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1.
  • Kröll, T., et al. (author)
  • Transfer Reactions on Neutron-rich Nuclei at REX-ISOLDE
  • 2009
  • In: AIP Conference Proceedings. - 1551-7616 .- 0094-243X. ; 1165, s. 363-368 461
  • Conference paper (peer-reviewed)abstract
    • We report on one- and two-neutron transfer reactions to study the single-particle properties of nuclei at the border of the "island of inversion". The (d,p)- and (t,p)-reactions in inverse kinematics on the neutron-rich isotope Mg-30, delivered as radioactive beam by the REX-ISOLDE facility, have been investigated. The outgoing protons have been detected and identified by a newly built array of Si detectors. The gamma-decay of excited states has been detected in coincidence by the MINIBALL array. First results for Mg-31 and from the search for the second, spherical, 0(+) state in Mg-32 are presented.
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2.
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3.
  • Bianco, L., et al. (author)
  • Discovery of W-157 and Os-161
  • 2010
  • In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 690:1, s. 15-18
  • Journal article (peer-reviewed)abstract
    • The nuclides W-157 and Os-161 have been discovered ill reactions of Ni-58 ion beams with a Cd-106 target. The Os-161 alpha-decay energy and half-life were 6890 +/- 12 keV and 640 +/- 60 mu s. The daughter W-157 nuclei beta-decayed with a half-life of 275 +/- 40 ms, populating both low-lying alpha-decaying states in Ta-157, which is consistent with a 7/2(-) ground state in W-157. Fine structure observed in the alpha decay of Os-161 places the lowest excited state in W-157 with 1(pi) = 9/2(-) at 318 +/- 30 key. The branching ratio of 5.5(-2.2)(+3.1)% indicates that Os-161 also has a 7/2(-) ground state. Shell-model calculations analysing the effects of monopole shifts and a tensor force on the relative energies of 2f(7/2) and 1h(9/2) neutron states in N = 83 isotones are presented. (C) 2010 Elsevier B.V. All rights reserved.
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4.
  • Bree, N, et al. (author)
  • Shape Coexistence in the Neutron-Deficient Even-Even Hg182-188 Isotopes Studied via Coulomb Excitation.
  • 2014
  • In: Physical Review Letters. - 1079-7114. ; 112:16
  • Journal article (peer-reviewed)abstract
    • Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hg isotopes were performed with 2.85 MeV/nucleon mercury beams from REX-ISOLDE. Magnitudes and relative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in Hg182-188 were extracted. Information on the deformation of the ground and the first excited 0+ states was deduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformed and of oblate nature, while a larger deformation for the excited 0+ state was noted in Hg182,184. The results are compared to beyond mean field and interacting-boson based models and interpreted within a two-state mixing model. Partial agreement with the model calculations was obtained. The presence of two different structures in the light even-mass mercury isotopes that coexist at low excitation energy is firmly established.
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5.
  • Jigmeddorj, B., et al. (author)
  • New low-spin states of 122Xe observed via high-statistics beta-decay of 122Cs
  • 2018
  • In: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 178, s. 02026-02026
  • Journal article (peer-reviewed)abstract
    • Excited states of 122Xe were studied via the β+/EC decay of 122Cs with the 8π γ-ray spectrometer at the TRIUMF-ISAC facility. Compton-suppressed HPGe detectors were used for measurements of γ-ray intensities, γγ coincidences, and γ-γ angular correlations. Two sets of data were collected to optimize the decays of the ground (21.2 s) and isomeric (3.7 min) states of 122Cs. The data collected have enabled the observation of about 505 new transitions and about 250 new levels, including 51 new low-spin states. Spin assignments have been made for 58 low-spin states based on the deduced β-decay feeding and γ-γ angular correlation analyses.
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6.
  • Wrzosek-Lipska, K., et al. (author)
  • Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes : Coulomb excitation of 182Hg, 184Hg, 186Hg and 188Hg
  • 2019
  • In: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 55:8
  • Journal article (peer-reviewed)abstract
    • The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 01,2+, 21,2+ and 41+ states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.
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7.
