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Kryger, R. A.; Azhari, A.; Hellström, M.; Kelley, J. H.; Kubo, T.; Pfaff, R.; Ramakrishnan, E.; Sherrill, B. M.; Thoennessen, M.; Yokoyama, Sumi; Charity, R. J.; Dempsey, James F.; Kirov, A.; Robertson, N J; Sarantites, D. G.; Sobotka, L. G.; Winger, J. A.

doi:10.1103/physrevlett.74.860

Cited by 143 publications

(92 citation statements)

References 31 publications

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“…After deconvolution with the experimental resolution, which was estimated to be 1.0(5) MeV based on the 16 Oðp; tÞ data, we obtained natural decay widths of 0.6(5) and 1.2(6) MeV for the ground and excited states, respectively. The former agrees with the previous values of 0.40 (25) [20] and 0.578(205) MeV [22], while they disagree with the theoretical predictions of less than 0.1 MeV [30,31]. Note that the narrow width of the ground state ensures that the 1.8 MeV peak has a different origin.…”

Section: Prl 103 152503 (2009) P H Y S I C a L R E V I E W L E T T Esupporting

confidence: 74%

Breakdown of theZ=8Shell Closure in UnboundO12and its Mirror Symmetry

Suzuki¹,

Iwasaki²,

Beaumel³

et al. 2009

Phys. Rev. Lett.

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An excited state in the proton-rich unbound nucleus 12 O was identified at 1.8(4) MeV via missing-mass spectroscopy with the 14 Oðp; tÞ reaction at 51 AMeV. The spin-parity of the state was determined to be 0 þ or 2 þ by comparing the measured differential cross sections with distorted-wave calculations. The lowered location of the excited state in 12 O indicates the breakdown of the major shell closure at Z ¼ 8 near the proton drip line. This demonstrates the persistence of mirror symmetry in the disappearance of the magic number 8 between 12 O and its mirror partner 12 Be. DOI: 10.1103/PhysRevLett.103.152503 PACS numbers: 25.40.Hs, 21.10.Hw, 24.10.Eq, 27.20.+n Symmetry and its breaking have played an important role in physics. The CP violation in particle physics led to the discovery of the third generation of quarks [1]; superconductivity of solid states is a manifestation of the gauge symmetry breaking in electron motion [2].Mirror symmetry in atomic nuclei is a unique feature of the two-fermionic quantum system comprised of protons and neutrons. Because of the charge invariance of the nuclear force, ''mirror'' nuclei, a pair of nuclei where numbers of protons and neutrons are interchanged, show a marked similarity in their level schemes. However, the presence of the strong Coulomb field in the proton-rich mirror partner can degrade the symmetry, enhancing complex but rich aspects of the finite system.The increasing availability of radioactive ion (RI) beams opens new possibilities to test mirror symmetry among nuclei with large isospin even beyond the drip lines. The isospin degree of freedom of the nuclear shell structure makes a sharp contrast to other quantum systems such as the quantum dots [3] and the metal clusters [4], where the electromagnetic or spatial degree of freedom is employed in manipulating the shell structure. Recent experimental studies on exotic nuclei have shown that the conventional magic numbers disappear in the neutron-rich regions at N ¼ 8, 20 and 28 [5][6][7][8][9][10][11], and possibly in superheavy elements [12]. Theoretical works point to various underlying mechanisms in terms of the isospin-dependent part of the nuclear effective interaction [13,14], reduction of the spin-orbit potential [15], coupling to the continuum [16], and deformation [17] or clustering [18,19]. However, the validity of the mirror symmetry of these effects at extreme conditions of isospin and binding energies remains an open question, limiting predictions for very proton-rich nuclei. The present Letter presents a study of shell quenching at Z ¼ 8 in the proton-unbound nucleus 12 O. Mirror symmetry in the shell quenching phenomena between 12 8 O 4 and its mirror partner 12 4 Be 8 is investigated experimentally from the low-lying excitation properties.We studied the structure of 12 O via missing-mass spectroscopy with the 14 Oðp; tÞ reaction at 51 AMeV. The systematics of the low-lying excited states in even-even nuclei provides a sensitive probe for the evolution of the shell structure. In 12 Be, the a...

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Section: Prl 103 152503 (2009) P H Y S I C a L R E V I E W L E T T Esupporting

confidence: 74%

Breakdown of theZ=8Shell Closure in UnboundO12and its Mirror Symmetry

Suzuki¹,

Iwasaki²,

Beaumel³

et al. 2009

Phys. Rev. Lett.

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“…The interest in genuine two-proton decays have increased recently especially due to the improved experimental techniques [10][11][12]. This fact has motivated different investigations on light proton rich nuclei.…”

Section: Introductionmentioning

confidence: 99%

Three-body structure of the low-lying 17Ne-states

2004

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The Borromean nucleus 17 Ne ( 15 O+p + p) is investigated by using the hyperspheric adiabatic expansion for a a three-body system. The measured size of 15 O and the low-lying resonances of 16 F ( 15 O+p) are first used as constraints to determine both central and spin-dependent two-body interactions. Then, the ground state structure of 17 Ne is found to be an almost equal mixture of s 2 and d 2 proton-15 O relative states, the two lowest excited states have about 80% of sd-mixed components, and for the next two excited three-body states the proton-15 O relative s-states do not contribute. The spatial extension is as in ordinary nuclei. The widths of the resonances are estimated by the WKB transmission through the adiabatic potentials and found in agreement with the established experimental limits. We compare with experimental information and previous works.

