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Sökning: WFRF:(Seidlitz J)

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1.
  • Bethlehem, RAI, et al. (författare)
  • Brain charts for the human lifespan
  • 2022
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 604:79057906, s. 525-
  • Tidskriftsartikel (refereegranskat)abstract
    • Over the past few decades, neuroimaging has become a ubiquitous tool in basic research and clinical studies of the human brain. However, no reference standards currently exist to quantify individual differences in neuroimaging metrics over time, in contrast to growth charts for anthropometric traits such as height and weight1. Here we assemble an interactive open resource to benchmark brain morphology derived from any current or future sample of MRI data (http://www.brainchart.io/). With the goal of basing these reference charts on the largest and most inclusive dataset available, acknowledging limitations due to known biases of MRI studies relative to the diversity of the global population, we aggregated 123,984 MRI scans, across more than 100 primary studies, from 101,457 human participants between 115 days post-conception to 100 years of age. MRI metrics were quantified by centile scores, relative to non-linear trajectories2 of brain structural changes, and rates of change, over the lifespan. Brain charts identified previously unreported neurodevelopmental milestones3, showed high stability of individuals across longitudinal assessments, and demonstrated robustness to technical and methodological differences between primary studies. Centile scores showed increased heritability compared with non-centiled MRI phenotypes, and provided a standardized measure of atypical brain structure that revealed patterns of neuroanatomical variation across neurological and psychiatric disorders. In summary, brain charts are an essential step towards robust quantification of individual variation benchmarked to normative trajectories in multiple, commonly used neuroimaging phenotypes.
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5.
  • Warr, N., et al. (författare)
  • The Miniball spectrometer
  • 2013
  • Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 49:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The Miniball germanium detector array has been operational at the REX (Radioactive ion beam EXperiment) post accelerator at the Isotope Separator On-Line facility ISOLDE at CERN since 2001. During the last decade, a series of successful Coulomb excitation and transfer reaction studies have been performed with this array, utilizing the unique and high-quality radioactive ion beams which are available at ISOLDE. In this article, an overview is given of the technical details of the full Miniball setup, including a description of the.-ray and particle detectors, beam monitoring devices and methods to deal with beam contamination. The specific timing properties of the REX-ISOLDE facility are highlighted to indicate the sensitivity that can be achieved with the full Miniball setup. The article is finalized with a summary of some physics highlights at REX-ISOLDE and the utilization of the Miniball germanium detectors at other facilities.
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6.
  • Clément, E., et al. (författare)
  • Low-energy Coulomb excitation of Sr 96,98 beams
  • 2016
  • Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 94:5, s. 054326-
  • Tidskriftsartikel (refereegranskat)abstract
    • The structure of neutron-rich Sr96,98 nuclei was investigated by low-energy safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN, with the MINIBALL spectrometer. A rich set of transitional and diagonal E2 matrix elements, including those for non-yrast structures, has been extracted from the differential Coulomb-excitation cross sections. The results support the scenario of a shape transition at N=60, giving rise to the coexistence of a highly deformed prolate and a spherical configuration in Sr98, and are compared to predictions from several theoretical calculations. The experimental data suggest a significant contribution of the triaxal degree of freedom in the ground state of both isotopes. In addition, experimental information on low-lying states in Rb98 has been obtained.
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7.
  • Clément, E, et al. (författare)
  • Spectroscopic Quadrupole Moments in ^{96,98}Sr: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60.
  • 2016
  • Ingår i: Physical Review Letters. - 1079-7114. ; 116:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Neutron-rich ^{96,98}Sr isotopes have been investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross sections. These results allow, for the first time, the drawing of definite conclusions about the shape coexistence of highly deformed prolate and spherical configurations. In particular, a very small mixing between the coexisting states is observed, contrary to other mass regions where strong mixing is present. Experimental results have been compared to beyond-mean-field calculations using the Gogny D1S interaction in a five-dimensional collective Hamiltonian formalism, which reproduce the shape change at N=60.
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9.
