Search for Signs of Neutron and Proton Halos in the Excited Isobaric Analog States of A = 14 Nuclei
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Search for Signs of Neutron and Proton Halos in the Isobaric Analog Excited States of A = 14 Nuclei A. S. Demyanova+1) , A. N. Danilov+ , A. A. Ogloblin+ , S. A. Goncharov∗, T. L. Belyaeva×, W. H. Trzaska◦ , V. I. Starastsin+ + National
Research Centre Kurchatov Institute, 123182 Moscow, Russia
∗ Lomonosov × Universidad ◦ Department
Moscow State University, 119991 Moscow, Russia
Aut´ onoma del Estado de M´ exico, 50000 Toluca, M´exico
of Physics, University of Jyv¨ askyl¨ a, FI-40014 Jyv¨ askyl¨ a, Finland Submitted 4 September 2020 Resubmitted 4 September 2020 Accepted 16 September 2020
The isobaric analog states with isospin T = 1 in triplet of the A = 14 nuclei: 14 C, 14 N, and 14 O, are studied. Signs of neutron halo in the 1− (6.09 MeV) state of 14 C have been revealed earlier by two groups. We confirm this result and study isobaric analog 1− states of neighboring 14 N and 14 O nuclei. The differential cross sections of the 14 C(α, α)14 C∗ (6.09 MeV, 1− ) inelastic scattering, the 13 C(3 He, d)14 N* (8.06 MeV, 1− ), and the 14 N(3 He, t)14 O* (5.17 MeV, 1− ) reactions are analyzed by two methods: the modified diffraction method and the method of asymptotic normalization coefficients. The rms radii for all three mirror nuclei in the studied 1− states are found almost the same: 2.7 ± 0.1 fm for 14 C, 2.67 ± 0.07 fm for 14 N, and 2.6 ± 0.2 fm for 14 O. The signs of proton halo in the 1− state of 14 N are identified for the first time. DOI: 10.1134/S0021364020200011
1. Introduction. One of the most striking discoveries in nuclear physics made at the end of the past century was the finding the neutron halo in the ground states of some light nuclei [1] located near the neutron stability boundary. The halo manifests itself in the presence of a diffuse surface region surrounding a core with a normal nuclear density and containing only neutrons. The result is a long “tail” of their wave function and, correspondingly, an increase in the radius of the entire nucleus in a given state. According to [2–6], the halo state is characterized by (i) a large probability for finding a cluster component in the total many-body wave function and (ii) a large spatial extension implying that more than half of the probability should be in the classically forbidden region outside the outer classical turning point. These are quite strict requirements, and it is important to answer the question of whether realistic halos satisfy these criteria and how the halo features appear in less developed halos. Until recently, it was believed that the halo can be formed only in the ground states of radioactive nuclei located near stability boundaries. However, back in the late 1950s, long before the discovery of the halo phe1) e-mail:
nomenon, A. I. Baz practically has predicted [7] the possibility of neutron halo in stable nuclei near the thresholds of neutron emission. The first indication of a neutron halo in the stable 13 C nucleus in its first excited state of 3.09 MeV, 1/2+ was obtained in [8] and confirmed in [9]. It turned out that the region of ex
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