19 research outputs found
Alpha cluster condensation in 12C and 16O
A new -cluster wave function is proposed which is of the
-particle condensate type. Applications to C and O show
that states of low density close to the 3 resp. 4 -particle threshold
in both nuclei are possibly of this kind. It is conjectured that all
self-conjugate 4 nuclei may show similar features.Comment: 4 pages, 2 tables, 2 figure
How quantum bound states bounce and the structure it reveals
We investigate how quantum bound states bounce from a hard surface. Our
analysis has applications to ab initio calculations of nuclear structure and
elastic deformation, energy levels of excitons in semiconductor quantum dots
and wells, and cold atomic few-body systems on optical lattices with sharp
boundaries. We develop the general theory of elastic reflection for a composite
body from a hard wall. On the numerical side we present ab initio calculations
for the compression of alpha particles and universal results for two-body
states. On the analytical side we derive a universal effective potential that
gives the reflection scattering length for shallow two-body states.Comment: final publication version, new lattice results on alpha particle
compression, 5 pages, 2 figure
Relation between the phenomenological interactions of the algebraic cluster model and the effective two--nucleon forces
We determine the phenomenological cluster--cluster interactions of the
algebraic model corresponding to the most often used effective two--nucleon
forces for the O + system.Comment: Latex with Revtex, 1 figure available on reques
Nuclear Alpha-Particle Condensates
The -particle condensate in nuclei is a novel state described by a
product state of 's, all with their c.o.m. in the lowest 0S orbit. We
demonstrate that a typical -particle condensate is the Hoyle state
( MeV, state in C), which plays a crucial role for
the synthesis of C in the universe. The influence of antisymmentrization
in the Hoyle state on the bosonic character of the particle is
discussed in detail. It is shown to be weak. The bosonic aspects in the Hoyle
state, therefore, are predominant. It is conjectured that -particle
condensate states also exist in heavier nuclei, like O,
Ne, etc. For instance the state of O at MeV
is identified from a theoretical analysis as being a strong candidate of a
condensate. The calculated small width (34 keV) of ,
consistent with data, lends credit to the existence of heavier Hoyle-analogue
states. In non-self-conjugated nuclei such as B and C, we discuss
candidates for the product states of clusters, composed of 's,
triton's, and neutrons etc. The relationship of -particle condensation
in finite nuclei to quartetting in symmetric nuclear matter is investigated
with the help of an in-medium modified four-nucleon equation. A nonlinear order
parameter equation for quartet condensation is derived and solved for
particle condensation in infinite nuclear matter. The strong qualitative
difference with the pairing case is pointed out.Comment: 71 pages, 41 figures, review article, to be published in "Cluster in
Nuclei (Lecture Notes in Physics) - Vol.2 -", ed. by C. Beck,
(Springer-Verlag, Berlin, 2011
cluster structure in B
The cluster structures of the excited states in B are studied by
analyzing the isoscalar monopole and quadrupole strengths in the
B(,) reaction at MeV. The excitation strengths are
compared with the predictions by the shell-model and antisymmetrized
molecular-dynamics (AMD) calculations. It is found that the large monopole
strength for the state at MeV is well described by the AMD
calculation and is an evidence for a developed cluster structure.Comment: Revised according to the referees' comment