| 1. |
- Borge, M. J. G., et al.
(författare)
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Probing the Li-11 halo structure through beta-decay into the Be-11(*) (18 MeV) state
- 1997
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Ingår i: Nuclear Physics A. - 0375-9474. ; 613:3, s. 199-208
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Tidskriftsartikel (refereegranskat)abstract
- An experimental study of beta-delayed charged particles (H, He, Be) from Li-11 shows a beta-feeding to an excited state at 18.15(15) MeV in Be-11 with a large Gamow-Teller strength, B-GT greater than or equal to 1.6. Branching ratios and reduced widths of 2-, 3- and 5- particle decay channels of this state are extracted, A strong suppression of the neutron branch from the 18 MeV state to the Be-10(g.s.) is observed, We suggest that the measured partial width may be sensitive to the (p(1/2))(2) component in the Li-11 halo, A rough estimate indicates that the (p(1/2))(2) component is not the dominant one in the halo wave-function.
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| 2. |
- Nilsson, Thomas, 1965, et al.
(författare)
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He-6 and neutron momentum distributions from He-8 in nuclear break-up reactions at 240 MeV/u
- 1996
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Ingår i: Nuclear Physics A. - 0375-9474. ; 598:3, s. 418-434
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Tidskriftsartikel (refereegranskat)abstract
- Neutron and He-6 momentum distributions from He-8 break-up reactions in a C target have been measured at 240 MeV/u. The two-neutron removal cross section was found to be sigma(-2n) = 0.27 +/- 0.03 b. The nature of the momentum distributions is interpreted in some simple reaction scenarios.
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| 3. |
- Anne, R., et al.
(författare)
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Dissociation Reactions of the Be-11 One-Neutron Halo - the Interplay between Structure and Reaction-Mechanism
- 1993
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 304:1-2, s. 55-59
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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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| 4. |
- Anne, R., et al.
(författare)
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Exclusive and Restricted-Inclusive Reactions Involving the Be-11 One-Neutron Halo
- 1994
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 575:1, s. 125-154
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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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| 5. |
- Borge, M. J. G., et al.
(författare)
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Elucidating halo structure by beta decay: beta gamma from the Li-11 decay
- 1997
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 55:1, s. R8-R11
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Tidskriftsartikel (refereegranskat)abstract
- New values for the gamma ray intensities following the beta decay of Li-11 are presented. Special emphasis is put on the determination of the Gamow-Teller transition Li-11 --> Be-11 (1/2(-), 320 keV) to the only bound excited state in Be-11. We show that a shell-model calculation can simultaneously reproduce the half-life of Li-11 and the newly measured branching ratio to the 1/2(-) state provided the Li-11 ground state wave function contains about 50% of s-wave neutron components.
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| 6. |
- Humbert, F., et al.
(författare)
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Longitudinal and Transverse-Momentum Distributions of Li-9 Fragments from Break-up of Li-11
- 1995
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 347:3-4, s. 198-204
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Tidskriftsartikel (refereegranskat)abstract
- Transverse and longitudinal momentum distributions of Li-9 fragments from Li-11 break-up reactions in C, Al and Pb targets have been measured at 280 MeV/u. The two-neutron removal cross-section was measured to be sigma(-2n), = 0.26 +/- 0.02 b for the carbon target, sigma(-2n) = 0.47 +/- 0.08 b for the aluminum target and sigma(-2n), = 1.9 +/- 0.4 b for the lead target. No significant difference is observed between the narrow widths (FWHM approximate to 47 MeV/c) of the transverse and longitudinal momentum distributions of the Li-9 fragments. The physical implications of this are discussed.
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| 7. |
- Keller, H., et al.
(författare)
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Search for Forbidden Beta-Decays of the Drip-Line Nucleus Be-12
- 1994
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Ingår i: Zeitschrift fur Physik A Hadrons and Nuclei. - 1431-5831 .- 0939-7922. ; 348:1, s. 61-62
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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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| 8. |
- Mukha, I., et al.
(författare)
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Observation of the Li-11(beta d) decay
- 1996
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 367:1-4, s. 65-69
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Tidskriftsartikel (refereegranskat)abstract
- Experimental data from the decay of Li-11 show for the first time the presence of beta-delayed deuterons with a branching ratio larger than 10(-4). To distinguish between beta d and beta t events the decays of the daughter nuclei Li-9 and Li-8 were identified in the energy and decay time spectra. Furthermore, a time correlation analysis between the beta d events and the subsequent daughter decays was performed.
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| 9. |
- Mukha, I., et al.
(författare)
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Super-strong beta-decay of Li-11 into Be-11* (18 MeV) state: A probe for halo p-wave component?
- 1997
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Ingår i: Nuclear Physics A. - 0375-9474. ; 616:1-2, s. C201-C207
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Konferensbidrag (refereegranskat)abstract
- An experimental study of beta-delayed charged particles (H, He, Be), neutrons and gamma-rays that follow the Li-11 beta-decay, clearly indicates a beta-feeding to an exited state at 18.1 MeV in Be-11 with a large Gamow-Teller strength, B-GT greater than or equal to 1.0. The large strength of this beta-transition implies a broad overlap of the Be-11* state at 18.1 MeV and the ground state of Li-11. The deduced width of this resonance is similar or equal to 1 MeV. A strong suppression of the branch from 18.1 MeV state into the Be-10+n channel is observed. This branch, with the largest decay energy, has a partial width less than 1% of the total width. A centrifugal barrier consideration fails to explain this effect. A possible consequence of the observed effect for the Li-11 structure is that the admixture of (p(1/2))(2) configuration in Li-11 might be small.
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| 10. |
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