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1.
  • Andgren, Karin, et al. (författare)
  • Excited states in the neutron-deficient nuclei Rn-197,Rn-199,Rn-201
  • 2008
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 77:5, s. 054303-1-054303-7
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of the extremely neutron-deficient radon isotopes with N = 111, 113, 115 have been studied for the first time in a series of in-beam experiments performed at the Accelerator Laboratory of the University of Jyvaskyla. The reactions used were: Sn-118(Kr-82, 3n)Rn-197, Sn-120(Kr-82, 3n)Rn-199, Sm-150(Cr-52, 3n)Rn-199, and Sn-122(Kr-82, 3n)Rn-201. The gamma rays emitted from excited states in the different isotopes were identified using the recoil-alpha-decay tagging technique. The estimated cross section for the production of Rn-197(m) was 7(3) nb, which is the lowest cross section reported so far for an in-beam study. The energies of the (17/2(+)) levels built on the isomeric (13/2(+)) states in Rn-197,Rn-199,Rn-201 indicate a transition from an anharmonic vibrational structure toward a rotational structure at low spins for these nuclei. However, the transition is not as sharp as predicted by theory.
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2.
  • Andgren, Karin, et al. (författare)
  • gamma-ray spectroscopy of At-197
  • 2008
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 78:4, s. 044328-1-044328-8
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of the extremely neutron-deficient nucleus At-197 have been studied in an in-beam experiment using the fusion-evaporation reaction Sn-118(Kr-82,p2n)At-197. gamma rays belonging to At-197 feeding the I-pi=(9/2(-)) ground state, as well as gamma rays feeding the 311-keV I-pi=(13/2(+)) isomer, decaying via the emission of gamma rays, and the 52-keV I-pi=(1/2(+)) alpha-decaying isomer have been identified using the recoil-alpha-decay tagging technique. Total Routhian surface calculations predict a near-spherical shape for the (9/2(-)) ground state and oblate shapes with beta(2) around -0.2 for the (1/2(+)) and the (13/2(+)) states. These predictions agree with our experimental findings.
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3.
  • Andgren, Karin, et al. (författare)
  • Low-spin collective behavior in the transitional nuclei Mo-86,Mo-88
  • 2007
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:1, s. 014307-
  • Tidskriftsartikel (refereegranskat)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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4.
  • Bianco, L., et al. (författare)
  • Discovery of W-157 and Os-161
  • 2010
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 690:1, s. 15-18
  • Tidskriftsartikel (refereegranskat)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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5.
  • 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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6.
  • 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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7.
  • Carroll, R. J., et al. (författare)
  • Excited states in the proton-unbound nuclide Ta-158
  • 2016
  • Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 93:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the neutron-deficient odd-odd proton-unbound nuclide Ta-158 have been investigated in two separate experiments. In the first experiment, Ir-166 nuclei were produced in the reactions of 380 MeV Kr-78 ions with an isotopically enriched Mo-92 target. The alpha-decay chain of the 9(+) state in Ir-166 was analyzed. Fine structure in the a decay of the 9(+) state in Re-162 established a 66 keV difference in excitation energy between the lowest-lying 9(+) and 10(+) states in Ta-158. Higher-lying states in Ta-158 were populated in the reactions of 255 MeV Ni-58 ions with an isotopically enriched Pd-102 target. Gamma-ray decay paths that populate, depopulate, and bypass a 19(-) isomeric state have been identified. The general features of the deduced level scheme are discussed and the prospects for observing proton emission branches from excited states are considered.
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8.
  • 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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9.
  • Cederwall, Bo, et al. (författare)
  • Evidence for a spin-aligned neutron-proton paired phase from the level structure of 92Pd
  • 2011
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 469:7328, s. 68-71
  • Tidskriftsartikel (refereegranskat)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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10.
  • Darby, I. G., et al. (författare)
  • Decay of the high-spin isomer in Re-160 : Changing single-particle structure beyond the proton drip line
  • 2011
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 695:1-4, s. 78-81
  • Tidskriftsartikel (refereegranskat)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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11.
