| 11. |
- Fan, G. W., et al.
(författare)
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Structure of 8Li from a reaction cross-section measurement
- 2014
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Ingår i: Phys. Rev. C. - American Physical Society. ; 90, s. 044321-
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Tidskriftsartikel (refereegranskat)abstract
- We have precisely measured reaction cross sections (σR) for 8Li using 9Be, 12C, 27Al, and proton targets at intermediate energies by the transmission method. From the energy dependence of the σR including the high energy data, the density distribution of 8Li was deduced through a modified Glauber model. It is shown that 8Li has a shorter tail structure in the density as compared with that of 8B and the matter radius of 8Li is similar to those of the other nonhalo Li isotopes. The result is consistent with the previous experiments that there is a tendency for 8Li to be a skin nucleus.
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| 12. |
- Moriguchi, T., et al.
(författare)
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Density distribution of 14Be from reaction cross-section measurements
- 2014
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 929:0, s. 83-93
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Tidskriftsartikel (refereegranskat)abstract
- Abstract We measured the reaction cross sections of the two-neutron halo nucleus 14Be with proton and carbon targets at about 41 and 76 MeV/nucleon. Based on a Glauber model calculation, we deduced the matter density distribution of 14Be in which previously measured interaction cross sections at relativistic energies were also included. An s-wave dominance in 14Be has been confirmed, although the halo tail of 14Be is not distributed as much as that of 11Li. Significant mixing of the p-wave in addition to the s- and d-wave is also suggested.
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| 13. |
- Moriguchi, T., et al.
(författare)
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Density distributions of 11Li deduced from reaction cross-section measurements
- 2013
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 88:2, s. 024610-1-024610-7
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Tidskriftsartikel (refereegranskat)abstract
- We measured the reaction cross sections of the two-neutron halo nucleus 11Li with solid hydrogen and carbon targets at around 31 and 41 MeV/nucleon. The neutron density distribution of 11Li was deduced for the first time by the Glauber model calculation based on the optical limit approximation. The uncertainty of the matter density of 11Li was improved, compared with earlier measurements. The present root-mean-square radius of the proton distribution agrees with the previous one derived from an optical isotope shift measurement. The present root-mean-square radii reproduce theoretical calculations by the tensor optimized shell model by assuming core excitation. This consistency suggests the possibility that 9Li in 11Li is excited and the disappearance of the N=8 shell gap of 11Li is caused by correlations originating from the nucleon force, such as the tensor and the pairing.
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| 14. |
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| 15. |
- Takahashi, H., et al.
(författare)
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A thermal-neutron detector with a phoswich system of LiCaAlF6 and BGO crystal scintillators onboard PoGOLite
- 2010
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Ingår i: 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, NSS/MIC 2010 and 17th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, RTSD 2010. ; , s. 32-37
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Konferensbidrag (refereegranskat)abstract
- To measure the flux of atmospheric neutrons and study the neutron contribution to the background of the main detector of the PoGOLite (Polarized Gamma-ray Observer) balloon-borne experiment, a thermal-neutron detector with a phoswich system of LiCaAlF6 (Eu) and BGO crystal scintillators is developed. The performance to separate thermal-neutron events from those of gamma-rays and charged particles is validated with 252Cf on ground. The detector is attached to the PoGOLite instrument and is launched in 2011 from the Esrange facility in the North of Sweden. Although the emission wavelength of the LiCaAlF6 (Ce) is 300 nm and overlaps with the absorption wavelength of the BGO, the phoswich capability of the LiCaAlF6 (Ce) with the BGO is also confirmed with installing a waveform shifter.
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| 16. |
- Yamaguchi, T., et al.
(författare)
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Energy-dependent charge-changing cross sections and proton distribution of 28Si
- 2010
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Ingår i: Phys. Rev. C. ; 82, s. 014609-1-014609-6
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Tidskriftsartikel (refereegranskat)abstract
- The charge-changing cross sections (σcc) of 28Si on a carbon target were measured with high precision atintermediate energies from 100 to 600 MeV/nucleon. The measured σcc decreases rapidly from low energies upto 200 MeV/nucleon, whereas at higher energies it appears almost constant. The energy dependence of σcc iscompared with a Glauber-type model calculation where only the proton distribution of 28Si is taken into account.A phenomenological correction factor deduced from the present data satisfactorily reproduces the experimentalσcc for other stable nuclei, whose charge distributions were determined by electron scattering and muon captureexperiments.
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| 17. |
- Hudson, Lawrence N., et al.
(författare)
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The PREDICTS database : a global database of how local terrestrial biodiversity responds to human impacts
- 2014
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 4:24, s. 4701-4735
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Tidskriftsartikel (refereegranskat)abstract
- Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species' threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project - and avert - future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups - including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems - ). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.
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| 18. |
- Kole, Merlin, et al.
(författare)
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Neutron background detection for a hard X-ray balloon-borne polarimeter
- 2014
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Ingår i: Proceedings of Science. - : Proceedings of Science (PoS).
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Konferensbidrag (refereegranskat)abstract
- PoGOLite is a balloon-borne hard X-ray polarimeter. It determines polarisation by measuring the azimuthal angular distribution of Compton scattered photons in a plastic scintillator array. The use of an all-plastic target yields a relatively large, low-mass detection area. The dominant source of background for these measurements has been shown, through Geant4 simulations, to originate from high energy (MeV range) atmospheric neutrons. Neutrons can pass the instrument's Bismuth Germanium Oxide (BGO) anti-coincidence shield undetected and subsequently scatter between plastic scintillator elements to produce a polarisation signature. A passive 15 cm thick polyethylene shield surrounding the polarimeter reduces the neutron induced background by an order of magnitude. The background level remains however significant, prompting the need for active monitoring of the continuously changing neutron flux. For this purpose PoGOLite makes use of a phoswich scintillator cell. The phoswich cell consists of a 5 mm thick Lithium Calcium Aluminium Fluoride (LiCAF) scintillator, used for neutron detection. The LiCAF is surrounded by a BGO anti-coincidence system. This small light weight detector can therefore be used to measure the neutron flux even in high radiation environments. This type of neutron detector was tested on a separate dedicated stratospheric balloon mission in March 2013, called PoGOLino, prior to the PoGOLite flight which took place in July 2013. Results from the test flight and implications for the measurements performed on the PoGOLite flight will be discussed.
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| 19. |
- Ehara, M., et al.
(författare)
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Symmetry and vibrationally resolved absorption spectra near the N K edges of N2O : experiment and theory
- 2011
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 83:6, s. 062506-
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Tidskriftsartikel (refereegranskat)abstract
- In this study, angle-resolved energetic-ion yield spectra were measured in the N 1s excitation region of N2O. A Franck-Condon analysis based on ab initio two-dimensional potential energy surfaces of the core-excited Rydberg states, which were calculated by the symmetry-adapted cluster-configuration interaction method, reproduced observed vibrational excitations specific to the individual Rydberg states well and enabled quantitative assignments. Geometric changes in the terminal nitrogen N-t 1s and the central nitrogen N-c 1s excited states with respect to the 3p pi, 3p sigma, and 4s sigma transitions were analyzed. The coupling of these valence and Rydbergs states was examined based on the second moment analysis. Irregular Rydberg-state behavior in the N-c 1s(-1) 4s sigma state was observed.
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| 20. |
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