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Sökning: WFRF:(DOMBRADI Z)

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1.
  • Stanoiu, M., et al. (författare)
  • Disappearance of the N=14 shell gap in the carbon isotopic chain
  • 2008
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 78:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The structure of C-17-20(6) nuclei was investigated by means of the in-beam gamma-ray spectroscopy technique using fragmentation reactions of radioactive beams. Based on particle-gamma and particle-gamma gamma coincidence data, level schemes are constructed for the neutron-rich C17-20 nuclei. The systematics of the first excited 2(+) states in the carbon isotopes is extended for the first time to A = 20 showing that in contrast to the case of the oxygen isotopes, the N = 14 subshell closure disappears. Experimental results are compared with shell-model calculations. Agreement between them is found only if a reduced neutron-neutron effective interaction is used. Implications of this reduced interaction in some properties of weakly bound neutron-rich Carbon are discussed.
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2.
  • Stanoiu, M., et al. (författare)
  • Study of drip line nuclei through two-step fragmentation
  • 2004
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 20:1, s. 95-96
  • Tidskriftsartikel (refereegranskat)abstract
    • We have studied the structure of light neutron-rich nuclei around N = 16 by employing the in-beam gamma-ray spectroscopy technique using the fragmentation of secondary beams of Ne-25,Ne-26, Na-27,Na-28 and Mg-29,Mg-30 isotopes. This secondary-beam cocktail was obtained by the fragmentation of a 36 S beam at 77.5 MeV.A by the SISSI/GANIL facility. By a second-step fragmentation, we have measured gamma-ray-residue coincidences in C17-20 and O-23,O-24 and described the obtained levels in the framework of the shell model.
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3.
  • Stanoiu, M., et al. (författare)
  • Study of neutron rich carbon and oxygen nuclei up to drip line
  • 2004
  • Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 746, s. 135C-139C
  • Tidskriftsartikel (refereegranskat)abstract
    • In-beam gamma-spectroscopy using fragmentation reactions of radioactive beams have been performed in order to study the structure of excited states in neutron rich oxygen and carbon isotopes. For the produced fragments, gamma-ray energies, intensities and gamma-gamma coincidences have been measured. The experiment was performed at GANIL. New gamma-lines have been identified and placed in level schemes for C17-20. The non observation of any gamma-ray in O-23,O-24 suggests that their first excited states lie above the neutron threshold. These results are discussed in the framework of shell model calculations.
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4.
  • Holl, Matthias, 1986, et al. (författare)
  • Border of the island of inversion: Unbound states in Ne-29
  • 2022
  • Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 105:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The nucleus Ne-29 is situated at the border of the island of inversion. Despite significant efforts, no bound low-lying intruder f(7/2) state, which would place Ne-29 firmly inside the island of inversion, has yet been observed. Here, the first investigation of unbound states of Ne-29 is reported. The states were populated in Ne-30(p, pn) and Na-30(p, 2p) reactions at a beam energy of around 230 MeV/nucleon, and analyzed in terms of their resonance properties, partial cross sections, and momentum distributions. The momentum distributions are compared to calculations using the eikonal, direct reaction model, allowing assignments for the observed states. The lowest lying resonance at an excitation energy of 1.48(4) MeV shows clear signs of a significant l = 3 component, giving first evidence for f(7/2) single particle strength in Ne-29. The excitation energies and strengths of the observed states are compared to shell-model calculations using the SDPF-U-MIX interaction.
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5.
  • Kondo, Y., et al. (författare)
  • First observation of 28 O
  • 2023
  • Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 620:7976, s. 965-970
  • Tidskriftsartikel (refereegranskat)abstract
    • Subjecting a physical system to extreme conditions is one of the means often used to obtain a better understanding and deeper insight into its organization and structure. In the case of the atomic nucleus, one such approach is to investigate isotopes that have very different neutron-to-proton (N/Z) ratios than in stable nuclei. Light, neutron-rich isotopes exhibit the most asymmetric N/Z ratios and those lying beyond the limits of binding, which undergo spontaneous neutron emission and exist only as very short-lived resonances (about 10−21s), provide the most stringent tests of modern nuclear-structure theories. Here we report on the first observation of 28O and 27O through their decay into 24O and four and three neutrons, respectively. The 28O nucleus is of particular interest as, with the Z = 8 and N = 20 magic numbers1,2, it is expected in the standard shell-model picture of nuclear structure to be one of a relatively small number of so-called ‘doubly magic’ nuclei. Both 27O and 28O were found to exist as narrow, low-lying resonances and their decay energies are compared here to the results of sophisticated theoretical modelling, including a large-scale shell-model calculation and a newly developed statistical approach. In both cases, the underlying nuclear interactions were derived from effective field theories of quantum chromodynamics. Finally, it is shown that the cross-section for the production of 28O from a 29F beam is consistent with it not exhibiting a closed N = 20 shell structure.
