Mass measurements of neutron-rich nuclei near the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mi>N</mml:mi><mml:mo>=</mml:mo><mml:mn>20</mml:mn></mml:math> and 28 shell closures

Jurado, B.; Savajols, H.; Mittig, W.; Orr, N. A.; Roussel‐Chomaz, P.; Baiborodin, D.; Catford, W. N.; Chartier, M.; Demonchy, C. E.; Dlouhý, Z.; Gillibert, A.; Giot, L.; Khouaja, A.; Lépine‐Szily, A.; Lukyanov, S. M.; Mrázek, J.; Penionzhkevich, Yu. É.; Pita, S.; Rousseau, M.; Villari, A. C. C.

doi:10.1016/j.physletb.2007.04.006

Cited by 143 publications

(74 citation statements)

References 26 publications

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“…Owing to the fact that this fitting function is less adapted to the shape of the resonances, the errors bars on these energy centroids are larger, E 1 rel = 366(119) keV and E 2 rel = 2430(650) keV, but the centroids themselves are fully compatible with those obtained previously and listed in Table II. Single-particle widths Table II), which, within the large uncertainties, is compatible with an = 2 component. As 26 F populated via the one-proton-knockout reaction 27 Ne(−1p) under the assumption that S n = 1071(130) keV [18]. Resonance energies E i r , excitation energies E i exc , and widths i r of the three resonances are given in keV with calculated single-particle widths ( ) sp , assuming various values of the resonance.…”

Section: Experimental Results For 26 Fmentioning

confidence: 99%

“…This broad component can encompass One important word of caution must be added concerning the S n value of 26 F and its consequence on a possible shift in excitation energy of the resonances. The tabulated S n value of 0.80(12) MeV was derived from a time-of-flight measurement of 26 F nuclei produced in a fragmentation reaction [18] in which the existence of the 4 1 + isomer at 643 keV [3] was not known. Therefore, this value possibly contains some mixture of the ground state and isomeric states, and should be considered as a lower value of S n .…”

Section: Discussion On the Results Of 26 Fmentioning

confidence: 99%

“…This (π 0d 5/2 ) 1 (ν0d 3/2 ) 1 coupling results in a J π = 1 1 + − 4 1 + multiplet. Energies of the bound J π = 1 1 + ,2 1 + , and 4 1 + states were measured using different experimental techniques [3,17,18], and only a firm identification of the J π = 3 1 + component is missing. In particular, the spin assignments of the ground state (1 + ) [3,19] and of the weakly bound isomeric state (4 1 + at 643 keV) [3] were proposed from their decay pattern to low-and high-energy spin values, respectively, in the daughter nucleus 26 Ne.…”

Section: Introductionmentioning

confidence: 99%

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Effective proton-neutron interaction near the drip line from unbound states in F25,26

Vandebrouck¹,

Lepailleur²,

Sorlin³

et al. 2017

Phys. Rev. C

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Background: Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The 26 F nucleus, composed of a deeply bound π 0d 5/2 proton and an unbound ν0d 3/2 neutron on top of an 24 O core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a J π = 1 1 + − 4 1 + multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The J π = 1 1 + , 2 1 + , 4 1 + bound states have been determined, and only a clear identification of the J π = 3 1 + is missing. Purpose: We wish to complete the study of the J π = 1 1 + − 4 1 + multiplet in 26 F, by studying the energy and width of the J π = 3 1 + unbound state. The method was first validated by the study of unbound states in 25 F, for which resonances were already observed in a previous experiment. Method: Radioactive beams of 26 Ne and 27 Ne, produced at about 440A MeV by the fragment separator at the GSI facility were used to populate unbound states in 25 F and 26 F via one-proton knockout reactions on a CH 2 target, located at the object focal point of the R 3 B/LAND setup. The detection of emitted γ rays and neutrons, added to the reconstruction of the momentum vector of the A − 1 nuclei, allowed the determination of the energy of three unbound states in 25 F and two in 26 F. Results: Based on its width and decay properties, the first unbound state in 25 F, at the relative energy of 49(9) keV, is proposed to be a J π = 1/2 − arising from a p 1/2 proton-hole state. In 26 F, the first resonance at 323(33) keV is proposed to be the J π = 3 1 + member of the J π = 1 1 + − 4 1 + multiplet. Energies of observed states in 25,26 F have been compared to calculations using the independent-particle shell model, a phenomenological shell model, and the ab initio valence-space in-medium similarity renormalization group method. Conclusions: The deduced effective proton-neutron interaction is weakened by about 30-40% in comparison to the models, pointing to the need for implementing the role of the continuum in theoretical descriptions or to a wrong determination of the atomic mass of 26 F.

