| 1. |
- Ade, P. A. R., et al.
(författare)
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Planck 2015 results XXVI. The Second Planck Catalogue of Compact Sources
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 594
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Tidskriftsartikel (refereegranskat)abstract
- The Second Planck Catalogue of Compact Sources is a list of discrete objects detected in single-frequency maps from the full duration of the Planck mission and supersedes previous versions. It consists of compact sources, both Galactic and extragalactic, detected over the entire sky. Compact sources detected in the lower frequency channels are assigned to the PCCS2, while at higher frequencies they are assigned to one of two subcatalogues, the PCCS2 or PCCS2E, depending on their location on the sky. The first of these (PCCS2) covers most of the sky and allows the user to produce subsamples at higher reliabilities than the target 80% integral reliability of the catalogue. The second ( PCCS2E) contains sources detected in sky regions where the diffuse emission makes it difficult to quantify the reliability of the detections. Both the PCCS2 and PCCS2E include polarization measurements, in the form of polarized flux densities, or upper limits, and orientation angles for all seven polarization-sensitive Planck channels. The improved data-processing of the full-mission maps and their reduced noise levels allow us to increase the number of objects in the catalogue, improving its completeness for the target 80% reliability as compared with the previous versions, the PCCS and the Early Release Compact Source Catalogue (ERCSC).
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| 2. |
- Ade, P. A. R., et al.
(författare)
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XXIV. Cosmology from Sunyaev-Zeldovich cluster counts
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 594
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Tidskriftsartikel (refereegranskat)abstract
- We present cluster counts and corresponding cosmological constraints from the Planck full mission data set. Our catalogue consists of 439 clusters detected via their Sunyaev-Zeldovich (SZ) signal down to a signal-to-noise ratio of 6, and is more than a factor of 2 larger than the 2013 Planck cluster cosmology sample. The counts are consistent with those from 2013 and yield compatible constraints under the same modelling assumptions. Taking advantage of the larger catalogue, we extend our analysis to the two-dimensional distribution in redshift and signal-to-noise. We use mass estimates from two recent studies of gravitational lensing of background galaxies by Planck clusters to provide priors on the hydrostatic bias parameter, (1 - b). In addition, we use lensing of cosmic microwave background (CMB) temperature fluctuations by Planck clusters as an independent constraint on this parameter. These various calibrations imply constraints on the present-day amplitude of matter fluctuations in varying degrees of tension with those from the Planck analysis of primary fluctuations in the CMB; for the lowest estimated values of (1 b) the tension is mild, only a little over one standard deviation, while it remains substantial (3.7 sigma) for the largest estimated value. We also examine constraints on extensions to the base flat Lambda CDM model by combining the cluster and CMB constraints. The combination appears to favour non-minimal neutrino masses, but this possibility does little to relieve the overall tension because it simultaneously lowers the implied value of the Hubble parameter, thereby exacerbating the discrepancy with most current astrophysical estimates. Improving the precision of cluster mass calibrations from the current 10%-level to 1% would significantly strengthen these combined analyses and provide a stringent test of the base Lambda CDM model.
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| 3. |
- Khuyagbaatar, J., et al.
(författare)
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48Ca+249Bk Fusion Reaction Leading to Element Z=117: Long-Lived α-Decaying 270Db and Discovery of 266Lr
- 2014
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Ingår i: Physical Review Letters. - 1079-7114. ; 112:17
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Tidskriftsartikel (refereegranskat)abstract
- The superheavy element with atomic number Z=117 was produced as an evaporation residue in the 48Ca+249Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-μs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope 294-117 and its decay products. A hitherto unknown α-decay branch in 270Db (Z=105) was observed, which populated the new isotope 266Lr (Z=103). The identification of the long-lived (T1/2=1.0+1.9−0.4 h) α-emitter 270Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an “island of stability.”
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| 4. |
- Khuyagbaatar, J., et al.
(författare)
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Fusion reaction 48Ca + 249Bk leading to formation of the element Ts (Z=117)
- 2019
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Ingår i: Physical Review C. - 2469-9985. ; 99:5
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Tidskriftsartikel (refereegranskat)abstract
- The heaviest currently known nuclei, which have up to 118 protons, have been produced in 48Ca induced reactions with actinide targets. Among them, the element tennessine (Ts), which has 117 protons, has been synthesized by fusing 48Ca with the radioactive target 249Bk, which has a half-life of 327 d. The experiment was performed at the gas-filled recoil separator TASCA. Two long and two short α decay chains were observed. The long chains were attributed to the decay of 294Ts. The possible origin of the short-decay chains is discussed in comparison with the known experimental data. They are found to fit with the decay chain patterns attributed to 293Ts. The present experimental results confirm the previous findings at the Dubna Gas-Filled Recoil Separator on the decay chains originating from the nuclei assigned to Ts.
