123473601
STUDIES OF SUPERHEAVY ELEMENTS AT SHIP
An overview of present experimental investigation of superheavy elements is given. The data are compared with theoretical descriptions. Results are reported from an experiment to confirm production of element 112 isotopes in irradiation of 238UF4 with 48Ca. One spontaneous fission event was measured, which agrees with three events of previously measured data which had been assigned to the decay of 283112. However, more experimental work is needed in order to obtain an independent and unambiguous confirmation of previous results.
122536153
Formation of superheavy elements in cold fusion reactions
The process of the synthesis of superheavy elements ~SHEs! is not yet understood completely. In the presented work we make an attempt to describe the cold fusion reactions of the type X1(Pb,Bi)→SHE 11n at subbarrier energies. The process of the formation of SHEs is subdivided into three steps. ~1! The capture of two spherical nuclei and the formation of a common shape of the two touching nuclei. Low-energy surface vibrations and transfer of few nucleons are taken into account in the first step of the reaction. ~2! The formation of a spherical or near spherical compound nucleus. ~3! The survival of the excited compound nucleus due to evaporation of neutrons and g-ray emission in competition with fission. A lowering of the fission barrier was taken into account, which arises from a reduction of shell effects at increasing excitation energy of the compound nucleus. The following reactions were analyzed in detail: (Fe, Ni, Zn, Ge)1Pb, (Ti, Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se)1Pb, (Fe, Ni, Zn, Ge) 1Pb, and (Ti, Cr, Fe, Ni, Zn, Ge)1Bi. The presented model describes well the available experimental cross-section data and allows for predicting cross-section values for the synthesis of so-far unknown heavier elements.
13153867
Mass measurements of very neutron-deficient Mo and Tc isotopes and their impact on rp process nucleosynthesis.
The masses of ten proton-rich nuclides, including the N=Z+1 nuclides ⁸⁵Mo and ⁸⁷Tc, were measured with the Penning trap mass spectrometer SHIPTRAP. Compared to the Atomic Mass Evaluation 2003 a systematic shift of the mass surface by up to 1.6 MeV is observed causing significant abundance changes of the ashes of astrophysical x-ray bursts. Surprisingly low α separation energies for neutron-deficient Mo and Tc are found, making the formation of a ZrNb cycle in the rp process possible. Such a cycle would impose an upper temperature limit for the synthesis of elements beyond Nb in the rp process.
16408480
Effective Kaon energy from a novel chiral SU(3) model
Abstract A new chiral SU(3) Lagrangian is proposed to describe the properties of kaons and anti-kaons in the nuclear medium, The saturation properties of nuclear matter are reproduced as well as the results of the Dirac-Briickner theory, After introducing the coupling between the omega meson and the kaon, our results for effective kaon and anti-kaon energy are quite similar as calculated in the one-boson-exchange model.
201093324
Proton Radioactivity
121183473
Observation of rotating nuclear molecules and determination of their lifetimes
Long-living rotating nuclear molecules (or “dinuclear systems”) have been observed at the velocity filter SHIP at GSI in reactions of 64Ni + 207Pb at Coulomb barrier energies. The rotation was directly revealed by the velocity spectra of deep inelastic target-like transfer products which are formed during the lifetime of the nuclear molecule and emitted after its breakup. The corresponding rotation angles were about 180 degree pointing to long nuclear interaction times or lifetimes of the system, respectively. We deduced the lifetimes from the lines in the velocity spectra originating from two different rotation angles. Further, the unambiguous correlation of a certain transfer product with its individual velocity spectrum allowed us to study the lifetimes as a function of the number of transferred protons.
6846518
Island of stability for consistent deformations of Einstein's gravity.
We construct deformations of general relativity that are consistent and phenomenologically viable, since they respect, in particular, cosmological backgrounds. These deformations have unique symmetries in accordance with their Minkowski cousins (Fierz-Pauli theory for massive gravitons) and incorporate a background curvature induced self-stabilizing mechanism. Self-stabilization is essential in order to guarantee hyperbolic evolution in and unitarity of the covariantized theory, as well as the deformation's uniqueness. We show that the deformation's parameter space contains islands of absolute stability that are persistent through the entire cosmic evolution.
37255447
A Quantum Bound-State Description of Black Holes
A relativistic framework for the description of bound states consisting of a large number of quantum constituents is presented, and applied to black-hole interiors. At the parton level, the constituent distribution, number and energy density inside black holes are calculated, and gauge corrections are discussed. A simple scaling relation between the black hole mass and constituent number is established.
119430795
The Casimir effect in the presence of compactified universal extra dimensions
Abstract The Casimir force in a system consisting of two parallel conducting plates in the presence of compactified universal extra dimensions (UXD) is analyzed. The Casimir force with UXDs differs from the force obtained without extra dimensions. A new power law for the Casimir force is derived. By comparison to experimental data the size R of the universal extra dimensions can be restricted to R ⩽10 nm for one extra dimension.
118647223
Interpretation of the Weyl tensor
According to folklore in general relativity, the Weyl tensor can be decomposed into parts corresponding to Newton-like, incoming and outgoing wavelike field components. It is shown here that this one-to-one correspondence does not hold for space-time geometries with cylindrical isometries. This is done by investigating some well-known exact solutions of Einstein's field equations with whole-cylindrical symmetry, for which the physical interpretation is very clear, but for which the standard Weyl interpretation would give contradictory results. For planar or spherical geometries, however, the standard interpretation works for both, static and dynamical space-times. It is argued that one reason for the failure in the cylindrical case is that for waves spreading in two spatial dimensions there is no local criterion to distinguish incoming and outgoing waves already at the linear level. It turns out that Thorne's local energy notion, subject to certain qualifications, provides an efficient diagnostic tool to extract the proper physical interpretation of the space-time geometry in the case of cylindrical configurations.
1452681
FORMATION OF SMALL-SCALE STRUCTURE IN SUSY CDM
The lightest supersymmetric particle, most likely the lightest neutralino, is one of the most prominent particle candidates for cold dark matter (CDM). We show that the primordial spectrum of density fluctuations in neutralino CDM has a sharp cut-off, induced by two different damping mechanisms. During the kinetic decoupling of neutralinos, non-equilibrium processes constitute viscosity effects, which damp or even absorb density perturbations in CDM. After the last scattering of neutralinos, free streaming induces neutralino flows from overdense to underdense regions of space. Both damping mechanisms together define a minimal mass scale for perturbations in neutralino CDM, before the inhomogeneities enter the nonlinear epoch of structure formation. We find that the very first gravitationally bound neutralino clouds ought to have masses above 10 −6 M⊙, which is six orders of magnitude above the mass of possible axion miniclusters.