6,335 research outputs found
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 fm and fm the upper bound
on the net charge is given by the universal relation , and for
larger radii (measured in fm or km) . For objects with nuclear density the relation corresponds to
() and (), where 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 Pu parent nucleus emitting -particles and 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 α decay of 252Cf are given
Hadron yields from thermalized minijets at RHIC and LHC
We calculate the yields of pions, kaons, and -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
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