1
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Lopez-Saavedra E, Almaraz-Calderon S, Asher BW, Baby LT, Gerken N, Hanselman K, Kemper KW, Kuchera AN, Morelock AB, Perello JF, Temanson ES, Volya A, Wiedenhöver I. Observation of a Near-Threshold Proton Resonance in ^{11}B. PHYSICAL REVIEW LETTERS 2022; 129:012502. [PMID: 35841540 DOI: 10.1103/physrevlett.129.012502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/26/2022] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
A near-threshold proton resonance in ^{11}B at E_{ex}=11.44±0.04 MeV is observed via the reaction ^{10}Be(d,n)^{11}Be→^{10}Be+p in inverse kinematics, measured with a beam of the radioactive isotope ^{10}Be. The resonance energy at E_{res}=211(40) keV is consistent with a proton signal observed by Ayyad et al. in the β-delayed proton decay of ^{11}Be. By comparison to a distorted wave Born approximation calculation, a 0.27(6) spectroscopic factor is extracted and a tentative (ℓ=0) character is assigned for this resonance. The significant cross section in the proton-transfer (d,n) reaction, as well as the observation of its proton-decay signal, point to the threshold-resonance character of this state. The position of this state, its structure, and strong coupling to the s-wave continuum represent an ideal case to study quantum near-threshold many-body dynamics of unstable states. The presence of this state is an important step toward understanding the excessively large beta-delayed proton-decay branch of ^{11}Be.
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Affiliation(s)
- E Lopez-Saavedra
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - S Almaraz-Calderon
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - B W Asher
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - L T Baby
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - N Gerken
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - K Hanselman
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - K W Kemper
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - A N Kuchera
- Department of Physics, Davidson College, Davidson, North Carolina 28035, USA
| | - A B Morelock
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - J F Perello
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - E S Temanson
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - A Volya
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - I Wiedenhöver
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
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2
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Abstract
Applications of configuration-mixing methods for nuclei near the proton and neutron drip lines are discussed. A short review of magic numbers is presented. Prospects for advances in the regions of four new “outposts” are highlighted: 28O, 42Si, 60Ca and 78Ni. Topics include shell gaps, single-particle properties, islands of inversion, collectivity, neutron decay, neutron halos, two-proton decay, effective charge, and quenching in knockout reactions.
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3
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Abstract
The Gamow shell model (GSM) is a powerful method for the description of the exotic properties of drip line nuclei. Internucleon correlations are included via a configuration interaction framework. Continuum coupling is directly included at basis level by using the Berggren basis, in which, bound, resonance, and continuum single-particle states are treated on an equal footing in the complex momentum plane. Two different types of Gamow shell models have been developed: its first embodiment is that of the GSM defined with phenomenological nuclear interactions, whereas the GSM using realistic nuclear interactions, called the realistic Gamow shell model, was introduced later. The present review focuses on the recent applications of the GSM to drip line nuclei.
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4
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Kravvaris K, Volya A. Study of Nuclear Clustering from an Ab Initio Perspective. PHYSICAL REVIEW LETTERS 2017; 119:062501. [PMID: 28949635 DOI: 10.1103/physrevlett.119.062501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Indexed: 06/07/2023]
Abstract
We put forward a new ab initio approach that seamlessly bridges the structure, clustering, and reactions aspects of the nuclear quantum many-body problem. The configuration interaction technique combined with the resonating group method based on a harmonic oscillator basis allows us to treat the reaction and multiclustering dynamics in a translationally invariant way and preserve the Pauli principle. Our presentation includes studies of ^{8,10}Be and an exploration of 3α clustering in ^{12}C.