  • Darby, I. G., et al. (författare)
  • Precision measurements of proton emission from the ground states of Ta-156 and Re-160
  • 2011
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 83:6, s. 064320-
  • Tidskriftsartikel (refereegranskat)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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12.
  • Davis-Merry, T. R., et al. (författare)
  • Collective excitations in the transitional nuclei Re-163 and Re-165
  • 2015
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 91:3
  • Tidskriftsartikel (refereegranskat)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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13.
  • Drummond, M. C., et al. (författare)
  • Low-lying excited states in the neutron-deficient isotopes Os-163 and Os-165
  • 2013
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:5, s. 054309-
  • Tidskriftsartikel (refereegranskat)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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14.
  • Ertoprak, Aysegul, et al. (författare)
  • Evidence for octupole collectivity in 172Pt
  • 2020
  • Ingår i: European Physical Journal A. - : Springer. - 1434-6001 .- 1434-601X. ; 56:2
  • Tidskriftsartikel (refereegranskat)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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15.
  • Ghazi Moradi, Farnaz, et al. (författare)
  • High-spin study of 162Ta
  • 2011
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 84:6, s. 064312-
  • Tidskriftsartikel (refereegranskat)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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16.
  • Hadinia, Baharak, et al. (författare)
  • First identification of excited states in 106Te and evidence for isoscalar-enhanced vibrational collectivity
  • 2005
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 72:4, s. 041303-1-041303-5
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-ray transitions in the extremely neutron-deficient nucleus Te-106 have been identified for the first time. The experiment utilized the Fe-54(Fe-54,2n)Te-106(*) reaction, and the gamma-ray transitions from excited states in Te-106 were selected by use of the recoil-decay-tagging technique. The production cross section was estimated at 25 nb, a new limit for in-beam gamma-ray spectroscopy. A ground-state band tentatively extending up to I-pi=10(+) is proposed. The systematics of low-lying yrast states in the Te isotopes is discussed within the context of vibrational excitations and residual nucleon-nucleon interactions.
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17.
  • Hadinia, Baharak, et al. (författare)
  • First identification of gamma-ray transitions in 107Te
  • 2004
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 70:6, s. 064314-1-064314-4
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-ray transitions in Te-107 have been identified for the first time. The experiment, which utilized the recoil decay tagging technique, was performed at the accelerator laboratory of the University of Jyvaskyla, Finland. Prompt gamma rays produced in Ni-58(Cr-52,3n)Te-107(*) reactions were detected by the JUROGAM gamma-ray spectrometer. The gamma rays belonging to Te-107 were selected based on the recoil identification provided by the RITU gas-filled recoil separator and the GREAT focal plane spectrometer. A first excited state at 90 keV, tentatively of g(7/2) character, is proposed.
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18.
  • Hadinia, Baharak, et al. (författare)
  • First identification of gamma-rays in Te-106 using recoil decay tagging technique
  • 2006
  • Ingår i: Frontiers in Nuclear Structure Astrophysics, and Reactions: FINUSTAR. - MELVILLE, NY : AMER INST PHYSICS. - 0735403236 - 9780735403239 ; , s. 457-459
  • Konferensbidrag (refereegranskat)abstract
    • Gamma-ray transitions from excited states in Te-106 have been identified using the recoil decay tagging technique. The experiment which was the reaction Fe-54(Fe-54,2n)Te-106* was performed at the JYFL accelerator facility at the University of Jyvaskyla, Finland. The production cross section was estimated at 25 nb, a new limit for in-beam gamma-ray spectroscopy. A tentative level structure for the ground state band of Te-106 is proposed.
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19.
  • Hadinia, Baharak, et al. (författare)
  • Identification of gamma rays from Au-172 and alpha decays of Au-172, Ir-168, and Re-164
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 80:6, s. 064310-
  • Tidskriftsartikel (refereegranskat)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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20.