  • Butler, P. A., et al. (författare)
  • The observation of vibrating pear-shapes in radon nuclei
  • 2019
  • Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1
  • Tidskriftsartikel (refereegranskat)abstract
    • There is a large body of evidence that atomic nuclei can undergo octupole distortion and assume the shape of a pear. This phenomenon is important for measurements of electric-dipole moments of atoms, which would indicate CP violation and hence probe physics beyond the Standard Model of particle physics. Isotopes of both radon and radium have been identified as candidates for such measurements. Here, we observed the low-lying quantum states in 224Rn and 226Rn by accelerating beams of these radioactive nuclei. We show that radon isotopes undergo octupole vibrations but do not possess static pear-shapes in their ground states. We conclude that radon atoms provide less favourable conditions for the enhancement of a measurable atomic electric-dipole moment.
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10.
  • Illana, A., et al. (författare)
  • Coulomb excitation of 74,76Zn
  • 2023
  • Ingår i: Physical Review C. - 2469-9985. ; 108:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The first experiment using radioactive beams post-accelerated by the HIE-ISOLDE facility has enabled to obtain a precise set of B(E2) transition probabilities in neutron-rich 74,76Zn isotopes. The resulting B(E2; 2+1→0+1) values are consistent with those determined in earlier REX-ISOLDE measurements. While the B(E2; 4+1→2+1) transition probability in 76Zn is also in agreement with earlier Coulomb-excitation results, the value obtained for 74Zn is considerably lower. For the first time, a spectroscopic quadrupole moment of the 2+1 state was measured for an exotic nucleus in this mass region. A detailed comparison is presented with large-scale shell-model and Monte Carlo shell-model calculations.
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11.
  • Kröll, Th, et al. (författare)
  • Quadrupole Collectivity of neutron-rich nuclei around 132Sn
  • 2008
  • Ingår i: Frontiers in Nuclear Structure, Astrophysics, and Reactions, FINUSTAR 2007. - : AIP. - 9780735405325 ; 1012, s. 296-299
  • Konferensbidrag (refereegranskat)abstract
    • We report on the "safe" Coulomb excitation of neutron-rich Cd, Xe, and Ba isotopes in the vicinity of the doubly-magic nucleus 132Sn. The radioactive nuclei have been produced by ISOLDE at CERN and postaccelerated by the REX-ISOLDE facility. The γ-decay of excited states has been detected by the MINIBALL array. The presented preliminary results for the B(E2) values are consistent with expectations from phenomenological systematics and will be compared with theoretical calculations.
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12.
  • Vogt, A., et al. (författare)
  • Isomers and high-spin structures in the N=81 isotones Xe-135 and Ba-137
  • 2017
  • Ingår i: PHYSICAL REVIEW C. - : AMER PHYSICAL SOC. - 2469-9985. ; 95:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The high-spin structures and isomers of the N = 81 isotones Xe-135 and Ba-137 are investigated after multinucleon-transfer (MNT) and fusion-evaporation reactions. Both nuclei are populated (i) in Xe-136+ U-238 and (ii) Xe-136+ Pb-208 MNT reactions employing the high-resolution Advanced Gamma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA, (iii) in the Xe-136+ Pt-198 MNT reaction employing the gamma-ray array GAMMASPHERE in combination with the gas-detector array CHICO, and (iv) via a B-11+ Te-130 fusion-evaporation reaction with the HORUS gamma-ray array at the University of Cologne. The high-spin level schemes of Xe-135 and Ba-137 are considerably extended to higher energies. The 2058-keV (19/2(-)) state in Xe-135 is identified as an isomer, closing a gap in the systematics along the N = 81 isotones. Its half-life is measured to be 9.0(9) ns, corresponding to a reduced transition probability of B(E2,19/2(-) -> 15/2(-)) = 0.52(6) W.u. The experimentally deduced reduced transition probabilities of the isomeric states are compared to shell-model predictions. Latest shell-model calculations reproduce the experimental findings generally well and provide guidance to the interpretation of the new levels.
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13.