  • Bianco, L., et al. (author)
  • alpha-Decay branching ratios measured by gamma-ray tagging
  • 2008
  • In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 597:2-3, s. 189-191
  • Research review (peer-reviewed)abstract
    • The nuclides Pt168-170 were produced by bombarding isotopically enriched Mo-92,Mo-94 targets with 336, 348 MeV Kr-78 ions. Prompt gamma rays were detected at the target position and provided a selection criterion for the Pt168-170 nuclei. This technique enables the problem of the background from higher-energy alpha decays in the spectrum to be circumvented. The Pt nuclei were separated in flight using the gas-filled separator RITU and implanted into the GREAT spectrometer, which was used to study subsequent alpha decays. The alpha-decay branching ratios of Os164-166 were deduced from the fraction of selected Pt168-170 nuclei correlated with a decays Of Os164-166. The resulting branching ratios agree with the literature values but can have improved precision.
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8.
  • Cederwall, Bo, et al. (author)
  • Evidence for a spin-aligned neutron-proton paired phase from the level structure of 92Pd
  • 2011
  • In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 469:7328, s. 68-71
  • Journal article (peer-reviewed)abstract
    • Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work(1) that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing(2-6), in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus Pd-92. Gamma rays emitted following the Ni-58(Ar-36,2n)Pd-92 fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction(2-6). We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling(7,8)) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.
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9.
  • Davis-Merry, T. R., et al. (author)
  • Collective excitations in the transitional nuclei Re-163 and Re-165
  • 2015
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 91:3
  • Journal article (peer-reviewed)abstract
    • Excited states in the neutron-deficient nuclei (163)(75) Re-88 and (165)(75) Re-90 were populated in the Cd-106(Ni-60, p2n gamma) and Mo-92(Kr-78, 3p2n gamma) fusion-evaporation reactions at bombarding energies of 270 and 380 MeV, respectively.. rays were detected at the target position using the JUROGAM spectrometer while recoiling ions were separated in-flight by the RITU gas-filled recoil separator and implanted in the GREAT spectrometer. The energy level schemes for Re-163 and Re-165 were identified using recoil-decay correlation techniques. At low spin, the yrast bands of these isotopes consist of signature partner bands based on a single pi h(11/2) quasiproton configuration. The bands display large energy splitting consistent with the soft triaxial shape typical of transitional nuclei above N = 82. The configurations of the excited states are proposed within the framework of the cranked shell model.
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10.
  • Drummond, M. C., et al. (author)
  • Low-lying excited states in the neutron-deficient isotopes Os-163 and Os-165
  • 2013
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:5, s. 054309-
  • Journal article (peer-reviewed)abstract
    • Excited states in the neutron-deficient isotopes Os-163 and Os-165 were identified using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. The Os-163 and Os-165 nuclei were populated via the Cd-106(Ni-60,3n) and Mo-92(Kr-78,2p3n) reactions at bombarding energies of 270 MeV and 357 MeV, respectively. Gamma-ray emissions from these nuclei have been established unambiguously using the recoil-decay tagging technique and a coincidence analysis has allowed level schemes to be established. These results suggest that the yrast states are based upon negative-parity configurations originating from the f(7/2) and h(9/2) orbitals.
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11.
  • Ertoprak, Aysegul, et al. (author)
  • Evidence for octupole collectivity in 172Pt
  • 2020
  • In: European Physical Journal A. - : Springer. - 1434-6001 .- 1434-601X. ; 56:2
  • Journal article (peer-reviewed)abstract
    • Excited states in the extremely neutron-deficient nucleus 172Pt were populated via 96Ru(78Kr,2p) and 92Mo(83Kr,3n) reactions. The level scheme has been extended up to an excitation energy of  ~ 5 MeV and tentative spin-parity assignments up to Iπ = 18+. Linear polarization and angular distribution measurements were used to determine the electromagnetic E1 character of the dipole transitions connecting the positive-parity ground-state band with an excited side-band, firmly establishing it as a negative-parity band. The lowest member of this negative-parity structure was firmly assigned spin-parity 3-. In addition, we observed an E3 transition from this 3- state to the ground state, providing direct evidence for octupole collectivity in 172Pt. Large-scale shell model (LSSM) and total Routhian surface (TRS) calculations have been performed, supporting the interpretation of the 3- state as a collective octupole-vibrational state.
