| 1. |
- Aleksandrov, D., et al.
(author)
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Invariant mass spectrum and alpha-n correlation function studied in the fragmentation of He-6 on a carbon target
- 1998
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In: Nuclear Physics A. - 0375-9474. ; 633:2, s. 234-246
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Journal article (peer-reviewed)abstract
- Momentum distributions and invariant mass spectra from the breakup of He-6 ions with an energy of 240 MeV/u interacting with a carbon target have been studied. The data were used to extract information about the reaction mechanism which is influenced by the structure of He-6. It is found that the dominant reaction mechanism is a two-step process: knock out of one neutron followed by the decay of the He-5 resonance. The shape of the (alpha+n) two-body invariant mass spectrum is interpreted as mainly reflecting the 5He ground state which is a J(pi) = 3/2(-) resonance. However, no evidence for correlations between cu particles and neutrons is observed in the momentum widths of the distributions. It is demonstrated that a combined analysis of the two-body invariant mass spectrum and an appropriate correlation function may be used to determine the properties of the intermediate resonance. (C) 1998 Elsevier Science B.V.
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| 2. |
- Chulkov, L. V., et al.
(author)
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Large spin alignment of the unbound He-5 fragment after fragmentation of 240 MeV/nucleon He-6
- 1997
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In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 79:2, s. 201-204
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Journal article (peer-reviewed)abstract
- Peripheral fragmentation of a 240 MeV/nucleon beam of the halo nucleus He-6 incident on carbon target has been studied in a kinematically complete experiment. It is found that one-neutron stripping to the unbound nucleus He-5 is the dominant fragmentation mechanism and that it leads to a spin alignment of He-5 in a plane perpendicular to the He-5 momentum vector. This is expected to be a common feature for all neutron halo nuclei.
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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. |
- Thottappillil, Rajeev, 1958-, et al.
(author)
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Properties of M components from currents measured at triggered lightning channel base
- 1995
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In: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 100:D12, s. 25711-25720
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Journal article (peer-reviewed)abstract
- Channel base currents from triggered lightning were measured at the NASA Kennedy Space Center, Florida, during summer 1990 and at Fort McClellan, Alabama, during summer 1991. An analysis of the return stroke data and overall continuing current data has been published by Fisher et al. [1993]. Here an analysis is given of the impulsive processes, called M components, that occur during the continuing current following return strokes. The 14 flashes analyzed contain 37 leader-return stroke sequences and 158 M components, both processes lowering negative charge from cloud to ground. Statistics are presented for the following M current pulse parameters: magnitude, rise time, duration, half-peak width, preceding continuing current level, M interval, elapsed time since the return stroke, and charge transferred by the M current pulse. A typical M component in triggered lightning is characterized by a more or less symmetrical current pulse having an amplitude of 100–200 A (2 orders of magnitude lower than that for a typical return stroke [Fisher et al., 1993]), a 10–90% rise time of 300–500 Όs (3 orders of magnitude larger than that for a typical return stroke [Fisher et al., 1993]), and a charge transfer to ground of the order of 0.1 to 0.2 C (1 order of magnitude smaller than that for a typical subsequent return stroke pulse [Berger et al., 1975]). About one third of M components transferred charge greater than the minimum charge reported by Berger et al. [1975] for subsequent leader-return stroke sequences. No correlation was found between either the M charge or the magnitude of the M component current (the two are moderately correlated) and any other parameter considered. M current pulses occurring soon after the return stroke tend to have shorter rise times, shorter durations, and shorter M intervals than those which occur later. M current pulses were observed to be superimposed on continuing currents greater than 30 A or so, with one exception out of 140 cases, wherein the continuing current level was measured to be about 20 A. The first M component virtually always (one exception out of 34 cases) occurred within 4 ms of the return stroke. This relatively short separation time between return stroke and the first M component, coupled with the observation of Fisher et al. [1993] that continuing currents lasting longer than 10 ms never occur without M current pulses, implies that the M component is a necessary feature of the continuing current mode of charge transfer to ground.
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| 5. |
- Goldberg, Y P, et al.
(author)
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Increased instability of intermediate alleles in families with sporadic Huntington disease compared to similar sized intermediate alleles in the general population.
- 1995
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In: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 4:10, s. 1911-8
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Journal article (peer-reviewed)abstract
- We have directly compared intergenerational stability of intermediate alleles (IAs) derived from new mutation families (IANM) for Huntington disease (HD) with IAs in the general population (IAGP) which occur in approximately 1 in 50 persons. Analysis of meiotic events in blood and sperm reveals that IANM are significantly more unstable than IAGP despite similar size. However, for both IANM and IAGP CAG changes were small and risks for inheriting an expansion into the HD affected range were low. Sequence analysis reveals that the CAG tract is generally interrupted by a penultimate CAA in IAGP, IANM and alleles in the affected range. In one new mutation family, however, two A-->G mutations result in a pure CAG tract which is associated with very marked instability. These mutations alter the predicted DNA hairpin structure with a predicted increase in the likelihood of large expansion, supporting the model that hairpin loop formation plays an important role in trinucleotide instability.
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| 6. |
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