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1.
  • 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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2.
  • 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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3.
  • 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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4.
  • Svensson, C. E., et al. (författare)
  • Smooth Termination of Rotational Bands in 62Zn: Evidence for a Loss of Collectivity
  • 1998
  • Ingår i: Physical Review Letters. - 1079-7114. ; 80:12, s. 2558-2561
  • Tidskriftsartikel (refereegranskat)abstract
    • Two sets of strongly coupled rotational bands have been identified in Zn-62. These bands have been observed up to the terminating states of their respective configurations. Lifetime measurements indicate that the transition quadrupole moments in these bands decrease as termination is approached. These results establish the first terminating states of rotational bands in the A similar to 60 mass region and confirm the predicted loss of collectivity associated with smooth band termination.
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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.
  • 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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10.
  • Pfohl, J., et al. (författare)
  • Highly deformed rotational structures in 136Pm
  • 2000
  • Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 62:3, s. 313041-313045
  • Tidskriftsartikel (refereegranskat)abstract
    • Four highly deformed structures in the odd-odd nucleus 13661Pm75 were observed via the 105Pd(35Cl,2p2n) reaction at 180 and 173 MeV using the GAMMASPHERE γ-ray spectrometer and the Microball charged-particle detector array. Quadrupole moment measurements were performed on all of the bands. In contrast to lighter odd-Ζ Pm and Pr nuclei, bands based on the g9/2[404]9/2 proton orbital were not observed. Instead, the four observed sequences are assigned as a coupling of an i13/2 neutron with the low-Ω h11/2 and mixed d5/2g7/2 orbitals. Comparisons with neighboring highly deformed structures are discussed and cranked Nilsson-Strutinsky calculations for 136Pm are presented.
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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.
  • Yu, C. H., et al. (författare)
  • Comparison of Superdeformed Bands in 61Zn and 60Zn: Possible Evidence for T=0 Pairing
  • 1999
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 60:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The yrast superdeformed band in Zn-61 has been established using Si-28(Ar-36, 2pn)Zn-61 and Ca-40(Si-29, 2 alpha)Zn-61 fusion-evaporation reactions. The excitation energy of this band was determined via two transitions that link this band to the normally deformed states. Lifetime analysis of this band resulted in a quadrupole moment of Q(t) = 3.0 +/- (0.5)(0.4)e b, which corresponds to a deformation of beta(2) = 0.50+/-(0.07)(0.06). A comparison of the J((2)) dynamical moments of inertia of the yrast superdeformed band in Zn-61 with those in Zn-60 shows a nearly complete blocking of the observed alignment in Zn-60, indicating that T=0 proton-neutron pair correlations may be present in Zn-60. [S0556-2813(99)51109-6].
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14.
  • Yu, C. H., et al. (författare)
  • Superdeformed and Highly Deformed Bands in 65Zn and Neutron-proton Interactions in Zn Isotopes
  • 2000
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 62:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Superdeformed and highly deformed rotational bands were established in Zn-65 using the Ca-40(Si-29,4p)Zn-65 reaction, and averaged quadrupole moments were measured for two of these bands. The configurations of these bands were assigned based on Hartree-Fock calculations. One of the three bands exhibits at low (h) over bar omega a rise in the J((2)) dynamic moments of inertia that is similar to the alignment gain observed in Zn-60. A comparison of the rotational band configurations and their J((2)) moments of inertia for light Zn isotopes suggests that the rise in J((2)) is most likely caused by np interactions associated with the valence protons and neutrons occupying the g(9/2) intruder orbits.
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15.
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16.
  • Andersson, T., et al. (författare)
  • High-spin States in the A=39 Mirror Nuclei 39Ca and 39K
  • 1999
  • Ingår i: European Physical Journal A. Hadrons and Nuclei. - 1434-6001. ; 6, s. 5-8
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states of the mass A = 39 mirror pair K-39 and Ca-39 were investigated via the fusion-evaporation reaction Si-28+O-16 at 125 MeV beam energy. The GAMMASPHERE array in conjunction with the 4 pi charged-particle detector array MICROBALL and neutron detectors was used to detect gamma rays in coincidence with evaporated light particles. The results of the first high-spin study of the T-z = -1/2 nucleus Ca-39 are discussed in terms of mirror symmetry and compared to spherical shell-model calculations in the 1d(3/2)-1f(7/2) configuration space.