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12.
  • Gaffney, L. P., et al. (author)
  • Collectivity in the light radon nuclei measured directly via Coulomb excitation
  • 2015
  • In: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:6
  • Journal article (peer-reviewed)abstract
    • Background: Shape coexistence in heavy nuclei poses a strong challenge to state-of-the-art nuclear models, where several competing shape minima are found close to the ground state. A classic region for investigating this phenomenon is in the region around Z = 82 and the neutron midshell at N = 104. Purpose: Evidence for shape coexistence has been inferred from a-decay measurements, laser spectroscopy, and in-beam measurements. While the latter allow the pattern of excited states and rotational band structures to be mapped out, a detailed understanding of shape coexistence can only come from measurements of electromagnetic matrix elements. Method: Secondary, radioactive ion beams of Rn-202 and Rn-204 were studied by means of low-energy Coulomb excitation at the REX-ISOLDE in CERN. Results: The electric-quadrupole (E2) matrix element connecting the ground state and first excited 2(1)(+) state was extracted for both Rn-202 and Rn-204, corresponding to B(E2; 2(1)(+) -> 0(1)(+)) = 29(-8)(+8) and 43(-12)(+17) W.u., respectively. Additionally, E2 matrix elements connecting the 2(1)(+) state with the 4(1)(+) and 2(2)(+) states were determined in Rn-202. No excited 0(+) states were observed in the current data set, possibly owing to a limited population of second-order processes at the currently available beam energies. Conclusions: The results are discussed in terms of collectivity and the deformation of both nuclei studied is deduced to be weak, as expected from the low-lying level-energy schemes. Comparisons are also made to state-of-the-art beyond-mean-field model calculations and the magnitude of the transitional quadrupole moments are well reproduced.
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13.
  • Joss, D. T., et al. (author)
  • Evolving collective structures in the transitional nuclei W-162 and W-164
  • 2016
  • In: PHYSICAL REVIEW C. - : American Physical Society. - 2469-9985. ; 93:2
  • Journal article (peer-reviewed)abstract
    • Excited states in the neutron-deficient nuclides(74)(162)W(88) and W-164(74)90 were investigated by using the gamma-ray spectrometer Jurogam. A change in structure is apparent from the first rotational alignments in W-162 and W-164, whose rotationally aligned bands are interpreted as nu(h(9/2))(2) and nu(i(13/2))(2) configurations, respectively. The level schemes have been extended using recoil (-decay) correlations with the observation of excited collective structures. Configuration assignments have been made on the basis of comparisons of the deduced aligned angular momentum, as a function of rotational frequency, with the predictions of the cranked shell model.
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14.
  • Page, R. D., et al. (author)
  • alpha decay of Re-159 and proton emission from Ta-155
  • 2007
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 75:6, s. 061302-
  • Journal article (peer-reviewed)abstract
    • The alpha decay of Re-159 has been observed for the first time in reactions of 300 MeV Ni-58 ions with an isotopically enriched Cd-106 target. The Re-159 ions were separated in-flight using the RITU separator and implanted into the GREAT spectrometer. The alpha decay emanates from the proton-emitting pi h(11/2) state in Re-159 with an energy of E-alpha=6776 +/- 26 keV and a branching ratio of 7.5 +/- 3.5%. This alpha decay populates a state in the closed neutron shell nucleus Ta-155, which decays by emitting 1444 +/- 15 keV protons with a half-life of 2.9(-1.1)(+1.5) ms. These values are consistent with the emission of the proton from a pi h(11/2) orbital. These results fit in with the systematics of proton and alpha-particle separation energies in the region, but disagree with the previously reported decay properties of Ta-155.
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15.
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16.
  • Singh, B. S. Nara, et al. (author)
  • Coulomb shifts and shape changes in the mass 70 region
  • 2007
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 75:6
  • Journal article (peer-reviewed)abstract
    • The technique of recoil beta tagging has been developed which allows prompt gamma decays in nuclei from excited states to be correlated with electrons from their subsequent short-lived beta decay. This technique is ideal for studying nuclei very far from stability and improves in sensitivity for very short-lived decays and for high decay Q-values. The method has allowed excited states in Y-78 to be observed for the first time, as well as an extension in the knowledge of T=1 states in Rb-74. From this new information it has been possible to compare Coulomb energy differences (CED) between T=1 states in Br-70/Se-70, Rb-74/Kr-74, and Y-78/Sr-78. The A=70 CED exhibit an anomalous behavior which is inconsistent with all other known CED. This behavior may be accounted for qualitatively in terms of small variations in the Coulomb energy arising from shape changes.
