| 1. |
- Doornenbal, P., et al.
(författare)
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RISING: Gamma‐ray Spectroscopy with Radioactive Beams at GSI
- 2007
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X. - 9780735413283 ; 891, s. 99-107
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Konferensbidrag (refereegranskat)abstract
- The Rare Isotope Spectroscopic INvestigation at GSI (RISING) project is a major pan‐European collaboration. Its physics aims are the studies of exotic nuclear matter with abnormal proton‐to‐neutron ratios compared with naturally occurring isotopes. RISING combines the FRagment Separator (FRS) which allows relativistic energies and projectile fragmentation reactions with EUROBALL Ge Cluster detectors for γ spectroscopic research. The RISING setup can be used in two different configurations. Either the nuclei of interest are investigated after being stopped or the heavy ions hit a secondary target at relativistic energies and the thereby occurring excitations are studied. For the latter case, MINIBALL Ge detectors and the HECTOR array are used in addition. Example achievements of the Fast Beam setup are presented and compared to various shell model calculations, while for the Stopped Beam setup initial results are shown.
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| 2. |
- Pietri, S., et al.
(författare)
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First Results from the Stopped Beam Isomer RISING Campaign at GSI
- 2007
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Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 38:4, s. 1255-1264
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Tidskriftsartikel (refereegranskat)abstract
- The first results from a series of experiments focused on the study of the internal structure of nuclei at the extremes of N:Z ratio using isomer spectroscopy are reported. These experiments represent the first of the Stopped Beam section of the Rare Isotopes Investigations at GSI (RISING) project. Exotic nuclei were synthesized using relativistic projectile fragmentation of similar to 500 -> 1000 MeV/u beams of Ag-107, Pb-208, Xe-136 and Ni-58, or fission of 750 MeV/u U-238 provided by the SIS synchrotron at GSI. A detailed description of the RISING stopped beam set up is given, together with a report of the performance of the associated gamma-ray spectrometer array. Selected results of the first experimental campaign are presented together with a discussion on the use of isomeric spectroscopy to study GeV range nuclear fragmentation. Details on future research plans of this collaboration are also outlined.
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| 3. |
- Regan, P. H., et al.
(författare)
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First Results from the Stopped RISING Campaign at GSI: The Mapping of Isomeric Decays in Highly Exotic Nuclei
- 2007
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X. - 9780735413283 ; 899, s. 19-22
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Konferensbidrag (refereegranskat)abstract
- The first results from the Stopped Beam RISING experimental campaign performed at the GSI laboratory in Darmstadt, Germany, are presented. RISING (Rare ISotope INvestigations at GSI) constitutes a major new experimental program in European nuclear structure physics research aimed at using relativistic‐energy, projectile‐fragmentation reactions to study nuclei with exotic proton‐to‐neutron ratios. This paper introduces the physics aims of the Stopped RISING collaboration and presents some technical details and initial results from experiments using the RISING array to study decays from metastable nuclear states in both proton and neutron‐rich nuclei.
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| 4. |
- Rudolph, Dirk, et al.
(författare)
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Exciting Isomers from the First Stopped-beam RISING Campaign
- 2007
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Ingår i: The European Physical Journal. Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 150, s. 173-176
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Tidskriftsartikel (refereegranskat)abstract
- First results are reported from a major new initiative of experiments, which focus on nuclear structure studies at extreme isospin values by means of isomer spectroscopy. The experiments represent the first part of the so-called stopped-beam campaign within the Rare ISotope INvestigations at GSI (RISING) project. Time-correlated gamma decays from individually identified nuclear species have been measured, allowing the clean identification of isomeric decays in a wide range of exotic nuclei both at the proton drip-line and in heavy, neutron-rich systems. An overview of the experimental technique will be given, together with the performance of the new germanium detector array and future research plans for the collaboration.
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| 5. |
- Podolyak, Zs., et al.
(författare)
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Isomeric Decay Studies Around 204Pt and 148Tb
- 2007
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Ingår i: The European Physical Journal. Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 150, s. 165-168
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Tidskriftsartikel (refereegranskat)abstract
- Relativistic energy projectile fragmentation of Pb-208 has been used to produce a range of exotic nuclei. The nuclei of interest were studied by detecting delayed gamma rays following the decay of isomeric states. Experimental information on the excited states of the neutron-rich N = 126 nucleus, Pt-204, following internal decay of two isomeric states, was obtained for the first time. In addition, decays from the previously reported isomeric I=27h and I=(49/2)h states in Tb-148 and Gd-147, respectively, have been observed. These isomeric decays represent the highest spin discrete states observed to date following a projectile fragmentation reaction, and opens further the possibility of doing 'high-spin physics' using this technique.
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| 6. |
- Rudolph, Dirk, et al.
(författare)
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Isospin Symmetry and Proton Decay: Identification of the 10+ Isomer in 54Ni
- 2008
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 78:2
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Tidskriftsartikel (refereegranskat)abstract
- The gamma decays from an isomeric 10+ state at 6457 keV in the nucleus 54Ni have been identified using the GSI fragment separator in conjunction with the RISING Ge-detector array. The state is interpreted as the isobaric analog of the 6527-keV 10+ isomer in 54Fe. The results are discussed in terms of isospin-dependent shell-model calculations. Clear evidence is presented for a discrete l = 5 proton decay branch into the first excited 9/2- state of the daughter 53Co. This decay is the first of its kind observed following projectile fragmentation reactions.
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| 7. |
- Johansson, Emma M., et al.
