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1.
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2.
  • Svensson, C. E., et al. (författare)
  • Decay Out of the Doubly Magic Superdeformed Band in the N=Z Nucleus 60Zn
  • 1999
  • Ingår i: Physical Review Letters. - 1079-7114. ; 82:17, s. 3400-3403
  • Tidskriftsartikel (refereegranskat)abstract
    • The doubly magic superdeformed band in the N = Z nucleus Zn-60 has been identified. Linking transitions connecting this band to the yrast line provide the first spin, parity, and excitation energy measurements for superdeformed states in the A similar to 60 region. The stretched-E2 character and relatively large B(E2) values of these transitions suggest a nonstatistical decay-out process.
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3.
  • Gellanki, Jnaneswari, et al. (författare)
  • Characterization of Superdeformed Bands in 62Zn
  • 2009
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Combined data from four fusion-evaporation reaction experiments were utilized to investigate deformed and superdeformed structures in Zn-62(30)32. Combination of the Gammasphere gamma-ray spectrometer and ancillary particle detection systems allowed for the connection of rotational bands to well-known, low-lying excited states in Zn-62, as well as spectroscopy of discrete high-spin states reaching excitation energies of E-x=42.5 MeV. Four well- or superdeformed bands in Zn-62 are characterized and described by means of cranked Nilsson-Strutinsky calculations.
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4.
  • Svensson, C. E., et al. (författare)
  • Collective rotational motion in the N=Z nucleus 36Ar
  • 2001
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 682:1-4, s. 1-11
  • Tidskriftsartikel (refereegranskat)abstract
    • A superdeformed rotational band has been identified in the N = Z nucleus 36Ar, firmly linked to known low-spin states, and observed to its high-spin termination at Iπ = 16+. Lifetime measurements by the Doppler shift attenuation method establish a large low-spin deformation (β2 ≈ 0.46) and a decrease in the collectivity as the band approaches termination. Comparisons with cranked Nilsson-Strutinsky and large-scale spherical shell model calculations lead to a consistent description of the band based on a configuration in which four particles are promoted to the pf shell. With two major shells active for both protons and neutrons, yet a valence space dimension small enough to be approached from the shell model perspective, this band offers an excellent opportunity to investigate the microscopic structure of collective rotational motion in nuclei.
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5.
  • Svensson, C. E., et al. (författare)
  • Superdeformation in the N = z Nucleus 36Ar : Experimental, deformed mean field, and spherical shell model descriptions
  • 2000
  • Ingår i: Physical Review Letters. - 0031-9007. ; 85:13, s. 2693-2696
  • Tidskriftsartikel (refereegranskat)abstract
    • A superdeformed rotational band has been identified in 36Ar, linked to known low-spin states, and observed to its high-spin termination at Iπ = 16+. Cranked Nilsson-Strutinsky and spherical shell model calculations assign the band to a configuration in which four pf-shell orbitals are occupied, leading to a low-spin deformation β2 ≈ 0.45. Two major shells are active for both protons and neutrons, yet the valence space remains small enough to be confronted with the shell model. This band thus provides an ideal case to study the microscopic structure of collective rotational motion.
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6.
  • Ward, D., et al. (författare)
  • Band Structure of 68Ge
  • 2001
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 63:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The nucleus Ge-68 has been studied by gamma-ray spectroscopy following its population at high spin in the reaction Ca-40(S-32,4p) Ge-68. The reaction channel was selected with the Microball array and gamma rays were detected with the Gammasphere array. The level scheme is very complex, reflecting the many different, and presumably mixed, excitation modes in this nucleus. Nevertheless, there appear to be some simplifications in the spin range above 18 (h) over bar where we have identified a superdeformed band and several terminating bands. The results are compared with a cranked Nilsson-Strutinsky model without pairing.
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7.
  • Fischer, S. M., et al. (författare)
  • Alignment delays in the N = Z nuclei Kr-72, Sr-76, and Zr-80
  • 2001
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 8713:13
  • Tidskriftsartikel (refereegranskat)abstract
    • The ground state rotational bands of the N = Z nuclei Kr-72, Sr-76, and Zr-80 have been extended into the angular momentum region where rotation alignment of particles is normally expected. By measuring the moments of inertia of these bands we have observed a consistent increase in the rotational frequency required to start pair breaking, when compared to neighboring nuclei. Kr-72 shows the most marked effect. It has been widely suggested that these delayed alignments arise from np-pairing correlations. However, alignment frequencies are very sensitive to shape degrees of freedom and normal pairing, so the new experimental observations are still open to interpretation.
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8.