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17.
  • Andgren, Karin, et al. (author)
  • Low-spin collective behavior in the transitional nuclei Mo-86,Mo-88
  • 2007
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:1, s. 014307-
  • Journal article (peer-reviewed)abstract
    • Low-spin structures in Mo-86,Mo-88 were populated using the Ni-58(Ar-36, x alpha yp) heavy-ion fusion-evaporation reaction at a beam energy of 111 MeV. Charged particles and gamma rays were emitted in the reactions and detected by the DIAMANT CsI ball and the EXOGAM Ge array, respectively. In addition to the previously reported low-to-medium spin states in these nuclei, new low-spin structures were observed. Angular correlation and linear polarization measurements were performed in order to unambiguously determine the spins and parities of intensely populated states in Mo-88. Quasiparticle Random Phase Approximation (QRPA) calculations were performed for the first and second excited 2(+) states in Mo-86 and Mo-88. The results are in qualitative agreement with the experimental results, supporting a collective interpretation of the low-spin states for these transitional nuclei.
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18.
  • Darby, I. G., et al. (author)
  • Decay of the high-spin isomer in Re-160 : Changing single-particle structure beyond the proton drip line
  • 2011
  • In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 695:1-4, s. 78-81
  • Journal article (peer-reviewed)abstract
    • A new high-spin isomeric state (t(1/2) = 2.8 +/- 0.1 mu s) in Re-160 has been identified. This high-spin isomer is unique in that it only decays by gamma-decay and not by proton or alpha-particle emission as is the case in every other proton emitter between Z = 64 and 80. Shell model calculations indicate how the convergence of the h(9/2) and f(7/2) neutron levels in this region could open up a gamma-decay path from the high-spin isomer to the low-spin ground state of 160Re. providing a natural explanation for this anomalous absence of charged-particle emission. The consequences of these observations for future searches for proton emission from even more exotic nuclei and in-beam spectroscopic studies are considered.
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19.
  • Darby, I. G., et al. (author)
  • Precision measurements of proton emission from the ground states of Ta-156 and Re-160
  • 2011
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 83:6, s. 064320-
  • Journal article (peer-reviewed)abstract
    • The decays of the pi d(3/2) ground states of Ta-156 and Re-160 have been studied in detail using the GREAT spectrometer. More than 7000 Re-160 nuclei were produced in reactions of 290- and 300-MeV Ni-58 ions with an isotopically enriched Cd-106 target and separated in flight using the RITU separator. The proton and alpha decays of the pi d(3/2) level were confirmed and the half-life and branching ratios of this state were determined with improved precision to be t(1/2) = 611 +/- 7 mu s and b(p) = 89 +/- 1% and b(alpha) = 11 +/- 1%, respectively. The alpha-decay branch populated the ground state of Ta-156, allowing improved values for the proton-decay energy and half-life to be obtained (E-p = 1011 +/- 5 keV; t(1/2) = 106 +/- 4 ms). The beta decay of this level was identified for the first time and a branching ratio of b(beta) = 29 +/- 3% was deduced. The spectroscopic factors deduced from these measurements are compared with predictions.
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20.
  • Ghazi Moradi, Farnaz, et al. (author)
  • High-spin study of 162Ta
  • 2011
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 84:6, s. 064312-
  • Journal article (peer-reviewed)abstract
    • Excited states in the odd-odd neutron deficient nucleus (162)Ta (Z = 73, N = 89) have been studied for the first time. The gamma spectroscopy analysis using gamma - gamma - gamma coincidences revealed a strongly coupled rotational structure that was established up to large angular momentum states. The rotational band was assigned to the configuration pi h(11/2)[514]9/2 circle times nu i(13/2)[660]1/2 based on its rotational and electromagnetic properties. The data are interpreted within the framework of total Routhian surface calculations, which suggests an axially symmetric shape with a gamma-softminimum at beta(2) approximate to 0.16 and gamma approximate to 6 degrees. The crossing of the signature partners observed in heavier (N >= 91) odd-odd nuclides in this mass region is found to be absent at N = 89. This might be correlated with a change in S-band structure above the paired band crossing at these neutron numbers.