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Section: Experimental Results For 26 Fmentioning

confidence: 99%

Section: Discussion On the Results Of 26 Fmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effective proton-neutron interaction near the drip line from unbound states in F25,26

Vandebrouck¹,

Lepailleur²,

Sorlin³

et al. 2017

Phys. Rev. C

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“…The disappearance of the spherical shell closure together with a large deformation, however, has been suggested for 42 Si from the observation of a low energy 2 + 1 state [4]. Several experiments have been performed so far [5][6][7][8][9][10], but no experimental data have been reported on higher-lying state, such as 4 + 1 state, which may contribute valuable information on the nature of the collectivity and/or shell evolution.…”

Section: Introductionmentioning

confidence: 99%

In-beamγ-ray spectroscopy of^38,40,42Si

Matsushita

Takeuchi

Aoi

et al. 2014

EPJ Web of Conferences

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Abstract. Excited states in the nuclei 38,40,42 Si have been studied using in-beam γ-ray spectroscopy following multi-nucleon removal reactions to investigate the systematics of excitation energies along the Z=14 isotopic chain. The most probable candidates for the transition from the yrast 4 + state were tentatively assigned among several γ lines newly observed in the present study. The energy ratios between the 2 + 1 and 4 + 1 states were obtained to be 2.09(5), 2.56(5) and 2.93(5) for 38,40,42 Si, respectively, indicating a rapid development of deformation in Si isotopes from N=24 to, at least, N=28.

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“…The reduced radius r 0 and the depth of the potential were chosen to reproduce r sp and S eff n (effective neutron separation energy), respectively, where r sp = √ A/(A − 1) r HF . The S eff n was calculated to be 6.88 MeV adopting S n ( 24 O) = 4.09 ± 0.13 MeV [18]. The elastic S -matrix for the proton-neutron (proton-core) scattering was calculated by the finite-range Gaussian profile function [19] with a nucleon density of the core obtained from the HF calculation.…”

mentioning

confidence: 99%

Neutron occupancy of 0d_5/2orbital in²⁴O

Tshoo

Satou

Bhang

et al. 2014

EPJ Web of Conferences

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Abstract. The partial one-neutron removal cross section of 24 O leading to the first excited state in 23 O has been measured to be 65.7 ± 5.3 mb with a proton target in inverse kinematics at the beam energy of 62 MeV/nucleon. The decay energy spectrum of the neutron unbound state of 23 O was reconstructed from the measured four momenta of 22 O and the emitted neutron. A sharp peak was observed at E decay = 48 ± 3 keV, confirming the previous measurements. The measured partial longitudinal momentum distribution of 23 O * showed the d-wave knockout character, providing a support for the J π assignment of 5/2 + for this state. The spectroscopic factor for the neutrons in 0d 5/2 orbital was deduced, for the first time, to be C 2 S (0d 5/2 ) = 3.7 ± 0.3 (preliminary) by comparing with the result of Glauber model. The relatively large spectroscopic factor supports the N = 16 shell closure in the neutron drip-line nucleus 24 O.Magic numbers (2, 8, 20, 28, . . . ) in nuclei near the β-stability were key feature to understand the many-body quantum system over the past few decades. Thanks to recent developments in radioactive ion-beam technique, the proton-and neutron-rich nuclei have been extensively studied, and the changing of magic numbers was discovered as the proton or neutron drip lines are approached. The N = 16 neutron drip-line nucleus 24 O, which has been studied extensively in Refs. [1][2][3][4][5][6], was suggested as a new doubly closed shell nucleus. The high excitation energy of the first 2 + state and the small a

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Mass measurements of neutron-rich nuclei near the N=20 and 28 shell closures

Cited by 143 publications

References 26 publications

Effective proton-neutron interaction near the drip line from unbound states in F25,26

Effective proton-neutron interaction near the drip line from unbound states in F25,26

In-beamγ-ray spectroscopy of^38,40,42Si

Neutron occupancy of 0d_5/2orbital in²⁴O

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Mass measurements of neutron-rich nuclei near the N=20 and 28 shell closures

Cited by 143 publications

References 26 publications

Effective proton-neutron interaction near the drip line from unbound states in F25,26

Effective proton-neutron interaction near the drip line from unbound states in F25,26

In-beamγ-ray spectroscopy of38,40,42Si

Neutron occupancy of 0d5/2orbital in24O

Contact Info

Product

Resources

About

In-beamγ-ray spectroscopy of^38,40,42Si

Neutron occupancy of 0d_5/2orbital in²⁴O