Energy levels of light nuclei A= 12

The 16.1 MeV 2 + resonance in 12 C situated slightly above the proton threshold can decay by proton-, α-, and γ emission. The partial width for proton emission cannot be directly measured due to the low proton energy and the small branching ratio. Instead it must be indirectly derived from other observables. However, due to several inconsistent data the derived partial width varies by almost a factor 2 dependent on the data used. Here we trace the majority of this inconsistency to different measurements of the (p, α) cross sections. We have remeasured this cross section using modern large area silicon strip detectors allowing to measure all final state particles, which circumvents a normalization issue affecting some of the previous measurements. Based on this we determine Γp = 21.0(13) eV. We discuss the implications for other observables related to the 16.1 MeV 2 + resonance and for isospin symmetry in the A = 12 system. In addition, we conclude that the dataset currently used for the NACRE and NACRE II evaluation of the 11 B(p, 3α) reaction should be scaled by a factor of 2/3. This impacts the reaction rate accordingly.PACS. 23.20.+e α decay -27.20.+n Properties of specific nuclei listed by mass ranges; 6 ≤ A ≤ 19

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“…The proton width recommended by ref. [15] results in good agreement with this spectroscopic factor, while that of ref. [12] does not.…”

Section: Introductionsupporting

confidence: 89%

“…Both values are consistent, within the errors, with that of the latest compilation [15], but not with the value favored in the recent review in ref. [12].…”

Section: Derived Partial Widthssupporting

confidence: 73%

The partial widths of the 16.1 MeV 2+ resonance in 12C

Münch

Fynbo

2018

Eur. Phys. J. A

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“…The potential parameters V (0,2) c and V ls are adjusted to fix the scattering length of this virtual state and to provide a 5/2 + resonance just below the 2 + excitation threshold in 12 Be, i.e. at 2.11 MeV [50]. Note that, in this scheme, the 5/2 + state may decay via d 5/2 neutrons to the ground state of 12 Be, but also via s 1/2 to the 2 + excited state, given its finite width.…”

Section: Three-body Calculationsmentioning

confidence: 99%

Structure of 13Be probed via quasi-free scattering

et al. 2019

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We present an investigation of the structure of 13 Be obtained via a kinematically complete measurement of the (p, pn) reaction in inverse kinematics at 265 MeV/nucleon. The relative energy spectrum of 13 Be is compared to Transfer-to-the-Continuum calculations which use as structure inputs the overlaps of the 14 Be ground-state wave function, computed in a three-body model, with the unbound states of the 13 Be residual nucleus. The key role of neutron p-wave orbital in the interpretation of the low-relative-energy part of the spectrum is discussed.

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“…B(EL) values in8 Be,12 C and16 O in e 2 fm 2L . Experimental data are taken from[78][79][80], and theoretical ACM results from[39,41,62].…”

mentioning

confidence: 99%

Cluster structure of light nuclei

Bijker

Iachello

2020

Progress in Particle and Nuclear Physics

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We review recent studies of the cluster structure of light nuclei within the framework of the algebraic cluster model (ACM) for nuclei composed of k α-particles and within the framework of the cluster shell model (CSM) for nuclei composed of k α-particles plus x additional nucleons. The calculations, based on symmetry considerations and thus for the most part given in analytic form, are compared with experiments in light cluster nuclei. The comparison shows evidence for Z 2 , D 3h and T d symmetry in the even-even nuclei 8 Be (k = 2), 12 C (k = 3) and 16 O (k = 4), respectively, and for the associated double groups Z ′ 2 and D ′ 3h in the odd nuclei 9 Be, 9 B (k = 2, x = 1) and 13 C (k = 3, x = 1), respectively. configurations for nuclei composed of k α-particles, here referred as kα nuclei.In particular, the suggested configurations of the ground state were, for k = 2 a dumbbell configuration with Z 2 symmetry ( 8 Be), for k = 3 an equilateral triangle with D 3h symmetry ( 12 C) and for k = 4 a tetrahedron with T d symmetry ( 16 O), as shown in Fig. 1. Brink's suggestion stimulated a considerable amount of work in an attempt to derive cluster properties from the shell model, especially by the Japanese school [8][9][10][11] and from mean field theories [12]. Also, the cluster structure of specific nuclei was extensively investigated, as for example in 16 O [13,14], and Brink's model was applied to a wide range of cluster nuclei from 12 C to 44 Ti in [15,16]. A review of cluster models up to 2006 can be found in [17], and more recent ones in [18] and [19].In recent years, there has been considerable renewed interest in the structure of α-cluster nuclei, especially for the nucleus 12 C [20]. The observation of new rotational states built on the ground state [21-24] and the Hoyle state [25-27] has stimulated a large effort to understand the structure of 12 C ranging from studies based on Antisymmetric Molecular Dynamics (AMD) [28], Fermion Molecular Dynamics (FMD) [29], BEC-like cluster model [30], ab initio no-core shell model [31-33], lattice EFT [34-36], no-core symplectic model [37] and the Algebraic Cluster Model (ACM) [38][39][40][41]. In the first part of this paper, we review the ACM as applied to kα nuclei with k = 2, 3, 4.An important question is the extent to which cluster structures survive the addition of nucleons (protons and neutrons). We refer to nuclei composed of k α-particles plus x nucleons as kα + x nuclei. This question has also been addressed in the past, especially in the case of the Be isotopes seen as 8 Be + x nucleons, with a variety of methods [42][43][44][45][46][47] culminating, in the 1970's, in the extensive work of Okabe, Abe and Tanaka [48, 49] using the Linear Combination of Atomic Orbitals (LCAO) method and its generalizations. In recent years, FMD [50-53] and AMD [54-56] calculations have provided very detailed and accurate microscopic descriptions of the Be isotopes with large overlap with the Brink model [7]. In another seminal development, Von Oertzen [57-60] hasdiscussed the ...

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Energy levels of light nuclei A= 12

Cited by 144 publications

References 2,612 publications

The partial widths of the 16.1 MeV 2+ resonance in 12C

The partial widths of the 16.1 MeV 2+ resonance in 12C

Structure of 13Be probed via quasi-free scattering

Cluster structure of light nuclei

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