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Träfflista för sökning "WFRF:(Wilhelmsen Rolander Katarina 1962 ) "

Sökning: WFRF:(Wilhelmsen Rolander Katarina 1962 )

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1.
  • Anne, R., et al. (författare)
  • Dissociation Reactions of the Be-11 One-Neutron Halo - the Interplay between Structure and Reaction-Mechanism
  • 1993
  • Ingår i: Physics Letters B. - 0370-2693. ; 304:1-2, s. 55-59
  • Tidskriftsartikel (refereegranskat)abstract
    • The angular distributions of the forward neutrons in the exclusive (Be-10 + n) channel have been measured. They can be accounted for quantitatively and without free parameters in terms of Coulomb and diffraction dissociation. The results show that the transverse momentum distributions result from an interplay between the tail of the wave function (the halo) and the reaction mechanism.
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2.
  • Anne, R., et al. (författare)
  • Exclusive and Restricted-Inclusive Reactions Involving the Be-11 One-Neutron Halo
  • 1994
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 575:1, s. 125-154
  • Tidskriftsartikel (refereegranskat)abstract
    • Reactions of a 41 MeV/u beam of the radioactive halo nucleus Be-11 have been studied with a counter telescope coupled to an array of neutron detectors covering angles up to 97-degrees. The technique allows to determine single-neutron inclusive and exclusive angular distributions. The targets (Be, Ti and Au) were chosen to illustrate the relative roles played by nuclear and Coulomb mechanisms. The channels leading to Be-10, the dissociation channels, correspond to impact parameters larger than the sum of the radii of the target and the Be-10 core. It is shown that for the dissociation process it is possible to account almost quantitatively for the integral, single- and double-differential cross sections from models without free parameters including the Coulomb, Serber and Glauber (diffraction-dissociation) mechanisms. The neutron distributions from the nondissociative reaction channels show little individuality and it is convenient to group them together as the channel ''neutron plus anything different from Be-10''. We refer to these as ''restricted-inclusive'' reactions. These seem to be a promising tool for obtaining accurate information on the halo wave function in momentum coordinates.
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3.
  • Anne, R., et al. (författare)
  • Projectile Coulomb-Excitation with Fast Radioactive Beams
  • 1995
  • Ingår i: Zeitschrift Fur Physik a-Hadrons and Nuclei. - 0939-7922. ; 352:4, s. 397-401
  • Tidskriftsartikel (refereegranskat)abstract
    • We report a search for gamma rays emanating from Coulomb excitation of fast (30-46 MeV/u) radioactive projectiles He-8, Be-11,Be-12,Be-14 interacting with a lead target. These are clearly identified by their Doppler shift. The 320 keV 1/2(-) --> 1/2(+)gamma transition from Be-11 was observed with a cross-section of 191 +/- 26 mb which is noticeably less than expected from the known lifetime and in the perturbation limit of pure Coulomb excitation. In the other nuclei rather stringent upper limits of 0.01 to 0.2 Weisskopf units, are placed on the hypothetical transition to 1(-) states.
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4.
  • Bergmann, U. C., et al. (författare)
  • Analysis of decay data from neutron-rich nuclei
  • 2001
  • Ingår i: European Physical Journal A. - 1434-6001. ; 11:3, s. 279-284
  • Tidskriftsartikel (refereegranskat)abstract
    • The beta -decays of the neutron-rich nuclei Be-12 and Ne-29 have been studied. The statistical correlations between the almost identical half-lives of Be-12 and its daughter B-12 are analysed for a large sample of Be-12 decay data. Stringent mutual bounds are obtained on the parameter set, leading to a precise determination of the Be-12 half-life of 21.50 +/- 0.04 ms. From a simultaneous detection of beta -particles and neutrons from the decay of Ne-29 the neutron emission probability, P-n, is determined to 17 +/- 5%. No indication of two-neutron emission is seen from this nucleus. An upper limit of 2.2% (90% confidence level) is established for P-2n.
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5.