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6.
  • Revel, A., et al. (författare)
  • Extending the Southern Shore of the Island of Inversion to F-28
  • 2020
  • Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 124:15
  • Tidskriftsartikel (refereegranskat)abstract
    • Detailed spectroscopy of the neutron-unbound nucleus F-28 has been performed for the first time following proton/neutron removal from Ne-29/F-29 beams at energies around 230 MeV=nucleon. The invariant-mass spectra were reconstructed for both the F-27((*)) + n and F-26((*)) + 2n coincidences and revealed a series of well-defined resonances. A near-threshold state was observed in both reactions and is identified as the F-28 ground state, with S-n(F-28) = -199(6) keV, while analysis of the 2n decay channel allowed a considerably improved S-n(F-27) = 1620(60) keV to be deduced. Comparison with shell-model predictions and eikonal-model reaction calculations have allowed spin-parity assignments to be proposed for some of the lower-lying levels of F-28. Importantly, in the case of the ground state, the reconstructed F-27 + n momentum distribution following neutron removal from F-29 indicates that it arises mainly from the 1p(3/2) neutron intruder configuration. This demonstrates that the island of inversion around N = 20 includes F-28, and most probably F-29, and suggests that O-28 is not doubly magic.
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7.
  • Steer, S. J., et al. (författare)
  • Isomeric Decay Studies In Neutron-Rich N Approximate To 126 Nuclei
  • 2009
  • Ingår i: International Journal Of Modern Physics E-Nuclear Physics. - 0218-3013. ; 18:4, s. 1002-1007
  • Konferensbidrag (refereegranskat)abstract
    • Heavy neutron-rich nuclei were populated via relativistic energy fragmentation of a E/A= 1 GeV Pb-208 beam. The nuclei of interest were selected and identified by a fragment separator and then implanted in a passive plastic stopper. Delayed. rays following internal isomeric decays were detected by the RISING array. Experimental information was obtained on a number of nuclei with Z=73-80 (Ta-Hg), providing new information both on the prolate-oblate transitional region as well as on the N=126 closed shell nuclei.
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8.
  • Al-Dahan, N., et al. (författare)
  • Structure of N≥126 Nuclei Produced in Fragmentation of 238U
  • 2009
  • Ingår i: Proceedings of the 13th International Symposium on Capture Gamma‐Ray Spectroscopy and Related Topics. - : AIP. - 0094-243X. ; 1090, s. 145-148
  • Konferensbidrag (refereegranskat)abstract
    • The nuclear structure of neutron-rich N≥126 nuclei have been investigated following their production via relativistic projectile fragmentation of a E/A=l GeV 238U beam on a Be target. The cocktail of secondary beam products were separated and identified using the GSI FRagment Separator (FRS). The nuclei of interest were implanted in a high-granularity active stopper detector set-up consisting of 6 double sided silicon strip detectors. The associated gamma-ray transitions were detected with the RISING array, consisting of 15 Euroball cluster Ge-detectors. Time-correlated gamma decays from individually identified nuclear species have been recorded, allowing the clean identification of isomeric decays.
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9.
  • Gottardo, A., et al. (författare)
  • New μs Isomers in the Neutron-rich 210Hg Nucleus
  • 2013
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 725:4-5, s. 292-296
  • Tidskriftsartikel (refereegranskat)abstract
    • Neutron-rich nuclei in the lead region, beyond N = 126, have been studied at the FRS-RISING setup at GSI, exploiting the fragmentation of a primary uranium beam. Two isomeric states have been identified in Hg-210: the 8(+) isomer expected from the seniority scheme in the vg(9/2) shell and a second one at low spin and low excitation energy. The decay strength of the 8(+) isomer confirms the need of effective three-body forces in the case of neutron-rich lead isotopes. The other unexpected low-lying isomer has been tentatively assigned as a 3(-) state, although this is in contrast with theoretical expectations. (C) 2013 Elsevier B.V. All rights reserved.
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10.
  • Palacz, M, et al. (författare)
  • In-beam gamma-ray spectroscopy of Cd-101
  • 1996
  • Ingår i: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 608:2, s. 227-242
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Excited states of Cd-101 were studied in the reaction Ni-58(Cr-50,2p alpha n)Cd-101. The NORDBALL array with a Neutron Wall and a Silicon Ball was employed for the detection of gamma-rays and evaporated particles, The level scheme of Cd-101 was significan
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11.
  • Palacz, M, et al. (författare)
  • In-beam gamma-ray spectroscopy of Cd-103
  • 1997
  • Ingår i: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 624:2, s. 210-224
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Excited states of Cd-103 were studied in the reaction Ni-58(Cr-50,4pn)Cd-103. The NORDBALL array with neutron and charged particle detectors was employed for the detection of gamma rays and light evaporated particles. The level scheme of Cd-103 was signif
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12.