  • Kelsall, N. S., et al. (författare)
  • Testing mean-field models near the N=Z line : gamma-ray spectroscopy of the T-z=1/2 nucleus Kr-73
  • 2002
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 65:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the N=Z+1 nucleus Kr-73 have been investigated using the Ca-40(Ar-36,2pn) and Ca-40(Ca-40,alpha2pn) reactions at 145 and 160 MeV, respectively. gamma rays were detected using the Gammasphere array and events were recorded in coincidence with charged-particle and neutron detectors. The three previously observed bands were extended to high spin, and a new unfavored positive-parity band has been observed. The alignment characteristics and decay properties of the bands are all consistent with large-deformation prolate rotation, with no clear evidence for oblate bands or shape coexistence. This is quite different from neighboring Kr-72,Kr-74, indicating a strong shape-stabilizing role for the valence neutron. The experimental results are compared to extended total Routhian surface, cranked Nilsson Strutinsky, and cranked relativistic mean-field calculations. The results suggest that the paired calculations lack some important physics. Neutron-proton correlations may be the missing ingredient. There is also evidence for an unusual band crossing in the negative-parity bands, which may indicate the presence of T=0 pairing correlations. At high spin all the models can reproduce the experimental data.
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9.
  • Lauritsen, T., et al. (författare)
  • Characterization of a gamma-ray tracking array : A comparison of GRETINA and Gammasphere using a 60Co source
  • 2016
  • Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 836, s. 46-56
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we provide a formalism for the characterization of tracking arrays with emphasis on the proper corrections required to extract their photopeak efficiencies and peak-to-total ratios. The methods are first applied to Gammasphere, a well characterized 4π array based on the principle of Compton suppression, and subsequently to GRETINA. The tracking efficiencies are then discussed and some guidelines as to what clustering angle to use in the tracking algorithm are presented. It was possible, using GEANT4 simulations, to scale the measured efficiencies up to the expected values for the full 4π implementation of GRETA.
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10.
  • Lipoglavsek, M., et al. (författare)
  • First Observation of Excitation Across the 100Sn Core
  • 2001
  • Ingår i: Nuclear Physics, Section A. - 0375-9474. ; 682, s. 399-403
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of nuclei near the doubly-magic nucleus Sn-100 were studied with the Ni-58+Cr-50 reaction. The experimental setup consisted of the GAMMASPHERE array augmented with light charged-particle and neutron detectors. Excited states were identified for the first time in the proton emitting nucleus Sb-105. Excitations across the N=Z=50 doubly closed shell were observed in Cd-99 and In-101. Some results of large-scale shell-model calculations are discussed.
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11.
  • Valiente-Dobon, JJ, et al. (författare)
  • High-spin rotational structures in Kr-76
  • 2005
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 71:3
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in Kr-76(36)40 have been populated in the Ca-40(Ca-40,4p)Kr-76 fusion-evaporation reaction at abeam energy of 165 MeV and studied using the Gammasphere and Microball multidetector arrays. The ground-state band and two signature-split negative parity bands of Kr-76 have been extended to similar to 30 (h) over bar. Lifetime measurements. using the Doppler-shift attenuation method show that the transition quadrupole moment of these three bands decrease as they approach their maximum-spin states. Two signatures of a new rotational structure with remarkably rigid rotational behavior have been identified. The high-spin properties of these rotational bands are analyzed within the framework of configuration-dependent cranked Nilsson-Strutinsky calculations.
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12.
  • Valiente-Dobon, JJ, et al. (författare)
  • Lifetimes of high-spin states in Kr-76
  • 2005
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 36:4, s. 1339-1342
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in Kr-76(36)40 have been populated in the Ca-40 (Ca-40,4p) Kr-76 fusion-evaporation reaction at a beam energy of 165 MeV, and studied using the GAMMASPHERE and MICROBALL multi-detector arrays. The ground-state band and two signature-split negative-parity bands of Kr-76 have been extended to similar to 30h. Lifetime measurements using the Doppler-shift attenuation method indicate that the transition quadrupole moment of these three bands decrease as they approach their maximum-spin states.
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13.
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14.
  • Andreyev, A. N., et al. (författare)
  • α decay of the neutron-deficient isotope 190At
  • 2023
  • Ingår i: Physical Review C. - 2469-9985. ; 108:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The α decay of the neutron-deficient 190At isotope was observed following the 103Rh(90Zr,3n)190At reaction at Argonne National Laboratory. The reaction products were separated from the beam using the Argonne Gas-Filled Analyzer and implanted into a double-sided Si strip detector. The spatial and temporal correlations between implanted nuclei and subsequent α decays towards the known daughter isotope 186Bi were used to identify and characterize 190At nuclei. Two possible decay scenarios are proposed for the 190At→186Bi decay.
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15.