  • Butler, P. A., et al. (författare)
  • Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive ^{222}Ra and ^{228}Ra Beams
  • 2020
  • Ingår i: Physical Review Letters. - 1079-7114. ; 124:4
  • Tidskriftsartikel (refereegranskat)abstract
    • There is sparse direct experimental evidence that atomic nuclei can exhibit stable "pear" shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in radium isotopes, electric octupole (E3) matrix elements have been determined for transitions in ^{222,228}Ra nuclei using the method of sub-barrier, multistep Coulomb excitation. Beams of the radioactive radium isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of E3 matrix elements for different nuclear transitions is explained by describing ^{222}Ra as pear shaped with stable octupole deformation, while ^{228}Ra behaves like an octupole vibrator.
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14.
  • Doornenbal, P., et al. (författare)
  • RISING: Gamma‐ray Spectroscopy with Radioactive Beams at GSI
  • 2007
  • Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X. - 9780735413283 ; 891, s. 99-107
  • Konferensbidrag (refereegranskat)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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15.
  • Gaffney, L. P., et al. (författare)
  • Collectivity in the light radon nuclei measured directly via Coulomb excitation
  • 2015
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Shape coexistence in heavy nuclei poses a strong challenge to state-of-the-art nuclear models, where several competing shape minima are found close to the ground state. A classic region for investigating this phenomenon is in the region around Z = 82 and the neutron midshell at N = 104. Purpose: Evidence for shape coexistence has been inferred from a-decay measurements, laser spectroscopy, and in-beam measurements. While the latter allow the pattern of excited states and rotational band structures to be mapped out, a detailed understanding of shape coexistence can only come from measurements of electromagnetic matrix elements. Method: Secondary, radioactive ion beams of Rn-202 and Rn-204 were studied by means of low-energy Coulomb excitation at the REX-ISOLDE in CERN. Results: The electric-quadrupole (E2) matrix element connecting the ground state and first excited 2(1)(+) state was extracted for both Rn-202 and Rn-204, corresponding to B(E2; 2(1)(+) -> 0(1)(+)) = 29(-8)(+8) and 43(-12)(+17) W.u., respectively. Additionally, E2 matrix elements connecting the 2(1)(+) state with the 4(1)(+) and 2(2)(+) states were determined in Rn-202. No excited 0(+) states were observed in the current data set, possibly owing to a limited population of second-order processes at the currently available beam energies. Conclusions: The results are discussed in terms of collectivity and the deformation of both nuclei studied is deduced to be weak, as expected from the low-lying level-energy schemes. Comparisons are also made to state-of-the-art beyond-mean-field model calculations and the magnitude of the transitional quadrupole moments are well reproduced.
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16.
  • Johansen, J. G., et al. (författare)
  • Experimental study of bound states in Be-12 through low-energy Be-11(d,p)-transfer reactions
  • 2013
  • Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 88:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The bound states of Be-12 have been studied through a Be-11(d, p) Be-12 transfer reaction experiment in inverse kinematics. A 2.8 MeV/u beam of Be-11 was produced using the REX-ISOLDE facility at CERN. The outgoing protons were detected with the T-REX silicon detector array. The MINIBALL germanium array was used to detect gamma rays from the excited states in Be-12. The gamma-ray detection enabled a clear identification of the four known bound states in Be-12, and each of the states has been studied individually. Differential cross sections over a large angular range have been extracted. Spectroscopic factors for each of the states have been determined from distorted wave Born approximation (DWBA) calculations and have been compared to previous experimental and theoretical results.
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17.
  • Kesteloot, N., et al. (författare)
  • Deformation and mixing of coexisting shapes in neutron-deficient polonium isotopes
  • 2015
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 92:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient Po-196,Po-198,Po-200,Po-202 isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, Po-196,Po-198, the transitional and diagonal matrix elements of the 2(1)(+) state are determined. In Po-196,Po-198 multistep Coulomb excitation is observed, populating the 4(1)(+), 0(2)(+), and 2(2)(+) states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from Po-196 onwards. Three model descriptions are used to compare to the data. Calculations with the beyond-mean-field model, the interacting boson model, and the general Bohr Hamiltonian model show partial agreement with the experimental data. Finally, calculations with a phenomenological two-level mixing model hint at the mixing of a spherical structure with a weakly deformed rotational structure.
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18.