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| 5. |
- Khuyagbaatar, J., et al.
(författare)
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Search for elements 119 and 120
- 2020
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Ingår i: Physical Review C. - 2469-9985. ; 102:6
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Tidskriftsartikel (refereegranskat)abstract
- A search for production of the superheavy elements with atomic numbers 119 and 120 was performed in the 50Ti+249Bk and 50Ti+249Cf fusion-evaporation reactions, respectively, at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. Over four months of irradiation, the 249Bk target partially decayed into 249Cf, which allowed for a simultaneous search for both elements. Neither was detected at cross-section sensitivity levels of 65 and 200 fb for the 50Ti+249Bk and 50Ti+249Cf reactions, respectively, at a midtarget beam energy of Elab = 281.5 MeV. The nonobservation of elements 119 and 120 is discussed within the concept of fusion-evaporation reactions including various theoretical predictions on the fission-barrier heights of superheavy nuclei in the region of the island of stability.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Di Nitto, A., et al.
(författare)
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Study of Non-fusion Products in the 50Ti+249Cf Reaction
- 2018
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 784, s. 199-205
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Tidskriftsartikel (refereegranskat)abstract
- The isotopic distribution of nuclei produced in the 50Ti + 249Cf reaction has been studied at the gas-filled recoil separator TASCA at GSI Darmstadt, which separates ions according to differences in magnetic rigidity. The bombardment was performed at an energy around the Bass barrier and with the TASCA magnetic fields set for collecting fusion-evaporation reaction products. Fifty-three isotopes located “north-east” of 208Pb were identified as recoiling products formed in non-fusion channels of the reaction. These recoils were implanted with energies in two distinct ranges; besides one with higher energy, a significant low-energy contribution was identified. The latter observation was not expected to occur according to kinematics of the known types of reactions, namely quasi-elastic, multi-nucleon transfer, deep-inelastic collisions or quasifission. The present observations are discussed within the framework of two-body kinematics passing through the formation of a composite system.
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| 10. |
- Forsberg, Ulrika, et al.
(författare)
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Spectroscopic Tools Applied to Element Z = 115 Decay Chains
- 2014
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X .- 2101-6275. - 9782759811755 - 9782759811762 ; 66, s. 02036-02036
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Konferensbidrag (refereegranskat)abstract
- Nuclides that are considered to be isotopes of element Z = 115 were produced in the reaction 48Ca + 243Am at the GSI Helmholtzzentrum für Schwerionenforschung Darmstadt. The detector setup TASISpec was used. It was mounted behind the gas-filled separator TASCA. Thirty correlated α-decay chains were found, and the energies of the particles were determined with high precision. Two important spectroscopic aspects of the offline data analysis are discussed in detail: the handling of digitized preamplified signals from the silicon strip detectors, and the energy reconstruction of particles escaping to upstream detectors relying on pixel-by-pixel dead-layer thicknesses.
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| 11. |
- Düllmann, Ch. E., et al.
(författare)
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Production and Decay of Element 114: High Cross Sections and the New Nucleus 277Hs
- 2010
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Ingår i: Physical Review Letters. - 1079-7114. ; 104:25
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Tidskriftsartikel (refereegranskat)abstract
- The fusion-evaporation reaction 244Pu(48Ca, 3-4n)288,289114 was studied at the new gas-filled recoil separator TASCA. Thirteen correlated decay chains were observed and assigned to the production and decay of 288,289114. At a compound nucleus excitation energy of E* = 39.8-43.9 MeV, the 4n evaporation channel cross section was 9.8(-3.1)(+3.9) pb. At E* = 36.1-39.5 MeV, that of the 3n evaporation channel was 8.0-(+7.4)(4.5) pb. In one of the 3n evaporation channel decay chains, a previously unobserved alpha branch in 281Ds was observed ( probability to be of random origin from background: 0.1%). This alpha decay populated the new nucleus 277Hs, which decayed by spontaneous fission after a lifetime of 4.5 ms.
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| 12. |
- Såmark-Roth, A., et al.