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21.
  • Gorska, M., et al. (author)
  • Evolution of the N=82 Shell Gap below 132Sn Inferred from Core Excited States in 131In
  • 2009
  • In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 672:4-5, s. 313-316
  • Journal article (peer-reviewed)abstract
    • The gamma-ray decay of ail excited state in In-131, the one proton hole neighbor of the doubly magic (132)sn has been measured. A high-spin, core-excited isomer with T-1/2 = 630(60) us was identified following production by both relativistic fragmentation of a Xe-136 beam and fission Of a U-238 beam. This state deexcites by a single gamma-ray branch of 3782(2) keV from which direct evidence for the size of the N = 82 shell gal) is inferred. The results are discussed in comparison to a shell-model Calculation including configurations across the closed shells at N = 82 and Z = 50. (C) 2009 Elsevier B.V. All rights reserved.
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22.
  • Hadinia, Baharak, et al. (author)
  • Identification of gamma rays from Au-172 and alpha decays of Au-172, Ir-168, and Re-164
  • 2009
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 80:6, s. 064310-
  • Journal article (peer-reviewed)abstract
    • The very neutron deficient odd-odd nucleus Au-172 was studied in reactions of 342 and 348 MeV Kr-78 beams with an isotopically enriched Ru-96 target. The alpha decays previously reported for Au-172 were confirmed and the decay chain extended down to Tm-152 through the discovery of a new alpha-decaying state in Re-164 [E-alpha=5623(10) keV; t(1/2)=864(-110)(+150) ms; b(alpha)=3(1)%]. Fine structure in these alpha decays of Au-172 and Ir-168 were identified. A new alpha-decaying state was also observed and assigned as the ground state in Au-172 [E-alpha=6762(10) keV; t(1/2)=22(-5)(+6) ms]. This decay chain was also correlated down to Tm-152 through previously reported alpha decays. Prompt gamma rays from excited states in Au-172 have been identified using the recoil-decay tagging technique. The partial level scheme constructed for Au-172 indicates that it has an irregular structure. Possible configurations of the alpha-decaying states in Au-172 are discussed in terms of the systematics of nuclei in this region and total Routhian surface calculations.
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23.
  • Hadinia, B., et al. (author)
  • IN-BEAM gamma-RAY SPECTROSCOPY ABOVE THE HIGH-SPIN ISOMERIC STATE IN Lu-155
  • 2013
  • In: CAPTURE GAMMA-RAY SPECTROSCOPY AND RELATED TOPICS. - : WORLD SCIENTIFIC PUBL CO PTE LTD. ; , s. 139-144
  • Conference paper (peer-reviewed)abstract
    • Excited states in Lu-155 have been studied at the Accelerator Laboratory of the University of Jyvaskyla in Finland. The Lu-155 nuclei were populated using the reaction of Ni-58 on (102)pd at a beam energy of 280 MeV. The nuclei of interest were selected using the RITU gas filled recoil separator and the prompt gamma rays belonging to 155Lu were identified using the recoil-decay tagging technique. The gamma-ray transitions de-exciting the excited states above the high-spin isomeric a-decaying state in Lu-155 have been identified. A gamma-ray coincidence analysis shows that the previously reported level scheme for Lu-155 should be revised.
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24.
  • Hornillos, M. B. G., et al. (author)
  • gamma-ray spectroscopy approaching the limits of existence of atomic nuclei : A study of the excited states of Pt-168 and Pt-169
  • 2009
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:6
  • Journal article (peer-reviewed)abstract
    • Excited states in the N=90 and N=91 Pt nuclei have been investigated using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. These nuclei were populated via the reactions Mo-92(Kr-78,2n) and Mo-94(Kr-78,3n) at 335 and 348 MeV, respectively. The recoil-decay tagging technique has been used to correlate prompt gamma radiation with the characteristic alpha decays of Pt-168 and Pt-169. A gamma-gamma analysis has allowed a level scheme for Pt-168 to be reported for the first time and the level scheme for Pt-169 to be extended. The excitation energies of the proposed positive-parity yrast states of Pt-168 are compared with calculations based on the interacting boson model and found to be in excellent agreement. These data show a continuation of the trend toward vibrational nuclei as the N=82 shell gap is approached. In addition, new excited states constituting two decay paths have been discovered in Pt-169. .  
