Observation of a two-proton halo in 17Ne

Kanungo, R.; Chiba, M.; Abu-Ibrahim, B.; Adhikari, S.; Fang, DQ; Iwasa, N.; Kimura, K.; Maeda, K.; Nishimura, S.; Ohnishi, T.; Ozawa, A.; Samanta, C.; Suda, T.; Suzuki, Tomokazu; Wang, Q; Wu, Changqi; Yamaguchi, Yoshitaka; Yamada, Kazunari; Yoshida, Akihiro; Tao, Zheng; Tanihata, I.

doi:10.1140/epjad/i2005-06-184-y

Cited by 12 publications

(10 citation statements)

References 10 publications

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“…For 17 Ne FMD agrees with the measured radius, attributed to a clearly visible tail in the proton density distribution (shown together with neutron and matter distributions in Fig. 3), which implies a narrow proton momentum distribution [7] of protons relative to the compact 15 O core (FMD matter and charge radii: r m ¼ 2:46 fm, r ch ¼ 2:63 fm). Because of the missing centrifugal barrier, weakly bound s orbits are much more extended than d orbits.…”

supporting

confidence: 83%

“…The first information on the 17 Ne wave function was an asymmetry in the first-forbidden decay compared to the decay rate in the mirror nucleus 17 N [2], which was either attributed to a halo structure in the excited state of 17 F or to differences in the 17 Ne and 17 N wave functions due to Coulomb effects [3]. Using Glauber theory, interaction cross-section measurements [4] gave a matter radius of 2.75(7) fm, significantly larger than in 17 N. Two-proton emission was observed from higher-lying excited states of 17 Ne [5], whereas a large cross section and a narrow momentum distribution were found in two-proton removal reactions [6,7], which provided (within the Glauber model) a very large s 2 component. In contrast to the above investigations, the magnetic moment of 17 Ne, measured using collinear laser spectroscopy [8], was reproduced by shellmodel calculations giving only a small s 2 occupation.…”

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confidence: 99%

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Masses and Charge Radii ofNe17–22and the Two-Proton-Halo CandidateNe17

et al. 2008

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High-precision mass and charge radius measurements on ;{17-22}Ne, including the proton-halo candidate 17Ne, have been performed with Penning trap mass spectrometry and collinear laser spectroscopy. The 17Ne mass uncertainty is improved by factor 50, and the charge radii of ;{17-19}Ne are determined for the first time. The fermionic molecular dynamics model explains the pronounced changes in the ground-state structure. It attributes the large charge radius of 17Ne to an extended proton configuration with an s;{2} component of about 40%. In 18Ne the smaller radius is due to a significantly smaller s;{2} component. The radii increase again for ;{19-22}Ne due to cluster admixtures.

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supporting

confidence: 83%

mentioning

confidence: 99%

Masses and Charge Radii ofNe17–22and the Two-Proton-Halo CandidateNe17

et al. 2008

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“…This is in accord with the simplest picture that 17 Ne consists of an 15 O core plus two protons in either s 2 or d 2 configurations. Interaction cross sections [18] and longitudinal momentum distributions [19] support the halo picture. In 18 Ne the situation is similar but in the same simple picture the core is now the doubly magic 16 O, which leads to a significantly smaller s 2 component and hence a smaller charge radius.…”

Section: Neon Isotopes and Two-proton Halomentioning

confidence: 54%

“…The subsequent increase in charge radius for 19 Ne is of different origin. The fact that the experimental 1/2 + and 1/2 − states are almost degenerate and the cluster thresh- Figure 3.…”

Section: Neon Isotopes and Two-proton Halomentioning

confidence: 96%

Clusters, Halos, And S-Factors In Fermionic Molecular Dynamics^*

Feldmeier

Neff

2013

EPJ Web of Conferences

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Abstract. In Fermionic Molecular Dynamics antisymmetrized products of Gaussian wave packets are projected on angular momentum, linear momentum, and parity. An appropriately chosen set of these states span the many-body Hilbert space in which the Hamiltonian is diagonalized. The wave packet parameters -position, momentum, width and spin -are obtained by variation under constraints. The great flexibility of this basis allows to describe not only shell-model like states but also exotic states like halos, e.g. the two-proton halo in 17 Ne, or cluster states as they appear for example in 12 C close to the α breakup threshold where the Hoyle state is located. Even a fully microscopic calculation of the 3 He(α,γ) 7 Be capture reaction is possible and yields an astrophysical S-factor that compares very well with newer data. As representatives of numerous results these cases will be discussed in this contribution, some of them not published so far. The Hamiltonian is based on the realistic Argonne V18 nucleon-nucleon interaction. Fermionic Molecular Dynamics (FMD)In the FMD approach we employ Gaussian wave packetsas single-particle basis states. The complex parameters b encode the mean positions and momenta of the wave packets and a the widths of the wave packets. The spins can assume any direction, isospin is ±1 denoting a proton or a neutron. Intrinsic many-body basis states are Slater determinantsthat reflect deformation or clustering and break the symmetries of the Hamiltonian with respect to parity, rotation and translation. To restore the symmetries the intrinsic basis states are projected on parity, angular momentum and total linear momentumIn a full FMD calculation the many-body Hilbert space is spanned by a set of N projected intrinsic basis states Q (a) ; J π MK; P = 0 , a = 1, . . . , N . By diagonalizing the Hamiltonian in this set of non-orthogonal basis states the amplitudes of the various configurations contained in the many-body eigenstate are determined.Starting from the realistic Argonne V18 interaction [1] we derive a phase-shift-equivalent effective lowmomentum interaction using the unitary correlation operator method (UCOM). The basic idea of the UCOM approach is to explicitly include short-range central and Cluster States in 1CThe structure of the second 0 + 2 state in 12 C, the Hoyle state, is enjoying renewed and still growing interest in nuclear structure research [5][6][7][8][9]. In [10] we investigated its structure with a model space spanned by angular momentum projected FMD configurations obtained by variation plus a full set of projected three-α triangular configurations. We found that the Hoyle state is very dilute and extended, consisting mainly of well distinguished α-clusters. This is illustrated in the top part of Fig. 1 where we show the density distribution of those intrinsic FMD basis states that have the largest overlap with the ground state and the Hoyle state.While the leading intrinsic configuration of the ground state is very compact, and after projection on good angular moment...

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“…Yet, there is no final conclusion: the three-body model of Grigorenko et al [6], which is the benchmark for our study, predicts a value of 48 %. Kanungo et al [7] have measured narrow longitudinal-momentum distributions of the 15 O core in connection with a large cross section in 2p-removal reactions from 17 Ne beams on a Be target. They determined an s 2 -weight of 70 % and concluded to observe a 2-proton halo.…”

Section: Introductionmentioning

confidence: 99%