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Träfflista för sökning "WFRF:(Hoischen R.) srt2:(2007-2009)"

Search: WFRF:(Hoischen R.) > (2007-2009)

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1.
  • Neyens, G., et al. (author)
  • g-Factor Measurements on Relativistic Isomeric Beams Produced by Fragmentation and U-fission: The g-RISING Project at GSI
  • 2007
  • In: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 38:4, s. 1237-1247
  • Journal article (peer-reviewed)abstract
    • Within the RISING (Rare ISotope INvestigations @ GSI) Collaboration at GSI, g factor measurements have been performed on isomeric states in neutron-rich isotopes approaching Sn-132 and in the neutron deficient Pb-region (the g-RISING campaign). We present the experimental technique and some typical aspects related to such studies on relativistic beams selected with the FRS fragment separator. First results are presented for the (19/2(+)) 4.5 mu s isomeric state in Sn-127, which has been produced by means of fission of a relativistic U-238 beam on the one hand, and by the fragmentation of a relativistic Xe-136 beam on the other hand. Spin-alignment has been observed in both reactions. It was the first time that spin-alignment has been established in a relativistic fission reaction.
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2.
  • Wadsworth, R., et al. (author)
  • THE NORTHWEST FRONTIER : SPECTROSCOPY OF N similar to Z NUCLEI BELOW MASS 100
  • 2009
  • In: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 40:3, s. 611-620
  • Journal article (peer-reviewed)abstract
    • The spectroscopy and structure of excited states of N similar to Z nuclei in the mass 70-100 region has been investigated using two techniques. In the A similar to 70-80 region fusion evaporation reactions coupled with the recoil-beta-tagging method have been employed at Jyvaskyla to study low-lying states in odd-odd N = Z nuclei. Results from these and other data for known odd-odd nuclei above mass 60 will be discussed. In the heavier mass 90 region a fragmentation experiment has been performed using the RIS-ING/FRS setup at GSI. This experiment was primarily aimed at searching for spin gap isomers in nuclei around A similar to 96. The objectives of the latter experiment will be discussed.
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3.
  • Al-Dahan, N., et al. (author)
  • Structure of N≥126 Nuclei Produced in Fragmentation of 238U
  • 2009
  • In: Proceedings of the 13th International Symposium on Capture Gamma‐Ray Spectroscopy and Related Topics. - : AIP. - 0094-243X. ; 1090, s. 145-148
  • Conference paper (peer-reviewed)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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4.
  • Alkhomashi, N., et al. (author)
  • beta(-)-delayed spectroscopy of neutron-rich tantalum nuclei: Shape evolution in neutron-rich tungsten isotopes
  • 2009
  • In: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:6
  • Journal article (peer-reviewed)abstract
    • The low-lying structure of W-188,W-190,W-192 has been studied following beta decays of the neutron-rich mother nuclei Ta-188,Ta-190,Ta-192 produced following the projectile fragmentation of a 1-GeV-per-nucleon Pb-208 primary beam on a natural beryllium target at the GSI Fragment Separator. The beta-decay half-lives of Ta-188, Ta-190, and Ta-192 have been measured, with gamma-ray decays of low-lying states in their respective W daughter nuclei, using heavy-ion beta-gamma correlations and a position-sensitive silicon detector setup. The data provide information on the low-lying excited states in W-188, W-190, and W-192, which highlight a change in nuclear shape at W-190 compared with that of lighter W isotopes. This evolution of ground-state structure along the W isotopic chain is discussed as evidence for a possible proton subshell effect for the A similar to 190 region and is consistent with maximization of the gamma-softness of the nuclear potential around N similar to 116.
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5.
  • Gorska, M., et al. (author)
  • Evolution of the N=82 Shell Gap below 132Sn Inferred from Core Excited States in 131In
  • 2009
  • In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 672:4-5, s. 313-316
  • Journal article (peer-reviewed)abstract
    • The gamma-ray decay of ail excited state in In-131, the one proton hole neighbor of the doubly magic (132)sn has been measured. A high-spin, core-excited isomer with T-1/2 = 630(60) us was identified following production by both relativistic fragmentation of a Xe-136 beam and fission Of a U-238 beam. This state deexcites by a single gamma-ray branch of 3782(2) keV from which direct evidence for the size of the N = 82 shell gal) is inferred. The results are discussed in comparison to a shell-model Calculation including configurations across the closed shells at N = 82 and Z = 50. (C) 2009 Elsevier B.V. All rights reserved.
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6.
