| 1. |
- Díaz-Cortes, J., et al.
(författare)
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Systematic reduction of the proton-removal cross section in neutron-rich medium-mass nuclei
- 2020
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 811
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Tidskriftsartikel (refereegranskat)abstract
- Single-neutron and single-proton removal cross sections have been measured for medium-mass neutron-rich nuclei around Z=50 and energies around 1000A MeV using the FRagment Separator (FRS) at GSI. The measured cross sections confirm the relative low values of the proton-removal cross sections, observed since a long time ago and not yet understood. Model calculations considering the knock-out process together with initial- and final-state interactions describe the measured neutron-removal cross sections. Proton-removal cross sections are, however, significantly over-predicted by the same calculations. The observed difference can be explained to a large extent by the knock-out of short-range correlated nucleons from dominant neutron-proton pairs in neutron-rich nuclei.
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| 2. |
- Perez-Loureiro, D., et al.
(författare)
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Neutron-rich fragments produced by in-flight fission of U 238
- 2019
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Ingår i: Physical Review C. - 2469-9993 .- 2469-9985. ; 99:5
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Tidskriftsartikel (refereegranskat)abstract
- The production cross sections of neutron-rich fission residues in reactions induced by U238 projectiles at 950A MeV impinging on Pb and Be targets are investigated at the Fragment Separator at GSI. These two targets allow us to investigate fission processes induced by two reaction mechanisms, Coulomb and nuclear excitations, and to study the role of these mechanisms in the neutron excess of the final fragments.
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| 3. |
- Tuskan, G A, et al.
(författare)
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The genome of black cottonwood, Populus trichocarpa (Torr. & Gray).
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 313:5793, s. 1596-604
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Tidskriftsartikel (refereegranskat)abstract
- We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.
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| 4. |
- Andreyev, A. N., et al.
(författare)
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In-beam and alpha-decay spectroscopy of Po-191 and evidence for triple shape coexistence at low energy in the daughter nucleus Pb-187
- 2002
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 66:1
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Tidskriftsartikel (refereegranskat)abstract
- Prompt gamma rays have been observed for the first time from the neutron-deficient nucleus Po-191 using the recoil-decay tagging technique at the RITU gas-filled separator. In addition improved alpha decay data have been measured for Po-191 and its daughter product Pb-187. The complementary gamma- and alpha-decay data point to the onset of oblate deformation in the light odd-mass Po nuclei by approaching the neutron midshell at N=104. The pattern of the favored and unfavored states observed on top of the 13/2(+) isomer in Po-191 indicates a change from the weak-coupling towards the strong-coupling scheme in Po-191m. In the daughter nucleus Pb-187, the 13/2(+) and 3/2(-) isomeric states become degenerate within the experimental accuracy. Evidence for triple shape coexistence at low energy has been found in the high-spin isomer in Pb-187. The results are supported by potential-energy surface calculations and by particle-plus-rotor calculations.
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| 5. |
- Nieminen, P., et al.
(författare)
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gamma-ray spectroscopy of Bi-191,Bi-193
- 2004
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69:6, s. 064326-
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Tidskriftsartikel (refereegranskat)abstract
- Prompt and delayed gamma rays from Bi-191,Bi-193 have been identified using the recoil-decay tagging, isomer tagging, and recoil gating techniques, resulting in extensive level schemes for both nuclei. Excitation energies of the isomeric 13/2(+) states have been established and oblate strongly coupled bands built on them have been observed. The nearly spherical 9/2(-) ground-state bands appear to be crossed by more oblate-deformed low-lying structures. The properties of the bands feeding the 1/2(+) intruder states indicate some structural change between Bi-193 and Bi-191. The deformation associated with each of these states has been extracted from total Routhian surface calculations which also reveal the development of prolate minima with decreasing neutron number. B(M1)/B(E2) ratios have been measured for the observed strongly coupled bands in order to resolve the intrinsic excitations. The observed quasiparticle structures in Bi-193 and high-spin isomers both in Bi-193 and Bi-191 are interpreted based on the coupling of the odd proton to the even-even Pb core.