  • Carroll, R. J., et al. (författare)
  • Blurring the Boundaries : Decays of Multiparticle Isomers at the Proton Drip Line
  • 2014
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 112:9, s. 092501-
  • Tidskriftsartikel (refereegranskat)abstract
    • A multiparticle spin-trap isomer has been discovered in the proton-unbound nucleus 158 73 Ta 85. The isomer mainly decays by (h) over bar -ray emission with a half-life of 6.1d(1) mu s. Analysis of the gamma-ray data shows that the isomer lies 2668 keV above the known 9(+) state and has a spin 10h higher and negative parity. This 19(-) isomer also has an 8644(11) keV, 1.4(2)% alpha-decay branch that populates the 9(+) state in Lu-154. No proton-decay branch from the isomer was identified, despite the isomer being unbound to proton emission by 3261(14) keV. This remarkable stability against proton emission is compared with theoretical predictions, and the implications for the extent of observable nuclides are considered.
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16.
  • Carroll, R. J., et al. (författare)
  • Competing decay modes of a high-spin isomer in the proton-unbound nucleus 158Ta
  • 2015
  • Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 46:3, s. 695-698
  • Tidskriftsartikel (refereegranskat)abstract
    • An isomeric state at high spin and excitation energy was recently observed in the proton-unbound nucleus 158Ta. This state was observed to decay by both α and γ decay modes. The large spin change required to decay via γ-ray emission incurs a lifetime long enough for α decay to compete. The α decay has an energy of 8644(11) keV, which is among the highest observed in the region, a partial half-life of 440(70) μs and changes the spin by 11h. In this paper, additional evidence supporting the assignment of this α decay to the high-spin isomer in 158Ta will be presented.
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17.
  • Fahlander, Claes, et al. (författare)
  • Excited States in 103Sn: Neutron Single-particle Energies with Respect to 100Sn
  • 2001
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813 .- 1089-490X. ; 63:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-ray lines from Sn-103 have been identified for the first time using EUROBALL and ancillary detectors. The level scheme of Sn-103 has been established by means of particle-gated gamma gamma coincidences. The energy spacing between the g(7/2) and d(5/2) neutron single-particle orbitals is determined from the excited states in Sn-103.
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18.
  • Ideguchi, E., et al. (författare)
  • Orbifold projection in supersymmetric QCD at N(f) ≤ N(c)
  • 2000
  • Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 492:3-4, s. 369-375
  • Tidskriftsartikel (refereegranskat)abstract
    • Supersymmetric orbifold projection of N = 1 SQCD with relatively small number of flavors (N(f) ≤ N(c)) is considered. The purpose is to check whether orbifolding commutes with the infrared limit. On the one hand, one considers the orbifold projection of SQCD and obtains the low-energy description of the resulting theory. On the other hand, one starts with the low-energy effective theory of the original SQCD, and only then performs orbifolding. It is shown that at finite N(c) the two low-energy theories obtained in these ways are different. However, in the case of stabilized run-away vacuum these two theories are shown to coincide in the large N(c) limit. In the case of quantum modified moduli space, topological solitons carrying baryonic charges are present in the orbifolded low-energy theory. These solitons may restore the correspondence between the two theories provided that the soliton mass tends to zero in the large N(c) limit. (C) 2000 Elsevier Science B.V.
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19.
  • Joss, D. T., et al. (författare)
  • Spectroscopy at the two-proton drip line : Excited states in 158W
  • 2017
  • Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 772, s. 703-707
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states have been identified in the heaviest known even-Z N=84 isotone 158W, which lies in a region of one-proton emitters and the two-proton drip line. The observation of γ-ray transitions feeding the ground state establishes the excitation energy of the yrast 6+ state confirming the spin-gap nature of the α-decaying 8+ isomer. The 8+ isomer is also expected to be unbound to two-proton emission but no evidence for this decay mode was observed. An upper limit for the two-proton decay branch has been deduced as b2p≤ 0.17% at the 90% confidence level. The possibility of observing two-proton emission from multiparticle isomers in nearby nuclides is considered.
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20.
  • Palacz, M, et al. (författare)
  • In beam gamma-ray spectroscopy of very neutron deficient odd-cadmium isotopes
  • 1997
  • Ingår i: Acta Physica Polonica B. - : ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS. - 0587-4254 .- 1509-5770. ; 28:1-2, s. 309-313
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the very neutron deficient odd cadmium isotopes Cd-99, Cd-101 and Cd-103 are discussed in terms of the nuclear shell model. Systematics of excited states in Cd99-109 is presented.
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21.