  • Lozeva, R. L., et al. (author)
  • New sub-us Isomers in 125Sn, 127Sn, 129Sn and Isomer Systematics of 124-130Sn
  • 2008
  • In: Physical Review C (Nuclear Physics). - 0556-2813. ; 77:6
  • Journal article (peer-reviewed)abstract
    • New sub-mu s isomers have been observed in the neutron-rich Sn isotopes. Sn-125,Sn-127,Sn-129 nuclei have been produced in a relativistic fission reaction of U-238 on a Be-9 target at 750 A.MeV and by the fragmentation of Xe-136 at 600 A.MeV populating high-spin yrast states. In addition to the already known mu s isomers, three new ones with sub-mu s half-lives have been observed. These yrast isomers are the high-spin members of the nu(d(3/2)(-1)h(11/2)(-2)) and nu h(11/2)(-n), seniority v = 3 multiplets leading to isomeric (23/2(+)) and (27/2(-)) states, respectively. Added to the already known 19/2(+)mu s isomers in this region the current work completes the systematic information of neutron-hole excitations toward the filling of the last h(11/2) orbital at N = 82. The results are discussed in the framework of state-of-the-art shell-model calculations using realistic interactions.
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7.
  • Al-Dahan, N., et al. (author)
  • Isomeric States In 208Hg And 209Tl Populated In Fragmentation Of 238U
  • 2009
  • In: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 40:3, s. 871-874
  • Journal article (peer-reviewed)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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8.
  • Al-Dahan, N., et al. (author)
  • Nuclear Structure "Southeast" of 208Pb: Isomeric states in 208Hg and 209Tl
  • 2009
  • In: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:6
  • Journal article (peer-reviewed)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. Metastable states in the N=128 isotones Hg-208 and Tl-209 have been identified. Delayed gamma-ray transitions are interpreted as arising from the decay of I-pi=(8(+)) and (17/2(+)) isomers, respectively. The data allow for the so far most comprehensive verification of the shell-model approach in the region determined by magic numbers Z < 82 and N>126.
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9.
  • Bacelar, A. M. Denis, et al. (author)
  • Angular Momentum Population In Fragmentation Reactions
  • 2009
  • In: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 40:3, s. 889-892
  • Journal article (peer-reviewed)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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10.
  • Doornenbal, P., et al. (author)
  • RISING: Gamma‐ray Spectroscopy with Radioactive Beams at GSI
  • 2007
  • In: AIP Conference Proceedings. - : AIP. - 0094-243X. - 9780735413283 ; 891, s. 99-107
  • Conference paper (peer-reviewed)abstract
    • The Rare Isotope Spectroscopic INvestigation at GSI (RISING) project is a major pan‐European collaboration. Its physics aims are the studies of exotic nuclear matter with abnormal proton‐to‐neutron ratios compared with naturally occurring isotopes. RISING combines the FRagment Separator (FRS) which allows relativistic energies and projectile fragmentation reactions with EUROBALL Ge Cluster detectors for γ spectroscopic research. The RISING setup can be used in two different configurations. Either the nuclei of interest are investigated after being stopped or the heavy ions hit a secondary target at relativistic energies and the thereby occurring excitations are studied. For the latter case, MINIBALL Ge detectors and the HECTOR array are used in addition. Example achievements of the Fast Beam setup are presented and compared to various shell model calculations, while for the Stopped Beam setup initial results are shown.
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11.
  • Farrelly, G. F., et al. (author)
  • Revision of the K-Isomer in 190W
  • 2009
  • In: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 40:3, s. 885-888
  • Journal article (peer-reviewed)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.
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12.
  • Podolyak, Zs., et al. (author)
  • Weakly Deformed Oblate Structures in 198Os
  • 2009
  • In: Physical Review C (Nuclear Physics). - 0556-2813. ; 79:3
  • Journal article (peer-reviewed)abstract
    • Gamma rays de-exciting isomeric states in the neutron-rich nucleus Os-198(76)122 have been observed following relativistic projectile fragmentation of a 1 GeV per nucleon Pb-208 beam. The ground-state band has properties compatible with oblate deformation. The evolution of the structure of Os isotopes characterized by sudden prolate-oblate shape change is discussed and contrasted with the smooth change known in the Pt chain.
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13.
  • Alkhomashi, N., et al. (author)
  • Beta(-)-Delayed And Isomer Spectroscopy Of Neutron-Rich Ta And W Isotopes
  • 2009
  • In: Acta Physica Polonica B. - 0587-4254. ; 40:3, s. 875-878
  • Conference paper (peer-reviewed)abstract
    • Decays of neutron-rich A similar to 190 nuclei have been studied following projectile fragmentation of a Pb-208 beam on a Be-9 target at the GSI Fragment Separator. Gamma-ray decays from previously reported isomeric states in Ta-188, W-190 and (192,193) Re were used as internal calibrations for the particle identification analysis, together with the identification of previously unreported isomeric decays in Ta-189 and W-191. The current work also identifies beta-delayed gamma rays following the decay of Ta-188 to W-188 for the first time.
