Universal Charge-Radius Relation for Subatomic and Astrophysical Compact Objects

Electron-positron pair creation in supercritical electric fields limits the net charge of any static, spherical object, such as superheavy nuclei, strangelets, and Q-balls, or compact stars like neutron stars, quark stars, and black holes. For radii between $4\times10^2$ fm and $10^4$ fm the upper bound on the net charge is given by the universal relation $Z=0.71R_{fm}$, and for larger radii (measured in fm or km) $Z = 7 \times 10^{-5} R_{fm}^2 = 7 \times 10^{31} R_{km}^2$. For objects with nuclear density the relation corresponds to $Z \approx 0.7 A^{1/3}$ ($10^{8} < A < 10^{12}$) and $Z \approx 7\times10^{-5} A^{2/3}$ ($A > 10^{12}$), where $A$ is the baryon number. For some systems this universal upper bound improves existing charge limits in the literature

12C emission from 114Ba and nuclear properties

We investigate the influence of nuclear masses, radii, and interaction potentials on 12C radioactivity of 114the best representative of a new island of cluster emitters leading to daughter nuclei around the doubly magic 100Sn. Three different models are considered: one derived by Blendowske, Fliessbach, and Walliser (BFW) from the many-body theory of alpha decay, as well as our analytical (ASAF) and numerical (NuSAF) superasymmetric fission models. A Q value larger by 1 MeV or an ASAF potential barrier reduced by 3% are producing a half-life shorter by 2 orders of magnitude. A similar effect can be obtained within BFW and NuSAF by a decrease of the action integral with less than 10% and 5%, respectively. By increasing the radius constant within ASAF or BFW models by 10%, the half-life becomes shorter by 3 orders of magnitude

Three-cluster nuclear molecules

A three-center phenomenological model able to explain, at least from a qualitative point of view, the difference in the observed yield of a particle-accompanied fission and that of binary fission was developed. It is derived from the liquid drop model under the assumption that the aligned configuration, with the emitted particle between the light and heavy fragment is obtained by increasing continuously the separation distance, while the radii of the light fragment and of the light particle are kept constant. During the first stage of the deformation one has a two-center evolution until the neck radius becomes equal to the radius of the emitted particle. Then the three center starts developing by decreasing with the same amount the two tip distances. In such a way a second minimum, typical for a cluster molecule, appears in the deformation energy. Examples are presented for $^{240}$Pu parent nucleus emitting $\alpha$-particles and $^{14}$C in a ternary process

Two-dimensional nuclear inertia : analytical relationships

The components of the nuclear inertia tensor, functions of the separation distance R and of the radius of the light fragment R2, BRR(R,R2), BRR2(R,R2), and BR2R2(R,R2) are calculated within the Werner-Wheeler approximation, by using the parametrization of two intersected symmetric or asymmetric spheres. Analytical relationships are derived. When projected to a path R2=R2(R), the reduced mass is obtained at the touching point. The two one-dimensional parametrizations with R2=const, and the volume V2=const previously studied, are found to be particular cases of the present more general approach. Illustrations for the cold fission, cluster radioactivity, and &#945; decay of 252Cf are given

Hadron yields from thermalized minijets at RHIC and LHC

We calculate the yields of pions, kaons, and $\phi$-mesons for RHIC and LHC energies assuming thermodynamical equilibration of the produced minijets, and using as input results from pQCD for the energy densities at midrapidity. In the calculation of the production of partons and of transverse energy one has to account for nuclear shadowing. By using two parametrizations for the gluon shadowing one derives energy densities differing strongly in magnitude. In this publication we link those perturbatively calculated energy densities of partons via entropy conservation in an ideal fluid to the hadron multiplicities at chemical freeze-out.Comment: Talk given at the International Europhysics Conference on High Energy Physics, EPS-HEP99, Tampere, Finland, July 1999, 3 page

New island of cluster emitters

A new region of proton-rich parent nuclei decaying by spontaneous cluster emission with a measurable branching ratio relative to alpha decay is predicted within the analytical superasymmetric fission model. After a brief presentation of the model and of the seven mass tables used to calculate the released energy, the obtained results are discussed. Measurable half-lives and branching ratios are estimated for 12C, 16O, 28Si, and other cluster radioactivities of some nuclides having proton and neutron numbers in the range Z=56–64 and N=58–72. Such nuclei far from stability could be produced in reactions induced by radioactive beams