A recent comparison of the average fusion cross section,
σ
F
, for energies just above the Coulomb barrier for the
12
-
15
C +
12
C systems found that the behaviour as a function of projectile ...neutron excess could not be satisfactorily explained by static barrier penetration model calculations and suggested that the neutron dynamics plays an important rôle. In this work we demonstrate that the (
15
C,
14
C) single neutron transfer has a significant influence on the above barrier
15
C +
12
C total fusion, although not quite in the way expected since it leads to a reduction in the cross section, contrary to the trend in the measured
σ
F
. However, this result underlines the danger of ignoring the effect of neutron transfer reactions on fusion in systems involving neutron halo nuclei.
While it is well established that the ground state reorientation coupling can have a significant influence on the elastic scattering of deformed nuclei, the effect of such couplings on transfer ...channels has been much less well investigated. In this letter we demonstrate that the
208
Pb
(
7
Li
,
6
He
)
209
Bi
proton stripping reaction at an incident energy of 52 MeV can be well described by the inclusion of the
7
Li
ground state reorientation coupling within the coupled channels Born approximation formalism. Full finite-range distorted wave Born approximation calculations were previously found to be unable to describe these data. Addition of coupling to the 0.478-MeV
1
/
2
-
excited state of
7
Li
, together with the associated two-step transfer path, has little or no influence on the shape of the angular distributions (except that for stripping leading to the 1.61-MeV
13
/
2
+
level of
209
Bi
which is significantly improved) but does affect appreciably the values of the
209
Bi
→
208
Pb
+
p
spectroscopic factors. Implications for experiments with weakly-bound light radioactive beams are discussed.
Accurate elastic scattering angular distribution data measured at bombarding energies just above the Coulomb barrier have shapes that can markedly differ from or be the same as the expected classical ...Fresnel scattering pattern depending on the structure of the projectile, the target or both. Examples are given such as
18
O +
184
W and
16
O +
148, 152
Sm, where the expected rise above Rutherford scattering due to Coulomb-nuclear interference is damped by coupling to the target excited states, and the extreme case of
11
Li scattering, where coupling to the
9
Li +
n
+
n
continuum leads to an elastic scattering shape that cannot be reproduced by any standard optical model parameter set. An early indication that the projectile structure can modify the elastic scattering angular distribution was the large vector analyzing powers observed in polarised
6
Li scattering. The recent availability of high-quality
6
He,
11
Li and
11
Be data provides further examples of the influence that coupling effects can have on elastic scattering. Conditions for strong projectile-target coupling effects are presented with special emphasis on the importance of the beam-target charge combination being large enough to bring about the strong coupling effects. Several measurements are proposed that can lead to further understanding of strong coupling effects by both inelastic excitation and nucleon transfer on near-barrier elastic scattering. A final note on the anomalous nature of
8
B elastic scattering is presented as it possesses a more or less normal Fresnel scattering shape whereas one would
a priori
not expect this due to the very low breakup threshold of
8
B . The special nature of
11
Li is presented as it is predicted that no matter how far above the Coulomb barrier the elastic scattering is measured, its shape will not appear as Fresnel like whereas the elastic scattering of all other loosely bound nuclei studied to date should eventually do so as the incident energy is increased, making both
8
B and
11
Li truly “exotic”.
Ultrafast light pulses can modify electronic properties of quantum materials by perturbing the underlying, intertwined degrees of freedom. In particular, iron-based superconductors exhibit a strong ...coupling among electronic nematic fluctuations, spins and the lattice, serving as a playground for ultrafast manipulation. Here we use time-resolved X-ray scattering to measure the lattice dynamics of photoexcited BaFe2As2. On optical excitation, no signature of an ultrafast change of the crystal symmetry is observed, but the lattice oscillates rapidly in time due to the coherent excitation of an A1g mode that modulates the Fe-As-Fe bond angle. We directly quantify the coherent lattice dynamics and show that even a small photoinduced lattice distortion can induce notable changes in the electronic and magnetic properties. Our analysis implies that transient structural modification can be an effective tool for manipulating the electronic properties of multi-orbital systems, where electronic instabilities are sensitive to the orbital character of bands.
In a recent experiment investigating the origin of the
α
particle yield in the
7
Li +
144
Sm system the measured
α
+
d
coincidences at a bombarding energy of 30 MeV were shown to arise from decay of ...the 2.186-MeV
3
+
resonance of
6
Li. In this work we demonstrate that the laboratory frame
α
particle angular distribution extracted from these data can be well described by a standard coupled channels Born approximation calculation and, furthermore, that the mechanism is dominated by direct, one-step single neutron stripping to the
3
+
resonance, as shown previously for the
7
Li +
65
Cu and
93
Nb systems.
Is the Structure of Si 42 Understood? Gade, A.; Brown, B. A.; Tostevin, J. A. ...
Physical review letters,
06/2019, Letnik:
122, Številka:
22
Journal Article
Jacque Raynal’s coupled channels code ECIS has played an important role in the effort to search for shell effects in exotic isotopes using both intermediate energy Coulomb excitation and inverse ...kinematics proton scattering to probe their level structures and to extract neutron and proton excitation modes through their
M
n
/
M
p
values. It will continue to be an important tool as nuclei very far from the stable ones are produced in new exotic beam accelerator centers.
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