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17.
  • Andreoiu, Corina, et al. (författare)
  • Yrast Superdeformed Band in 59Cu
  • 2000
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 62:5, s. 513011-513015
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in 59Cu were populated using the fusion-evaporation reactions 28Si+40Ca at a beam energy of 125 MeV and 36Ar+28Si at a beam energy of 143 MeV. The Gammasphere array in conjunction with ancillary detector systems allowed for the identification of a superdeformed rotational band in 59Cu, which was firmly linked to low-spin yrast states. Using directional correlations of oriented states, a spin-parity assignment of Iπ = 25/2+ to the band head was possible. The average quadrupole moment of the band is measured to be Qt = (2.24±0.40) e b. The characteristics of the band are compared to neighboring nuclei and predictions of different mean-field theories.
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18.
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19.
  • Döring, J., et al. (författare)
  • Band terminations in the valence space of 86Zr
  • 2000
  • Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 61:3, s. 343101-343106
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in 86Zr up to 30+ and 27- were observed via the 58Ni(32S,4p) reaction at 135 MeV beam energy using the combined GAMMASPHERE and MICROBALL systems. Calculations performed with the configuration-dependent shell-correction approach show that these states are built from six g9/2 neutrons and at most four protons excited from the p1/2,p3/2,f5/2 subshells to the g9/2 subshell at small deformation. The highest observed states at 27- and 30+ are interpreted as band-terminating states with the latter having the highest spin available in the valence space for 86Zr.
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20.
  • 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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21.
  • LaFosse, D R, et al. (författare)
  • Search for hyperdeformation in Gd-146,Gd-147
  • 1996
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 54:4, s. 1585-1588
  • Tidskriftsartikel (refereegranskat)abstract
    • A search was undertaken to look for evidence of hyperdeformation in Gd-146,Gd-147. Three experiments employing Gammasphere for gamma-ray detection coupled with the Microball for channel selection via charged particle detection were carried out with increasing detection sensitivity and statistics. No definitive evidence for band structures that could be assigned to hyperdeformation could be found. Candidates previously reported are shown not to have properties consistent with a band structure.
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22.
  • O'Leary, C. D., et al. (författare)
  • Evidence for isovector neutron-proton pairing from high-spin states in N = Z 74Rb
  • 2003
  • Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 67:2, s. 213011-213015
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in the odd-odd N = Z nucleus 3774Rb37 were studied using the 40Ca(40Ca,αnp) reaction. A previously observed odd-spin T = 0 band has been extended to Iπ = (31+) and an even-spin T = 0 band has been observed for the first time to Iπ = (22+); both have a π(g9/2)⊗ν(g9/2) structure. A strongly coupled low-spin T = 0, K = 3 band has been interpreted as being based upon a π[312]3/2 ⊗ ν[312]3/2 configuration. Cranked relativistic Hartree-Bogoliubov calculations, which are corrected for the t = 1 np-pair field by restoring isospin symmetry, reproduce the observed spectrum. These new results provide evidence for the existence of an isovector pair field that contains a neutron-proton component with the proper strength for ensuring isospin conservation.
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23.
  • Rudolph, Dirk, et al. (författare)
  • Shell-model Influence in the Rotational Nucleus 86Mo
  • 1996
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 54:1, s. 117-124
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in Mo-86 were studied by means of the fusion evaporation reaction Ni-58(S-32,2p2n) Mo-86 at 135 MeV beam energy. Charged-particle-gamma gamma and -gamma gamma gamma coincidences recorded with the early implementation of the GAMMASPHERE array and the MICROBALL charged-particle detection system were used to largely extend the level scheme of the T-tau=1 nucleus Mo-86 to a possible spin of I=24h at 13 MeV excitation energy. The excitation scheme is compared to neighboring nuclei. There is evidence for enhanced shell-model influence in the 4 quasiparticle region (I=12-16h). The observed (pi=+,alpha=0) sequence at spin I greater than or equal to 16 h appears to be associated with a triaxial collective rotational band. This interpretation is supported by calculations within the configuration-dependent shell-correction approach with the cranked Nilsson potential.
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24.
  • 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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25.