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“…For example, the first p-p correlations observed in the 2p radioactivity of 94m Ag have revealed strong proton yields either in the same or opposite directions which called for a theory of 2p emission from deformed nuclei [1]. Two-proton emission can also occur from short-lived nuclear resonances or excited states (see, e.g., [2,3,4]). Though in this case the mechanism of 2p emission may depend on the reaction populating the parent state, such nuclei can be easily studied in-flight.…”

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confidence: 99%

Proton-proton correlations observed in two-proton decay ofMg19andNe16
Mukha¹,
Grigorenko²,
Sümmerer³
et al. 2008
Phys. Rev. C
74
6
35
0
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Proton-proton correlations were observed for the two-proton decays of the ground states of 19 Mg and 16 Ne. The trajectories of the respective decay products, 17 Ne+p+p and 14 O+p+p, were measured by using a tracking technique with microstrip detectors. These data were used to reconstruct the angular correlations of fragments projected on planes transverse to the precursor momenta. The measured three-particle correlations reflect a genuine three-body decay mechanism and allowed us to obtain spectroscopic information on the precursors with valence protons in the sd shell.PACS numbers: 21.10.-k; 21.45.+v; 23.50.+z The recently discovered two-proton (2p) radioactivity is a specific type of genuine three-particle nuclear decays. It occurs when a resonance in any pair of fragments is located at higher energies than in the initial three-body (p+p+"core") nucleus, and thus simultaneous emission of two protons is the only decay channel. Three-body systems have more degrees of freedom in comparison with two-body systems, hence additional observables appear. In the case of 2p emission, the energy spectra of single protons become continuous, and proton-proton (p-p) correlations are available, which makes them a prospective probe for nuclear structure or/and the decay mechanism. For example, the first p-p correlations observed in the 2p radioactivity of 94m Ag have revealed strong proton yields either in the same or opposite directions which called for a theory of 2p emission from deformed nuclei [1]. Two-proton emission can also occur from short-lived nuclear resonances or excited states (see, e.g., [2,3,4]). Though in this case the mechanism of 2p emission may depend on the reaction populating the parent state, such nuclei can be easily studied in-flight. E.g., the cases of 6 Be [2, 5] and 16 Ne [6]were studied by analyzing their p-p correlations in the framework of a three-body partialwave analysis developed for three-particle decays of light nuclei. In particular, the study of 6 Be revealed the existence of three-particle p+p+α correlations [2] which matched the three-body components found theoretically in the p-shell structure of 6 Be [7]. Very recently, p-p correlations were also observed in 2p radioactivity of 45 Fe [8,9] where both the lifetime and p-p correlations were found to reflect the structure of pf -shell 2p precursors [9]. Such a way of obtaining spectroscopic information is a novel feature compared to studies of two-particle decays.In the present paper, we study for the first time the p-p correlations in sd shell nuclei via examples of the 2p decays of 19 Mg and 16 Ne. These nuclei with very different half lives (T 1/2 ≈ 4 · 10 −9 s [10] and T 1/2 ≈ 4 · 10 −19 s [11], respectively) and presumably different spectroscopic properties may serve as reference cases illuminating the nuclear structure of other possible 2p emitters with sdwave configuration.The decay properties of the 16 Ne and 19 Mg ground states and the related resonances in 15 F and 18 Na are shown in Fig. 1 which compiles the data from Refs....

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Two-Proton Emission from the Ground State ofO12

Cited by 143 publications

References 31 publications

Breakdown of theZ=8Shell Closure in UnboundO12and its Mirror Symmetry

Breakdown of theZ=8Shell Closure in UnboundO12and its Mirror Symmetry

Three-body structure of the low-lying 17Ne-states

Proton-proton correlations observed in two-proton decay ofMg19andNe16
Mukha¹,
Grigorenko²,
Sümmerer³
et al. 2008
Phys. Rev. C
74
6
35
0
View full text Add to dashboard Cite

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Two-Proton Emission from the Ground State ofO12

Cited by 143 publications

References 31 publications

Breakdown of theZ=8Shell Closure in UnboundO12and its Mirror Symmetry

Breakdown of theZ=8Shell Closure in UnboundO12and its Mirror Symmetry

Three-body structure of the low-lying 17Ne-states

Proton-proton correlations observed in two-proton decay ofMg19andNe16Mukha1, Grigorenko2, Sümmerer3 et al. 2008Phys. Rev. C746350View full textAdd to dashboardCite

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Proton-proton correlations observed in two-proton decay ofMg19andNe16
Mukha¹,
Grigorenko²,
Sümmerer³
et al. 2008
Phys. Rev. C
74
6
35
0
View full text Add to dashboard Cite