  • Hadinia, Baharak, et al. (författare)
  • In-beam gamma-ray and alpha-decay spectroscopy of 170Ir
  • 2007
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:4, s. 044312-1-044312-8
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the highly neutron deficient odd-odd nucleus Ir-170 have been investigated. The experiment was performed using the Sn-112(Ni-60, pn)Ir-170 reaction and employing the recoil-decay tagging technique. Gamma rays were detected using the JUROGAM gamma-ray spectrometer and those belonging to Ir-170 were selected based on recoil identification provided by the RITU gas-filled recoil separator and the GREAT spectrometer at the RITU focal plane. A partial level scheme of Ir-170 is presented for the first time. New alpha-decay branches are assigned to Ir-170 and a tentative level structure for Re-166 is deduced from a study of the alpha-decay fine structure and the associated alpha-gamma correlations.
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21.
  • Hadinia, Baharak (författare)
  • In-beam study of 106Te and 107Te using the recoil decay tagging technique
  • 2006
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Atomic nuclei are complex many-body systems and exhibit an interplay between single-particle and collective degrees of freedom. In order to describe and predict the “behavior” of nucleons inside the nuclei a variety of theoretical models have been created, each applicable to their own domain of nuclear phenomena. Experimental information is needed in order to test and improve the various theoretical models with the ultimate goal of creating unified theory of nuclear structure. In-beam γ-ray spectroscopy is one way of probing the inner structure of nuclei and it is the subject of this thesis, which describes the first identification of excited states in the extremely neutron deficient nuclei 106Te and 107Te. The experiments were performed at the Accelerator Laboratory of the University of Jyväskylä, Finland, using the recoil-decay tagging technique. Prompt γ rays emitted following fusion evaporation reactions were detected by the Jurogam detector array and the selection of the γ rays of interest was based on the recoil identification provided by the RITU gas-filled recoil separator and the GREAT focal plane spectrometer. The production cross sections were estimated to be 25nb and 1μb for 106Te and 107Te, respectively. In case of the nucleus 106Te, several γ rays have been observed. A vibrational-like yrast band has been suggested. For 107Te a number of γ rays have been assigned and a tentative partial level scheme has been suggested. The experimental data have been compared to shell model calculations.
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22.
  • Hadinia, Baharak, 1975- (författare)
  • In-beam Study of Extremely Neutron deficient Nuclei Using the Recoil-Decay Tagging Technique
  • 2008
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The low-lying structures of the extremely neutron-deficient nuclei 106Te, 107Te, 110Xe, 170Ir and 172Au have been investigated experimentally. Prompt gamma rays emitted in fusion-evaporation reactions were detected by the Jurogam HPGe array. The gamma rays were assigned to specific reaction channels using the recoil-decay tagging technique provided by the gas-filled separator RITU and the GREAT focal-plane spectrometer. The experimental set-up and the technique used to extract the information from the experimental data are described in detail. Results were interpreted in terms of the nuclear shell model and Total Routhian Surface calculations. In addition, decay studies on 170Ir, 172Au and 164Re led to the discovery of new alpha-decay branches in these nuclei.
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23.
  • Hornillos, M. B. G., et al. (författare)
  • gamma-ray spectroscopy approaching the limits of existence of atomic nuclei : A study of the excited states of Pt-168 and Pt-169
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:6
  • Tidskriftsartikel (refereegranskat)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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24.
  • Ideguchi, E., et al. (författare)
  • High-spin intruder band in In-107
  • 2010
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 81:3, s. 034303-
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in the neutron-deficient nucleus In-107 were studied via the Ni-58(Cr-52,3p) reaction. In-beam gamma rays were measured using the JUROGAM detector array. A rotational cascade consisting of ten gamma-ray transitions, which decays to the 19/2(+) level at 2.002 MeV, was observed. The band exhibits the features typical for smooth terminating bands that also appear in rotational bands of heavier nuclei in the A similar to 100 region. The results are compared with total Routhian surface and cranked Nilsson-Strutinsky calculations.
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25.
  • Jakobsson, U., et al. (författare)
  • Prompt and delayed spectroscopy of At-199
  • 2010
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 82:4, s. 044302-
  • Tidskriftsartikel (refereegranskat)abstract
    • The neutron-deficient nucleus At-199 has been studied through gamma-ray and electron spectroscopy, using the recoil-decay tagging technique. Two experiments were conducted, using a gas-filled recoil separator with a focal-plane spectrometer alone and together with a germanium-detector array at the target position. The resulting level scheme for 199At includes a new isomer with a half-life of 0.80(5) mu s and a spin and parity of (29/2(+)). The 13/2(+) isomer, which de-excites via an M2 transition to the 9/2 ground state, was measured to have a half-life of 70(20) ns. Our earlier version of the level scheme for At-197 has been updated as well.
