurations of 6d(10)7s(2) and 6d(10)7s(2)7p1/2(2), respectively, predicted them to be noble-gas-like due to very strong relativistic effects on the 7s and 7p1/2 valence orbitals. Recent fully relativistic calculations studying Cn and Fl in different environments suggest them to be less reactive compared to their lighter homologues in the groups, but still exhibiting a metallic character. Expe…
First Observation of the Unbound NucleusNe15
2014
We report on the first observation of the unbound proton-rich nucleus Ne-15. Its ground state and first excited state were populated in two-neutron knockout reactions from a beam of 500 MeV/u Ne-17. The Ne-15 ground state is found to be unbound by 2.522(66) MeV. The decay proceeds directly to O-13 with simultaneous two-proton emission. No evidence for sequential decay via the energetically allowed 2(-) and 1(-) states in F-14 is observed. The Ne-15 ground state is shown to have a strong configuration with two protons in the (sd) shell around O-13 with a 63(5)% (1s(1/2))(2) component.
Analysis of the Electronic Structure of Non-Spherical Ligand-Protected Metal Nanoclusters : The Case of a Box-Like Ag67
2017
In this work we introduce a new strategy to investigate the electronic shell structure of ligand-protected metal nanoclusters of polyhedral core shape. The central idea is to identify the symmetry of the Kohn–Sham molecular orbitals of an atomistic structure based on their projection onto the electronic states of a jellium system with a similar shape of the background charge density. Herein, we study the connection between a reduced atomistic model of the recently reported box-like [Ag67(SR)32(PR3)8]3+ nanocluster and a jellium box consisting of 32 free electrons. With this approach, we determine the symmetry of electronic states of the metal core and identify those that are involved in the…