  • Kröll, T., et al. (författare)
  • Transfer Reactions on Neutron-rich Nuclei at REX-ISOLDE
  • 2009
  • Ingår i: AIP Conference Proceedings. - 1551-7616 .- 0094-243X. ; 1165, s. 363-368 461
  • Konferensbidrag (refereegranskat)abstract
    • We report on one- and two-neutron transfer reactions to study the single-particle properties of nuclei at the border of the "island of inversion". The (d,p)- and (t,p)-reactions in inverse kinematics on the neutron-rich isotope Mg-30, delivered as radioactive beam by the REX-ISOLDE facility, have been investigated. The outgoing protons have been detected and identified by a newly built array of Si detectors. The gamma-decay of excited states has been detected in coincidence by the MINIBALL array. First results for Mg-31 and from the search for the second, spherical, 0(+) state in Mg-32 are presented.
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19.
  • Rosiak, D., et al. (författare)
  • Enhanced Quadrupole and Octupole Strength in Doubly Magic Sn 132
  • 2018
  • Ingår i: Physical Review Letters. - 0031-9007. ; 121:25
  • Tidskriftsartikel (refereegranskat)abstract
    • The first 2+ and 3- states of the doubly magic nucleus Sn132 are populated via safe Coulomb excitation employing the recently commissioned HIE-ISOLDE accelerator at CERN in conjunction with the highly efficient MINIBALL array. The Sn132 ions are accelerated to an energy of 5.49 MeV/nucleon and impinged on a Pb206 target. Deexciting γ rays from the low-lying excited states of the target and the projectile are recorded in coincidence with scattered particles. The reduced transition strengths are determined for the transitions 0g.s.+→21+, 0g.s.+→31-, and 21+→31- in Sn132. The results on these states provide crucial information on cross-shell configurations which are determined within large-scale shell-model and Monte Carlo shell-model calculations as well as from random-phase approximation and relativistic random-phase approximation. The locally enhanced B(E2;0g.s.+→21+) strength is consistent with the microscopic description of the structure of the respective states within all theoretical approaches. The presented results of experiment and theory can be considered to be the first direct verification of the sphericity and double magicity of Sn132.
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20.
  • Spagnoletti, P., et al. (författare)
  • Coulomb excitation of Rn 222
  • 2022
  • Ingår i: Physical Review C. - 2469-9985. ; 105:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The nature of quadrupole and octupole collectivity in Rn222 was investigated by determining the electric-quadrupole (E2) and octupole (E3) matrix elements using subbarrier, multistep Coulomb excitation. The radioactive Rn222 beam, accelerated to 4.23 MeV/u, was provided by the HIE-ISOLDE facility at CERN. Data were collected in the Miniball γ-ray spectrometer following the bombardment of two targets, Sn120 and Ni60. Transition E2 matrix elements within the ground-state and octupole bands were measured up to 10ℏ and the results were consistent with a constant intrinsic electric-quadrupole moment, 518(11)efm2. The values of the intrinsic electric-octupole moment for the 0+→3- and 2+→5- transitions were found to be respectively 2360-210+300efm3 and 2300-500+300efm3 while a smaller value, 1200-900+500efm3, was found for the 2+→1- transition. In addition, four excited non-yrast states were identified in this work via γ-γ coincidences.
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21.
  • Henrich, C., et al. (författare)
  • Coulomb excitation of 142Xe
  • 2018
  • Ingår i: Acta Physica Polonica B. - 0587-4254. ; 49:3, s. 529-533
  • Tidskriftsartikel (refereegranskat)abstract
    • The even-even nucleus 142Xe lies north-east of the doubly magic 132Sn on the neutron-rich side of the nuclear chart. In order to gain further information on the octupole collectivity and the evolution of quadrupole collectivity in this region, a "safe" Coulomb excitation experiment was carried out at the new HIE-ISOLDE facility (CERN) at the end of 2016. As the gamma-ray detector the Miniball spectrometer was used. Beam and target nuclei were detected using C-REX, i.e. an array of segmented Si detectors, covering forward as well as backward angles in the laboratory frame.
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22.