  • Podolyak, Z., et al. (författare)
  • gamma-ray spectroscopy with a He-8 beam
  • 2003
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 511:3, s. 354-359
  • Tidskriftsartikel (refereegranskat)abstract
    • The He-8 + Pb-208 reaction was studied in the first experiment with the EXOGAM germanium detector array using beam delivered by the SPIRAL facility. gamma-rays from direct and fusion-evaporation reactions were observed with high resolution. gamma-gamma coincidence data were obtained at a beam intensity level of 105 8He particles per second. Specially designed absorbers and beam detectors could further reduce the background radiation by orders of magnitude.
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13.
  • Vajta, Zs., et al. (författare)
  • Excited states in the neutron-rich nucleus F-25
  • 2014
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 89:5, s. 054323-
  • Tidskriftsartikel (refereegranskat)abstract
    • The structure of the nucleus F-25(9) was investigated through in-beam. gamma-ray spectroscopy of the fragmentation of Ne-26 and Na-27,Na-28 ion beams. Based on the particle-gamma and particle-gamma gamma coincidence data, a level scheme was constructed and compared with shell model and coupled-cluster calculations. Some of the observed states were interpreted as quasi-single-particle states built on top of the closed-shell nucleus O-24, while the others were described as states arising from coupling of a single proton to the 2(broken vertical bar) core excitation of O-24.
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14.
  • Wang, H., et al. (författare)
  • Intruder configurations in 29 Ne at the transition into the island of inversion: Detailed structure study of 28 Ne
  • 2023
  • Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 843
  • Tidskriftsartikel (refereegranskat)abstract
    • Detailed γ-ray spectroscopy of the exotic neon isotope 28Ne has been performed for the first time using the one-neutron removal reaction from 29Ne on a liquid hydrogen target at 240 MeV/nucleon. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for 28Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N=20 and N=28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.
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15.
  • Al-Dahan, N., et al. (författare)
  • Isomeric States In 208Hg And 209Tl Populated In Fragmentation Of 238U
  • 2009
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 40:3, s. 871-874
  • Tidskriftsartikel (refereegranskat)abstract
    • The nuclear structure of neutron-rich N > 126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A = 1 GeV U-238 beam on a Be target. The preliminary analysis indicates the presence of previously unreported isomeric states in the N = 128 isotones Hg-208 and Tl-209.
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16.
  • Bacelar, A. M. Denis, et al. (författare)
  • Angular Momentum Population In Fragmentation Reactions
  • 2009
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 40:3, s. 889-892
  • Tidskriftsartikel (refereegranskat)abstract
    • Neutron-deficient nuclei with N = 126 have been populated following projectile fragmentation of a U-238 beam with energy 1 GeV/A. The decay of several previously reported isomers has been measured. This will allow us to calculate high-spin isomeric ratios and compare them with model calculations to allow a better understanding of the reaction mechanism.
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17.
  • Banu, A, et al. (författare)
  • 108Sn Studied with Intermediate-energy Coulomb Excitation
  • 2005
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 72:6
  • Tidskriftsartikel (refereegranskat)abstract
    • The unstable neutron-deficient Sn-108 isotope has been studied in inverse kinematics by intermediate-energy Coulomb excitation using the RISING/FRS experimental setup at GSI. This is the highest Z nucleus studied so far with this method. Its reduced transition probability B (E2;0(g.s.)(+)-> 2(1)(+)) has been measured for the first time. The extracted B(E2) value of 0.230(57)e(2) b(2) has been determined relative to the known value in the stable Sn-112 isotope. The result is discussed in the framework of recent large-scale shell model calculations performed with realistic effective interactions. The roles of particle-hole excitations of the Sn-100 core and of the Z=50 shell gap for the E2 polarization are investigated.
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18.
  • Caceres, L., et al. (författare)
  • Nuclear structure studies of F-24
  • 2015
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 92:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The structure of the F-24 nucleus has been studied at GANIL using the beta decay of O-24 and the in-beam.-ray spectroscopy from the fragmentation of Na-27,Na-28, Ne-25,Ne-26, and Mg-29,Mg-30 nuclei. Combining these complementary experimental techniques, the level scheme of F-24 has been constructed up to 3.6 MeV by means of particle-gamma and particle-gamma gamma coincidence relations. Experimental results are compared to shell-model calculations using the standard USDA and USDB interactions as well as ab initio valence-space Hamiltonians calculated from the in-medium similarity renormalization group based on chiral two- and three-nucleon forces. Both methods reproduce the measured level spacings well, and this close agreement allows unidentified spins and parities to be consistently assigned.
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19.