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25.
  • Joss, D. T., et al. (author)
  • Discovery of the proton emitting nucleus 159Re
  • 2007
  • In: Proton Emitting Nuclei and Related Topics. - : American Institute of Physics (AIP). - 9780735404755 ; , s. 28-33
  • Conference paper (peer-reviewed)abstract
    • The observation of the new nuclide 159Re provides important insights into the evolution of single-particle structure in heavy nuclei beyond the proton drip line. The nuclide 159Re was synthesised in the reaction 106Cd(58Ni, p4n) and identified via its proton radioactivity using the RITU gas-filled separator and the GREAT focal-plane spectrometer. Comparisons of the measured proton energy (Ep = 1805±20 keV) and decay half-life (t1/2 = 21±4 μs) with values calculated using the WKB method indicate that the proton is emitted from an h11/2 state. The implications of these results for future experimental investigations into even more proton unbound Re isotopes using in-flight separation techniques are considered.
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26.
  • Joss, D. T., et al. (author)
  • Probing the limit of nuclear existence : Proton emission from Re-159
  • 2006
  • In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 641:1, s. 34-37
  • Journal article (peer-reviewed)abstract
    • The observation of the new nuclide Re-159(75)84 provides important insights into the evolution of single-particle structure and the mass surface in heavy nuclei beyond the proton drip line. This nuclide, 26 neutrons away from the nearest stable rhenium isotope, was synthesised in the reaction Cd-106(Ni-58, p4n) and identified via its proton radioactivity using the RITU gas-filled separator and the GREAT focal-plane spectrometer. Comparisons of the measured proton energy (E-p = 1805 +/- 20 keV) and decay half-life (t(1/2) = 21 +/- 4 mu s) with values calculated using the WKB method indicate that the proton is emitted from an h(11/2) state. The implications of these results for future experimental investigations into even more proton unbound nuclei using in-flight separation techniques are considered.
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27.
  • Joss, D. T., et al. (author)
  • The influence of quasineutron configurations on 161Ta and nearby odd-A nuclei
  • 2011
  • In: AIP Conf. Proc.. - : AIP. - 9780735409835 ; , s. 43-48
  • Conference paper (peer-reviewed)abstract
    • Several strongly coupled bands in the neutron-deficient nucleus 161Ta have been identified and quasiparticle configuration assignments have been made on the basis of rotational alignments and cranked shell model calculations. The level scheme elucidated for 161Ta highlights the competition between the ν(h 9/2) and ν(i 13/2) orbitals to form the yrast spectrum. The band structures in 161Ta also provide new insights into the structural features of other heavy odd-A nuclei populated with much lower reaction cross sections in this region at the proton drip line.
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28.
  • Joss, D. T., et al. (author)
  • Yrast states and band crossings in the neutron-deficient platinum isotopes Pt169-173
  • 2006
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 74:1
  • Journal article (peer-reviewed)abstract
    • The yrast states in the light platinum isotopes Pt169-173 have been investigated in a recoil-decay tagging experiment using the JUROGAM gamma-ray spectrometer in conjunction with the RITU gas-filled recoil separator and the GREAT tagging spectrometer. Gamma-ray transitions have been established for the first time in the odd-N isotopes, Pt-169 and Pt-173, and the yrast sequences in Pt-170 and Pt-172 have been extended. We discuss the possibility that the weakly deformed yrast structures of Pt-170, Pt-172, and Pt-173 are crossed by a deformed intruder configuration at spin similar to 8h.
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29.