  • Johansen, Jacob G., et al. (författare)
  • Study of bound states in 10Be by one neutron removal reactions of 11Be
  • 2017
  • Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 44:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The bound states of 10Be have been studied by removing single neutrons from 11Be nuclei. A 2.8 MeV u-1 beam of 11Be was produced at ISOLDE, CERN and directed on to both proton and deuteron targets inducing one-neutron removal reactions. Charged particles were detected to identify the two reaction channels (d, t) and (p, d), and the individual states in 10Be were identified by gamma detection. All bound states but one were populated and identified in the (d, t) reaction. The combination of REX-ISOLDE and MINIBALL allowed for a clean separation of the high-lying states in 10Be. This is the first time these states have been separated in a reaction experiment. Differential cross sections have been calculated for all the reaction channels and compared to DWBA calculations. Spectroscopic factors are derived and compared to values from the litterature. While the overall agreement between the spectrocopic factors is poor, the ratio between the ground state and the first excited state is in agreement with the previous measured ones. Furthermore, a significant population of the state is observed, which which may indicate the presence of multi-step processes at our beam energy.
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23.
  • Seidlitz, M., et al. (författare)
  • Coulomb excitation of Na-29,Na-30: Mapping the borders of the island of inversion
  • 2014
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 89:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Nuclear shell evolution in neutron-rich Na nuclei around N = 20 was studied by determining reduced transition probabilities, i.e., B(E2) and B(M1) values, in order to map the border of the island of inversion. To this end Coulomb-excitation experiments, employing radioactive Na-29,Na-30 beams with a final beam energy of 2.85 MeV/nucleon, were performed at REX-ISOLDE, CERN. De-excitation gamma rays were detected by the MINIBALL gamma-ray spectrometer in coincidence with scattered particles in a segmented Si detector. Transition probabilities to excited states were deduced. The measured B(E2) values agree well with shell-model predictions, supporting the idea that in the Na isotopic chain the ground-state wave function contains significant intruder admixture already at N = 18, with N = 19 having an almost pure two-particle-two-hole deformed ground-state configuration.
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24.
  • DiJulio, Douglas, et al. (författare)
  • Coulomb excitation of In-107
  • 2013
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 87:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The radioactive isotope In-107 was studied using sub-barrier Coulomb excitation at the REX-ISOLDE facility at CERN. Two gamma rays were observed during the experiment, corresponding to the low-lying 11/2(+) and 3/2(-)states. The reduced transition probability of the 11/2(+) state was determined with the semiclassical Coulomb excitation code GOSIA2. The result is discussed in comparison to large-scale shell-model calculations, previous unified-model calculations, and earlier Coulomb excitation measurements in the odd-mass In isotopes. DOI: 10.1103/PhysRevC.87.017301
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25.
  • DiJulio, Douglas, et al. (författare)
  • Coulomb excitation of Sn-107
  • 2012
  • Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 48:7
  • Tidskriftsartikel (refereegranskat)abstract
    • The radioactive isotope Sn-107 was studied using Coulomb excitation at the REX-ISOLDE facility at CERN. This is the lightest odd-Sn nucleus examined using this technique. The reduced transition probability of the lowest-lying 3/2(+) state was measured and is compared to shell-model predictions based on several sets of single-neutron energies relative to Sn-100. Similar to the transition probabilities for the 2(+) states in the neutron-deficient even-even Sn nuclei, the measured value is underestimated by shell-model calculations. Part of the strength may be recovered by considering the ordering of the d(5/2) and g(7/2) single-neutron states.
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26.
  • DiJulio, Douglas, et al. (författare)
  • Excitation strengths in Sn-109: Single-neutron and collective excitations near Sn-100
  • 2012
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 86:3
  • Tidskriftsartikel (refereegranskat)abstract
    • A set of B(E2) values for the low-lying excited states in the radioactive isotope Sn-109 were deduced from a Coulomb excitation experiment. The 2.87-MeV/u radioactive beam was produced at the REX-ISOLDE facility at CERN and was incident on a secondary Ni-58 target. The B(E2) values were determined using the known 2(+) -> 0(+) reduced transition probability in Ni-58 as normalization with the semiclassical Coulomb excitation code GOSIA2. The transition probabilities are compared to shell-model calculations based on a realistic nucleon-nucleon interaction and the predictions of a simple core-excitation model. This measurement represents the first determination of multiple B(E2) values in a light Sn nucleus using the Coulomb excitation technique with low-energy radioactive beams. The results provide constraints for the single-neutron states relative to Sn-100 and also indicate the importance of both single-neutron and collective excitations in the light Sn isotopes.
