2,231 research outputs found
Similarity between nuclear rainbow and meteorological rainbow -- evidence for nuclear ripples
We present evidence for the nuclear ripples superimposed on the Airy
structure of the nuclear rainbow, which is similar to the meteorological
rainbow. The mechanism of the nuclear ripples is also similar to that of the
meteorological rainbow, which is caused by the interference between the
externally reflective waves and refractive waves. The nuclear ripple structure
was confirmed by analyzing the elastic angular distribution in
O+C rainbow scattering at =115.9 MeV using the coupled
channels method by taking account of coupling to the excited states of C
and O with a double folding model derived from a density-dependent
effective nucleon-nucleon force with realistic wave functions for C and
O. The coupling to the excited states plays the role of creating the
external reflection.Comment: 6 pages, 6 figure
Evidence for a secondary bow in Newton's zero-order nuclear rainbow
Rainbows are generally considered to be caused by static refraction and
reflection. A primary and a secondary rainbow appear due to refraction and
internal reflection in a raindrop as explained by Newton. The quantum nuclear
rainbow, which is generated by refraction in the nucleus droplet, only has a
"primary" rainbow. Here we show for the first time evidence for the existence
of a secondary nuclear rainbow generated dynamically by coupling to an excited
state without internal reflection. This has been demonstrated for experimental
O+C scattering using the coupled channel method with an extended
double folding potential derived from microscopic realistic wave functions for
C and O.Comment: 5 pages, 4 figure
Emergence of a secondary rainbow and the dynamical polarization potential for <sup>16</sup>O on <sup>12</sup>C at 330 MeV
Background: It was shown recently that an anomaly in the elastic scattering of 16O on 12C at around 300 MeV is resolved by including within the scattering model the inelastic excitation of specific collective excitations of both nuclei, leading to a secondary rainbow. There is very little systematic knowledge concerning the contribution of collective excitations to the interaction between nuclei, particularly in the overlap region when neither interacting nuclei are light nuclei.
Purpose: Our goals are to study the dynamic polarization potential (DPP) generated by channel coupling that has been experimentally validated for a case (16O on 12C at around 300 MeV) where scattering is sensitive to the nuclear potential over a wide radial range; to exhibit evidence of the nonlocality due to collective coupling; to validate, or otherwise invalidate, the representation of the DPP by uniform renormalizing folding models or global potentials.
Methods: S-matrix to potential, SL → V (r), inversion yields local potentials that reproduce the elastic channel S matrix of coupled channel calculations. Subtracting the elastic channel uncoupled potential yields a local L-independent representation of the DPP. The dependence of the DPP on the nature of the coupled states and other parameters can be studied.
Results: Local DPPs were found due to the excitation of 12C and the combined excitation of 16O and 12C. The radial forms were different for the two cases, but each were very different from a uniform renormalization of the potential. The full coupling led to a 10% increase in the volume integral of the real potential. Evidence for the nonlocality of the underlying formal DPP and for the effect of direct coupling between the collective states is presented.
Conclusions: The local DPP generating the secondary rainbow has been identified. In general, DPPs have forms that depend on the nature of the specific excitations generating them, but, as in this case, they cannot be represented by a uniform renormalization of a global model or folding model potential. The method employed herein is a useful tool for further exploration of the contribution of collective excitations to internuclear potentials, concerning which there is still remarkably little general information
+ Zr cluster structure in Mo
In the evaluation of the half-life of the neutrinoless double- decay
() of a doubly closed-subshell nucleus Zr, the structure
of the nucleus Mo is essentially important. The -clustering
aspects of Mo are investigated for the first time. By studying the
nuclear rainbows in scattering from Zr at high energies and the
characteristic structure of the excitation functions at the extreme backward
angle at the low-energy region, the interaction potential between the
particle and the Zr nucleus is determined well in the double folding
model. The validity of the double folding model was reinforced by studying
scattering from neighboring nuclei Zr, Zr, and
Zr. The double-folding-model calculations reproduced well all the
observed angular distributions over a wide range of incident energies and the
characteristic excitation functions. By using the obtained potential the
+Zr cluster structure of Mo is investigated in the
spirit of a unified description of scattering and structure. The existence of
the second-higher nodal band states with the + Zr cluster
structure, in which two more nodes are excited in the relative motion compared
with the ground band, is demonstrated. The calculation reproduces well the
ground-band states of Mo in agreement with experiment. The experimental
value of the transition in the ground band is also reproduced well. The
effect of clustering in Mo on the the half-life of the
double- decay of Zr is discussed.Comment: 11 pages, 9 figure
Current and fluctuation in a two-state stochastic system under non-adiabatic periodic perturbation
We calculate a current and its fluctuation in a two-state stochastic system
under a periodic perturbation. The system could be interpreted as a channel on
a cell surface or a single Michaelis-Menten catalyzing enzyme. It has been
shown that the periodic perturbation induces so-called pump current, and the
pump current and its fluctuation are calculated with the aid of the geometrical
phase interpretation. We give a simple calculation recipe for the statistics of
the current, especially in a non-adiabatic case. The calculation scheme is
based on the non-adiabatic geometrical phase interpretation. Using the Floquet
theory, the total current and its fluctuation are calculated, and it is
revealed that the average of the current shows a stochastic-resonance-like
behavior. In contrast, the fluctuation of the current does not show such
behavior.Comment: 7 pages, 1 figur
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