  • Bergmann, U. C., et al. (författare)
  • On the beta-decay of C-9
  • 2001
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 692:3-4, s. 427-450
  • Tidskriftsartikel (refereegranskat)abstract
    • In beta -decay experiments on C-9 at CERN/ISOLDE the beta -strength was determined to the ground state, the 12.2 MeV excited state and the Isobaric Analog State (IAS) at 14.655 MeV in B-9. A large beta -strength asymmetry is deduced for the mirror transitions of C-9 and Li-9 to states around 12 MeV excitation energy. A satisfactory description of the three-body decay from a narrow energy region around the 12.2 MeV resonance is obtained within a sequential model involving the ground and first-excited states of Li-5 and Be-8. From the study of angular correlations the spin of the 12.2 MeV state is determined as 5/2(-). For the first time the population of the IAS is observed in beta -decay and new information on the decay of this state is obtained. The advantages of a closely packed. highly segmented detector setup are demonstrated. (C) 2001 Elsevier Science B.V. All rights reserved.
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6.
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7.
  • Borge, M. J. G., et al. (författare)
  • Study of Charged-Particles Emitted in the Beta-Decay of He-6,He-8
  • 1993
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 560:2, s. 664-676
  • Tidskriftsartikel (refereegranskat)abstract
    • The beta-delayed charged particle spectra from He-6 and He-8 were measured with a telescope consisting of a gas counter and a Si surface barrier detector. Beta-delayed deuterons and tritons are emitted in the two cases with branching ratios of (7.6 +/- 0.6) x 10(-6), E(d) > 350 keV and (8.0 +/- 0.5) x 10(-3), respectively. Both spectra present anomalies that must be due to the special structure of these nuclei (an alpha core surrounded by several neutrons).
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8.
  • Jeppesen, H., et al. (författare)
  • News on beta delayed particle emission from Be-14
  • 2002
  • Ingår i: Progress of Theoretical Physics Supplement. - 0375-9687. ; :146, s. 520-524
  • Konferensbidrag (refereegranskat)abstract
    • Beta delayed charged particles from Be-14 have been measured and give an upper limit on beta delayed alpha particles of B(betaalpha)<6.7x10(-5) and a tentative branching ratio on beta delayed tritons of 7.5x10(-5)<B(betat)<3.9x10(-4). We combine the knowledge on beta delayed particles from Be-14 to deduce information on the beta strength distribution.
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9.
  • Jeppesen, H., et al. (författare)
  • Search for beta-delayed charged particles from the halo nucleus Be-14
  • 2002
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 709, s. 119-130
  • Tidskriftsartikel (refereegranskat)abstract
    • In a search for beta-delayed charged particles from Be-14 we have obtained an upper limit on beta-delayed a particles, B(betaalpha) < 1.2 x 10(-4), and found evidence for beta-delayed tritons at intensity of 6 x 10(-5) < B(betat) < 4 x 10(-4) (both at 95% confidence level). By adding information on the beta-delayed neutron branches from direct measurements at low neutron energy and indirect detection via recoiling nuclei at high energy, and by including also information from earlier experiments, we deduce the beta strength distribution from Be-14. This differs significantly from shell-model calculations at high excitation energy. (C) 2002 Elsevier Science B.V. All rights reserved.
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10.
  • Keller, H., et al. (författare)
  • Search for Forbidden Beta-Decays of the Drip-Line Nucleus Be-12
  • 1994
  • Ingår i: Zeitschrift Fur Physik a-Hadrons and Nuclei. - 0939-7922. ; 348:1, s. 61-62
  • Tidskriftsartikel (refereegranskat)abstract
    • Beta-coincident gamma-rays have been measured from implanted pure samples of Be-12 separated at the LISE3 spectrometer at GANIL. An intensity of 0.040(26)% can be estimated for the branching ratio of the isospin forbidden pure-Fermi transition to the 0+ excited state of B-12 and of 0.008(6) % of the transition to the 1- excited state. Both are taken to represent upper limits. The halflife has been re-measured to be 26.1(2.4) ms.
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