1,720,965 research outputs found
Band Structure of Nuclear Levels and Pairing Correlation Interactions
No full textThe modern theory of superconductivity applied to a statistical model of
nuclei predicts the phase transition energy all at 2.73 Mev or so for a wide
range of mass number. This transition energy curve is identified with cne of
the curves which were found by Sakai from a plot of the number of levels
against the excitation energy
Angular Momentum Distributions in the Thomas-Fermi and Thomas-Fermi-Dirac Models of the Atom
No full textThe angular momentum distributions in the Thomas-Fermi and Thomas-Fermi-Dirac
models of the atom are calculated by an ™i mproved method proposed previously.
The maximum energy (El),== for a given orbital angular momentum state is not
neglected and is treated as an eigenvalue by the WKB method.
The effective central field potentials in terms of the universal approximate
Thomas-Fermi function proposed by Latter are utilized. The determination of the
maximum energy (El),n,, and, therefore, the number of electrons rzl for a given
angular momentum state 2 is greatly facilitated by the term values computed by
Latter; The calculated angular momentum distributions are checked with the dia-grams
of term values against Z given in the Latter ™s paper to assure that our.pro-posed
method prouduces no appreciable error. .
Comparing with the empirical data, we then tind that the accuracy of the
Thomas-Fermi-Dirac model is far better than that of the Thomas-Fermi model. The
prediction of the first appearance of the s, p, d and f electrons by the Thomas-Fermi-
Dirac model is almost perfectly exact
Angular Momentum Distributions in the Atomic Nuclei
No full textThe problem of how many protons (neutrons) of a given orbital angular mo-mentum
Itr are to be found in a nucleus of a given proton number Z (neutron
number N) is reinvestigated by means of the improved Thomas-Fermi method.
Three kinds of nuclear models are calculated: The types of potentials chosen arc
(i) square well potential, (ii)-the Green™s potential, and (iii) the Green™s potential
plus 45 times the Thomas-Frenkel spin orbit term. The parameters involved in the
potentials are adopted from the paper of Hwang and Yang, which may exactly re-produce
the nuclear radii, trends of binding energies, and location of 3s and 4s
maxima in the neutron scattering cross section. The eigenvalues calculated by Green
are used to simplify the procedure of calculation. The results are then compared
with the empirical data compiled by Klinkenbeig. For the last type of potential,
the calculation is almost perfectly exact. The first appearance of particles of the
next higher angular momentum is almost exact for each model. The puzzle in the
Yang™s treatment of the first appearance problem is then solved. The crigin of the
appearance of magic numbers in the Yang s calculation is explained in the light of
the present theory
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