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27.
  • Gaffney, L. P., et al. (författare)
  • Studies of pear-shaped nuclei using accelerated radioactive beams
  • 2013
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 497:7448, s. 199-204
  • Tidskriftsartikel (refereegranskat)abstract
    • There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are 'octupole deformed', that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflection-symmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments were performed using accelerated beams of heavy, radioactive ions. Our data on Rn-220 and Ra-224 show clear evidence for stronger octupole deformation in the latter. The results enable discrimination between differing theoretical approaches to octupole correlations, and help to constrain suitable candidates for experimental studies of atomic electric-dipole moments that might reveal extensions to the standard model.
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28.
  • Ilieva, S., et al. (författare)
  • Coulomb excitation of neutron-rich Cd isotopes
  • 2014
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 89:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The isotopes (122),(124),Cd-126 were studied in a "safe" Coulomb-excitation experiment at the radioactive ion-beam facility REX-ISOLDE at CERN. The reduced transition probabilities B(E2; 0(g. s)(vertical bar) -> 2(1)(+)) and limits for the quadrupole moments of the first 2(+) excited states in the three isotopes were determined. The onset of collectivity in the vicinity of the Z = 50 and N = 82 shell closures is discussed by comparison with shell model and beyond mean-field calculations.
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29.
  • Scheck, M., et al. (författare)
  • Do nuclei go pear-shaped? Coulomb excitation of Rn-220 and Ra-224 at REX-ISOLDE (CERN)
  • 2015
  • Ingår i: Cgs15 - Capture Gamma-ray Spectroscopy and Related Topics. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 93, s. 01038-01038
  • Konferensbidrag (refereegranskat)abstract
    • The IS475 collaboration conducted Coulomb-excitation experiments with post-accelerated radioactive Rn-220 and Ra-224 beams at the REX-ISOLDE facility. The beam particles (E-beam: 2.83 MeV/u) were Coulomb excited using Ni-60, Cd-14, and Sn-120 scattering targets. De-excitation gamma-rays were detected employing the Miniball array and scattered particles were detected in a silicon detector. Exploiting the Coulomb-excitation code GOSIA for each nucleus several matrix elements could be obtained from the measured gamma-ray yields. The extracted < 3 parallel to E3 parallel to 0(+)> matrix element allows for the conclusion that, while Rn-220 represents an octupole vibrational system, Ra-224 has already substantial octupole correlations in its ground state. This finding has i(m)plications for the search of CP-violating Schiff moments in the atomic systems of the adjacent odd-mass nuclei.
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30.
  • Gaffney, L. P., et al. (författare)
  • Low-energy Coulomb excitation of 62Fe and 62Mn following in-beam decay of 62Mn
  • 2015
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 51:10, s. 1-9
  • Tidskriftsartikel (refereegranskat)abstract
    • Sub-barrier Coulomb excitation was performed on a mixed beam of 62Mn and 62Fe, following in-trap β− decay of 62Mn at REX-ISOLDE, CERN. The trapping and charge breeding times were varied in order to alter the composition of the beam, which was measured by means of an ionisation chamber at the zero-angle position of the Miniball array. A new transition was observed at 418 keV, which has been tentatively associated to a (2+,3+)→ 1g.s. + transition. This fixes the relative positions of the β-decaying 4+ and 1+ states in 62Mn for the first time. Population of the 21 + state was observed in 62Fe and the cross-section determined by normalisation to the 109Ag target excitation, confirming the B(E2) value measured in recoil-distance lifetime experiments.
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31.