  • Sun, H., et al. (författare)
  • New Band Structures and an Unpaired Crossing in 78Kr
  • 1999
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 59:2, s. 655-664
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in Kr-78 were studied using the Ni-58(Na-23,3p) reaction at 70 MeV and the Ni-58(Si-23,alpha 4p) reaction at 130 MeV. Prompt gamma-gamma coincidences were measured using the Pitt-FSU detector array and the GAMMASPHERE-MICROBALL array. Results from these experiments have led to 26 new excitation levels, some of which have been grouped into 3 new bands. Spins were assigned based on directional correlations of oriented nuclei. Two of the new negative-parity bands appear to form a signature-partner pair based on a two-quasineutron structure, in contrast to the previously known two-quasiproton negative-parity bands. A forking has been observed at the 24(+) state in the yrast band, which calculations suggest may result from an unpaired crossing. The available evidence suggests oblate shapes in the yrast band coexist with prolate shapes in the negative-parity bands. [S0556-2813(99)04602-6].
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26.
  • Svensson, C. E., et al. (författare)
  • Observation and Quadrupole Moment Measurement of the First Superdeformed Band in the A~60 Mass Region
  • 1997
  • Ingår i: Physical Review Letters. - 1079-7114. ; 79:7, s. 1233-1236
  • Tidskriftsartikel (refereegranskat)abstract
    • A high-spin rotational cascade of six gamma rays has been observed in Zn-62. The quadrupole moment of 2.7(-0.5)(+0.7) e b measured for this band corresponds to a deformation beta(2) = 0.45(-0.07)(+0.10). The properties of this band are in excellent agreement with calculations that predict high-spin superdeformed bands in Zn-62 with deformations beta(2) = 0.41-0.49. These results establish a new region of superdeformation for nuclei with neutron and proton numbers N, Z approximate to 30-32.
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27.
  • Sylvan, G N, et al. (författare)
  • Deformation driving intruder orbitals in Kr-77
  • 1997
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 56:2, s. 772-781
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in Kr-77 were identified via analysis of prompt gamma-gamma coincidences in the Ni-58(Si-29,2 alpha 2p) reaction at 128 MeV at the Gammasphere facility. Evaporation channel selection was achieved using the 95 element Microball charged-particle detector. 27 new states and 42 new transitions were found, The positive-parity bands were confirmed and the alpha=-1/2 band extended to 39/2(+). The negative-parity signature pair was extended to 31/2(-) and 37/2(-). Two new high-lying negative-parity bands were found extending from a state of spin I = 15/2 and energy 2.6 MeV to 17.4 MeV at I = (55/2). The new bands appear highly deformed and become yrast at high spin. A three-quasiparticle structure based on deformation driving, low-K unique-parity and intruder orbitals is suggested for them.
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28.
  • 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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29.
  • 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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30.
  • 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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31.
  • 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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32.
  • 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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33.
  • 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.
  •  
34.
  • 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.
  •  
35.
  • Evans, A. O., et al. (författare)
  • Magnetic properties of deformed dipole bands in Te-110,Te-112
  • 2006
  • Ingår i: Physica Scripta. - 0031-8949. ; T125, s. 192-193
  • Tidskriftsartikel (refereegranskat)abstract
    • A lifetime analysis using the Doppler-shift attenuation method has been performed on the Tellurium isotopes Te-110,Te-112. The experiment was performed using the Gammasphere array in conjunction with the MICROBALL charged-particle detector. Three strongly coupled bands were previously established in Te-110,Te-112 which were observed up to unusually high spins. In the current experiment, it has been possible to extract lifetime measurements using a Doppler broadened lineshape analysis on one of the Delta I = 1 band structures in Te-110. In contrast to similar Delta I = 1 structures in other nuclei in this mass region, the extracted B(M1) values did not rapidly decrease with increasing angular momentum. Instead, the strongly coupled band in Te-110 represents a deformed 1p-1h structure, rather than a weakly deformed structure showing the shears mechanism.
  •  
36.
  • 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.
  •  
37.
  • 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.
  •  
38.
  • 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.
  •  
39.
  • 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.
  •  
40.
  • 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.
  •  
41.
  • LaFosse, D. R., et al. (författare)
  • Collective structures and band termination in 107Sb
  • 2000
  • Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 62:1
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in the near proton-dripline nucleus 107Sb have been identified, and collectivity in this nucleus has been observed for the first time in the form of two rotational bands. One of the observed rotational structures is a ΔI = 1 band, and is interpreted as based on a π(g9/2)-1 ⊗ π(g7/2d5/2)2 proton configuration. A second structure has ΔI = 2 character, and is explained as being based on a πh11/2⊗[π(g9/2)-2 ⊗ π(g7/2d5/2)2] proton configuration through comparison with cranked Nilsson-Strutinsky model calculations. The calculations predict that this band terminates at a spin of 79/2 (Latin small letter h with stroke).
