The angular distributions for the 11.28, 11.82, and 13.79 MeV states were obtained and analyzed from the scattering of light particles by the
Be nucleus. The MDM method was used to estimate the ...radii. The radius of the 11.82 MeV state turned out to be equal to the radius of the ground state. For the 11.28 MeV the radius turned out to be increased. As for the 13.79 MeV state, the obtained value of the diffraction radius was ambiguous. The spin–parity values were estimated using the semiempirical Bohr–Mottelson formula. A conclusion was made on assignment of these states to the corresponding bands in the
Be nucleus.
A theoretical analysis of available experimental data on elastic and inelastic
C scattering in the energy region extending up to 90 MeV is performed. The parameters of a semimicroscopic potential are ...found on the basis of the dispersive optical model. The potentials found in this way are used in analyzing, by the distorted-wave Born approximation, data that the authors recently measured for inelastic scattering at energies of 65 and 90 MeV. Experimental data for the states at 3.68 and 7.55 MeV are presented for the first time. These states are considered under the assumption that, within the standard rotational model, they are members of the ground-state rotational band. A satisfactory description of angular distributions is obtained, and deformation lengths are determined. A model phenomenological form factor is used for the remaining excitations in the energy range extending up to 11 MeV. The present analysis confirms the presence of a neutron halo in the 3.09-MeV state. A similarity of form of the inelastic form factors obtained for the 8.86-, 10.996-, and 11.08 MeV states and the proximity of their radii gives grounds to assume that the
C nucleus in these three states has an enhanced size and similar structures. A comparison of the radial dependences of the form factors for the 9.90- and 8.86-MeV states shows that the wave function for the 9.90-MeV state has a substantially smaller spatial extension. These results agree with the values obtained for the radii of the states under discussion on the basis of the modified diffraction model.
The famous 7.65-MeV 0
Hoyle state of
C is always attracting plenty attention. This state has dilute 3
configuration and plays important role in nucleosynthesis. Question is if there are states analog ...to the Hoyle state in other 4
nuclei. It is possible that
-cluster 0
state in
Ne can be considered as an analog of the 7.65-MeV 0
Hoyle state of
C.
Size Isomers at Threshold States Demyanova, A. S.; Danilov, A. N.; Starastsin, V. I. ...
Physics of atomic nuclei,
08/2023, Letnik:
86, Številka:
4
Journal Article
Recenzirano
Odprti dostop
An overview is provided for a new class of states, which we have named as the size isomers. Such states are weakly bound and have an exotic structure (cluster states, halo/‘‘skin’’). The development ...of methods for measuring the radii of nuclei in their short-lived excited states led to the discovery of new classes of states. The size of a nucleus defined by the radius of its nucleon (proton and neutron) density distribution and the proton charge distribution is one of the most fundamental and important nuclear characteristics. Nuclear radius determines the basic properties of nuclei and is a consequence of the fundamental features of the strong interaction. Up to now two groups of the size isomers were identified: the excited states with halos (
Be,
Be,
C,
N) and some specific alpha-cluster states (
B,
C,
C). All the observed states are dilute, however, some indication to possible existence of more compact than the ground states was obtained as well (in
C). The phenomenon of size isomerism occurred to be not a rare one especially if we take into account rotational bands based on some of such states. The structure of size isomers is related with some new features, e.g., rotating halos, halos in continuum, different types of quasimolecular configurations. Some rudimentary signs of alpha-particle condensation (a ‘‘ghost’’ of condensate) were observed in the Hoyle state of
C, however, we cannot speak about confirmation of this ambitious theory. Analogs to the Hoyle state, expected in
B,
C,
O,
Ne near the
-emission thresholds, are considered.
Search for Exotic States in 13C Demyanova, A. S.; Danilov, A. N.; Dmitriev, S. V. ...
JETP letters,
2021/9, Letnik:
114, Številka:
6
Journal Article
Recenzirano
New experimental data on the inelastic scattering of α-particles on
13
C at
and 90 MeV with the excitation of the
state are reported. Data are analyzed using the modified diffraction model. The ...determined rms radius of this state coincides within errors with the radius of the
8.86 MeV state in
13
C and the Hoyle state in
12
C. This result is an argument for a similar structure of these states. The unusual result for the compact 3/2
–
9.90 MeV state in
13
C has been tested by considering its isobar-analog 3/2
–
9.48 MeV state in
13
N. It has been found that these states have a normal non-increased radius.
This article is devoted to study of isobar-analogue states 1− in triplet A=14: 14C-14N-14O. Previously signs of neutron halo in the 1−, 6.09 MeV state of 14C were obtained by two independent groups. ...In this article we propose to study neighbouring nuclei 14N and 14O using the Modified diffraction model (MDM) method and the method of Asymptotic normalization coefficients (ANC). Methods were applied to experimental differential cross sections of 14C(α,α)14C scattering and reactions 13C(3He,d)14N and 14N(3He,t)14O. MDM and ANC gave practically similar within errors radii for the studied 1− states: the 6.09 MeV state in 14C - 2.7±0.1 fm, the 8.06 MeV state in 14N - 2.7 ± 0.1 fm, the 5.17 MeV state in 14O - 2.6 ± 0.2 fm. Moreover, the signs of proton halo in the 1− state of 14N were obtained for the first time.
The differential cross sections for the
12
C(
3
He,
t
)
12
N reaction leading to formation of the 1
+
(ground state), 2
+
(0.96 MeV), 2
−
(1.19 MeV), and 1
−
(1.80 MeV) states of
12
N are measured at
...E
(
3
He) = 40 MeV. The analysis of the data is carried out within the modified diffraction model and distorted wave Born approximation. Increased rms radii have been obtained for the ground, 2
−
(1.19 MeV), and 1
−
(1.80 MeV) states. We revealed that
12
B,
12
N, and
12
C in the isobaric analogue states with
T
= 1, and spin-parities 2
−
and 1
−
have increased radii and exhibit properties of neutron and proton halo states.
The review is concerned with studies of one-nucleon and two-nucleon halos in isobar analog states of light nuclei with
. The study allow us to investigate manifestations of isotopic invariance in new ...objects and to relate properties of the neutrino and proton halos. The existence of a halo in isobar analog states has been little studied experimentally so far. It is proposed to solve the problem of experimentally determining the radii of some possible halo states in nuclei from
6
Li to
14
O that make up isobar analog doublets and triplets. New possible halo candidates are found in the
13
C and
13
N mirror nuclei, in the
= 12 and
= 14 isobar analog multiplets. Note that the isobar analog states with
in the
triplet are experimentally investigated for the first time in the transfer and charge-exchange reactions. It is established that the root-mean-square radii of the
states in the
multiplet coincide within errors. The results are obtained by two independent methods, ANC and MDM.
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