| 1. |
- Riley, M A, et al.
(författare)
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Beyond band termination in Er-157 and the search for wobbling excitations in strongly deformed Hf-174
- 2005
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. 1735-1740
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Tidskriftsartikel (refereegranskat)abstract
- High-spin terminating bands in heavy nuclei were first identified in nuclei around Er-158(90). While examples of special terminating states have been identified in a number of erbium isotopes, almost nothing is known about the states lying beyond band termination. In the present work the high-spin structure of Er-157 has been studied using the Gammasphere spectrometer. The subject of triaxial superdeformation and 'wobbling' modes in Lu nuclei has rightly attracted a great deal of attention. Very recently, four strongly or superdeformed (SD) sequences have been observed in Hf-174 and ultimate cranker calculations predict, such structures may have significant triaxial deformation. We have performed two experiments in an attempt to verify the possible triaxial nature of these bands. A lifetime measurement was performed to confirm the large (and similar) deformation of the bands. In addition, a high-statistics, thin-target experiment was run to search for linking transitions between the SD bands and possible wobbling modes.
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| 2. |
- Riley, M. A., et al.
(författare)
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Observation of states beyond band termination in Er-156,Er-157,Er-158 and strongly deformed structures in Hf-173,Hf-174,Hf-175
- 2006
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Ingår i: Physica Scripta. - 0031-8949. ; T125, s. 123-126
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Tidskriftsartikel (refereegranskat)abstract
- High-spin terminating bands in heavy nuclei were first identified in nuclei around Er-158(90). While examples of terminating states have been identified in a number of erbium isotopes, almost nothing is known about the states lying beyond band termination. In the present work, the high-spin structure of Er-156,Er-157,Er-158 has been studied using the Gammasphere spectrometer. The subject of triaxial superdeformation and 'wobbling' modes in Lu nuclei has rightly attracted a great deal of attention. Very recently four strongly or superdeformed (SD) sequences have been observed in Hf-174, and cranking calculations using the Ultimate Cranker code predict that such structures may have significant triaxial deformation. We have performed two experiments in an attempt to verify the possible triaxial nature of these bands. A lifetime measurement was performed to confirm the large (and similar) deformation of the bands. In addition, a high-statistics, thin-target experiment took place to search for linking transitions between the SD bands, possible wobbling modes, and new SD band structures.
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| 3. |
- Bianco, L., et al.
(författare)
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alpha-Decay branching ratios measured by gamma-ray tagging
- 2008
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 597:2-3, s. 189-191
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Forskningsöversikt (refereegranskat)abstract
- The nuclides Pt168-170 were produced by bombarding isotopically enriched Mo-92,Mo-94 targets with 336, 348 MeV Kr-78 ions. Prompt gamma rays were detected at the target position and provided a selection criterion for the Pt168-170 nuclei. This technique enables the problem of the background from higher-energy alpha decays in the spectrum to be circumvented. The Pt nuclei were separated in flight using the gas-filled separator RITU and implanted into the GREAT spectrometer, which was used to study subsequent alpha decays. The alpha-decay branching ratios of Os164-166 were deduced from the fraction of selected Pt168-170 nuclei correlated with a decays Of Os164-166. The resulting branching ratios agree with the literature values but can have improved precision.
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| 4. |
- Campbell, D. B., et al.
(författare)
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Rotational structures and their evolution with spin in Gd-152
- 2007
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 75:6
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Tidskriftsartikel (refereegranskat)abstract
- The fusion-evaporation reaction involving a 175 MeV S-36 beam and a Sn-124 target was performed, and the emitted gamma rays were observed with the Gammasphere spectrometer. Significant additions to the level scheme of Gd-152 were made in spite of the relative weakness of the alpha 4n exit channel, being only similar to 2% of the total fusion cross-section. The high-spin behavior of Gd-152 was compared with that of other N=88 nuclei. A striking similarity was observed with Dy-154 and it is therefore suggested that the angular-momentum-induced shape changes that take place in Dy-154 also occur in Gd-152 in the 30-40h spin range. This is supported by Cranked Nilsson-Strutinsky calculations which were used to interpret the high-spin bands. It is found that a better agreement between calculation and experiment is obtained if the Z=64 shell gap increases with a decreasing number of valence particles outside the doubly-closed Gd-146(64)82 nucleus.
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| 5. |
- Mach, Henryk, et al.
(författare)
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The single-particle and collective features in the nuclei just above Sn-132
- 2007
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 38:4, s. 1213-1218
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Tidskriftsartikel (refereegranskat)abstract
- The Advanced Time Delayed method has been used to measure the lifetimes of excited states in the exotic nuclei Sb-134, Sb-135 and Te-136 populated in the beta decay of Sn-134, Sn-135 and Sn-136, respectively. High purity Sn beams were extracted at the ISOLDE separator using a novel production technique utilizing the molecular SnS+ beams to isolate Sn from contaminating other fission products. Among the new results we have identified the 1/2(+) state in Sb-135 and its E2 transition to the lower-lying 5/2(+) state was found to be surprisingly collective. This measurement represents also one of the first applications of the LaBr3 scintillator to ultra fast timing.