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Affiliation(s)
| | - Alexander Volya
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
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5
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Hagen G, Jansen GR, Papenbrock T. Structure of ^{78}Ni from First-Principles Computations. PHYSICAL REVIEW LETTERS 2016; 117:172501. [PMID: 27824459 DOI: 10.1103/physrevlett.117.172501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Indexed: 06/06/2023]
Abstract
Doubly magic nuclei have a simple structure and are the cornerstones for entire regions of the nuclear chart. Theoretical insights into the supposedly doubly magic ^{78}Ni and its neighbors are challenging because of the extreme neutron-to-proton ratio and the proximity of the continuum. We predict the J^{π}=2_{1}^{+} state in ^{78}Ni from a correlation with the J^{π}=2_{1}^{+} state in ^{48}Ca using chiral nucleon-nucleon and three-nucleon interactions. Our results confirm that ^{78}Ni is doubly magic, and the predicted low-lying states of ^{79,80}Ni open the way for shell-model studies of many more rare isotopes.
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Affiliation(s)
- G Hagen
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - G R Jansen
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - T Papenbrock
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
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6
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Possible role of interference, protein noise, and sink effects in nonphotochemical quenching in photosynthetic complexes. J Math Biol 2016; 74:43-76. [DOI: 10.1007/s00285-016-1016-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 04/08/2016] [Indexed: 10/21/2022]
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7
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Bogner SK, Hergert H, Holt JD, Schwenk A, Binder S, Calci A, Langhammer J, Roth R. Nonperturbative shell-model interactions from the in-medium similarity renormalization group. PHYSICAL REVIEW LETTERS 2014; 113:142501. [PMID: 25325636 DOI: 10.1103/physrevlett.113.142501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Indexed: 06/04/2023]
Abstract
We present the first ab initio construction of valence-space Hamiltonians for medium-mass nuclei based on chiral two- and three-nucleon interactions using the in-medium similarity renormalization group. When applied to the oxygen isotopes, we find experimental ground-state energies are well reproduced, including the flat trend beyond the drip line at (24)O. Similarly, natural-parity spectra in (21,22,23,24)O are in agreement with experiment, and we present predictions for excited states in (25,26)O. The results exhibit a weak dependence on the harmonic-oscillator basis parameter and reproduce spectroscopy within the standard sd valence space.
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Affiliation(s)
- S K Bogner
- Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48844, USA
| | - H Hergert
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - J D Holt
- Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48844, USA and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany and Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - A Schwenk
- ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany and Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - S Binder
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - A Calci
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - J Langhammer
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - R Roth
- Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
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8
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Hagen G, Papenbrock T, Hjorth-Jensen M, Dean DJ. Coupled-cluster computations of atomic nuclei. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:096302. [PMID: 25222372 DOI: 10.1088/0034-4885/77/9/096302] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In the past decade, coupled-cluster theory has seen a renaissance in nuclear physics, with computations of neutron-rich and medium-mass nuclei. The method is efficient for nuclei with product-state references, and it describes many aspects of weakly bound and unbound nuclei. This report reviews the technical and conceptual developments of this method in nuclear physics, and the results of coupled-cluster calculations for nucleonic matter, and for exotic isotopes of helium, oxygen, calcium, and some of their neighbors.
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Affiliation(s)
- G Hagen
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA
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9
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Tshoo K, Satou Y, Bhang H, Choi S, Nakamura T, Kondo Y, Deguchi S, Kawada Y, Kobayashi N, Nakayama Y, Tanaka KN, Tanaka N, Aoi N, Ishihara M, Motobayashi T, Otsu H, Sakurai H, Takeuchi S, Togano Y, Yoneda K, Li ZH, Delaunay F, Gibelin J, Marqués FM, Orr NA, Honda T, Matsushita M, Kobayashi T, Miyashita Y, Sumikama T, Yoshinaga K, Shimoura S, Sohler D, Zheng T, Cao ZX. N = 16 spherical shell closure in 24O. PHYSICAL REVIEW LETTERS 2012; 109:022501. [PMID: 23030155 DOI: 10.1103/physrevlett.109.022501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Indexed: 06/01/2023]
Abstract
The unbound excited states of the neutron drip-line isotope 24O have been investigated via the 24O(p,p')23O + n reaction in inverse kinematics at a beam energy of 62 MeV/nucleon. The decay energy spectrum of 24O* was reconstructed from the momenta of 23O and the neutron. The spin parity of the first excited state, observed at E(x) = 4.65±0.14 MeV, was determined to be J(π) = 2+ from the angular distribution of the cross section. Higher-lying states were also observed. The quadrupole transition parameter β2 of the 2(1)+ state was deduced, for the first time, to be 0.15±0.04. The relatively high excitation energy and small β2 value are indicative of the N = 16 shell closure in 24O.
