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| 2. |
- Borge, M. J. G., et al.
(författare)
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Beta-delayed multiparticle emission studies at ISOL-type facilities
- 2004
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 746, s. 243-243
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Konferensbidrag (refereegranskat)abstract
- We report here on the recent beta-decay studies made at ISOL-type Facilities to determine the multiparticle breakup mechanism of excited states in light nuclei by studying them in full kinematics. In particular the results obtained for the A = 9 isobars and the breakup of the 12.7 MeV state in C-12 of unnatural parity are discussed. The breakup of the latter has been debated since more than a decade. Mirror beta transitions in the A = 9 chain are compared and a large asymmetry factor is deduced for the transitions to high excitation energy in Be-9 (11.8 MeV) and B-9 (12.2 MeV) fed in the beta-decay of Li-9 and C-9 respectively. It is shown that the asymmetry is not due to experimental problems or differences in the mechanisms of breakup or in the spin of the states. As no asymmetry is found in the gs to gs transition it must be due to the particular structure of these excited states. The controversy on the breakup mechanism of the 12.7 MeV state is resolved.
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| 3. |
- Fynbo, H. O. U., et al.
(författare)
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News on C-12 from beta-decay studies
- 2004
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 738, s. 59-65
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Konferensbidrag (refereegranskat)abstract
- We discuss the importance of the spectroscopic properties of the resonances of C-12 just above the 3alpha-threshold, and review the existing experimental information of this region with emphasis on 0(+) and 2(+) states. A new experimental approach for studying the beta-decays of B-12 and N-12 is presented based on techniques developed in the context of Radioactive beam (rare isotope) physics. Finally preliminary results from an ongoing analysis of two recent experiments are given.
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| 4. |
- Lumpkin, A. H., et al.
(författare)
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Evidence for microbunching "sidebands" in a saturated free-electron laser using coherent optical transition radiation
- 2002
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Ingår i: Physical Review Letters. - 1079-7114. ; 88:23, s. 4-4
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Tidskriftsartikel (refereegranskat)abstract
- We report the first measurements of z -dependent coherent optical transition radiation (COTR) due to electron-beam microbunching at high gains (>10(4) ) including saturation of a self-amplified spontaneous emission free-electron laser (FEL). In these experiments the fundamental wavelength was near 530 nm, and the COTR spectra exhibit the transition from simple spectra to complex spectra (5% spectral width) after saturation. The COTR intensity growth and angular distribution data are reported as well as the evidence for transverse spectral dependencies and an "effective" core of the beam being involved in microbunching.
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| 5. |
- Rosenblatt, A, et al.
(författare)
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Familial influence on age of onset among siblings with Huntington disease.
- 2001
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Ingår i: American Journal of Medical Genetics. - 0148-7299 .- 1096-8628. ; 105:5, s. 399-403
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Tidskriftsartikel (refereegranskat)abstract
- In order to provide data relevant to a search for modifying genes for age of onset in Huntington disease, we examined the relationship between CAG number and age of onset in a total of 370 individuals from 165 siblingships, in two cohorts of siblings with Huntington disease: an American group of 144 individuals from 64 siblingships, and a Canadian population of 255 individuals from 113 siblingships. Using a logarithmic model to regress the age of onset on the number of CAG triplets, we found that CAG number alone accounted for 65%-71% of the variance in age of onset. The siblingship an individual belonged to accounted for 11%-19% of additional variance. This adds to the previous evidence that there are familial modifiers of the age of onset, independent of the CAG number. Such modifiers may consist of additional genes, which could be the target of a linkage study. A linkage study is feasible with the cooperation of a number of major centers and may be made more efficient by concentrating on sibling pairs that are highly discordant for age of onset.
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| 6. |
- Soffel, M., et al.
(författare)
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The IAU 2000 Resolutions for Astrometry, Celestial Mechanics, and Metrology in the Relativistic Framework: Explanatory Supplement
- 2003
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X. ; 126:6, s. 2687-2706
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the IAU resolutions B1.3, B1.4, B1.5, and B1.9 that wereadopted during the 24th General Assembly in Manchester, 2000, andprovides details on and explanations for these resolutions. It isexplained why they present significant progress over the correspondingIAU 1991 resolutions and why they are necessary in the light of presentaccuracies in astrometry, celestial mechanics, and metrology. In fact,most of these resolutions are consistent with astronomical models andsoftware already in use. The metric tensors and gravitational potentialsof both the Barycentric Celestial Reference System and the GeocentricCelestial Reference System are defined and discussed. The necessity andrelevance of the two celestial reference systems are explained. Thetransformations of coordinates and gravitational potentials arediscussed. Potential coefficients parameterizing the post-Newtoniangravitational potentials are expounded. Simplified versions of the timetransformations suitable for modern clock accuracies are elucidated.Various approximations used in the resolutions are explicated andjustified. Some models (e.g., for higher spin moments) that serve thepurpose of estimating orders of magnitude have actually never beenpublished before.
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| 7. |
- Zhang, Shi-Li, et al.
(författare)
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Abnormal anti-Stokes Raman scattering of carbon nanotubes
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:3
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Tidskriftsartikel (refereegranskat)abstract
- Abnormal anti-Stokes Raman scattering (AASR) was unambiguously observed in carbon nanotubes (CNT's). In contrast to traditional Raman scattering theory, the absolute value of the Raman frequency of the anti-Stokes peak is not the same as that of the corresponding Stokes peak. It was demonstrated that AASR scattering originates from the unique nanoscale cylindrical structure of CNT's that can be considered naturally as a graphite structure with an intrinsic defect from its rolling. The double-resonance Raman scattering theory was applied to interpret the scattering mechanism of the AASR phenomenon successfully and quantitatively.
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| 8. |
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| 9. |
- Huang, M, et al.
(författare)
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The continuing saga of the Si-like intercombination lines in highly charged ions, Si-like rhodium
- 2003
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - 0168-583X. ; 205, s. 119-122
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Tidskriftsartikel (refereegranskat)abstract
- The 3s(2)3p(2 3)P(1.2)-3s3p(3) S-5(2) intercombination lines for Si-like Rh have been investigated using the techniques of beam-foil spectroscopy. Two lines have been identified as belonging to these transitions having, however, different wavelengths from what would be expected based on published iso-electronic trends. The identifications suggested here are strengthened by requirements on (a) the known fine structure splitting in the ground configuration, (b) an intensity ratio based on branching ratios, (c) similar decay characteristics and (d) expected behaviour of the lines as a function of the ion beam energy. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 10. |
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