3,156 research outputs found
Electromagnetic Transition Strengths in Heavy Nuclei
We calculate reduced B(E2) and B(M1) electromagnetic transition strengths
within and between K-bands in support of a recently proposed model for the
structure of heavy nuclei. Previously, only spectra and a rough indication of
the largest B(E2) strengths were reported. The present more detailed
calculations should aid the experimental identification of the predicted ,
and bands and, in particular, act to confirm or refute the
suggestion that the model and bands correspond to the well known
and widespread beta and gamma bands. Furthermore they pinpoint transitions
which can indicate the presence of a so far elusive band by feeding
relatively strongly into or out of it. Some of these transitions may already
have been measured in Th, Th and U.Comment: 10 pages, 1 Figure, submitted to Physical Review
Complementarity and Scientific Rationality
Bohr's interpretation of quantum mechanics has been criticized as incoherent
and opportunistic, and based on doubtful philosophical premises. If so Bohr's
influence, in the pre-war period of 1927-1939, is the harder to explain, and
the acceptance of his approach to quantum mechanics over de Broglie's had no
reasonable foundation. But Bohr's interpretation changed little from the time
of its first appearance, and stood independent of any philosophical
presuppositions. The principle of complementarity is itself best read as a
conjecture of unusually wide scope, on the nature and future course of
explanations in the sciences (and not only the physical sciences). If it must
be judged a failure today, it is not because of any internal inconsistency.Comment: 29 page
A simple description of the states and in
A sixth-order quadrupole boson Hamiltonian is used to describe 26 states
and 67 states which have been recently identified in .
Two closed expressions are alternatively used for energy levels. One
corresponds to a semi-classical approach while the other one represents the
exact eigenvalue of the model Hamiltonian. The semi-classical expression
involves four parameters, while the exact eigenvalue is determined by five
parameters. In each of the two descriptions a least square fit procedure is
adopted.
Both expressions provide a surprisingly good agreement with the experimental
data.Comment: 9 pages, 5 figure
Triaxial quadrupole deformation dynamics in sd-shell nuclei around 26Mg
Large-amplitude dynamics of axial and triaxial quadrupole deformation in
24,26Mg, 24Ne, and 28Si is investigated on the basis of the quadrupole
collective Hamiltonian constructed with use of the constrained
Hartree-Fock-Bogoliubov plus the local quasiparticle random phase approximation
method. The calculation reproduces well properties of the ground rotational
bands, and beta and gamma vibrations in 24Mg and 28Si. The gamma-softness in
the collective states of 26Mg and 24Ne are discussed. Contributions of the
neutrons and protons to the transition properties are also analyzed in
connection with the large-amplitude quadrupole dynamics.Comment: 16 pages, 18 figures, submitted to Phys. Rev.
Spectral properties of a tractable collective Hamiltonian
The spectral properties of a tractable collective model Hamiltonian are
studied. The potential energy is truncated up to quartic terms in the
quadrupole deformation variables, incorporating vibrational,
-independent rotational and axially deformed rotational structures.
These physically significant limits are analysed in detail and confronted with
well-established approximation schemes. Furthermore, transitional Hamiltonians
in between the limits are presented and discussed. All results are obtained
within a recently presented Cartan-Weyl based framework to calculate
embedded quadrupole collective observables.Comment: submitted to PR
Quadrupole collective variables in the natural Cartan-Weyl basis
The matrix elements of the quadrupole collective variables, emerging from
collective nuclear models, are calculated in the natural Cartan-Weyl basis of
O(5) which is a subgroup of a covering structure. Making
use of an intermediate set method, explicit expressions of the matrix elements
are obtained in a pure algebraic way, fixing the -rotational structure
of collective quadrupole models.Comment: submitted to Journal of Physics
Three-body model calculations for 16C nucleus
We apply a three-body model consisting of two valence neutrons and the core
nucleus C in order to investigate the ground state properties and the
electronic quadrupole transition of the C nucleus. The discretized
continuum spectrum within a large box is taken into account by using a
single-particle basis obtained from a Woods-Saxon potential. The calculated
B(E2) value from the first 2 state to the ground state shows good agreement
with the observed data with the core polarization charge which reproduces the
experimental B(E2) value for C. We also show that the present
calculation well accounts for the longitudinal momentum distribution of
C fragment from the breakup of C nucleus. We point out that the
dominant ( configuration in the ground state of C plays a
crucial role for these agreement.Comment: 5 pages, 3 figures, 3 table
Gamma-soft Analog of the Confined Beta-soft Rotor Model
A gamma-soft analog of the confined beta-soft (CBS) rotor model is developed,
by using a gamma-independent displaced infinite well beta-potential in the Bohr
Hamiltonian, for which exact separation of variables is possible. Level schemes
interpolating between the E(5) critical point symmetry (with R(4/2)=E(4)/E(2)=
2.20) and the O(5) gamma-soft rotor (with R(4/2)=2.50) are obtained, exhibiting
a crossover of excited 0+ bandheads which leads to agreement with the general
trends of first excited 0+ states in this region and is observed experimentally
in 128-Xe and 130-Xe.Comment: 10 pages, LaTeX, including 7 eps figure
Study of the transition from pairing vibrational to pairing rotational regimes between magic numbers N=50 and N=82, with two-nucleon transfer
Absolute values of two-particle transfer cross sections along the Sn-isotopic
chain from closed shell to closed shell (100Sn,132Sn) are calculated taking
properly into account nuclear correlations, as well as the successive,
simultaneous and non-orthogonality contributions to the differential cross
sections. The results are compared with systematic, homogeneous bombarding
conditions (p, t) data. The observed agreement, almost within statistical
errors and without free parameters, testify to the fact that theory is able to
be quantitative in its predictions
Multipole strength function of deformed superfluid nuclei made easy
We present an efficient method for calculating strength functions using the
finite amplitude method (FAM) for deformed superfluid heavy nuclei within the
framework of the nuclear density functional theory. We demonstrate that FAM
reproduces strength functions obtained with the fully self-consistent
quasi-particle random-phase approximation (QRPA) at a fraction of computational
cost. As a demonstration, we compute the isoscalar and isovector monopole
strength for strongly deformed configurations in Pu by considering huge
quasi-particle QRPA spaces. Our approach to FAM, based on Broyden's iterative
procedure, opens the possibility for large-scale calculations of strength
distributions in well-bound and weakly bound nuclei across the nuclear
landscape.Comment: 5 pages, 3 figure
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