  • Palacz, M., et al. (författare)
  • Investigations of Neutron Deficient Nuclei Close to 100Sn with EUROBALL
  • 2001
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254 .- 1509-5770. ; 32, s. 999-1003
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of nuclei in the vicinity of Sn-100 have been studied using: the EUROBALL detector array. Gamma-ray lines from Sn-103 have been identified for the first time, and a level scheme of low-lying excited states of Sn-103 has been established. New constraints on energies of single particle orbitals with respect to the Sn-100 core are obtained.
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22.
  • Smith, J. F., et al. (författare)
  • Excited states and signature inversion in Cs-116
  • 2006
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 74:3, s. 034310-
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states have been observed for the first time in the very neutron-deficient, odd-odd nucleus, Cs-116(55)61. The assignment to Cs-116 has been made by the detection of gamma rays in coincidence with evaporated charged particles and with evaporation residues. The observed states form a rotational band which has been assigned to the nu(h(11/2)) circle times pi(h(11/2)) configuration. Tentative spin assignments have been made on the basis of systematic comparisons with neighboring cesium isotopes. A low-spin signature inversion is observed in the band at a rotational frequency of about 0.23 MeV/h. The observed signature inversions in the odd-odd Cs116-126 isotopes have been compared with the results of extended total Routhian surface calculations, in which signature inversion arises as a consequence of quadrupole-pairing correlations and triaxial deformation. As previously shown for some of the odd-odd A similar or equal to 120 isotopes, the calculations reproduce the signature inversions reasonably well.
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23.
  • Sohler, D, et al. (författare)
  • Band-terminating states in Ag-101
  • 2004
  • Ingår i: Nuclear Physics, Section A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 733:1-2, s. 37-52
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of the neutron deficient Ag-101 nucleus have been investigated via the Cr-50(Ni-58, 3rho1alpha) heavy-ion induced reaction at 261 meV by use of in-beam spectroscopic methods. On the basis of the measured gammagamma-cincidence relations and angular distribution ratios high-spin bands have been extended up to I-pi = 35/2(+), 45/2((-)) and (49/2(-)). The negative parity states at the highest energy have been interpreted as terminating non-collective oblate states in the framework of the Nilsson-Strutinsky cranking formalism.
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24.
  • Sohler, D, et al. (författare)
  • Maximally aligned states in Ag-99
  • 2003
  • Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 16:2, s. 171-175
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of Ag-99 were populated via the Cr-50 + Ni-58 (261 MeV) reaction using the NORDBALL detector array equipped with charged-particle and neutron. detector systems for reaction channel separation. On the basis of the measured gammagamma-coincidence relations and angular distribution ratios a significantly extended level scheme has been constructed up to E-x similar to 7.8 MeV and I = 35/2. The experimental results were described within the framework of the shell model. Candidates for states fully aligned in the pig(9/2)(-3)nu(d(5/2),g(7/2))(2) valence configuration space were found at 4109 and 6265 keV.
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25.
  • Sohler, D, et al. (författare)
  • Spectroscopy of neutron deficient Ge-65
  • 1997
  • Ingår i: Zeitschrift für Physik A Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 0939-7922 .- 1431-5831. ; 357:3, s. 239-240
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of 65Ge were populated via the 12C + 58Ni (261 MeV) reaction using the NORDBALL detector array equipped with charged-particle and neutron detector systems for reaction channel separation. On the basis of γγ-coincidence relations and angular distribution ratios a significantly extended level scheme was constructed up to E x = 9 MeV and J π = (33/2−). The low-energy states of the nucleus are discussed in the framework of the interacting boson-fermion model.
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26.
  • Valiente-Dobon, JJ, et al. (författare)
  • Evidence for nontermination of rotational bands in Kr-74
  • 2005
  • Ingår i: Physical Review Letters. - 1079-7114. ; 95:23
  • Tidskriftsartikel (refereegranskat)abstract
    • Three rotational bands in Kr-74 were studied up to (in one case one transition short of) the maximum spin I-max of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin I-max. This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at I=I-max.
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27.
  • Wadsworth, R., et al. (författare)
  • Evidence for shape coexistence at medium spin in Rb-76
  • 2011
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 701:3, s. 306-312
  • Tidskriftsartikel (refereegranskat)abstract
    • Four previously known rotational bands in Rb-76 have been extended to moderate spins using the Gammasphere and Microball gamma ray and charged particle detector arrays and the Ca-40(Ca-40,3pn) reaction at a beam energy of 165 MeV. The properties of two of the negative-parity bands can only readily be interpreted in terms of the highly successful Cranked Nilsson-Strutinsky model calculations if they have the same configuration in terms of the number of g(9/2) particles, but they result from different nuclear shapes (one near-oblate and the other near-prolate). These data appear to constitute a unique example of shape coexisting structures at medium spins. (C) 2011 Elsevier B.V. All rights reserved.
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28.