  •  
42.
  • Lerma, F., et al. (författare)
  • Superdeformed bands in Sr80-83, Y82-84, Zr-83,Zr-84 : Transition quadrupole moments, moments of inertia, and configuration assignments
  • 2003
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 67:4, s. 044310-
  • Tidskriftsartikel (refereegranskat)abstract
    • Multiple superdeformed bands in the nuclei Sr80-83, Y82-84, and Zr-83,Zr-84 have been studied in a backed-target experiment, using the Gammasphere and the Microball 4pi detector arrays. For 15 bands in these nuclei, average transition quadrupole moments have been measured with high accuracy, using the Doppler-shift attenuation method. Among these are the newly observed superdeformed bands in Y-83,Y-84, which are isospectral with the bands in Sr-82,Sr-83. These isospectral bands have nearly identical transition quadrupole moments. Two of the bands in Sr-81 interact and cross transitions between them are observed. The present measurements place stringent conditions on configuration assignments for the bands obtained from two types of mean-field calculations, leading to a consistent understanding of the mass similar to80 superdeformed bands. The assignments for different bands arise from one or more nucleons occupying the N-0=5h(11/2) intruder orbital.
  •  
43.
  • Paul, E. S., et al. (författare)
  • Smooth terminating bands in Te-112: Particle-hole induced collectivity
  • 2007
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 75:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The Gammasphere spectrometer, in conjunction with the Microball charged-particle array, was used to investigate high-spin states in Te-112 via Ni-58(Ni-58, 4p gamma) reactions at 240 and 250 MeV. Several smooth terminating bands were established, and lifetime measurements were performed for the strongest one using the Doppler-shift attenuation method. Results obtained in the spin range 18-32h yield a transition quadrupole moment of 4.0 +/- 0.5eb, which corresponds to a quadrupole deformation epsilon(2)=0.26 +/- 0.03; this value is significantly larger than the ground-state deformation of tellurium isotopes. It was also possible to extract a transition quadrupole moment for the yrast band in Xe-114, produced via the 58Ni (58Ni, 2p gamma) reaction. A value of 3.0 +/- 0.5eb was found in the spin range 16-24h, which corresponds to a quadrupole deformation epsilon(2)=0.19 +/- 0.03. Cranked Nilsson-Strutinsky calculations are used to interpret the results.
  •  
44.
  • Rudolph, D., et al. (författare)
  • Experimental and shell-model study of excited states in 55Fe29 and related notes on 55Cu26
  • 2021
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 104:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The fusion-evaporation reaction 32S+28Si at 125-MeV beam energy was used to populate excited states in 55Fe. Combining the Gammasphere spectrometer with ancillary devices including the Microball CsI(Tl) array and a shell of neutron detectors, a comprehensive level scheme could be derived. The experimental results are compared with theoretical results from shell-model calculations. Taking into account isospin-symmetry breaking terms is found to considerably improve the shell-model description for 55Fe. This motivated a predictive case study of near-yrast states in the mirror nucleus 55Cu.
  •  
45.
  • Rudolph, D., et al. (författare)
  • Low-, medium-, and high-spin states in the N=Z+1 nucleus 63Ga
  • 2021
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 103:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The fusion-evaporation reaction 28Si+40Ca at 122 MeV beam energy was used to populate excited states in the N=Z+1 nucleus 63Ga. With the combination of the Gammasphere spectrometer and the Microball CsI(Tl) charged-particle detector array, the level scheme of 63Ga was extended by more than a factor of two in terms of number of γ-ray transitions and excited states, excitation energy (Ex>30 MeV), and angular momentum (I>30 ℏ). Nine regular sequences of states were newly established in the high-spin part of the level scheme. The majority of these rotational band structures could be connected to the previously known part of the level scheme by high-energy γ-ray transitions in the energy range Eγ=4–6 MeV. Low-spin states were assessed by shell-model calculations. The high-spin rotational bands were interpreted and classified by means of cranked Nilsson-Strutinsky calculations.
  •  
46.
