Alpha Clusters in a Spherical Nucleus

1966 ◽  
Vol 141 (3) ◽  
pp. 1136-1137 ◽  
Author(s):  
F. C. Chang
Keyword(s):  
Spherical Nucleus

scholarly journals Isomers and shell evolution in neutron-rich nuclei below the doubly magic nucleus 132Sn

2018 ◽  
Vol 178 ◽  
pp. 02018
Author(s):  
Hiroshi Watanabe
Keyword(s):  
Half Life ◽  
Electric Quadrupole ◽  
Energy Difference ◽  
Magic Nucleus ◽  
Spherical Nucleus ◽  
Shell Closure ◽  
Quadrupole Transition ◽  
Electric Quadrupole Transition ◽  
Level Sequence ◽  
First Time

The level structures of the very neutron-rich nuclei 128Pd82 and 126Pd80 have been investigated for the first time. A new isomer with a half-life of 5.8(8) μs in 128Pd is proposed to have a spin and parity of 8+ and is associated with a maximally aligned configuration arising from the g9/2Pd proton subshell with seniority υ = 2. The level sequence below the 8+ isomer is similar to that in the N = 82 isotone 130Cd, but the electric quadrupole transition that depopulates the 8+ isomer is more hindered in 128Pd than in 130Cd, as expected in the seniority scheme for a semi-magic, spherical nucleus. For 126Pd, three new isomers with Jπ = (5-), (7-), and (10+) have been identified with half-lives of 0.33(4) μs, 0.44(3) μs, and 23.0(8) ms, respectively. The smaller energy difference between the 10+ and 7- isomers in 126Pd than in the heavier N = 80 isotones can be interpreted as being ascribed to the monopole shift of the h11/2 neutron orbit. The nature of the N = 82 shell closure scrutinized with these characteristic isomers is discussed.

THE ORIGIN OF NUCLEAR SHAPE TRANSITIONS

1993 ◽  
Vol 08 (13) ◽  
pp. 1185-1189 ◽  
Author(s):  
G. D. YEN ◽  
H. G. MILLER ◽  
R. M. QUICK
Keyword(s):  
Nuclear Energy ◽  
Mean Field ◽  
Closed Shell ◽  
Quadrupole Deformation ◽  
Spherical Nucleus ◽  
Nuclear Shape ◽  
Energy Spectra ◽  
Deformed Nuclei ◽  
Deformation Parameters ◽  
Rare Earth Nuclei

The experimental nuclear energy spectra indicate the rare-earth nuclei undergo a collective-to-noncollective transition even for a closed-shell spherical nucleus. For off-shell deformed nuclei this transition may be accompanied by a change in the nuclear shape in finite temperature mean field theories which is not seen in exact canonical calculations. Therefore, a theory using the quadrupole deformation parameters β and γ as the order parameter for this transition may be misleading.

scholarly journals Sperm morphology, ultrastructure, and motility in pikeperch Sander lucioperca (Percidae, Teleostei) associated with various activation media 

2014 ◽  
Vol 59 (No. 1) ◽  
pp. 1-10 ◽  
Author(s):  
J. Křišťan ◽  
A. Hatef ◽  
S.M.H. Alavi ◽  
T. Policar
Keyword(s):  
Sperm Morphology ◽  
Storage Period ◽  
Spherical Nucleus ◽  
Sander Lucioperca ◽  
Central Pair ◽  
Spermatozoa Motility ◽  
Sampling Times ◽  
Freshwater Teleosts

Spermatozoa morphology, ultrastructure, and spermatozoa motility traits were studied in pikeperch (Sander lucioperca) after activation in various media (AM 1 &ndash; 45mM NaCl, 5mM KCl, 20mM Tris, pH 8.5; AM 2 &ndash; 100mM sucrose, 20mM Tris, pH 8.5; AM 3 &ndash; 100mM sucrose, 1mM CaCl<sub>2</sub>, 20mM Tris, pH 8.5) during a 48-hour storage period. The spermatozoon was acrosomeless and differentiated into a spherical nucleus (head), midpiece, and flagellum. The nucleus length and width measured 1.83 &plusmn; 0.03 and 1.63 &plusmn; 0.02&nbsp;mm, respectively. The midpiece was located laterally to the nucleus and possessed proximal and distal centrioles and 2&ndash;4 mitochondria. Flagellar length was 33.2 &plusmn; 0.90 &micro;m, and a pair of lateral fin-like structures projections was observed. The axoneme consisted of nine peripheral doublet microtubules and a single central pair. After a 24 h storage in all activation media at all sampling times post-activation (15, 45, 90, and 120 s), spermatozoa motility was significantly decreased. Spermatozoa were motile after the 48-hour storage at all sampling times post-activation only in AM 3. After the 48-hour storage, no motile spermatozoa were observed in AM 2 and AM 1 at 90 and 120 s post-activation, respectively. Differences in spermatozoa velocity varied with activation medium during storage. After the 48-hour storage in AM 1 and AM 2, decrease of spermatozoa velocity at 15 s post-activation was observed, while in AM 3, velocity was decreased only after the 48-hour storage. Pikeperch spermatozoa morphology and ultrastructure was found similar to that of most freshwater teleosts, with differences in the arrangement of midpiece, number of mitochondria, and position of centrioles. Viable pikeperch sperm was observed after the 48-hour storage. Motility of spermatozoa was improved by addition of Ca<sup>2+</sup> to the activation medium, where higher spermatozoa velocity was observed.

A NEW LARGE AMPLITUDE COLLECTIVE MOTION IN NUCLEI: CLUSTERS AS SOLITONS ON THE NUCLEAR SURFACE

1992 ◽  
Vol 01 (01) ◽  
pp. 169-200 ◽  
Author(s):  
A. LUDU ◽  
A. SĂNDULESCU ◽  
W. GREINER
Keyword(s):  
Collective Motion ◽  
Liquid Drop ◽  
Total Potential Energy ◽  
Spherical Nucleus ◽  
Nuclear Surface ◽  
Hydrodynamic Equations ◽  
Liquid Drop Model ◽  
Shell Effects ◽  
Total Potential ◽  
Spectroscopic Factors

Based on the liquid drop model, by including nonlinear terms in the hydrodynamic equations, we show that stable solitons can exist on the nuclear surface of 208 Pb or dose to it, this being the most rigid double magic spherical nucleus. The shell effects related with this nucleus lead to a new minimum in the total potential energy. In order to connect this minimum with the cluster decays, which are spontaneous decays, we choose the corresponding energy to be degenerate with the ground state minimum. A new coexistence model consisting of the usual shell model and a cluster-like model describing a soliton moving on the nuclear surface is obtained. The corresponding amplitudes describe excellently the experimental spectroscopic factors for cluster decays.

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