  • Cederkall, J, et al. (författare)
  • First evidence for excited states in In-101
  • 1996
  • Ingår i: PHYSICAL REVIEW C-NUCLEAR PHYSICS. - : AMER INST PHYSICS. - 0556-2813. ; 53:4, s. 1955-1958
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The first evidence for excited states in In-101 is presented. In-101 is the lightest In isotope observed in an in-beam experiment. Two gamma-ray transitions at 1309 and 341 keV, respectively, are strong candidates for a cascade to the ground state in this
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20.
  • Cederkall, J, et al. (författare)
  • Maximum spin aligned states in Ag-98(47)51
  • 1998
  • Ingår i: EUROPEAN PHYSICAL JOURNAL A. - : SPRINGER VERLAG. - 1434-6001. ; 1:1, s. 7-9
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • New excited states have been observed in the neutron deficient isotope Ag-98 following the Ni-58+Cr-50-->Te-108* heavy-ion reaction. One of these states may be interpreted as a maximum spin aligned state of the pi g(9/2)(-3) nu vg(7/2) configuration. Othe
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21.
  • Danko, I, et al. (författare)
  • Collective and broken pair states of Ga-65,Ga-67
  • 1999
  • Ingår i: PHYSICAL REVIEW C-NUCLEAR PHYSICS. - : AMERICAN PHYSICAL SOC. - 0556-2813. ; 59:4, s. 1956-1974
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Excited states of Ga-65 and Ga-67 nuclei were populated through the C-12(Ni-58,alpha p) and C-12(Ni-58,3p) reactions, respectively, and investigated by in-beam gamma-ray spectroscopic methods. The NORDBALL array equipped with a charged particle ball and 1
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22.
  • DOMBRADI, Z, et al. (författare)
  • HIGH-SPIN SPECTROSCOPY OF TE-109
  • 1995
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 51:5, s. 2394-2399
  • Tidskriftsartikel (refereegranskat)
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23.
  • DOMBRADI, Z, et al. (författare)
  • IDENTIFICATION AND SPECTROSCOPY OF THE TE-108 NUCLEUS
  • 1994
  • Ingår i: Zeitschrift für Physik A Hadrons and Nuclei. - 0939-7922 .- 1431-5831. ; 350:1, s. 3-4
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of Te-108 were populated in the Fe-54 + Ni-58 (270 MeV) reaction using the NORDBALL detector array equipped with charged-particle and neutron detector systems for reaction channel separation. Gamma rays belonging to the neutron deficient nucleus Te-108 were identified for the first time. On the basis of gammagamma-coincidence and angular correlation relations a level scheme was constructed with tentative spin and parity assignments. The structure of the nucleus is discussed in the framework of systematics of heavier Te nuclei.
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24.
  • Ertoprak, Aysegul, et al. (författare)
  • Lifetime measurements of core-excited states in semi-magic 95Rh
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Lifetimes of negative-parity states have been determined in the semi-magic (N=50) nucleus 95Rh. The fusion-evaporation reaction 58Ni(40Ca, 3p) was used to populate high-spin states in 95Rh at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator facility. The results were obtained using the Doppler Shift Attenuation Method (DSAM) based on the Doppler broadened line shapes produced during the slowing down process of the residual nuclei in a thick 6~ mg/cm2 metallic target.  B(M1) and B(E2) reduced transition strengths are compared with predictions from large-scale shell-model calculations.
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25.
  • Ertoprak, Aysegul, et al. (författare)
  • LIFETIME MEASUREMENTS WITH THE DOPPLER SHIFT ATTENUATION METHOD USING A THICK HOMOGENEOUS PRODUCTION TARGET - VERIFICATION OF THE METHOD
  • 2017
  • Ingår i: Acta Physica Polonica B. - : Jagiellonian University Press. - 0587-4254 .- 1509-5770. ; 48:3, s. 325-329
  • Tidskriftsartikel (refereegranskat)abstract
    • Doppler Shift Attenuation Method (DSAM) analysis of excited-state lifetimes normally employs thin production targets mounted on a thick stopper foil ("backing") serving to slow down and stop the recoiling nuclei of interest in a well-defined manner. Use of a thick, homogeneous production target leads to a more complex analysis as it results in a substantial decrease in the energy of the incident projectile which traverses the target with an associated change in the production cross section of the residues as a function of penetration depth. Here, a DSAM lifetime analysis using a thick homogeneous target has been verified using the Doppler broadened lineshapes of gamma rays following the decay of highly excited states in the semi-magic (N = 50) nucleus Ru-94. Lifetimes of excited states in the Ru-94 nucleus have been obtained using a modified version of the LINESHAPE package from the Doppler broadened lineshapes resulting from the emission of the gamma rays, while the residual nuclei were slowing down in the thick (6 mg/cm(2)) metallic Ni-58 target. The results have been validated by comparison with a previous measurement using a different (RDDS) technique.
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26.