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14.
  • Caceres, L., et al. (author)
  • Spherical proton-neutron structure of isomeric states in Cd-128
  • 2009
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:1, s. 011301-
  • Journal article (peer-reviewed)abstract
    • The gamma-ray decay of isomeric states in the even-even nucleus Cd-128 has been observed. The nucleus of interest was produced both by the fragmentation of Xe-136 and the fission of U-238 primary beams. The level scheme was unambiguously constructed based on.. coincidence relations in conjunction with detailed lifetime analysis employed for the first time on this nucleus. Large-scale shell-model calculations, without consideration of excitations across the N = 82 shell closure, were performed and provide a consistent description of the experimental level scheme. The structure of the isomeric states and their decays exhibit coexistence of proton, neutron, and strongly mixed configurations due to p. interaction in overlapping orbitals for both proton and neutron holes.
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15.
  • Garnsworthy, A. B., et al. (author)
  • Isomeric States in Neutron-deficient A~80-90 Nuclei Populated in the Fragmentation of 107Ag
  • 2009
  • In: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:6
  • Journal article (peer-reviewed)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.
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16.
  • Garnsworthy, A B, et al. (author)
  • Neutron-proton pairing competition in N = Z nuclei: Metastable state decays in the proton dripline nuclei Nb-82(41) and Tc-86(43)
  • 2008
  • In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 660:4, s. 326-330
  • Journal article (peer-reviewed)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.
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17.
  • Morales, A. I., et al. (author)
  • beta -Delayed gamma -Ray Spectroscopy of Heavy Neutron Rich Nuclei "South" of Lead
  • 2009
  • In: Acta Physica Polonica B. - 0587-4254. ; 40:3, s. 867-870
  • Conference paper (peer-reviewed)abstract
    • Relativistic projectile fragmentation of a Pb-208 primary beam has been used to produce neutron-rich nuclei with proton-holes relative to the Z = 82 shell closure, i.e., "south" of Pb. beta-delayed gamma-ray spectroscopy allows to investigate the structural properties of such nuclei with A similar to 195 -> 205. The current work presents transitions de-exciting excited states in Au-204, which are the first spectroscopic information on this N = 125 isotone.
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18.
  • Pietri, S., et al. (author)
  • First Results from the Stopped Beam Isomer RISING Campaign at GSI
  • 2007
  • In: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 38:4, s. 1255-1264
  • Journal article (peer-reviewed)abstract
    • The first results from a series of experiments focused on the study of the internal structure of nuclei at the extremes of N:Z ratio using isomer spectroscopy are reported. These experiments represent the first of the Stopped Beam section of the Rare Isotopes Investigations at GSI (RISING) project. Exotic nuclei were synthesized using relativistic projectile fragmentation of similar to 500 -> 1000 MeV/u beams of Ag-107, Pb-208, Xe-136 and Ni-58, or fission of 750 MeV/u U-238 provided by the SIS synchrotron at GSI. A detailed description of the RISING stopped beam set up is given, together with a report of the performance of the associated gamma-ray spectrometer array. Selected results of the first experimental campaign are presented together with a discussion on the use of isomeric spectroscopy to study GeV range nuclear fragmentation. Details on future research plans of this collaboration are also outlined.
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19.
  • Podolyak, Zs., et al. (author)
  • Proton-hole excitation in the closed shell nucleus Au-205
  • 2009
  • In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 672:2, s. 116-119
  • Journal article (peer-reviewed)abstract
    • The neutron-rich N = 126 nucleus Au-205 has been populated following the relativistic energy projectile fragmentation of E/A = 1 GeV Pb-208, and studied via charged-particle decay spectroscopy. An internal decay with a transition energy of 907(5) keV and a half-life of T-1/2 = 6(2) s has been identified through the observation of the corresponding K and L internal conversion electron lines. The 907 keV energy level corresponds to the pi h(11/2)(-1) proton-hole state and decays both internally into the pi d(3/2)(-1) ground-state and via beta decay into Hg-205. The obtained data provides information on the evolution of single-proton hole energies which are vital inputs of shell model descriptions for nuclei around the Pb-208(82)126 doubly magic core. (C) 2009 Elsevier B.V. All rights reserved.
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20.