  • Wadsworth, R., et al. (författare)
  • Terminating states in the positive-parity structures of As 67
  • 2018
  • Ingår i: Physical Review C. - 2469-9985. ; 98:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The energy levels and γ-ray decay scheme of the positive-parity states in the Tz=12 nucleus As67 have been studied by using the Ca40(Ar36,2αp)As67 reaction at a beam energy of 145 MeV. Two new band structures have been identified which can be connected to the previously known levels. The results for these bands are compared with configuration-dependent cranked Nilsson-Strutinsky calculations. The good level of agreement between theory and experiment suggests that these structures can be interpreted in terms of configurations that involve three g92 particles and that both possess noncollective terminating states.
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29.
  • Wilson, A. N., et al. (författare)
  • High-spin structures and alignment properties in Ce-126
  • 2001
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 6305:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in Ce-126 have been observed with the GAMMASPHERE gamma -ray detector array, used in conjunction with the MICROBALL charged-particle detector. The reaction Zn-64(Zn-64, xpn alpha) (beam energy 260 MeV) was used to populate a wide range of nuclei in the neutron-deficient region with A approximate to 120. Ce-126 was populated via the 2p evaporation channel. The three previously observed bands have been extended to higher spins and some other structures have been identified. The yrast band shows evidence of a delayed neutron alignment occurring at a rotational frequency omega approximate to0.5 MeV/(h) over bar as observed in the neighboring odd-A nucleus Pr-127. One of the two excited bands shows evidence for a similar crossing at a slightly lower frequency and also exhibits a sudden gain in alignment at omega =0.57 MeV/(h) over bar. The third band may involve the coupling of a gamma -vibrational state. All three rotational bands are discussed in terms of standard and extended cranked shell model calculations.
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30.
  • Andersson, Lise-Lotte, et al. (författare)
  • Comprehensive Gamma-ray Spectroscopy of Rotational Bands in the N=Z+1 Nucleus 61Zn
  • 2009
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 79:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The Zn-61(30)31 nucleus has been studied via the combined data of two fusion-evaporation reaction experiments using a Ar-36 beam and a Si-28 target foil. The experimental setups involved the Ge array GAMMASPHERE and neutron and charged particle detectors placed around the target position. The resulting level scheme comprises about 120 excited states connected via some 180 gamma-ray transitions. In total, seven rotational structures were identified up to I similar to 25 or higher and compared with predictions from cranked Nilsson-Strutinsky calculations.
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31.
  • Andersson, Lise-Lotte, et al. (författare)
  • Extensive Gamma-ray Spectroscopy of Normally and Superdeformed Structures in 61Cu
  • 2008
  • Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 36:3, s. 251-278
  • Tidskriftsartikel (refereegranskat)abstract
    • A largely extended experimental knowledge of the Cu-61(29)32 nucleus has been obtained from three experiments. Excited states in Cu-61 were produced via the fusion-evaporation reaction Si-28(Ar-36, 3p)Cu-61. In addition to the Ge array GAMMASPHERE, neutron and charged-particle detectors placed around the target position were used for high-performance particle spectroscopy. The constructed level scheme includes more than 160 energy levels and 320 gamma-ray transitions belonging to both normally deformed as well as superdeformed rotational structures. The multipolarities have been determined for the gamma-ray transitions and as a result spin-parity assignments are given for nearly all energy levels. Experimental results in the normally deformed region are compared with predictions from large-scale shell model calculations. The collective structures are compared with results from cranked Nilsson-Strutinsky calculations. The results reveal the need to modify the standard Nilsson parameters in the mass A similar to 60 region.
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32.
  • Carroll, R. J., et al. (författare)
  • Multiparticle configurations of excited states in Lu-155
  • 2016
  • Ingår i: PHYSICAL REVIEW C. - 2469-9985. ; 94:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the neutron-deficient N = 84 nuclide Lu-155 have been populated by using the Pd-102(Ni-58, alpha p) reaction. The Lu-155 nuclei were separated by using the gas-filled recoil ion transport unit (RITU) separator and implanted into the Si detectors of the gamma recoil electron alpha tagging (GREAT) spectrometer. Prompt gamma-ray emissions measured at the target position using the JUROGAM Ge detector array were assigned to Lu-155 through correlations with alpha decays measured in GREAT. Structures feeding the (11/2(-)) and (25/2(-)) alpha-decaying states have been revised and extended. Shell-model calculations have been performed and are found to reproduce the excitation energies of several of the low-lying states observed to within an average of 71 keV. In particular, the seniority inversion of the 25/2(-) and 27/2(-) states is reproduced.
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33.