(författare)
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Quantitative analysis of exudates from soil-living basidiomycetes in pure culture as a response to lead, cadmium and arsenic stress
- 2008
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Ingår i: Soil Biology and Biochemistry. - Amsterdam : Elsevier. - 0038-0717 .- 1879-3428. ; 40:9, s. 2225-2236
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Tidskriftsartikel (refereegranskat)abstract
- Six different ectomycorrhizal fungi (Hebeloma velutipes, Piloderma byssinum, Paxillus involutus, Rhizopogonroseolus, Suillus bovinus and Suillus variegatus) and two saprotrophic fungi (Hypholoma fasciculare andHypholoma capnoides) were exposed to metal stress induced by Pb, Cd and As. After pre-growth ina nutrient solution in Petri dishes, metal exposure was performed either in a nutrient rich solution or ina nutrient poor solution for seven days. The fungi were exposed to two different metal concentrations,low and high (Pb: 10 þ 100 mM; Cd: 1 þ 10 mM; As: 1 þ 10 mM). Exudation of low molecular weightorganic compounds (low molecular weight organic acids (LMWOA), amino acids and dissolved monosaccharides),as well as dissolved organic carbon was quantified as a potential response to the metalstress. The main LMWOA identified was oxalate. Oxalate exudation increased significantly in response toboth low and high Pb and Cd concentrations, as well as low As exposure, relative to nutrient controls.Exposure to As and mixtures of metals (Pb þ Cd, Pb þ As) did not result in any significant increase inoxalate production compared to controls. The presence of a carbon source (glucose) in this study islikely to have been important for exudation of organic compounds. For the nutrient rich (þ1mMglucose) metal treatments exposure to Pb and Cd mainly increased exudation of oxalate and total aminoacids. Production of dissolved monosaccharides, as well as DOC, did not increase significantly in responseto metal exposure, irrespective of nutrient conditions. This may be explained by re-absorption ofthe organic compounds by the mycelium or by the fact that metals had no effect on exudation of thesecompounds.
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| 8. |
- Johansson, Emma M., et al.
(författare)
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Quantitative analysis of root and ectomycorrhizal exudates as a response to Pb, Cd and As stress
- 2008
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Ingår i: Plant and Soil. - Berlin : Springer. - 0032-079X .- 1573-5036. ; 313:1-2, s. 39-54
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Tidskriftsartikel (refereegranskat)abstract
- We examined exudation of low molecular weight (LMW) organic compounds of ectomycorrhizal (ECM) and non-mycorrhizal (NM) seedlings in relation to metals. Scots pine seedlings, either colonized by one of six different ECM fungi or NM, were grown in Petri dishes containing glass beads and liquid growth medium and exposed to elevated concentrations of Pb, Cd and As. Exudation of LMW organic compounds (LMW organic acids (LMWOAs), amino acids and dissolved monosaccharides) and dissolved organic carbon (DOC) was determined qualitatively and quantitatively and exudation rates were calculated. Metals had a significant impact on exudation, especially of oxalate. For Pb and Cd treatments, exudation of oxalate and total LMWOAs generally increased by 15–45% compared to nutrient controls. Production of amino acids, dissolved monosaccharides and DOC was not significantly stimulated by exposure to metals; however, there were non-significant trends towards increased exudation. Finally, exudation generally increased in the presence of mycorrhizal seedlings compared to NM seedlings. The results suggest that ECM fungi may reduce the toxicity of metals to plants through significant increases in the production of organic chelators. Axenic conditions are required to assess the full potential for production of these molecules but their overall significance in soil ecosystems needs to be determined using additional experiments under more ecologically realistic conditions.
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| 9. |
- Nilsson, Emma C, et al.
(författare)
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Sialic acid is a cellular receptor for coxsackievirus A24 variant, an emerging virus with pandemic potential
- 2008
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Ingår i: Journal of Virology. - Baltimore : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 82:6, s. 3061-3068
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Tidskriftsartikel (refereegranskat)abstract
- Binding to target cell receptors is a critical step in the virus life cycle. Coxsackievirus A24 variant (CVA24v) has pandemic potential and is a major cause of acute hemorrhagic conjunctivitis, but its cellular receptor has hitherto been unknown. Here we show that CVA24v fails to bind to and infect CHO cells defective in sialic acid expression. Binding of CVA24v to and infection of corneal epithelial cells are efficiently inhibited by treating cells with a sialic acid-cleaving enzyme or sialic acid-binding lectins and by treatment of the virus with soluble, multivalent sialic acid. Protease treatment of cells efficiently inhibited virus binding, suggesting that the receptor is a sialylated glycoprotein. Like enterovirus type 70 and influenza A virus, CVA24v can cause pandemics. Remarkably, all three viruses use the same receptor. Since several unrelated viruses with tropism for the eye use this receptor, sialic acid-based antiviral drugs that prevent virus entry may be useful for topical treatment of such infections.
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| 10. |
- Rudolph, Dirk, et al.
(författare)
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Evidence for an Isomeric 3/2- State in 53Co
- 2008
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 36:2, s. 131-138
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Tidskriftsartikel (refereegranskat)abstract
- The fragmentation of a 550MeV/u primary beam of Ni-58 on a Be-9 target has been used to measure time-and energy-correlated gamma decays following the implantation of event-by-event discriminated secondary fragments into a Be-9 stopper plate. A new isomeric gamma decay with T-1/2 = 14(6 4) ns and E-gamma = 646.2(2) keV is observed and attributed to the decay of the yrast 3/2-state in Co-53(27)26. This short-lived isomeric state has been populated by means of nuclear reactions during the stopping process of the secondary fragments. The experimental findings are discussed in the framework of large-scale spherical shell model calculations in conjunction with isospin symmetry-breaking residual interactions for the A = 53, Tz = +/- 1/2 mirror nuclei Co-53 and Fe-53.
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