  • Ertoprak, A., et al. (författare)
  • Lifetimes of core-excited states in semi-magic Rh-95
  • 2020
  • Ingår i: European Physical Journal A. - : SPRINGER. - 1434-6001 .- 1434-601X. ; 56:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Lifetimes of negative-parity states have been determined in the neutron deficient semi-magic (N = 50) nucleus Rh-95. The fusion-evaporation reaction Ni-58(Ca-40, 3p) was used to populate high-spin states in Rh-95 at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator facility. The results were obtained using the Doppler Shift Attenuation Method (DSAM) based on the Doppler broadened line shapes produced during the slowing down process of the residual nuclei in a thick 6 mg/cm(2) metallic target. B(M1) and B(E2) reduced transition strengths are compared with predictions from large-scale shell-model calculations. state-of-the-art theory. Remarkably, the structural features up to moderate angular momentum of nuclei immediately below the N = Z = 50 shell closures can be described with high accuracy in a very simple way by shell-model calculations including only the g(9/2) and p(1/2) subshells. Of special interest is the neutron-proton pair coupling scheme which is expected to appear in the heaviest N=Z nuclei [1,2] and the seniority structure of the N = 50 isotones [3-7]. However, multiple core-excited states have been observed in the semi-magic nuclei of the Sn-100 region [8-10]. The theoretical study of those states is a challenging task, which requires a significantly larger model space for their interpretation. Transition probabilities between nuclear states provide important constraints for theoretical modelling of the structure of the nuclei of interest. Our previous lifetime study of the semimagic (N = 50) nucleus Ru-94 [ 11,12] provided information on the electromagnetic decay properties of neutron-core excited states. We now address lifetime measurements in its closest, more neutron deficient, isotone Rh-95 using the same DSAM technique. The experimental results have been interpreted within the framework of large-scale shell-model (LSSM) calculations.
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27.
  • Ertoprak, Aysegul, 1987-, et al. (författare)
  • M1 and E2 transition rates from core-excited states in semi-magic 94Ru
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Lifetimes of high-spin states have been measured in the semi-magic (N=50) nucleus 94Ru. Excited states in 94Ru were populated in the 58Ni(40Ca, 4p)94Ru∗ fusion-evaporation reaction at the Grand Accelerateur National d’Ions Lourds (GANIL) accelerator complex. DSAM lifetime analysis was performed on the Doppler broadened line shapes in energy spectra obtained from γ-rays emitted while the residual nuclei were slowing down in a thick 6 mg/cm2 metallic 58Ni target. In total eight excited-state lifetimes in the angular momentum range I = (13 − 20)ħ have been measured, five of which were determined for the first time. The deduced corresponding B(M1) and B(E2)reduced transition strengths are discussed within the framework of large-scale shell model calculations to study the contribution of different particle-hole configurations, in particular for analyzing contributions from core-excited configurations.
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28.
  • Ertoprak, Aysegul, et al. (författare)
  • M1 and E2 transition rates from core-excited states in semi-magic Ru-94
  • 2018
  • Ingår i: European Physical Journal A. - : Springer. - 1434-6001 .- 1434-601X. ; 54:9
  • Tidskriftsartikel (refereegranskat)abstract
    • Lifetimes of high-spin states have been measured in the semi-magic (N = 50) nucleus Ru-94. Excited states in Ru-94 were populated in the Ni-58(Ca-40, 4p)Ru-94* fusion-evaporation reaction at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator complex. DSAM lifetime analysis was performed on the Doppler broadened line shapes in energy spectra obtained from gamma-rays emitted while the residual nuclei were slowing down in a thick 6 mg/cm(2) metallic Ni-58 target. In total eight excited-state lifetimes in the angular momentum range I = (13-20)h have been measured, five of which were determined for the first time. The corresponding B(M1) and B(E2) reduced transition strengths are discussed within the framework of large-scale shell model calculations to study the contribution of different particle-hole configurations, in particular for analyzing contributions from core-excited configurations.
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29.
  • Fahlander, Claes, et al. (författare)
  • Excited States in 103Sn: Neutron Single-particle Energies with Respect to 100Sn
  • 2001
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813 .- 1089-490X. ; 63:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-ray lines from Sn-103 have been identified for the first time using EUROBALL and ancillary detectors. The level scheme of Sn-103 has been established by means of particle-gated gamma gamma coincidences. The energy spacing between the g(7/2) and d(5/2) neutron single-particle orbitals is determined from the excited states in Sn-103.
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30.