(författare)
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Low-lying states in 219Ra and 215Rn : Sampling microsecond α-decaying nuclei
- 2018
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Ingår i: Physical Review C. - 2469-9985. ; 98:4
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Tidskriftsartikel (refereegranskat)abstract
- Short-lived α-decaying nuclei "northeast" of 208Pb in the chart of nuclides were studied using the reaction 48Ca+243Am with the decay station TASISpec at TASCA, GSI Darmstadt. Decay energies and times from pile-up events were extracted with a tailor-made pulse-shape analysis routine and specific α-decay chains were identified in a correlation analysis. Decay chains starting with the even-even 220Ra and its odd-A neighbors, 219Fr, and 219,221Ra, with a focus on the 219Ra→215Rn decay, were studied by means of α-γ spectroscopy. A revised α-decay scheme of 219Ra is proposed, including a new decay branch from a previously not considered isomeric state at 17 keV excitation energy. Conclusions on nuclear structure are drawn from the experimental data, aided by Geant4 simulations and a discussion on theoretical calculations.
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| 13. |
- Forsberg, U., et al.
(författare)
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Recoil-α-fission and recoil-α-α-fission events observed in the reaction 48Ca + 243Am
- 2016
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Ingår i: Nuclear Physics, Section A. - : Elsevier BV. - 0375-9474. ; 953, s. 117-138
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Tidskriftsartikel (refereegranskat)abstract
- Products of the fusion-evaporation reaction 48Ca + 243Am were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. Amongst the detected thirty correlated α-decay chains associated with the production of element Z=115, two recoil-α-fission and five recoil-α-α-fission events were observed. The latter five chains are similar to four such events reported from experiments performed at the Dubna gas-filled separator, and three such events reported from an experiment at the Berkeley gas-filled separator. The four chains observed at the Dubna gas-filled separator were assigned to start from the 2n-evaporation channel 289115 due to the fact that these recoil-α-α-fission events were observed only at low excitation energies. Contrary to this interpretation, we suggest that some of these recoil-α-α-fission decay chains, as well as some of the recoil-α-α-fission and recoil-α-fission decay chains reported from Berkeley and in this article, start from the 3n-evaporation channel 288115.
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| 14. |
- Graeger, R., et al.
(författare)
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Experimental Study of the 238U(36S,3-5n)269-271Hs Reaction Leading to the Observation of 270Hs
- 2010
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 81:6
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Tidskriftsartikel (refereegranskat)abstract
- The deformed doubly magic nucleus (270)Hs has so far only been observed as the four-neutron (4n) evaporation residue of the reaction Mg-26+Cm-248, where a maximum cross section of 3 pb was measured. Theoretical studies on the formation of (270)Hs in the 4n evaporation channel of fusion reactions with different entrance channel asymmetry in the framework of a two-parameter Smoluchowski equation predict that the reactions Ca-48+Ra-226 and S-36+U-238 result in higher cross sections due to lower reaction Q values, in contrast to simple arguments based on the reaction asymmetry, which predict opposite trends. Calculations using HIVAP predict cross sections for the reaction S-36+U-238 that are similar to those of the Mg-26+Cm-248 reaction. Here, we report on the first measurement of evaporation residues formed in the complete nuclear fusion reaction S-36+U-238 and the observation of (270)Hs, which is produced in the 4n evaporation channel, with a measured cross section of 0.8(-0.7)(+2.6) pb at 51-MeV excitation energy. The one-event cross-section limits (68% confidence level) for the 3n, 4n, and 5n evaporation channels at 39-MeV excitation energy are 2.9 pb, while the cross-section limits of the 3n and 5n channel at 51 MeV are 1.5 pb. This is significantly lower than the 5n cross section of the Mg-26+Cm-248 reaction at similar excitation energy.
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| 15. |
- Rudolph, Dirk, et al.
(författare)
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Alpha-Photon Coincidence Spectroscopy Along Element 115 Decay Chains
- 2014
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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. ; 45, s. 263-272
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Tidskriftsartikel (refereegranskat)abstract
- Produced in the reaction 48Ca+243Am, thirty correlated α-decay chains were observed in an experiment conducted at the GSI Helmholzzentrum für Schwerionenforschung, Darmstadt, Germany. The decay chains are basically consistent with previous findings and are considered to originate from isotopes of element 115 with mass numbers 287, 288, and 289. A set-up aiming specifically for high-resolution charged particle and photon coincidence spectroscopy was placed behind the gas-filled separator TASCA. For the first time, γ rays as well as X-ray candidates were observed in prompt coincidence with the α-decay chains of element 115.
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| 16. |
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| 17. |
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| 18. |
- Rudolph, Dirk, et al.
