<sup>6</sup>
                    He + α clustering in
                    <sup>10</sup>
                    Be

Soić, N.; Blagus, S.; Bogovać, M.; Fazinić, Stjepko; Латтуада, М.; Milin, Matko; Miljanić, Đ.; Rendić, D.; Spitaleri, C.; Tadić, Tonči; Задро, М.

doi:10.1209/epl/i1996-00407-y

Cited by 79 publications

(44 citation statements)

References 16 publications

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“…Recently, contributions of such higher shells were analyzed in Nϭ8 nuclei. A calculation based on the shell model has shown that the slow ␤ decay of 12 Be to 12 B can be explained by an admixture of the sd shell in 12 Be (Nϭ8) in which the closed p-shell component must be less than 30% ͓4͔. This shows that the concept of magic numbers is vague in 12 Be.…”

Section: Introductionmentioning

confidence: 99%

“…A calculation based on the shell model has shown that the slow ␤ decay of 12 Be to 12 B can be explained by an admixture of the sd shell in 12 Be (Nϭ8) in which the closed p-shell component must be less than 30% ͓4͔. This shows that the concept of magic numbers is vague in 12 Be. In the case of light nuclei, it has been shown that cluster structure appears in the vicinity of a threshold energy ͓5,6͔.…”

Section: Introductionmentioning

confidence: 99%

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Molecular orbital structures in10Be

2000

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The structure of 10 Be is investigated using a microscopic ␣ϩ␣ϩnϩn model based on the molecular orbit ͑MO͒ model. The low-lying states are characterized by several configurations of valence neutrons, which are constructed as combinations of three basic orbits. The model space employed is extended from the traditional MO models, and the orbits are expressed as linear combinations of local Gaussians. Their positions are determined variationally. Using this model, we reanalyze the structure of 9 Be and show that this extension enables us to use the original two-body spin-orbit interaction determined from a scattering phase-shift analysis of ␣-n. In 10 Be, all of the observed positive-parity bands and the negative-parity bands are described within the model. The 0 ϩ ground state of 10 Be is described by a dominant (3/2 Ϫ ) 2 configuration. The state has a rather large binding energy ͑8.38 MeV from the ␣ϩ␣ϩnϩn threshold experimentally͒, and the mechanism leading to binding, such as a pairing effect and reduction of the kinetic energy between two clusters, is discussed in detail. In spite of this large binding, the ␣-␣ clustering in the ground state persists due to a coupling effect between the 6 Heϩ␣ configuration and the 5 Heϩ 5 He configuration, which provides a smooth potential for the valence neutrons. The second 0 ϩ state of 10 Be has a large ␣-␣ structure with a (1/2 ϩ ) 2configuration. An enlargement of the ␣-␣ distance due to two-valence neutrons along the ␣-␣ axis makes their wave function smooth and reduces the kinetic energy drastically. Furthermore, the contribution of the spinorbit interaction due to coupling between the S z ϭ0 and the S z ϭ1 configurations is important. We also show the mediation effect of two valence neutrons between two ␣ clusters.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Molecular orbital structures in10Be

2000

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“…For instance, the presence of rotational bands with the α-α structure in the excited states of 10 Be and 12 Be and the breaking of the magic number (N = 8) due to the clustering of the core have attracted much attention [9][10][11][12][13][14][15][16]. We have suggested, based on the molecular-orbit model, that these phenomena can be well explained by introducing single-particle orbits around the α-α cluster structure [15].…”