  • FAHLANDER, C, et al. (författare)
  • IN-BEAM SPECTROSCOPY OF TE-110
  • 1994
  • Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 577:3-4, s. 773-785
  • Tidskriftsartikel (refereegranskat)abstract
    • The neutron-deficient nucleus Te-110 has been investigated by in-beam spectroscopic methods using the NORDBALL multi-detector array. Except for the energy of one level observed in alpha-decay, excited states in Te-110 were previously unknown. The level scheme constructed from gamma gamma-coincidence relationships is presented with tentative spin assignments up to I-pi = 21(-). Above spin 8(+) the yrast states have negative parity. They are most likely the members of a band predominantly based on the nu(h(11/2)g(7/2)) two-quasiparticle configuration. A band crossing is observed at I-pi approximate to 17(-). It is suggested to be caused by the alignment of two h(11/2) neutrons. The cranked shell model correctly predicts the spin alignment, but fails to reproduce the observed band crossing frequency, possibly because of octupole effects.
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31.
  • Farrelly, G. F., et al. (författare)
  • Revision of the K-Isomer in 190W
  • 2009
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 40:3, s. 885-888
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma rays from the decay of an isomer in W-190(116) have been observed following projectile fragmentation of a 1 GeV per nucleon Pb-208 beam. An earlier experiment indicated decay from a (10(-)) isomer to the ground state rotational band. Improved statistics have enabled gamma coincidence and time-difference measurements to be made which alter the previous interpretation. Blocked BCS calculations have also been used together with reduced hindrance factors to indicate possible values of spin-parity for the isomer.
  •  
32.
  • Garnsworthy, A. B., et al. (författare)
  • Isomeric States in Neutron-deficient A~80-90 Nuclei Populated in the Fragmentation of 107Ag
  • 2009
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:6
  • Tidskriftsartikel (refereegranskat)abstract
    • The relativistic projectile fragmentation of a 750 MeV per nucleon beam of Ag-107 was used to populate isomeric states in neutron-deficient nuclei around A=80-90. Reaction products were separated and unambiguously identified using the GSI FRagment Separator (FRS) and its ancillary detectors. At the final focal plane, the fragments were slowed from relativistic energies by means of an aluminium degrader and implanted in a passive stopper in the center of the high-efficiency, high-granularity Stopped Rare Isotope Spectroscopic INvestigation at GSI (RISING) germanium array. This allowed the identification of excited states in the N=Z nuclei Tc-86(43) and, for the first time, Nb-82(41). Isomeric states have also been identified for the first time in Tc-87,Tc-88, and a previously unreported isomer was observed in Nb-84. Experimental results are presented along with a discussion on the structure of these nuclei based on interpretations provided by several theoretical models.
  •  
33.
  • Garnsworthy, A. B., et al. (författare)
  • Isomeric States in the Light Tc Isotopes
  • 2007
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 38:4, s. 1265-1269
  • Tidskriftsartikel (refereegranskat)abstract
    • Preliminary results from the first experiment of the Stopped Beam RISING campaign are presented. The relativistic projectile fragmentation of a 750 MeV/u beam of Ag-107 populated isomeric states in very neutron deficient nuclei at the proton dripline around mass 80-90. Nuclei were unambiguously identified using the FRagment Separator (FRS) and its ancillary detectors located at GSI. The ions produced were slowed down from relativistic energies by means of an Al degrader and implanted in the centre of the high-efficiency Stopped RISING array. This allowed the identification of new excited states in the N = Z = 43 nucleus, Tc-86, populated following the de-excitation of a microsecond isomer. Preliminary results of this analysis, as well as previously unobserved isomeric states in Tc-87,Tc-88. are reported.
  •  
34.
  • Garnsworthy, A B, et al. (författare)
  • Neutron-proton pairing competition in N = Z nuclei: Metastable state decays in the proton dripline nuclei Nb-82(41) and Tc-86(43)
  • 2008
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 660:4, s. 326-330
  • Tidskriftsartikel (refereegranskat)abstract
    • The low-lying structures of the self-conjugate (N = Z) nuclei Nb-82(41)41 and Tc-86(43)43 have been investigated using isomeric-decay spectroscopy following the projectile fragmentation of a Ag-107 beam. These represent the heaviest odd-odd N = Z nuclei in which internal decays have been identified to date. The resulting level schemes shed light on the shape evolution along the N = Z line between the doubly-magic systems Ni-56(28) and Sn-100(50) and support a preference for T = 1 states in T-z = 0 odd-odd nuclei at low excitation energies associated with a T = 1 neutron-proton pairing gap. Comparison with Projected Shell Model calculations suggests that the decay in Nb-82 may be interpreted as an isospin-changing K isomer.
  •  
35.
  • Gorska, M., et al. (författare)
  • Evolution of the N=82 Shell Gap below 132Sn Inferred from Core Excited States in 131In
  • 2009
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 672:4-5, s. 313-316
  • Tidskriftsartikel (refereegranskat)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.
  •  
36.