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| 6. |
- Van de Vel, K., et al.
(författare)
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Identification of low-lying proton-based intruder states in Pb189-193
- 2002
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 65:6
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Tidskriftsartikel (refereegranskat)abstract
- Low-lying proton-based intruder states have been observed in the odd-mass isotopes Pb-189,Pb-191,Pb-193 in experiments at the RITU gas-filled recoil separator. The identification has been performed by observing the fine structure in the alpha decay of the parent Po-193,Po-195,Po-197 nuclei in prompt coincidence with conversion electrons and gamma rays in the daughter lead isotopes. Along with the literature data these results establish a systematics of intruder states in the odd-mass lead isotopes from Pb-197 down to Pb-185. Interpretation of these states involves the coupling of the 1i(13/2) or 3p(3/2) odd neutron to the 0(+) state in the oblate minimum in the even-mass lead core. Conversion coefficients have been determined for some of the transitions, revealing mixing between the coexisting states. The experimental results are compared to potential energy surface calculations.
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| 7. |
- King, S L, et al.
(författare)
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First observation of excited states in the neutron deficient nuclei (PT)-P-168 and Pt-170
- 1998
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Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 443:1-4, s. 82-88
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Tidskriftsartikel (refereegranskat)abstract
- Excited states have been observed for the first time in (XPt)-X-168 and Pt-170 using the alpha-decay recoil-tagging technique. The trend of decreasing deformation moving away from the N = 104 mid-shell continues far Pt-170 but the structure of Pt-168 is significantly different. The low spin level energy systematics in Pt168-184 are presented and discussed within the framework of the interacting boson model. (C) 1998 Elsevier Science B.V. All rights reserved.
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| 8. |
- Petts, A., et al.
(författare)
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Lifetime measurements and coulomb excitation of light Hg nuclei
- 2009
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Ingår i: Capture Gamma-Ray Spectroscopy and Related Topics. - : American Institute of Physics (AIP). - 9780735406230 ; , s. 414-418
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Konferensbidrag (refereegranskat)abstract
- Two complementary experimental programs have taken place to investigate the origin and evolution of shape coexistence in the light mercury region. Recoil Distance Doppler-shift measurements were performed at the University of Jyväskylä utilizing the Köln plunger device in conjunction with the JUROGAM + RITU + GREAT setup. In addition, Coulomb excitation measurements of 184,186,188Hg were performed at REX-ISOLDE using the MINIBALL Ge-detector array. The results of the lifetime measurements of the yrast states up to Iπ = 10+ in 182Hg are reported. Preliminary analysis of the Coulomb excitation data is also discussed.
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| 9. |
- Bark, R A, et al.
(författare)
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Bandcrossings in Os-171
- 1999
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Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 646:4, s. 399-413
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Tidskriftsartikel (refereegranskat)abstract
- The nucleus Os-171 has been populated using the reaction Sn-116(Ni-58,2pn). Four new bands are identified, and the previously known bands are extended in spin, to a maximum of 53/2 (h) over bar. One- and three-quasiparticle configurations are identified, and beta, gamma, and octupole configurations are assigned tentatively. The effects of a possible intruder configuration on the negative parity bands are tested using band-mixing calculations.
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| 10. |
- Bark, R A, et al.
(författare)
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Coexistence of triaxial and prolate shapes in Ir-171
- 1999
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Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 657:2, s. 113-133
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in Ir-171 have been observed for the first time. Gamma-rays were assigned to the nucleus by the recoil-decay tagging method, The ground-state band has a structure consistent with an h(11/2) proton coupled to a core of large triaxial deformation. At high spins, a bandcrossing occurs which is interpreted as a change in shape to a prolate deformation, Band-mixing calculations are performed for Ir171-175. These show that shape-coexistence between triaxial and prolate states in these nuclei follows the same systematics found in their Pt and Os neighbours. The systematics are also compared with deformations calculated for Ir171-179 using the code "Ultimate Cranker". Dipole bands were also observed, but tilted axis cranking calculations suggest that they are associated with a collective rotation.
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