  • Podolyak, Zs., et al. (author)
  • Structure of Neutron-rich Nuclei Around the N=126 Closed Shell; the Yrast Structure of 205Au up to Spin-parity I = (19/2+)
  • 2009
  • In: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 42:3, s. 489-493
  • Conference paper (peer-reviewed)abstract
    • Heavy neutron-rich nuclei have been populated through the relativistic fragmentation of a Pb-208(82) beam at E/A = 1 GeV on a 2.5 g/cm(2) thick Be target. The synthesised nuclei were selected and identified in-flight using the fragment separator at GSI. Approximately 300 ns after production, the selected nuclei were implanted in an similar to 8 mm thick perspex stopper, positioned at the centre of the RISING gamma-ray detector spectrometer array. A previously unreported isomer with a half-life T-1/2 = 163(5) ns has been observed in the N = 126 closed-shell nucleus Au-205(79). Through gamma-ray singles and gamma-gamma coincidence analysis a level scheme was established. The comparison with a shell model calculation tentatively identifies the spin-parity of the excited states, including the isomer itself, which is found to be I-pi = (19/2(+)).
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21.
  • Rudolph, Dirk, et al. (author)
  • Evidence for an Isomeric 3/2- State in 53Co
  • 2008
  • In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 36:2, s. 131-138
  • Journal article (peer-reviewed)abstract
    • The fragmentation of a 550MeV/u primary beam of Ni-58 on a Be-9 target has been used to measure time-and energy-correlated gamma decays following the implantation of event-by-event discriminated secondary fragments into a Be-9 stopper plate. A new isomeric gamma decay with T-1/2 = 14(6 4) ns and E-gamma = 646.2(2) keV is observed and attributed to the decay of the yrast 3/2-state in Co-53(27)26. This short-lived isomeric state has been populated by means of nuclear reactions during the stopping process of the secondary fragments. The experimental findings are discussed in the framework of large-scale spherical shell model calculations in conjunction with isospin symmetry-breaking residual interactions for the A = 53, Tz = +/- 1/2 mirror nuclei Co-53 and Fe-53.
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22.
  • Rudolph, Dirk, et al. (author)
  • Exciting Isomers from the First Stopped-beam RISING Campaign
  • 2007
  • In: The European Physical Journal. Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 150, s. 173-176
  • Journal article (peer-reviewed)abstract
    • First results are reported from a major new initiative of experiments, which focus on nuclear structure studies at extreme isospin values by means of isomer spectroscopy. The experiments represent the first part of the so-called stopped-beam campaign within the Rare ISotope INvestigations at GSI (RISING) project. Time-correlated gamma decays from individually identified nuclear species have been measured, allowing the clean identification of isomeric decays in a wide range of exotic nuclei both at the proton drip-line and in heavy, neutron-rich systems. An overview of the experimental technique will be given, together with the performance of the new germanium detector array and future research plans for the collaboration.
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23.
  • Rudolph, Dirk, et al. (author)
  • Isospin Symmetry and Proton Decay: Identification of the 10+ Isomer in 54Ni
  • 2008
  • In: Physical Review C (Nuclear Physics). - 0556-2813. ; 78:2
  • Journal article (peer-reviewed)abstract
    • The gamma decays from an isomeric 10+ state at 6457 keV in the nucleus 54Ni have been identified using the GSI fragment separator in conjunction with the RISING Ge-detector array. The state is interpreted as the isobaric analog of the 6527-keV 10+ isomer in 54Fe. The results are discussed in terms of isospin-dependent shell-model calculations. Clear evidence is presented for a discrete l = 5 proton decay branch into the first excited 9/2- state of the daughter 53Co. This decay is the first of its kind observed following projectile fragmentation reactions.
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24.
  • Steer, S. J., et al. (author)
  • Isomeric Decay Studies In Neutron-Rich N Approximate To 126 Nuclei
  • 2009
  • In: International Journal Of Modern Physics E-Nuclear Physics. - 0218-3013. ; 18:4, s. 1002-1007
  • Conference paper (peer-reviewed)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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25.
  • Steer, S. J., et al. (author)
  • Single-particle Behavior at N=126: Isomeric Decays in Neutron-rich 204Pt
  • 2008
  • In: Physical Review C (Nuclear Physics). - 0556-2813. ; 78:6
  • Journal article (peer-reviewed)abstract
    • The four proton-hole nucleus Pt-204 was populated in the fragmentation of an E/A = 1 GeV Pb-208 beam. The yrast structure of Pt-204 has been observed up to angular momentum I = 10h by detecting delayed gamma-ray transitions originating from metastable states. These long-lived excited states have been identified to have spin-parities of I-pi = (10(+)), (7(-)), and (5(-)) and half-lives of T-1/2 = 146(14) ns, 55(3) mu s, and 5.5(7) mu s, respectively. The structure of the magic N = 126 Pt-204 nucleus is discussed and understood in terms of the spherical shell model. The data suggest a revision of the two-body interaction for N = 126, Z < 82, which determines the evolution of nuclear structure toward the r-process waiting point nuclei.
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