  • Guastalla, G., et al. (författare)
  • Coulomb Excitation of Sn-104 and the Strength of the Sn-100 Shell Closure
  • 2013
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:17, s. 172501-
  • Tidskriftsartikel (refereegranskat)abstract
    • A measurement of the reduced transition probability for the excitation of the ground state to the first 2(+) state in Sn-104 has been performed using relativistic Coulomb excitation at GSI. Sn-104 is the lightest isotope in the Sn chain for which this quantity has been measured. The result is a key point in the discussion of the evolution of nuclear structure in the proximity of the doubly magic nucleus Sn-100. The value B(E2; 0(+) -> 2(+)) = 0.10(4) e(2)b(2) is significantly lower than earlier results for Sn-106 and heavier isotopes. The result is well reproduced by shell model predictions and therefore indicates a robust N = Z = 50 shell closure.
  •  
37.
  • Lagergren, K, et al. (författare)
  • Coexistence of superdeformed shapes in Er-154
  • 2001
  • Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 8702:2
  • Tidskriftsartikel (refereegranskat)abstract
    • A new superdeformed rotational band has been observed in Er-154 using the Euroball Ge detector array. The new band and the one previously observed can be understood as based on coexisting superdeformed structures at prolate and triaxial shapes, respectively. The observation resolves long-standing difficulties in the theoretical interpretation of superdeformed states in Er-154.
  •  
38.
  •  
39.
  • Lipoglavsek, M, et al. (författare)
  • Stability of Sn-100(50)50 deduced from excited states in Cd-99(48)51 stability of
  • 1996
  • Ingår i: PHYSICAL REVIEW LETTERS. - : AMER INST PHYSICS. - 0031-9007. ; 76:6, s. 888-891
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Excited states of neutron deficient nuclei close to Sn-100 were investigated in an in-beam spectroscopic experiment using the NORDBALL detector array. Excited states in Cd-99 were identified for the first time. The measured half-life of an isomeric state
  •  
40.
  • Mason, P, et al. (författare)
  • Octupole signatures in Ba-124,Ba-125
  • 2005
  • Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. S1729-S1733
  • Tidskriftsartikel (refereegranskat)abstract
    • The gamma decay of the nuclei Ba-121,Ba-125 has been investigated with the EUROBALL array, using the reaction Ni-64+Ni-64 at E-beam = 255 and 261 MeV. Six new E1 transitions have been found in the nucleus Ba-125, suggesting a significant role of octupole correlations in the origin of its parity doublets. The J(pi) = 3(-) level of the nucleus Ba-124 has been identified for the first time. Its excitation energy is in very good agreement with a prediction based on a microscopic model including octupole interactions.
  •  
41.
  • Myalski, S., et al. (författare)
  • Isomeric Ratio for the I=8+ Yrast State in 96Pd Produced in the Relativistic Fragmentation of 107Ag
  • 2007
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 38:4, s. 1277-1282
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the preliminary results from a study of the decay of the I-pi = 8(+) T-1/2 = 2 mu s isomer in Pd-96 performed as part of the Stopped-Beam RISING campaign within the Rare Isotope Investigation at GSI (RISING). The Pd-96 ions were produced following the projectile fragmentation of a 750 MeV per nucleon Ag-107 primary beam. The reaction products were separated and identified by the in-flight method using the GSI Fragment Separator. The residues of interest were stopped in a perspex stopper surrounded by an array of 15, seven-element germanium Cluster detectors. One of the goals of the current work is to investigate the population of high-spin states produced projectile fragmentation reactions using isomeric ratio measurements to infer information on the angular momentum population distribution. In this short contribution the method and results of determining the isomeric ratio for the I-pi = 8(+) microsecond isomer in Pd-96 nucleus are presented.
  •  
42.
  • Myalski, S., et al. (författare)
  • Isomeric Ratios For Nuclei With Z=62-67 And A=142-152 Produced In The Relativistic Fragmentation Of Pb-208
  • 2009
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 40:3, s. 879-883
  • Tidskriftsartikel (refereegranskat)abstract
    • Isomeric states in nuclei with Z = 62-67 and A = 142-152 produced in the fragmentation of the relativistic (1 GeV/nucleon) Pb-208 beam were investigated. Isomeric ratios were determined for 10 isomeric states. Significant differences between theoretical and experimental values were observed.
  •  
43.
  • Myalski, S., et al. (författare)
  • Study of Isomer Production Rates for A=142-152 and Z=62-67 in Fragmentation of a Relativistic 208Pb Beam
  • 2012
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 43:2, s. 253-259
  • Tidskriftsartikel (refereegranskat)abstract
    • We have investigated nuclear fragmentation reactions of a relativistic Pb-208 beam. Ten isomeric states for nuclei with A = 142-152 and Z = 62-67 were observed. Measured isomeric ratios were compared, together with values from other experiments, with prediction of theoretical models. The discrepancies between the experimental and theoretical values were discussed in terms of transitions by-passing the isomer that are not included in the models.