  • Rudolph, D., et al. (författare)
  • Onset of high-spin rotational bands in the N=Z nucleus 62Ga
  • 2020
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985. ; 102:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The fusion-evaporation reaction 28Si + 40Ca at 122 MeV beam energy was used to populate high-spin states in the odd-odd N = Z nucleus 62Ga. With the combination of the Gammasphere spectrometer and the Microball CsI(Tl) charged-particle detector array the decay scheme of 62Ga was extended beyond 10 MeV excitation energy. The onset of band structures was observed. These high-spin rotational states are interpreted and classified by means of cranked Nilsson-Strutinsky calculations.
  •  
47.
  • Rudolph, Dirk, et al. (författare)
  • Rotational Bands in the Doubly Magic Nucleus 56Ni
  • 1999
  • Ingår i: Physical Review Letters. - 1079-7114. ; 82:19, s. 3763-3766
  • Tidskriftsartikel (refereegranskat)abstract
    • Structures of the medium- to high-spin states in the doubly magic nucleus Ni-56 have been investigated using the reaction Si-28(Ar-36, 2 alpha) and the gamma-ray spectrometer Gammasphere in conjunction with the 4 pi charged-particle detector array Microball. Two well-deformed rotational bands have been identified. There is evidence that one of the bands, which is identical to a sequence in the odd-odd neighbor Cu-58, partially decays via proton emission into the ground state of Co-55. Predictions of extensive large-scale shell-model and cranked Hartree-Fock and Hartree-Fock-Bogolyubov calculations are compared with the experimental data.
  •  
48.
  • Rudolph, D., et al. (författare)
  • Single-particle and collective excitations in the N=28 isotones 54Fe and 53Mn
  • 2020
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985. ; 102:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The fusion-evaporation reaction 32S + 28Si at 125 MeV beam energy was used to populate high-spin states in the semimagic N = 28 nuclei 53Mn and 54Fe. With a combination of the Gammasphere spectrometer and ancillary devices including the Microball CsI(Tl) array, extensive high-spin level schemes are derived. They exhibit rotational-like collective structures and competing single-particle excitations. The experimental results are compared with predictions from shell-model calculations, for which the inclusion of isopin-symmetry-breaking terms is found to improve the description. An interpretation of the high-spin states is put forward using cranked Nilsson-Strutinsky calculations, indicative of contributions from collective excitations beyond some 8-MeV excitation energy and highlighting the importance of the g9/2 intruder orbital in this energy range.
  •  
49.
  • Sarantites, D. G., et al. (författare)
  • Triaxial superdeformed bands in [Formula Presented]
  • 1998
  • Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 57:1, s. 1-5
  • Tidskriftsartikel (refereegranskat)abstract
    • Four new superdeformed bands have been found in the nucleus [Formula Presented]. The good agreement between experiment and configuration-dependent shell correction calculations suggests that three of the bands have triaxial superdeformed shapes. Such unique features in mass [Formula Presented] superdeformed bands have been predicted, but not observed experimentally until now. A fourth band in [Formula Presented] is interesting due to a fairly constant and unusually high dynamic moment of inertia. Possible interpretations of this structure are discussed.
  •  
50.
  • Starosta, K., et al. (författare)
  • Smooth band termination at high spin in 113I
  • 2001
  • Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 64:1, s. 143041-1430419
  • Tidskriftsartikel (refereegranskat)abstract
    • The 113I nucleus has been studied using the 58Ni(58Ni,3p) reaction at 250 MeV with the Gammasphere/ Microball facility. Gamma-ray three-and four-fold data gated by charged particle combinations were analyzed. Multipolarities of the γ rays were assigned following the angular correlation measurements. The present study is focused on the high spin properties, where the structure is dominated by 2p-2h excitations across the Z=50 gap. Ten decoupled bands showing the features of smooth band termination were observed; three of those bands are linked to known low-spin states, which allows the identification of configurations by direct comparisons with configuration-dependent cranked Nilsson-Strutinsky calculations. The yrast band, which was linked along with the signature partner, was followed up to (101/2+) and ℏω∼1.3 MeV. The other linked band was a negative-parity band observed up to (95/2-). Tentative configurations for the unlinked bands are discussed. Comparisons with the theoretical results suggest that the band built on a configuration involving the neutron i13/2 intruder orbital originating from the N=6 harmonic oscillator subshell was observed in this experiment.
  •  
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