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26.
  • Joss, D. T., et al. (författare)
  • Discovery of the proton emitting nucleus 159Re
  • 2007
  • Ingår i: Proton Emitting Nuclei and Related Topics. - : American Institute of Physics (AIP). - 9780735404755 ; , s. 28-33
  • Konferensbidrag (refereegranskat)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.
  •  
27.
  • Joss, D. T., et al. (författare)
  • Evolving collective structures in the transitional nuclei W-162 and W-164
  • 2016
  • Ingår i: PHYSICAL REVIEW C. - : American Physical Society. - 2469-9985. ; 93:2
  • Tidskriftsartikel (refereegranskat)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.
  •  
28.
  • Joss, D. T., et al. (författare)
  • Probing structural changes in the very neutron-deficient Os isotopes with recoil-decay tagging
  • 2005
  • Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. S1593-S1598
  • Tidskriftsartikel (refereegranskat)abstract
    • In recent years, the exploitation of the iecoil-decay tagging (RDT) technique with,large arrays of germanium detectors has revealed much information about the structure of heavy nuclei approaching the proton drip line. The yrast bands of the N <= 93 osmium isotopes have been identified in a campaign of tagging experiments using various spectrometer arrays coupled to the RITU gas-filled separator based at the University of Jyvaskyla. Trends in the yrast state excitation energies have indicated a transition from gamma-soft triaxial to near-spherical shapes with decreasing neutron number. Recent experimental results for Os-162 obtained with the JUROGAM and GREAT spectrometers also indicate the importance of configurations involving the h(9/2) neutron states as the N = Z 82 shell gaps are approached.
  •  
29.
  • Joss, D. T., et al. (författare)
  • Probing the limit of nuclear existence : Proton emission from Re-159
  • 2006
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 641:1, s. 34-37
  • Tidskriftsartikel (refereegranskat)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.
  •  
30.
  • Joss, D. T., et al. (författare)
  • Recoil decay tagging of gamma rays in the extremely neutron-deficient nucleus Os-162
  • 2004
  • Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 70:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The neutron-deficient nucleus Os-162, produced in the Cd-106(Ni-58,2n) reaction, has been studied using the JUROGAM gamma-ray spectrometer in conjunction with the RITU gas-filled separator and the GREAT focal plane spectrometer. gamma-ray transitions in Os-162 have been assigned for the first time through the application of the recoil decay tagging technique. The excitation energy of the 2(+) state and the tentative energy of the 8(+) state are discussed in terms of the systematic energy trends as the N=82 shell gap is approached.
  •  
31.
  • 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.
  •  
32.
  • Joss, D. T., et al. (författare)
  • The influence of quasineutron configurations on 161Ta and nearby odd-A nuclei
  • 2011
  • Ingår i: AIP Conf. Proc.. - : AIP. - 9780735409835 ; , s. 43-48
  • Konferensbidrag (refereegranskat)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.
  •  
33.
  • Joss, D. T., et al. (författare)
  • Yrast structures in the light Pt isotopes Pt169-173
  • 2005
  • Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. S1715-S1718
  • Tidskriftsartikel (refereegranskat)abstract
    • The exploitation of the recoil-decay tagging (RDT) technique has reinvigorated experimental investigations of the shape coexistence phenomenon in heavy neutron-deficient nuclei. In a recent experiment using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator, excited states have been investigated in the light platinum isotopes. In addition to extending the yrast sequences in Pt-170 and Pt-172, the first observation of excited states in the odd-N isotopes, Pt-169 and Pt-173, is reported. The bands are discussed in terms of trends in level excitation energies as a function of neutron number.
  •  
34.
