| 11. |
- Adlarson, Patrik, et al.
(author)
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Neutron-proton scattering in the context of the d*(2380) resonance
- 2014
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 90:3, s. 035204-
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Journal article (peer-reviewed)abstract
- New data on quasifree polarized neutron-proton scattering in the region of the recently observed d* resonance structure are obtained by exclusive and kinematically complete high-statistics measurements with WASA at COSY. This paper details the determination of the beam polarization, checks of the quasifree character of the scattering process, on all obtained Ay angular distributions and on the new partial-wave analysis, which includes the new data producing a resonance pole in D-3(3)-(3)G(3) coupled partial waves at (2380 +/- 10 - i40 +/- 5) MeV-in accordance with the d* dibaryon resonance hypothesis. The effect of the new partial-wave solution on the description of total and differential cross-section data as well as specific combinations of spin-correlation and spin-transfer observables available from COSY-ANKE measurements at T-d = 2.27 GeV is discussed.
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| 12. |
- Adlarson, Patrik, et al.
(author)
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Abashian-Booth-Crowe resonance structure in the double pionic fusion to He-4
- 2012
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 86:3, s. 032201-
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Journal article (peer-reviewed)abstract
- Exclusive and kinematically complete high-statistics measurements of the double pionic fusion reaction dd -> He-4 pi(0)pi(0) have been performed in the energy range 0.8-1.4 GeV covering thus the region of the Abashian-Booth-Crowe effect, which denotes a pronounced low-mass enhancement in the pi pi invariant mass spectrum. The experiments were carried out with the WASA detector setup at the cooler synchrotron at Forshungszentrum Julich GmbH. Similar to the observation in the basic pn -> d pi(0)pi(0) reaction, the data reveal a correlation between the ABC effect and a resonancelike energy dependence in the total cross section. The maximum occurs at m = 2.37 GeV + 2m(N), i.e., at the same position as in the basic reaction. The observed resonance width Gamma approximate to 160 MeV can be understood from broadening due to Fermi motion of the nucleons in initial and final nuclei together with collision damping. Differential cross sections are described equally well by the hypothesis of a pn resonance formation during the reaction process.
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| 13. |
- Adlarson, Patrik, et al.
(author)
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Search for eta-mesic He-4 with the WASA-at-COSY detector
- 2013
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:3, s. 035204-
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Journal article (peer-reviewed)abstract
- An exclusive measurement of the excitation function for the dd -> (3)Hep pi(-) reaction was performed at the Cooler Synchrotron COSY-Julich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 to 2.400 GeV/c crossing the kinematic threshold for the eta-meson production in the dd -> He-4 eta reaction at 2.336 GeV/c. The corresponding excess energy with respect to the He-4-eta system varied from -51.4 to 22 MeV. The integrated luminosity in the experiment was determined using the dd -> (3)Hen reaction. The shape of the excitation function for the dd -> (3)Hep pi(-) reaction was examined. No signal of the He-4-eta bound state was observed. An upper limit for the cross section for the bound state formation and decay in the process dd -> (He-4-eta)(bound) -> (3)Hep pi(-) was determined on the 90% confidence level and it varies from 20 to 27 nb for the bound state width ranging from 5 to 35 MeV, respectively.
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| 14. |
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| 15. |
- Caesar, C., et al.
(author)
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Beyond the neutron drip line: The unbound oxygen isotopes O-25 and O-26
- 2013
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In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993 .- 0556-2813. ; 88:3
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Journal article (peer-reviewed)abstract
- The very neutron-rich oxygen isotopes O-25 and O-26 are investigated experimentally and theoretically. The unbound states are populated in an experiment performed at the R3B-LAND setup at GSI via proton-knockout reactions from F-26 and F-27 at relativistic energies around 442 and 414 MeV/nucleon, respectively. From the kinematically complete measurement of the decay into O-24 plus one or two neutrons, the O-25 ground-state energy and width are determined, and upper limits for the O-26 ground-state energy and lifetime are extracted. In addition, the results provide indications for an excited state in O-26 at around 4 MeV. The experimental findings are compared to theoretical shell-model calculations based on chiral two- and three-nucleon (3N) forces, including for the first time residual 3N forces, which are shown to be amplified as valence neutrons are added.
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| 16. |
- Cortina-Gil, D., et al.
(author)
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CALIFA, a Dedicated Calorimeter for the (RB)-B-3/FAIR
- 2014
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In: Nuclear Data Sheets. - : Elsevier BV. - 0090-3752. ; 120, s. 99-101
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Journal article (peer-reviewed)abstract
- The (RB)-B-3 experiment (Reactions with Relativistic Radioactive Beams) at FAIR (Facility for Antiproton and Ion Research) is a versatile setup dedicated to the study of reactions induced by high-energy radioactive beams. It will provide kinematically complete measurements with high efficiency, acceptance and resolution, making possible a broad physics program with rare-isotopes. CALIFA (CALorimeter for In-Flight detection of gamma-rays and high energy charged pArticles), is a complex detector based on scintillation crystals, that will surround the target of the (RB)-B-3 experiment. CALIFA will act as a total absorption gamma-calorimeter and spectrometer, as well as identifier of charged particles from target residues. This versatility is its most challenging requirement, demanding a huge dynamic range, to cover from low energy gamma-rays up to 300 MeV protons. This fact, along with the high-energy of the beams determine the conceptual design of the detector, presented in this paper, together with the technical solutions proposed for its construction.