(författare)
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Selected Spectroscopic Results on Element 115 Decay Chains
- 2015
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 303:2, s. 1185-1190
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Tidskriftsartikel (refereegranskat)abstract
- Thirty correlated alpha-decay chains were observed in an experiment studying the fusion-evaporation reaction 48Ca + 243Am at the GSI Helmholtzzentrum f¨ur Schwerionenforschung. The decay characteristics of the majority of these 30 chains are consistent with previous observations and interpretations of such chains to originate from isotopes of element Z = 115. High-resolution alpha-photon coincidence spectroscopy in conjunction with comprehensive Monte-Carlo simulations allow to propose excitation schemes of atomic nuclei of the heaviest elements, thereby probing nuclear structure models near the ‘Island of Stability’ with unprecedented experimental precision.
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| 19. |
- Rudolph, Dirk, et al.
(författare)
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Spectroscopy of Element 115 Decay Chains
- 2013
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Ingår i: Physical Review Letters. - 1079-7114. ; 111:11
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Tidskriftsartikel (refereegranskat)abstract
- A high-resolution , X-ray and gamma-ray coincidence spectroscopy experiment was conducted at the GSI Helmholtzzentrum für Schwerionenforschung. Thirty correlated alpha-decay chains were detected following the fusion-evaporation reaction 48Ca + 243Am. The observations are consistent with previous assignments of similar decay chains to originate from element Z = 115. For the first time, precise spectroscopy allows the derivation of excitation schemes of isotopes along the decay chains starting with elements Z > 112. Comprehensive Monte-Carlo simulations accompany the data analysis. Nuclear structure models provide a first level interpretation.
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| 20. |
- Yakushev, A., et al.
(författare)
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Superheavy Element Flerovium (Element 114) Is a Volatile Metal
- 2014
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 1520-510X .- 0020-1669. ; 53:3, s. 1624-1629
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of superheavy elements (Z ≥ 104) and their chemical properties are dominated by relativistic effects. Recently two superheavy elements were recognized by the IUPAC and named flerovium (Fl, Z = 114) and livermorium (Lv, Z = 116). Fl is the heaviest element with which chemical experiments were performed. Here, we report on experiments that help answering the long-standing question whether Fl behaves rather like a noble gas or like a metal.
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| 21. |
- Muller, C., et al.
(författare)
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Promising Prospects for Sc-44-/Sc-47-Based Theragnostics: Application of Sc-47 for Radionuclide Tumor Therapy in Mice
- 2014
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 2159-662X. ; 55:10, s. 1658-1664
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, Sc-47 has attracted attention because of its favorable decay characteristics (half-life, 3.35 d; average energy, 162 key; Ey, 159 key) for therapeutic application and for SPECT imaging. The aim of the present study was to investigate the suitability of Sc-47 for radionuclide therapy in a preclinical setting. For this purpose a novel DOTA-folate conjugate (cm10) with an albumin-binding entity was used. Methods: Sc-47 was produced via the Ca-46(n,gamma)Ca-47 -> Sc beta-47 nuclear reaction at the high-flux reactor at the Institut Laue-Langevin. Separation of the Sc-47 from the target material was performed by a semi-automated process using extraction chromatography and cation exchange chromatography. Sc-47-labeled cm10 was tested on folate receptor-positive KB tumor cells in vitro. Biodistribution and SPECT imaging experiments were performed in KB tumor-bearing mice. Radionuclide therapy was conducted with two groups of mice, which received either Sc-47-cm10 (10 MBq) or only saline. Tumor growth and survival time were compared between the two groups of mice. Results: Irradiation of Ca-46 resulted in approximately 1.8 GBq of Ca-47, which subsequently decayed to Sc-47. Separation of Sc-47 from Ca-47 was obtained with 80% yield in only 10 min. The Sc-47 was then available in a small volume (-500 pL) of an ammonium acetate/HCI (pH 4.5) solution suitable for direct radiolabeling. Sc-47-cm10 was prepared with a radiochemical yield of more than 96% at a specific activity of up to 13 MBq/nmol. In vitro 475ccm10 showed folate receptor-specific binding and uptake into KB tumor cells. In vivo SPECT/CT images allowed the visualization of accumulated radioactivity in KB tumors and in the kidneys. The therapy study showed a significantly delayed tumor growth in mice, which received Sc-47-cm10 (10 MBq, 10 Gy) resulting in a more than 50% increase in survival time, compared with untreated control mice. Conclusion: With this study, we demonstrated the suitability of using Sc-47 for therapeutic purposes. On the basis of our recent results obtained with Sc-44-folate, the present work confirms the applicability of Sc-44/Sc-47 as an excellent matched pair of nuclides for PET imaging and radionuclide therapy.
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