  • Bertelsen, N, et al. (författare)
  • Imbalanced social-communicative and restricted repetitive behavior subtypes of autism spectrum disorder exhibit different neural circuitry
  • 2021
  • Ingår i: Communications biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 4:1, s. 574-
  • Tidskriftsartikel (refereegranskat)abstract
    • Social-communication (SC) and restricted repetitive behaviors (RRB) are autism diagnostic symptom domains. SC and RRB severity can markedly differ within and between individuals and may be underpinned by different neural circuitry and genetic mechanisms. Modeling SC-RRB balance could help identify how neural circuitry and genetic mechanisms map onto such phenotypic heterogeneity. Here, we developed a phenotypic stratification model that makes highly accurate (97–99%) out-of-sample SC = RRB, SC > RRB, and RRB > SC subtype predictions. Applying this model to resting state fMRI data from the EU-AIMS LEAP dataset (n = 509), we find that while the phenotypic subtypes share many commonalities in terms of intrinsic functional connectivity, they also show replicable differences within some networks compared to a typically-developing group (TD). Specifically, the somatomotor network is hypoconnected with perisylvian circuitry in SC > RRB and visual association circuitry in SC = RRB. The SC = RRB subtype show hyperconnectivity between medial motor and anterior salience circuitry. Genes that are highly expressed within these networks show a differential enrichment pattern with known autism-associated genes, indicating that such circuits are affected by differing autism-associated genomic mechanisms. These results suggest that SC-RRB imbalance subtypes share many commonalities, but also express subtle differences in functional neural circuitry and the genomic underpinnings behind such circuitry.
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32.
  • Seidlitz, M., et al. (författare)
  • Coulomb excitation of Mg-31
  • 2011
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 700:3-4, s. 181-186
  • Tidskriftsartikel (refereegranskat)abstract
    • The ground state properties of Mg-31 indicate a change of nuclear shape at N = 19 with a deformed J(pi) = 1/2(+) intruder state as a ground state, implying that Mg-31 is part of the "island of inversion". The collective properties of excited states were the subject of a Coulomb excitation experiment at REX-ISOLDE, CERN, employing a radioactive Mg-31 beam. De-excitation gamma-rays were detected by the MINIBALL gamma-spectrometer in coincidence with scattered particles in a segmented Si-detector. The level scheme of Mg-3I was extended. Spin and parity assignment of the 945 keV state yielded 5/2(+) and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of Mg-30,Mg-31,Mg-32 establishes that for the N = 19 magnesium isotope not only the ground state but also excited states are largely dominated by a deformed pf intruder configuration. (C) 2011 Elsevier B.V. All rights reserved.
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33.
  • Stahl, K., et al. (författare)
  • Search for proton emission of the isomeric 10+ state in 54Ni
  • 2020
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 56:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Several experiments were conducted at the 10 MV Van-de-Graaff tandem accelerator at the Institute of Nuclear Physics, Cologne, to detect proton emission from the isomeric 6457-keV 10+ state in 54Ni. Excitation functions for two fusion–evaporation reactions were measured to maximise the population of the rare two-neutron evaporation channel from a 56Ni compound nucleus. The search for delayed proton emission was based on the 28Si(28Si,2n)54Ni reaction at a beam energy of 70 MeV. For this reaction, a cross-section limit for the population of the 10+ state in 54Ni and its proton-decay branch was determined to be σ< 22 nb.
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34.
  • Seidlitz, Jakob, et al. (författare)
  • The molecular genetic landscape of human brain size variation
  • 2023
  • Ingår i: Cell Reports. - 2211-1247. ; 42:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Human brain size changes dynamically through early development, peaks in adolescence, and varies up to 2-fold among adults. However, the molecular genetic underpinnings of interindividual variation in brain size remain unknown. Here, we leveraged postmortem brain RNA sequencing and measurements of brain weight (BW) in 2,531 individuals across three independent datasets to identify 928 genome-wide significant associations with BW. Genes associated with higher or lower BW showed distinct neurodevelopmental trajectories and spatial patterns that mapped onto functional and cellular axes of brain organization. Expression of BW genes was predictive of interspecies differences in brain size, and bioinformatic annotation revealed enrichment for neurogenesis and cell-cell communication. Genome-wide, transcriptome-wide, and phenome-wide association analyses linked BW gene sets to neuroimaging measurements of brain size and brain-related clinical traits. Cumulatively, these results represent a major step toward delineating the molecular pathways underlying human brain size variation in health and disease.
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35.
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