  •  
44.
  • 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.
  •  
45.
  • Palacz, M, et al. (författare)
  • In beam gamma-ray spectroscopy of very neutron deficient odd-cadmium isotopes
  • 1997
  • Ingår i: Acta Physica Polonica B. - : ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS. - 0587-4254 .- 1509-5770. ; 28:1-2, s. 309-313
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the very neutron deficient odd cadmium isotopes Cd-99, Cd-101 and Cd-103 are discussed in terms of the nuclear shell model. Systematics of excited states in Cd99-109 is presented.
  •  
46.
  • Palacz, M., et al. (författare)
  • Investigations of Neutron Deficient Nuclei Close to 100Sn with EUROBALL
  • 2001
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254 .- 1509-5770. ; 32, s. 999-1003
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of nuclei in the vicinity of Sn-100 have been studied using: the EUROBALL detector array. Gamma-ray lines from Sn-103 have been identified for the first time, and a level scheme of low-lying excited states of Sn-103 has been established. New constraints on energies of single particle orbitals with respect to the Sn-100 core are obtained.
  •  
47.
  • Palacz, M., et al. (författare)
  • N=50 Core Excited States Studied in the 96Pd Nucleus
  • 2012
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813 .- 1089-490X. ; 86:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The four-proton hole Pd-96 neighbor of the doubly-magic Sn-100 nucleus was studied in-beam, using a fusion-evaporation reaction of a Ni-58 beam on a Sc-45 target. States of Pd-96 were established up to an excitation energy of 9707 keV. A core-excited odd-parity isomer with T-1/2 = 37.7(1.1) ns was identified. Shell model calculations were performed in four different model spaces. Even-parity states of Pd-96 are very well reproduced in large-scale shell model (LSSM) calculations in which excitations are allowed of up to five g(9/2) protons and neutrons across the N = Z = 50 gap, to the g(7/2), d(5/2), d(3/2), and s(1/2) orbitals. The odd-parity isomer can be only qualitatively interpreted though, employing calculation in the full fpg shell model space, with just one particle-hole core excitation.
  •  
48.
  • Palacz, M., et al. (författare)
  • Odd-Parity Sn-100 Core Excitations
  • 2013
  • Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 44:3, s. 491-500
  • Tidskriftsartikel (refereegranskat)abstract
    • Odd-parity core excited states have been identified in two close neighbors of Sn-100: Pd-96 and Ag-97. This was done in an fusion-evaporation experiment, using a Ni-58 beam on a Sc-45 target. Even-parity core excited states in these nuclei are very well reproduced in large scale (LSSM) calculations in which particle-hole excitations are allowed with up to five g(9/2) protons and neutrons across the N = Z = 50 gap, to the g(7/2), d(5/2), d(3/2), and s(1/2) orbitals. The odd-parity states can only be qualitatively interpreted though, employing calculations in the full fpg shell model space, but with just one particle-hole core excitation allowed. A more complete model including odd-parity orbitals is need for the description of core excited states in the region of Sn-100. 
  •  
49.
  • Persson, J, et al. (författare)
  • In-beam gamma-ray spectroscopy of Cd-102
  • 1997
  • Ingår i: Nuclear Physics A. - : ELSEVIER SCIENCE BV. - 0375-9474 .- 1873-1554. ; 627:1, s. 101-118
  • Tidskriftsartikel (refereegranskat)abstract
    • Neutron deficient nuclei close to 100Sn have been studied using the NORDBALL Ge-detector array together with ancillary particle detectors. Evaporation residues from the compound nucleus 108Te were identified with charged particle and neutron detectors. In this paper a considerable extension of the level scheme of the nucleus 102Cd is presented. The strongest cascade of the new level scheme reveals an irregular sequence of dipole transitions above Iπ = 10+ extending up to spin 17. A strongly populated rather regular side band consisting of four quadrupole transitions ranging from spin 9 to spin 17 was also discovered. This band was tentatively assigned negative parity. Shell model calculations were performed and a very good agreement with the experimental results was found. The excited states could successfully be interpreted as neutron particle and proton hole excitations with respect to the doubly closed core 50100Sn50.
  •  
50.
  • Persson, J, et al. (författare)
  • New spectroscopic data on Cd-102
  • 1996
  • Ingår i: Acta Physica Polonica B. - : POLISH ACAD SCIENCES INST PHYSICS. - 0587-4254 .- 1509-5770. ; 27:1-2, s. 171-178
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma ray spectroscopy of neutron deficient nuclei close to the doubly magic nucleus Sn-100 has been performed using a heavy-ion reaction and the NORDBALL Ge-detector array. Evaporation residues were identified by means of charged particle and neutron detection. Transitions in 31 different evaporation residues were identified. New results on Cd-102 are presented.
  •  
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