  • Lagergren, Karin, et al. (författare)
  • gamma-soft shapes and quasiparticle excitations in Ta-161(73)88
  • 2011
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 83:1, s. 014313-
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the neutron-deficient odd-Z nuclide Ta-161 were identified for the first time using the Cd-106(Ni-58,3p gamma) reaction at a beam energy of 270 MeV. The pi h(11/2) band, yrast at low spin, was observed up to (47/2(-)) and a further four strongly coupled bands have been established to high spin. Quasiparticle configuration assignments for the new band structures have been made on the basis of cranked shell model calculations. This work suggests that the negative-parity nu(f(7/2), h(9/2)) orbitals are responsible for the first rotational alignment in the pi h(11/2) band.
  •  
35.
  • Lagergren, Karin, et al. (författare)
  • High-spin states in the proton-unbound nucleus Re-161
  • 2006
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 74:2, s. 024316-
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in Re-161 were populated using the Cd-106(Ni-58, p2n) reaction at a beam energy of 270 MeV, resulting in the first observation of gamma rays emitted from this nucleus. The reaction products were separated from scattered beam and fission fragments by the gas-filled recoil separator RITU, and were implanted in the double-sided silicon strip detectors of the GREAT spectrometer. Prompt gamma rays were detected by the JUROGAM Ge detector array and were assigned to Re-161 based on alpha- and proton-decay tagging of the implanted reaction products. The near-yrast high-spin level structure, which was delineated to spins around 39/2, is discussed in the context of the total Routhian surface formalism. The level scheme is interpreted in terms of the alignment of h(9/2)/f(7/2) neutrons at lower spins, followed by excitations involving the pi h(11/2) subshell at higher spins.
  •  
36.
  • Lalkovski, S., et al. (författare)
  • Core-coupled states and split proton-neutron quasiparticle multiplets in Ag122-126
  • 2013
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:3, s. 034308-
  • Tidskriftsartikel (refereegranskat)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.
  •  
37.
  • Naqvi, F., et al. (författare)
  • Isomer spectroscopy of (127)Cd
  • 2010
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 82:3, s. 034323-
  • Tidskriftsartikel (refereegranskat)abstract
    • The spin and configurational structure of excited states of (127)Cd, the two-proton and three-neutron hole neighbor of (132)Sn, has been studied. An isomeric state with a half-life of 17.5(3) mu s was populated in the fragmentation of a (136)Xe beam on a (9)Be target at a beam energy of 750 MeV/u. Time distributions of the delayed gamma transitions and gamma gamma coincidence relations were exploited to construct a decay scheme. The observed yrast (19/2)(+) isomer is proposed to have dominant configurations of nu(h(11/2)(-3))pi(g(9/2)(-1), p(1/2)(-1)), nu(h(11/2)(-2)d(3/2)(-1))pi(g(9/2)(-2)), and nu(h(11/2)(-2), s(1/2)(-1))pi(g(9/2)(-2)) and to decay by two competing stretched M2 and E3 transitions. Experimental results are compared with the isotone (129)Sn. The new information provides input for the proton-neutron interaction and the evolution of neutron hole energies in nuclei around the doubly magic (132)Sn core.
  •  
38.
  • O'Donnell, D., et al. (författare)
  • Spectroscopy of the neutron-deficient nucleus Os-167(91)
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of the nucleus Os-167 have been populated by the reaction Mo-92(Kr-78,2pn). The JUROGAM gamma-ray detector array has been used in conjunction with the RITU gas-filled separator and the GREAT spectrometer to observe prompt gamma rays in coincidence with recoiling fusion-evaporation residues and their subsequent decay by alpha particle emission. By correlating prompt gamma radiation with the characteristic alpha radioactivity of Os-167, it has been possible to extend the level scheme for this nucleus significantly. In particular, an extension of the yrast band and four previously unobserved bands are reported. In addition, the recoil distance Doppler-shift method was used to determine a lifetime of tau=20(4) ps for The I-pi=17/2(+) state in Os-167. Hence, the level of collectivity and magnitude of deformation of the low spin yrast band of this nucleus is established. .  
  •  
39.
  • Page, R. D., et al. (författare)
  • alpha decay of Re-159 and proton emission from Ta-155
  • 2007
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 75:6, s. 061302-
  • Tidskriftsartikel (refereegranskat)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.