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| 17. |
- Järrendahl, Kenneth, et al.
(author)
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Polarization of Light Reflected from Chiral Structures - Calculations Compared with Mueller Matrix Ellipsometry Measurements on Natural and Synthetic Samples
- 2012
-
Conference paper (other academic/artistic)abstract
- The Mueller matrix elements mij representing the polarization response from a nanostructured materialis determined by the constituent materials optical properties and the superstructure. Here, we investigate how chiral structures in form of helicoidally stacked uniaxial layers determine mij as a functionof polarization state, wavelength, incidence angle and azimuthal angle of the incoming light. The studied parameters include the layer materials ordinary/extraordinary optical properties, Euler angle values, and layer thickness as well as the thickness and pitch of the helicoidal superstructure. Sub- and superstructure inhomogeneity is also introduced. From the Fresnel-based calculations, mij aswell as the degree of polarization, ellipticity and azimuth of the polarization ellipse are obtained and presented as contour and trace plots to give a complete view of the polarization behavior. The results from the calculations are compared with Mueller matrix spectroscopic ellipsometry measurements of both natural and synthesized helicoidal structures. The measurements were performed with a dualrotating compensator system (RC2, J.A. Woollam Co., Inc.) for wavelengths in the range from 245 to 1000 nm and incident angles from 20 to 75°. For some measurements the azimuthal angle of the incident light was varied. The investigated natural chiral structures were exoskeletons from several beetles in the scarab subfamilies Cetoniinae and Rutelinae. As predicted from the calculations it isobserved that the reflection from these beetles can have a high degree of polarization and high ellipticity (near-circular polarization). Both left- and right-polarization was observed. The synthesized structures are helicoidal nanorods of Al1−xInxN grown on sapphire substrates with metal-nitride seedlayers using UHV magnetron sputtering. Due to an internal composition gradient (a variation of x) in the crystalline structure, the nanorods will tilt away from the substrate normal. Helicoidal structures can thus be obtained by rotating the substrate around its normal during deposition. Samples with different pitch and layer thickness with right-handed as well as left-handed chirality were grown. Also for these structures both left and right near-circular polarized light is observed. By combining calculations, ellipsometry measurements and scanning electron microscopy characterization we get agood input to build layered models of the natural and synthetic samples. After regression fitting agood agreement between calculated and measured optical data were obtained.
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| 18. |
- Urquia, ML, et al.
(author)
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Disparities in pre-eclampsia and eclampsia among immigrant women giving birth in six industrialised countries
- 2014
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In: Obstetrics and Gynecology. - : Wiley. - 0029-7844 .- 1873-233X. ; 121:12, s. 1492-1500
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Journal article (peer-reviewed)abstract
- ObjectiveTo assess disparities in pre‐eclampsia and eclampsia among immigrant women from various world regions giving birth in six industrialised countries.DesignCross‐country comparative study of linked population‐based databases.SettingProvincial or regional obstetric delivery data from Australia, Canada, Spain and the USA and national data from Denmark and Sweden.PopulationAll immigrant and non‐immigrant women delivering in the six industrialised countries within the most recent 10‐year period available to each participating centre (1995–2010).MethodsData was collected using standardised definitions of the outcomes and maternal regions of birth. Pooled data were analysed with multilevel models. Within‐country analyses used stratified logistic regression to obtain odds ratios (OR ) with 95% confidence intervals (95% CI ).Main outcome measuresPre‐eclampsia, eclampsia and pre‐eclampsia with prolonged hospitalisation (cases per 1000 deliveries).ResultsThere were 9 028 802 deliveries (3 031 399 to immigrant women). Compared with immigrants from Western Europe, immigrants from Sub‐Saharan Africa and Latin America & the Caribbean were at higher risk of pre‐eclampsia (OR : 1.72; 95% CI : 1.63, 1.80 and 1.63; 95% CI : 1.57, 1.69) and eclampsia (OR : 2.12; 95% CI : 1.61, 2.79 and 1.55; 95% CI : 1.26, 1. 91), respectively, after adjustment for parity, maternal age and destination country. Compared with native‐born women, European and East Asian immigrants were at lower risk in most industrialised countries. Spain exhibited the largest disparities and Australia the smallest.ConclusionImmigrant women from Sub‐Saharan Africa and Latin America & the Caribbean require increased surveillance due to a consistently high risk of pre‐eclampsia and eclampsia.
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