  • Cederkall, J, et al. (författare)
  • First evidence for excited states in In-101
  • 1996
  • Ingår i: PHYSICAL REVIEW C-NUCLEAR PHYSICS. - : AMER INST PHYSICS. - 0556-2813. ; 53:4, s. 1955-1958
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The first evidence for excited states in In-101 is presented. In-101 is the lightest In isotope observed in an in-beam experiment. Two gamma-ray transitions at 1309 and 341 keV, respectively, are strong candidates for a cascade to the ground state in this
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34.
  • Cederkall, J, et al. (författare)
  • Maximum spin aligned states in Ag-98(47)51
  • 1998
  • Ingår i: EUROPEAN PHYSICAL JOURNAL A. - : SPRINGER VERLAG. - 1434-6001. ; 1:1, s. 7-9
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • New excited states have been observed in the neutron deficient isotope Ag-98 following the Ni-58+Cr-50-->Te-108* heavy-ion reaction. One of these states may be interpreted as a maximum spin aligned state of the pi g(9/2)(-3) nu vg(7/2) configuration. Othe
  •  
35.
  • Chiara, C. J., et al. (författare)
  • Probing sd-fp Cross-shell Interactions via Terminating Configurations in 42Sc,43Sc
  • 2007
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 75:5
  • Tidskriftsartikel (refereegranskat)abstract
    • An experimental study of the lower fp-shell nuclei Sc-42,Sc-43 was performed via alpha pn and alpha p evaporation, respectively, from Ne-20 + Si-28 and Mg-24 + Mg-24 fusion-evaporation reactions. The experiments were conducted with the Gammasphere and Microball detector arrays. The level schemes of both nuclei have been extended considerably. Terminating states associated with the f(7/2)(n) and d(3/2)(-1)f(7/2)(n+1) configurations were identified in each nuclide and incorporated into detailed comparisons with neighboring nuclei and with shell model calculations. The energy differences between the terminating states provide a test of the sd-fp cross-shell interactions in these calculations.
  •  
36.
  • Danko, I, et al. (författare)
  • Collective and broken pair states of Ga-65,Ga-67
  • 1999
  • Ingår i: PHYSICAL REVIEW C-NUCLEAR PHYSICS. - : AMERICAN PHYSICAL SOC. - 0556-2813. ; 59:4, s. 1956-1974
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Excited states of Ga-65 and Ga-67 nuclei were populated through the C-12(Ni-58,alpha p) and C-12(Ni-58,3p) reactions, respectively, and investigated by in-beam gamma-ray spectroscopic methods. The NORDBALL array equipped with a charged particle ball and 1
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37.
  • Hayes, A. B., et al. (författare)
  • Coulomb excitation of a Am-242 isomeric target: E2 and E3 strengths, rotational alignment, and collective enhancement
  • 2010
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 82:4
  • Tidskriftsartikel (refereegranskat)abstract
    • A 98% pure Am-242m ( K = 5(-), t(1/2) = 141 years) isomeric target was Coulomb excited with a 170.5-MeV Ar-40 beam. The selectivity of Coulomb excitation, coupled with the sensitivity of Gammasphere plus CHICO, was sufficient to identify 46 new states up to spin 18h in at least four rotational bands; 11 of these new states lie in the isomer band, 13 in a previously unknown yrast K-pi = 6(-) rotational band, and 13 in a band tentatively identified as the predicted yrast K-pi = 5(+) band. The rotational bands based on the K-pi = 5- isomer and the 6(-) bandhead were populated by Coulomb excitation with unexpectedly equal cross sections. The gamma-ray yields are reproduced by Coulomb excitation calculations using a two-particle plus rotor model (PRM), implying nearly complete Delta K = 1 mixing of the two almost-degenerate rotational bands, but recovering the Alaga rule for the unperturbed states. The degeneracy of the 5(-) and 6(-) bands allows for precise determination of the mixing interaction strength V, which approaches the strong-mixing limit; this agrees with the 50% attenuation of the Coriolis matrix element assumed in the model calculations. The fractional admixture of the I-K(pi) = 6(6)(-) state in the nominal 6(5)(-) isomer band state is measured within the PRM as 45.6(-1.1)(+0.3)%. The E2 and M1 strengths coupling the 5(-) and 6(-) bands are enhanced significantly by the mixing, while E1 and E2 couplings to other low-K bands are not measurably enhanced. The yields of the 5(+) band are reproduced by an E3 strength of approximate to 15 W.u., competitive with the interband E2 strength. Alignments of the identified two-particle Nilsson states in Am-242 are compared with the single-particle alignments in Am-241.
  •  
38.