  • Lalkovski, S., et al. (author)
  • Core-coupled states and split proton-neutron quasiparticle multiplets in Ag122-126
  • 2013
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:3, s. 034308-
  • Journal article (peer-reviewed)abstract
    • Neutron-rich silver isotopes were populated in the fragmentation of a Xe-136 beam and the relativistic fission of U-238. The fragments were mass analyzed with the GSI Fragment Separator and subsequently implanted into a passive stopper. Isomeric transitions were detected by 105 high-purity germanium detectors. Eight isomeric states were observed in Ag122-126 nuclei. The level schemes of Ag-122,Ag-123,Ag-125 were revised and extended with isomeric transitions being observed for the first time. The excited states in the odd-mass silver isotopes are interpreted as core-coupled states. The isomeric states in the even-mass silver isotopes are discussed in the framework of the proton-neutron split multiplets. The results of shell-model calculations, performed for the most neutron-rich silver nuclei are compared to the experimental data.
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30.
  • Page, R. D., et al. (author)
  • Probing single-particle structures beyond the proton drip line
  • 2007
  • In: Proton Emitting Nuclei and Related Topics. - : American Institute of Physics (AIP). - 9780735404755 ; , s. 137-142
  • Conference paper (peer-reviewed)abstract
    • Single-particle energies have been investigated in the closed neutron shell proton emitter 155Ta. The 155Ta nuclei were populated through the α decay of 159Re, which has been observed for the first time. The 159Re nuclei were produced in reactions of 300 MeV 58Ni ions with an isotopically enriched 106Cd target, separated in-flight using the RITU separator and implanted into the GREAT spectrometer. The 159Re α decay emanates from the proton-emitting πh11/2 state and populates a state in 155Ta which decays by the emission of a proton from a πh 11/2 orbital. The results fit in with the systematics of proton and α-particle separation energies in the region, but disagree with the previously reported decay properties of 155Ta.
  •  
31.
  • Petri, M., et al. (author)
  • Nuclear levels in proton-unbound I-109 : Relative single-particle energies beyond the proton drip line
  • 2007
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:5
  • Journal article (peer-reviewed)abstract
    • A level scheme has been constructed for the proton-unbound, T-z=3/2 nuclide I-109(53)56 following a recoil-decay-tagging experiment using the Ni-58(Fe-54, p2n gamma) reaction at a beam energy of 195 MeV. The experiment was performed using the highly efficient JUROGAM gamma-ray spectrometer in conjunction with the RITU gas-filled recoil separator and the GREAT focal-plane spectrometer. Cranking calculations are used to interpret band structures built on pi g(7/2) and pi h(11/2) states in a weakly deformed, triaxial nucleus.
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32.
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33.
  • Thomson, J., et al. (author)
  • Competing quasiparticle configurations in W-163
  • 2010
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 81:1
  • Journal article (peer-reviewed)abstract
    • Excited states in the neutron-deficient nuclide W-163 were investigated using the Cd-106(Ni-60, 2pn)W-163 reaction at a beam energy of 270 MeV. The level scheme for W-163 was extended significantly with the observation of five new band structures. The yrast band based on a 13/2(+) isomeric state is extended up to (57/2(+)). Two band structures were established on the 7/2(-) ground state. Quasiparticle configuration assignments for the new band structures were made on the basis of cranked Woods-Saxon shell-model calculations. The results reported in this article suggest that the negative-parity nu(f(7/2), h(9/2)) orbitals are responsible for the first rotational alignment in the yrast band.
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34.
  • Wadsworth, R., et al. (author)
  • THE NORTHWEST FRONTIER : SPECTROSCOPY OF N similar to Z NUCLEI BELOW MASS 100
  • 2009
  • In: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 40:3, s. 611-620
  • Journal article (peer-reviewed)abstract
    • The spectroscopy and structure of excited states of N similar to Z nuclei in the mass 70-100 region has been investigated using two techniques. In the A similar to 70-80 region fusion evaporation reactions coupled with the recoil-beta-tagging method have been employed at Jyvaskyla to study low-lying states in odd-odd N = Z nuclei. Results from these and other data for known odd-odd nuclei above mass 60 will be discussed. In the heavier mass 90 region a fragmentation experiment has been performed using the RIS-ING/FRS setup at GSI. This experiment was primarily aimed at searching for spin gap isomers in nuclei around A similar to 96. The objectives of the latter experiment will be discussed.
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