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| 6. |
- Page, R. D., et al.
(författare)
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alpha decay of Re-159 and proton emission from Ta-155
- 2007
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 75:6, s. 061302-
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Tidskriftsartikel (refereegranskat)abstract
- The alpha decay of Re-159 has been observed for the first time in reactions of 300 MeV Ni-58 ions with an isotopically enriched Cd-106 target. The Re-159 ions were separated in-flight using the RITU separator and implanted into the GREAT spectrometer. The alpha decay emanates from the proton-emitting pi h(11/2) state in Re-159 with an energy of E-alpha=6776 +/- 26 keV and a branching ratio of 7.5 +/- 3.5%. This alpha decay populates a state in the closed neutron shell nucleus Ta-155, which decays by emitting 1444 +/- 15 keV protons with a half-life of 2.9(-1.1)(+1.5) ms. These values are consistent with the emission of the proton from a pi h(11/2) orbital. These results fit in with the systematics of proton and alpha-particle separation energies in the region, but disagree with the previously reported decay properties of Ta-155.
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| 7. |
- van Ree, R, et al.
(författare)
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The CREATE project: development of certified reference materials for allergenic products and validation of methods for their quantification.
- 2008
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Ingår i: Allergy. - : Wiley. - 1398-9995 .- 0105-4538. ; 63:3, s. 310-26
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Tidskriftsartikel (refereegranskat)abstract
- Allergen extracts have been used for diagnosis and treatment of allergy for around 100 years. During the second half of 20th century, the notion increasingly gained foothold that accurate standardization of such extracts is of great importance for improvement of their quality. As a consequence, manufacturers have implemented extensive protocols for standardization and quality control. These protocols have overall IgE-binding potencies as their focus. Unfortunately, each company is using their own in-house reference materials and their own unique units to express potencies. This does not facilitate comparison of different products. During the last decades, most major allergens of relevant allergen sources have been identified and it has been established that effective immunotherapy requires certain minimum quantities of these allergens to be present in the administered maintenance dose. Therefore, the idea developed to introduce major allergens measurements into standardization protocols. Such protocols based on mass units of major allergen, quantify the active ingredients of the treatment and will at the same time allow comparison of competitor products. In 2001, an EU funded project, the CREATE project, was started to support introduction of major allergen based standardization. The aim of the project was to evaluate the use of recombinant allergens as reference materials and of ELISA assays for major allergen measurements. This paper gives an overview of the achievements of the CREATE project.
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| 8. |
- Aguilar, A, et al.
(författare)
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New shape minimum in Yb-160: Evidence for a triaxial, strongly deformed band
- 2008
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 77:2, s. 5-021302
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Tidskriftsartikel (refereegranskat)abstract
- A high-spin rotational band was observed in the N=90 nucleus Yb-160 with moment of inertia and decay characteristics very similar to recently discovered sequences in Er-157,Er-158. These latter structures were discussed in terms of strongly deformed triaxial bands. Detailed cranked Nilsson-Strutinsky calculations were performed that predict that well-deformed triaxial structures are also expected at high spin in Yb-160. Within this interpretation the observed discontinuity in the dynamic moment of inertia around h omega=0.40-0.45 MeV can be explained as a crossing between i(13/2) neutron levels.
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| 9. |
- Becker, F, et al.
(författare)
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Status of the RISING Project at GSI
- 2005
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 25:Suppl 1, s. 719-722
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Tidskriftsartikel (refereegranskat)abstract
- The FRS-RISING set-up at GSI uses secondary radioactive beams at relativistic energies for nuclear structure studies. At GSI the fragmentation or fission of stable primary beams up to U-238 provide secondary beams with sufficient intensity to perform gamma-ray spectroscopy. The RISING set-up is described and results of the first RISING campaign are presented. New experimental methods at relativistic energies are being investigated. Future experiments focus on state-of-the art nuclear structure physics covering exotic nuclei all over the nuclear chart.
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| 10. |
- Bednarczyk, P, et al.
(författare)
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Status of the RISING Project at Relativistic Energies
- 2005
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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. ; 36:4, s. 1235-1244
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Tidskriftsartikel (refereegranskat)abstract
- The RISING project was designed to perform high-resolution gamma-ray spectroscopy with radioactive beams at GSI. Unstable beams were produced by fragmentation of relativistic heavy ion projectiles provided by the SIS synchrotron. The fragment separator FRS was used to select and to focus the exotic fragments at about 100A MeV energy on a secondary target. Various charged particle detectors enabled an event-by-event tracking of the incoming radioactive projectiles and the reaction products, thus allowing for a selection of the nuclei of interest and their velocity vector reconstruction. The gamma-ray detection system consisting of the EUROBALL Cluster Ge detectors and the large volume HECTOR BaF2 detectors measured prompt gamma-radiation from nuclei excited in the secondary target. Despite the huge Doppler shift due to the high recoil velocity (beta approximate to 40%), RISING achieved a gamma-energy resolution below 2%. The paper reviews the present status of the RISING project.
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