| 1. |
- Nilsson, Thomas, 1965, et al.
(author)
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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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In: Nuclear Physics A. - 0375-9474. ; 598:3, s. 418-434
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Journal article (peer-reviewed)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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| 2. |
- Zinser, M., et al.
(author)
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Invariant-mass spectroscopy of Li-10 and Li-11
- 1997
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In: Nuclear Physics A. - 0375-9474. ; 619:1-2, s. 151-176
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Journal article (peer-reviewed)abstract
- Break-up of secondary Li-11 ion beams (280 MeV/nucleon) on C and Pb targets into Li-9 and neutrons is studied experimentally. Cross sections and neutron multiplicity distributions are obtained, characterizing different reaction mechanisms. Invariant-mass spectroscopy for Li-11 and Li-10 is performed. The E1 strength distribution, deduced from electromagnetic excitation of Li-11 up to an excitation energy of 4 MeV comprises similar to 8% of the Thomas-Reiche-Kuhn energy-weighted sumrule strength. Two low-lying resonance-like structures are observed for Li-10 at decay energies of 0.21(5) and 0.62(10) MeV, the former one carrying 26(10)% of the strength and likely to be associated with an s-wave neutron decay. A strong di-neutron correlation in Li-11 can be discarded. Calculations in a quasi-particle RPA approach are compared with the experimental results for Li-10 and Li-11. (C) 1997 Elsevier Science B.V.
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| 3. |
- Axelsson, L., et al.
(author)
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Study of the unbound nucleus 11N by elastic resonance scattering
- 1996
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In: Physical Review C (Nuclear Physics). - 0556-2813 .- 2469-9985 .- 2469-9993. ; 54:4, s. 1511-1514
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Journal article (peer-reviewed)abstract
- Resonances in the unbound nucleus 11N have been studied, using the resonance scattering reaction 10C+p. The data give evidence for three states above the 10C+p threshold with energies 1.30, 2.04, and 3.72 MeV. These states can be interpreted, in a potential-model analysis, as the ground state and the first two excited states with spin-parity 1 / 2+, 1 / 2-, and 5 / 2+ arising from the shell-model orbitals 1s1 / 2, 0p1 / 2, and 0d5 / 2. A narrow state superposed on a broad structure found at higher energy could be interpreted as the mirror state of the 3 / 2- in 11Be shifted down in energy. This shift would suggest a large radius of the potential.
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| 4. |
- Bark, R A, et al.
(author)
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Coexistence of triaxial and prolate shapes in Ir-171
- 1999
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In: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 657:2, s. 113-133
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Journal article (peer-reviewed)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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| 5. |
- Grevy, S., et al.
(author)
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Core-breakup reactions of the halo nuclei Be-11 and Li-11: momentum distributions and shadow effects
- 1999
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In: Nuclear Physics A. - 0375-9474. ; 650:1, s. 47-61
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Journal article (peer-reviewed)abstract
- The halo nuclei Be-11 and Li-11 have been studied in core-breakup reactions where the halo neutrons are expected to be released without a major distortion due to the reaction. The widths of the halo-neutron momentum distributions have been extracted in coincidence with He fragments, Gamma = 32 +/- 4 MeV/c, and Li fragments, Gamma = 42 +/- 4 MeV/c for Be-11 and with He fragments, Gamma =42+/-6 MeV/c for Li-11. The Be-11 breakup gives a very low neutron multiplicity of 0.38+/-0.09 which is a manifestation of the shadowing of the neutron in the core-breakup reaction. This value can be understood from a simple theoretical calculation, which also accounts for the observed transverse momentum widths at small angles. (C) 1999 Elsevier Science B.V.
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| 6. |
- Humbert, F., et al.
(author)
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Longitudinal and Transverse-Momentum Distributions of Li-9 Fragments from Break-up of Li-11
- 1995
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 347:3-4, s. 198-204
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Journal article (peer-reviewed)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. |
- Marques, F. M., et al.