  •  
40.
  • Page, R. D., et al. (författare)
  • Probing single-particle structures beyond the proton drip line
  • 2007
  • Ingår i: Proton Emitting Nuclei and Related Topics. - : American Institute of Physics (AIP). - 9780735404755 ; , s. 137-142
  • Konferensbidrag (refereegranskat)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.
  •  
41.
  • Pietri, S., et al. (författare)
  • First observation of the decay of a 15(-) seniority v=4 isomer in Sn-128
  • 2011
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 83:4, s. 044328-
  • Tidskriftsartikel (refereegranskat)abstract
    • Isomeric states in the semimagic Sn128-130 isotopes were populated in the fragmentation of a Xe-136 beam on a Be-9 target at an energy of 750 A.MeV. The decay of an isomeric state in Sn-128 at an excitation energy of 4098 keV has been observed. Its half live has been determined to be T-1/2 = 220(30) ns from the time distributions of the delayed gamma rays emitted in its decay. gamma gamma coincidence relations were analyzed in order to establish the decay pattern of the newly established state toward the known (7(-)) and (10(+)) isomers at excitation energies of 2092 and 2492 keV, respectively. Based on a comparison with results of state-of-the-art shell-model calculations the new isomeric state is proposed to have the nu h(11/2)(-3)d(3/2)(-1) configuration with the four neutron holes in Sn-132 maximally aligned to a total spin of I-pi = 15(-).
  •  
42.
  • Sandzelius, Mikael, et al. (författare)
  • First identification of excited states in 169Ir
  • 2007
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 75:5, s. 054321-
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma rays populating the alpha-decaying isomeric state in Ir-169 have been observed for the first time. The experiment employed the recoil-decay tagging method using the JUROGAM gamma-ray spectrometer, the RITU gas-filled recoil separator and the GREAT spectrometer located at the RITU focal plane. The gamma-ray cascade feeding the isomeric alpha-decaying state exhibits a rotational structure consistent with a h(11/2) proton coupled to a triaxially deformed core. The experimental results are compared with predictions from total Routhian surface calculations.
  •  
43.
  • Sandzelius, Mikael, et al. (författare)
  • (gamma)-ray spectroscopy of 163Ta
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 80:5, s. 054316-
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in Ta-163 have been identified for the first time using the Cd-106(Ni-60,3p) fusion evaporation reaction. gamma rays were detected using the JUROGAM gamma-ray spectrometer and recoil discrimination was achieved using the recoil ion transport unit (RITU) gas-filled separator in conjunction with the GREAT spectrometer situated at the focal plane of the RITU. The yrast states are assigned to a strongly coupled rotational band based on a pi h(11/2) configuration. This structure exhibits large signature splitting at low spins that disappears after the paired band crossing because of the alignment of a pair of i(13/2) neutrons. This effect is ascribed to triaxial shape changes induced by the core-polarizing properties of the deformation-aligned h(11/2) proton and the rotation-aligned i(13/2) neutrons. Two additional strongly coupled band structures have been established and are discussed in terms of octupole-vibrational and two-quasiparticle excitations built on the yrast structure. The experimental results are compared with predictions from cranked-shell-model and total-Routhian-surface calculations.
  •  
44.
  • Sandzelius, Mikael, et al. (författare)
  • Indentification of Excited States in the Tz=1 Nucleus 110Xe : Evidence for Enhanced Collectivity Near the N=Z=50 Double Shell Closure
  • 2007
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 99, s. 022501-
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-ray transitions have been identified for the first time in the extremely neutron-deficient (N=Z+2) nucleus Xe110, and the energies of the three lowest excited states in the ground-state band have been deduced. The results establish a breaking of the normal trend of increasing first excited 2+ and 4+ level energies as a function of the decreasing neutron number as the N=50 major shell gap is approached for the neutron-deficient Xe isotopes. This unusual feature is suggested to be an effect of enhanced collectivity, possibly arising from isoscalar n-p interactions becoming increasingly important close to the N=Z line.
  •  
45.