  • Henning, G., et al. (författare)
  • Exploring the stability of super heavy elements: First measurement of the fission barrier of 254No
  • 2014
  • Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 66
  • Konferensbidrag (refereegranskat)abstract
    • The gamma-ray multiplicity and total energy emitted by the heavy nucleus 254No have been measured at 2 different beam energies. From these measurements, the initial distributions of spin I and excitation energy E * of 254No were constructed. The distributions display a saturation in excitation energy, which allows a direct determination of the fission barrier. 254No is the heaviest shell-stabilized nucleus with a measured fission barrier. © Owned by the authors, published by EDP Sciences, 2014.
  •  
39.
  • Henning, G., et al. (författare)
  • Fission Barrier of Superheavy Nuclei and Persistence of Shell Effects at High Spin: Cases of No-254 and Th-220
  • 2014
  • Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 113:26
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the first measurement of the fission barrier height in a heavy shell-stabilized nucleus. The fission barrier height of No-254 is measured to be B-f = 6.0 +/- 0.5 MeV at spin 15 (h) over bar and, by extrapolation, B-f = 6.6 +/- 0.9 MeV at spin 0 (h) over bar. This information is deduced from the measured distribution of entry points in the excitation energy versus spin plane. The same measurement is performed for Th-220 and only a lower limit of the fission barrier height can be determined: B-f (I) > 8 MeV. Comparisons with theoretical fission barriers test theories that predict properties of superheavy elements.
  •  
40.
  • Ideguchi, E., et al. (författare)
  • Superdeformation in the Doubly Magic Nucleus 40Ca
  • 2001
  • Ingår i: Physical Review Letters. - 1079-7114. ; 87:22
  • Tidskriftsartikel (refereegranskat)abstract
    • A rotational band with seven gamma -ray transitions between states with spin 2 (h) over bar and 16 (h) over bar has been observed in the doubly magic, self-conjugate nucleus Ca-40(20)20. The measured transition quadrupole moment of 1.80(-0.29)(+0.39)eb indicates a superdeformed shape with a deformation beta (2) = 0.59(-0.07)(+0.11). The features of this band are explained by cranked relativistic mean field calculations to arise from an 8-particle 8-hole excitation.
  •  
41.
  • Johansson, Emma, et al. (författare)
  • Prompt Proton Decay and Deformed Bands in 56Ni
  • 2008
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 77:6
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in the doubly magic N=Z nucleus Ni-56 have been investigated with three fusion-evaporation reaction experiments. New gamma-ray transitions are added, and a confirmation of a previously suggested prompt proton decay from a rotational band in Ni-56 into the ground state of Co-55 is presented. The rotational bands in Ni-56 are discussed within the framework of cranked Nilsson-Strutinsky calculations.
  •  
42.
  • Johansson, Emma, et al. (författare)
  • Prompt Proton Decay in the Vicinity of 56Ni
  • 2007
  • Ingår i: Proton Emitting Nuclei and Related Topics. - : AIP. - 1551-7616 .- 0094-243X. ; 961, s. 41-46
  • Konferensbidrag (refereegranskat)abstract
    • A new decay mode, the so called prompt proton decay, was discovered in 1998. It has since proven to be an important decay mechanism for several neutron deficient nuclei in the A similar to 60 region. To measure with high accuracy the energies and angular distributions of these protons, a state-of-the-art charged particle detector - LuWuSiA - was developed. It was first utilized during a fusion-evaporation reaction experiment performed at Argonne National Laboratory, U.S.A. In this contribution, the characteristics of the prompt proton decay are discussed along with the special features of LuWuSiA as well as a revisit to the prompt proton decay in Cu-58.
  •  
43.
  • Johansson, Emma, et al. (författare)
  • Thorough Gamma-ray and Particle Decay Investigations of 58Ni
  • 2009
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The combined data from three fusion-evaporation reaction experiments have been utilized to investigate the semi-magic nucleus Ni-58(28)30. To detect gamma rays in coincidence with evaporated particles, the Ge-detector array Gammasphere was used in conjunction with the charged-particle detectors Microball and LuWuSiA (the Lund Washington University Silicon Array), and a neutron detector array. The results yield a significantly extended level scheme of Ni-58 comprising some 340 gamma-ray transitions and include a total of at least 14 discrete particle decays into excited states of the daughter nuclei Fe-54 and Co-57. The level scheme is compared with large-scale shell-model calculations and cranked Nilsson-Strutinsky calculations.
  •  
44.