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Affiliation(s)
- K Tshoo
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Korea.
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10
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Hagen G, Hjorth-Jensen M, Jansen GR, Machleidt R, Papenbrock T. Continuum effects and three-nucleon forces in neutron-rich oxygen isotopes. PHYSICAL REVIEW LETTERS 2012; 108:242501. [PMID: 23004265 DOI: 10.1103/physrevlett.108.242501] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Indexed: 06/01/2023]
Abstract
We employ interactions from chiral effective field theory and compute binding energies, excited states, and radii for isotopes of oxygen with the coupled-cluster method. Our calculation includes the effects of three-nucleon forces and of the particle continuum, both of which are important for the description of neutron-rich isotopes in the vicinity of the nucleus 24O. Our main results are the placement of the neutron drip line at 24O, the assignment of spins, parities and resonance widths for several low-lying states of the drip line nucleus, and an efficient approximation that incorporates the effects of three-body interactions.
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Affiliation(s)
- G Hagen
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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11
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Hagen G, Papenbrock T, Hjorth-Jensen M. Ab initio computation of the 17F proton halo state and resonances in A = 17 nuclei. PHYSICAL REVIEW LETTERS 2010; 104:182501. [PMID: 20482168 DOI: 10.1103/physrevlett.104.182501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Indexed: 05/29/2023]
Abstract
We perform coupled-cluster calculations of the energies and lifetimes of single-particle states around the doubly magic nucleus (16)O based on chiral nucleon-nucleon interactions at next-to-next-to-next-to-leading order. To incorporate effects from the scattering continuum, we employ a Gamow-Hartree-Fock basis. Our calculations for the J(pi)=1/2(+) proton halo state in (17)F and the 1/2(+) state in (17)O agree well with experiment, while the calculated spin-orbit splitting between 5/2(+) and 3/2(+) states is too small due to the lack of three-nucleon forces. Continuum effects yield a significant amount of additional binding energy for the 1/2(+) and 3/2(+) states in (17)O and (17)F.
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Affiliation(s)
- G Hagen
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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12
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Schiller A, Frank N, Baumann T, Bazin D, Brown BA, Brown J, DeYoung PA, Finck JE, Gade A, Hinnefeld J, Howes R, Lecouey JL, Luther B, Peters WA, Scheit H, Thoennessen M, Tostevin JA. Selective population and neutron decay of an excited state of 23O. PHYSICAL REVIEW LETTERS 2007; 99:112501. [PMID: 17930431 DOI: 10.1103/physrevlett.99.112501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Revised: 06/29/2007] [Indexed: 05/25/2023]
Abstract
We have observed a resonance in neutron-fragment coincidence measurements that is presumably the first excited state of 23O at 2.8(1) MeV excitation energy which decays into the ground state of 22O. This interpretation is consistent with theory. The reaction mechanism supports the assignment of the observed state as the 5/2+ hole state. This assignment and the recently observed 3/2+ particle state advance the understanding of 23O.
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Affiliation(s)
- A Schiller
- National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA.