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confidence: 99%

Linear-chain structure of three α clusters inC13

2006

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We investigate a linear-chain configuration of three α clusters with a neutron in 13 C. To characterize this configuration, an operator P is introduced, which is the sum of parity inversion operators for each proton. The states with positive expectation values for this operator are found to form a rotational band structure, and the moment of inertia agrees well with the experimentally suggested value. Allowing a small bending angle stabilizes the linear-chain configuration of three α clusters with a valence neutron, which is a hyper-deformed state. The realization of linear-chain configurations has been a long-standing objective of nuclear structure physics. However, it is difficult to stabilize this configuration in nuclear systems, which is contrary to the case in atomic systems. The linearchain structure of three α clusters was suggested nearly half a century ago [1], and the second 0 + (0 + 2 ) state of 12 C at E x = 7.65 MeV just above the three α threshold energy is a candidate for having this structure. This state is considered to have an exotic cluster structure that is analogous with the so-called mysterious 0 + state of 16 O at E x = 6.06 MeV, which has a 12 C+α cluster structure and is not completely explained by a simple shell-model picture. However, the 0 + 2 state, which plays a crucial role in the synthesis of 12 C from three 4 He nuclei in stars [2], has been proven to contain not only the linear-chain configuration but also various three α configurations by many microscopic cluster models [3]. The state is gaslike without a specific geometric shape, and it has been recently reinterpreted as an α-condensed state [4]. The search for linear-chain states of α clusters has been extended to heavier N = Z nuclei [5][6][7][8]; however, further investigations are needed to confirm that those states are really linear-chain structures.The difficulty of the linear-chain configuration is briefly explained in the following way. From the harmonic-oscillator point of view, if three α clusters form a linear configuration on the z axis, four nucleons in the central α cluster occupy the lowest s orbits; however, eight nucleons in the other α clusters are excited to higher orbits such as the p(z) and sd(z 2 ) orbits due to the antisymmetrization effect. If the system has some bending angle, three α clusters form a two-dimensional configuration in the xz plane, and in this case four nucleons corresponding to the sd(z 2 ) orbits are deexcited to the p(x) orbits. We may conclude that in light nuclei, where the value ofhω is about 20 MeV, it is difficult to prevent the mixing of states with different bending angles.Another difficulty comes from the weak-coupling nature of the nuclear systems. If the state is largely clusterized, i.e., not only the total system of three α clusters, the α-α subsystem ( 8 Be) tends to have good angular momentum, since the angular momentum projection for the intrinsic wave function of 8 Be to the 0 + state induces a decrease in the energy by about 10 MeV.This angular momentum projection of...

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“…[13]), with associate states finally clearly established in 10 Be [14,15] as a rotational band starting with the 0…”

Section: Introductionmentioning

confidence: 99%

Clusters in neutron-rich light nuclei

Malenica

Milin

Pietro

et al. 2016

EPJ Web of Conferences

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Due to their high selectivity, transfer and sequential decay reactions are powerful tools for studies of both single particle (nucleon) and cluster states in light nuclei. Their use is particularly simple for investigations of α-particle clustering (because α-particle has J π =0 + , which simplifies spin and parity assignments to observed cluster states), but they are also easily applicable to other types of clustering. Recent results on clustering in neutron-rich isotopes of beryllium, boron and carbon obtained measuring the 10 B+ 10 B reactions (at 50 and 72 MeV) are presented. The highly efficient and segmented detector systems used, built from 4 Double Sided Silicon Strip Detectors (DSSSD) allowed detection of double and multiple coincidences and, in that way, studies of states populated in transfer reactions, as well as their sequential decay.Clustering was recognized [1] as an essential ingredient in description of light nuclei already in the early days of nuclear physics, even before the actual formulation of nuclear shell model. A systematic picture of the phenomenon for the α-conjugate nuclei (with N =Z) emerged in the late sixties,

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⁶ He + α clustering in ¹⁰ Be

Abstract: Abstract. -In a kinematically complete measurement of the 7 Li( 7 Li,α 6 He)

Cited by 79 publications

References 16 publications

Molecular orbital structures in10Be

Molecular orbital structures in10Be

Linear-chain structure of three α clusters inC13

Clusters in neutron-rich light nuclei

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6 He + α clustering in 10 Be

Abstract: Abstract. -In a kinematically complete measurement of the 7 Li( 7 Li,α 6 He)

Cited by 79 publications

References 16 publications

Molecular orbital structures in10Be

Molecular orbital structures in10Be

Linear-chain structure of three α clusters inC13

Clusters in neutron-rich light nuclei

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⁶ He + α clustering in ¹⁰ Be