  • Karlgren, Daniel, et al. (författare)
  • High-angular-momentum structures in Zn-64
  • 2004
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69, s. 1-034330
  • Tidskriftsartikel (refereegranskat)abstract
    • High-angular-momentum states in Zn-64 were populated in the Ca-40(Si-28,4p) reaction at a beam energy of 122 MeV. Evaporated, light, charged particles were identified by the Microball, while gamma rays were detected using the Gammasphere array. The main focus of this paper is on two strongly coupled, collective bands. The yrast band, which was previously known, has been linked to lower-lying states establishing the excitation energies and angular momenta of in-band states for the first time. The newly identified excited band decays to the yrast band but firm angular-momentum assignments could not be made. In order to interpret these structures cranked-Nilsson-Strutinsky calculations have been performed. The calculations have been extended to account for the distribution of nucleons within a configuration. The yrast collective band is interpreted as based on the pi(f(7/2))(-1)(p(3/2)f(5/2))(2)(g(9/2))(1)nu(p(3/2)f(5/2))(4)(g(9/2))(2) configuration. There are several possible interpretations of the second band but it is difficult to distinguish between the different possibilities.
  •  
45.
  • Kownacki, J, et al. (författare)
  • High-spin studies of the neutron deficient nuclei In-103, In-105, In-107, and In-109
  • 1997
  • Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 627:2, s. 239-258
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states of the isotopes 103,105,107,109In have been investigated using in-beam γ-ray spectroscopic methods. Results from three different experiments are presented. Targets of 54Fe, 50Cr, and 92Mo were bombarded by a 270 and 261 MeV 58Ni beam and by a 95 MeV 19F beam, respectively. Reaction channel separation was achieved with a charged-particle detector array and in the first two experiments also with a 1π neutron detector system. As a result of these experiments the level schemes of 103,105,107,109In were significantly extended. Excited states of these odd-A indium isotopes are discussed within the framework of the nuclear shell model and the hole-core coupling scheme. The systematics of excited states of light odd-A indium isotopes is also discussed.
  •  
46.
  • Lane, G. J., et al. (författare)
  • Identification of excited states in doubly odd [Formula Presented]Sb : Smooth band termination
  • 1997
  • Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 55:5, s. 2127-2131
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in [Formula Presented]Sb have been identified for the first time in a series of [Formula Presented]-spectroscopy experiments using both thin and backed targets, including neutron-fold and recoil-mass measurements to provide unambiguous channel identification. The three decoupled intruder bands observed in [Formula Presented]Sb are based upon configurations involving 2p-2h excitations across the [Formula Presented] shell gap and show the features of smooth band termination. The yrast intruder band, which has been connected to the low-spin levels, is tentatively identified up to its predicted termination at [Formula Presented]. Excellent agreement with configuration-dependent cranked Nilsson-Strutinsky calculations is obtained for the high-spin states near termination.
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47.
  •  
48.
  • Lipoglavsek, M, et al. (författare)
  • Stability of Sn-100(50)50 deduced from excited states in Cd-99(48)51 stability of
  • 1996
  • Ingår i: PHYSICAL REVIEW LETTERS. - : AMER INST PHYSICS. - 0031-9007. ; 76:6, s. 888-891
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Excited states of neutron deficient nuclei close to Sn-100 were investigated in an in-beam spectroscopic experiment using the NORDBALL detector array. Excited states in Cd-99 were identified for the first time. The measured half-life of an isomeric state
  •  
49.
  • Lopez-Martens, A., et al. (författare)
  • Stability and synthesis of superheavy elements: Fighting the battle against fission - example of No-254
  • 2016
  • Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759890118 ; 131
  • Konferensbidrag (refereegranskat)abstract
    • Superheavy nuclei exist solely due to quantum shell effects, which create a pocket in the potential-energy surface of the nucleus, thus providing a barrier against spontaneous fission. Determining the height of the fission barrier and its angular-momentum dependence is important to quantify the role that microscopic shell corrections play in enhancing and extending the limits of nuclear stability. In this talk, the first measurement of a fission barrier in the very heavy nucleus No-254 will be presented.
  •  
50.
  • Persson, J, et al. (författare)
  • In-beam gamma-ray spectroscopy of Cd-102
  • 1997
  • Ingår i: Nuclear Physics A. - : ELSEVIER SCIENCE BV. - 0375-9474 .- 1873-1554. ; 627:1, s. 101-118
  • Tidskriftsartikel (refereegranskat)abstract
    • Neutron deficient nuclei close to 100Sn have been studied using the NORDBALL Ge-detector array together with ancillary particle detectors. Evaporation residues from the compound nucleus 108Te were identified with charged particle and neutron detectors. In this paper a considerable extension of the level scheme of the nucleus 102Cd is presented. The strongest cascade of the new level scheme reveals an irregular sequence of dipole transitions above Iπ = 10+ extending up to spin 17. A strongly populated rather regular side band consisting of four quadrupole transitions ranging from spin 9 to spin 17 was also discovered. This band was tentatively assigned negative parity. Shell model calculations were performed and a very good agreement with the experimental results was found. The excited states could successfully be interpreted as neutron particle and proton hole excitations with respect to the doubly closed core 50100Sn50.
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