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13
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Celardo GL, Izrailev FM, Zelevinsky VG, Berman GP. Open system of interacting fermions: statistical properties of cross sections and fluctuations. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:031119. [PMID: 17930211 DOI: 10.1103/physreve.76.031119] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Indexed: 05/25/2023]
Abstract
Statistical properties of cross sections are studied for an open system of interacting fermions. The description is based on the effective non-Hermitian Hamiltonian that accounts for the existence of open decay channels preserving the unitarity of the scattering matrix. The intrinsic interaction is modeled by the two-body random ensemble of variable strength. In particular, the crossover region from isolated to overlapping resonances accompanied by the effect of the width redistribution creating superradiant and trapped states is studied in detail. The important observables, such as average cross section, its fluctuations, autocorrelation functions of the cross section, and scattering matrix, are very sensitive to the coupling of the intrinsic states to the continuum around the crossover. A detailed comparison is made of our results with standard predictions of statistical theory of cross sections, such as the Hauser-Feshbach formula for the average cross section and Ericson theory of fluctuations and correlations of cross sections. Strong deviations are found in the crossover region, along with the dependence on intrinsic interactions and the degree of chaos inside the system.
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Affiliation(s)
- G L Celardo
- Instituto de Física, Universidad Autónoma de Puebla, Apartado Postal J-48, Puebla, Pue. 72570, Mexico
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14
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Caamaño M, Cortina-Gil D, Mittig W, Savajols H, Chartier M, Demonchy CE, Fernández B, Gómez Hornillos MB, Gillibert A, Jurado B, Kiselev O, Lemmon R, Obertelli A, Rejmund F, Rejmund M, Roussel-Chomaz P, Wolski R. Resonance state in 7H. PHYSICAL REVIEW LETTERS 2007; 99:062502. [PMID: 17930818 DOI: 10.1103/physrevlett.99.062502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Indexed: 05/25/2023]
Abstract
The existence of the 7H nuclear system was investigated via a one-proton transfer reaction with a 8He beam at 15.4A MeV and a 12C gas target. The experimental setup was based on the active-target MAYA which allowed a complete reconstruction of the reaction kinematics. The existence of the 7H was confirmed with the identification of seven events where the system was formed with a resonance energy of 0.57(-0.21)(+0.42) MeV above the 3H+4n threshold and a resonance width of 0.09(-0.06)(+0.94) MeV. This study represents an unambiguous proof of the existence of the most neutron-proton unbalanced system presently found.
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Affiliation(s)
- M Caamaño
- Department of Particle Physics, Universidade de Santiago de Compostela, E-15782, Santiago de Compostela, Spain.
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15
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Lapoux V, Alamanos N, Keeley N. Structure of drip-line nuclei7,8He via direct reactions. ACTA ACUST UNITED AC 2006. [DOI: 10.1088/1742-6596/49/1/035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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16
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Wiedeking M, Tabor SL, Pavan J, Volya A, Aguilar AL, Calderin IJ, Campbell DB, Cluff WT, Diffenderfer E, Fridmann J, Hoffman CR, Kemper KW, Lee S, Riley MA, Roeder BT, Teal C, Tripathi V, Wiedenhöver I. p-sd Shell gap reduction in neutron-rich systems and cross-shell excitations in 20 O. PHYSICAL REVIEW LETTERS 2005; 94:132501. [PMID: 15903988 DOI: 10.1103/physrevlett.94.132501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Indexed: 05/02/2023]
Abstract
Excited states in 20O were populated in the reaction 10Be(14C,alpha) at Florida State University (FSU). Charged particles were detected with a particle telescope consisting of 4 annularly segmented Si surface barrier detectors and gamma radiation was detected with the FSU gamma detector array. Five new states were observed below 6 MeV from the alpha-gamma and alpha-gamma-gamma coincidence data. Shell model calculations suggest that most of the newly observed states are core-excited 1p-1h excitations across the N=Z=8 shell gap. Comparisons between experimental data and calculations for the neutron-rich O and F isotopes imply a steady reduction of the p-sd shell gap as neutrons are added.
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Affiliation(s)
- M Wiedeking
- Florida State University, Tallahassee, Florida 32306, USA
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