(author)
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Neutrons from the breakup of C-19
- 1996
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 381:4, s. 407-412
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Journal article (peer-reviewed)abstract
- Neutrons arising from the breakup of a 30 MeV/nucleon C-19 beam on a tantalum target have been measured using the 98 element array DEMON. A narrow, forward peaked neutron angular distribution, with a corresponding momentum spread considerably smaller than those measured simultaneously for N-21, O-22 and F-24 was observed for charged fragments with Z
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| 8. |
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| 9. |
- Nilsson, Thomas, 1965, et al.
(author)
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Neutron Momentum Distributions from Core Break-up Reactions of Halo Nuclei
- 1995
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In: Europhysics Letters. - 0295-5075 .- 1286-4854. ; 30:1, s. 19-24
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Journal article (peer-reviewed)abstract
- Neutron angular distributions from violent break-up reactions of Li-11 and Be-11 have been measured at 28 MeV/u and 280 MeV/u and at 41 MeV/u and 460 MeV/u, respectively. The derived neutron momentum distributions show a narrow component in transverse momentum that is within uncertainties independent of beam energy and target charge. This component is suggested to be simply related to the momentum distribution of the loosely bound halo neutron(s) in the projectiles.
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| 10. |
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| 11. |
- Anne, R., et al.
(author)
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Projectile Coulomb-Excitation with Fast Radioactive Beams
- 1995
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In: Zeitschrift fur Physik A Hadrons and Nuclei. - 1431-5831 .- 0939-7922. ; 352:4, s. 397-401
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Journal article (peer-reviewed)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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| 12. |
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| 13. |
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| 14. |
- Mottola, S, et al.
(author)
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The slow rotation of 253 Mathilde
- 1995
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In: PLANETARY AND SPACE SCIENCE. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0032-0633. ; 43:12, s. 1609-1613
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Journal article (peer-reviewed)abstract
- CCD photometry of the NEAR mission fly-by target 253 Mathilde is presented. Measurements taken during 52 nights of observations, from February to June 1995, allow a rotation period of 17.406 +/- 0.010 days and a lightcurve amplitude of 0.45 +/- 0.02 mag t
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| 15. |
- MUELLER, MJ, et al.
(author)
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Leukotriene A4 hydrolase: mapping of a henicosapeptide involved in mechanism-based inactivation
- 1995
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 92:18, s. 8383-8387
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Journal article (peer-reviewed)abstract
- Leukotriene A4 (LTA4) hydrolase [7E,9E,11Z,14Z)-(5S,6S)-5,6-epoxyicosa-7,9 ,11,14-tetraenoate hydrolase; EC 3.3.2.6] is a bifunctional zinc metalloenzyme which converts LTA4 into the chemotactic agent leukotriene B4 (LTB4). Suicide inactivation, a typical feature of LTA4 hydrolase/aminopeptidase, occurs via an irreversible, apparently mechanism-based, covalent binding of LTA4 to the protein in a 1:1 stoichiometry. Differential lysine-specific peptide mapping of unmodified and suicide-inactivated LTA4 hydrolase has been used to identify a henicosapeptide, encompassing the amino acid residues 365-385 of human LTA4 hydrolase, which is involved in the binding of LTA4, LTA4 methyl ester, and LTA4 ethyl ester to the native enzyme. A modified form of this peptide, generated by lysine-specific digestion of LTA4 hydrolase inactivated by LTA4 ethyl ester, could be isolated for complete Edman degradation. The sequence analysis revealed a gap at position 14, which shows that binding of the leukotriene epoxide had occurred via Tyr-378 in LTA4 hydrolase. Inactivation of the epoxide hydrolase and the aminopeptidase activity was accompanied by a proportionate modification of the peptide. Furthermore, both enzyme inactivation and peptide modification could be prevented by preincubation of LTA4 hydrolase with the competitive inhibitor bestatin, which demonstrates that the henicosapeptide contains functional elements of the active site(s). It may now be possible to clarify the molecular mechanisms underlying suicide inactivation and epoxide hydrolysis by site-directed mutagenesis combined with structural analysis of the lipid molecule, covalently bound to the peptide.
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| 16. |
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