Separation Between $d_{5/2}$ and $s_{1/2}$ Neutron Single Particle Strength in $^{15}$N

Mertin, C. E.; Caussyn, D. D.; Crisp, A. M.; Keeley, N.; Kemper, K. W.; Momotyuk, O.; Roeder, B. T.; Volya, Alexander

doi:10.5506/aphyspolb.45.159

Cited by 2 publications

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References 13 publications

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“…both strength (left) and integrated strength (right) functions are shown for15 N for neutron channels where |λ corresponds to different angular momentum channels constructed from 1 + ground state in14 N coupled to a single nucleon on either d 5/2 (top panels) or d 3/2 (bottom panels) single-particle states. This theoretical study follows recent experimental work in Ref [19]…”

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Computational approaches to many-body dynamics of unstable nuclear systems

Volya¹

2014

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The goal of this presentation is to highlight various computational techniques used to study dynamics of quantum many-body systems. We examine the projection and variable phase methods being applied to multi-channel problems of scattering and tunneling; here the virtual, energy-forbidden channels and their treatment are of particular importance. The direct time-dependent solutions using Trotter-Suzuki propagator expansion provide yet another approach to exploring the complex dynamics of unstable systems. While presenting computational tools, we briefly revisit the general theory of the quantum decay of unstable states. The list of questions here includes those of the internal dynamics in decaying systems, formation and evolution of the radiating state, and lowenergy background that dominates at remote times. Mathematical formulations and numerical approaches to time-dependent problems are discussed using the quasi-stationary methods involving effective Non-Hermitian Hamiltonian formulation.

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confidence: 65%

Computational approaches to many-body dynamics of unstable nuclear systems

Volya¹

2014

Preprint

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Neutron s states in loosely bound nuclei

2014

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In reviewing the data that has accumulated in light nuclei we find that the binding energy plays a critical role in describing the variation in energy of s states relative to other states. The behavior of states with zero angular momentum within a few MeV of threshold is qualitatively different from that of neutron states with any other value or of any proton state. This observation is explored for simple Woods-Saxon potentials and is remarkably successful in describing a wealth of experimental data for nuclei with neutron numbers between 5 and 10. The lingering of neutron s states just below threshold is associated with the increases in radii of the neutron density distributions, the neutron halos, and leads to speculations about possible halos in heavier nuclei.PACS numbers: 21.10. Dr, 21.10.Pc, 25.60.Je A description for the evolution of nuclear excitations with neutron excess, from tightly bound stable systems to loosely bound exotic ones, is a major challenge to our understanding of nuclear structure. Startling modifications to the spacing and sequence of single-particle excitations are now experimentally well documented [1] and closed shells with 'magic numbers' of nucleons, once thought to apply to all nuclei, are now known to change when moving away from stability.In light stable nuclei the 0p-shell closes with eight nucleons, accounting for the stability of 16 O. The 0d 5/2 and 1s 1/2 orbitals are close in binding energy in the vicinity of 16 O, but their spacing increases substantially in lighter nuclei, with the 5/2 + state moving more rapidly in excitation energy than the 1/2 + state. The 1/2 − state also moves rapidly with respect to the 1/2 + state. This is illustrated for a subset of the experimental information (nuclei with seven neutrons) in Fig. 1. In the present communication we focus on the behavior of the 1/2 + and 5/2 + single-neutron excitations.We show, through an examination of the simple geometrical effects of finite binding, that it is the qualitatively different behavior of neutron s states near threshold which plays an important role in determining the sequence of levels in loosely bound light nuclei. To explore the changing pattern of states, we examine the available data where there is only one neutron in the 1s0d-shell, spanning a range of neutron binding energies. The behavior of s states near threshold has been commented on before. Bohr and Mottelson [2] note "The orbits with small angular momentum and small binding energy spend an appreciable amount of time outside the nucleus and thus benefit less from an increase in the size of the potential than do the weakly bound orbits with large ". in light nuclei. More recently, the behavior of s states near threshold was discussed by Ozawa [7] in terms of a possible shell gap at N = 16, and by Hamamoto and Mottelson [8] in the context of various nuclear structure properties e.g., changing shell structure, pairing, deformation, and halos. Also related to the present work is a study by Sagawa et al.[9] on the behavior of even-parit...

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Separation Between $d_{5/2}$ and $s_{1/2}$ Neutron Single Particle Strength in $^{15}$N

Cited by 2 publications

References 13 publications

Computational approaches to many-body dynamics of unstable nuclear systems

Computational approaches to many-body dynamics of unstable nuclear systems

Neutron s states in loosely bound nuclei

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