  • Sandzelius, Mikael, et al. (författare)
  • Probing the collective degrees of freedom at the proton drip line in the extremely neutron deficient 172Hg
  • 2011
  • Ingår i: AIP Conf. Proc.. - : AIP. - 9780735409835 ; , s. 29-34
  • Konferensbidrag (refereegranskat)abstract
    • Excited states in the extremely neutron-deficient isotope 172Hg have been established for the first time. The 96Ru( 78Kr,2n) reaction was employed to populate excited states in 172Hg with a cross section σ ≈ 15 nb. The highly selective Recoil-Decay Tagging (RDT) technique was used to obtain clean in-beam γ-ray spectra for 172Hg. The yrast ground-state band has tentatively been established up to I=6h̄. The data have been interpreted within the framework of total Routhian surface and quasiparticle random phase approximation calculations. In addition to the well-known features of shape coexistence previously observed in light Hg isotopes, the systematic trends in the energy of the yrast 2 + and 4 + states in the chain of Hg isotopes indicate a pronounced vibrational collectivity which is reduced in strength, but at the same time shows a higher degree of harmonicity, as the neutron number decreases below the neutron midshell.
  •  
46.
  • Scholey, C., et al. (författare)
  • In-beam and decay spectroscopy of very neutron deficient iridium nuclei
  • 2005
  • Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. S1719-S1722
  • Tidskriftsartikel (refereegranskat)abstract
    • Iridium nuclei at and beyond the proton drip line have been studied via fusion evaporation reactions. A reaction of Mo-92(Kr-78, p2n) at a beam energy of 360 MeV and target thickness 500 mu g cm(-2) was employed to study (167,167m) Ir. A reaction of Sn-112(Ni-58, p2n) at a beam energy of 266 MeV and target thickness 500 mu g cm(-2) was used to study (169,169m) Ir. The experiments were performed at the University of Jyvaskyla utilizing the RITU separator in conjunction with the focal plane GREAT spectrometer and the JUROGAM Ge array at the target position. Excited states feeding. both the ground state and isomeric state in Ir-169, excited states feeding the ground state of Ir-167 and the ground state alpha decay of Re-165 have been observed for the first time along with excited states feeding (167)m Ir Experimental spectroscopic factors and reduced widths have been obtained for the proton and alpha decay of these nuclei.
  •  
47.
  • Singh, B. S. Nara, et al. (författare)
  • Recoil Beta Tagging : Application to the study of odd-odd near proton drip line nuclei, Rb-74 and Y-78
  • 2007
  • Ingår i: The European Physical Journal Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 150, s. 147-148
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a study of low-spin states in Rb-74 and Y-78 using the new technique of Recoil Beta Tagging. This yielded new information on Rb-74 and has provided the first evidence for non-isomeric T = 1 states in Y-78.
  •  
48.
  • Sohler, Dola, et al. (författare)
  • First identification of excited states in the T-z=1/2 nucleus Pd-93
  • 2004
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 19:2, s. 169-172
  • Tidskriftsartikel (refereegranskat)abstract
    • The first experimental information about excited states in the N=Z+1 nucleus Pd-93 is presented. The experiment was performed using a 205 MeV Ni-58 beam from the Vivitron accelerator at IReS, Strasbourg, impinging on a bismuth-backed Ca-40 target. Gamma-rays, neutrons and charged particles emitted in the reactions were detected using the Ge detector array Euroball, the Neutron Wall liquid-scintillator array and the Euclides Si charged-particle detector system. The experimental level scheme is compared with the results of new shell model calculations which predict a coupling scheme with aligned neutron-proton pairs to greatly influence the level structure of Napproximate toZ nuclei at low excitation energies.
  •  
49.
  • Thomson, J., et al. (författare)
  • Competing quasiparticle configurations in W-163
  • 2010
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 81:1
  • Tidskriftsartikel (refereegranskat)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.
  •  
50.
  • Wadsworth, R., et al. (författare)
  • THE NORTHWEST FRONTIER : SPECTROSCOPY OF N similar to Z NUCLEI BELOW MASS 100
  • 2009
  • Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 40:3, s. 611-620
  • Tidskriftsartikel (refereegranskat)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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