Jon Petter Omtvedt

• Attallah, Mohamed F.; Elchine, Dominik; Grödler, Dennis; Margreiter, Raphael; Maslo, Melisa & Michel, Marco [Show all 9 contributors for this article] (2024). Trace-scale extraction of carrier-free tungsten radioisotope as a homolog of Sg using ionic liquid from acid solutions: Kinetic study. Separation and Purification Technology. ISSN 1383-5866. 331. doi: 10.1016/j.seppur.2023.125418. Full text in Research Archive
• Bartl, P.; Němec, M.; Zach, V.; Bulíková, A.; Šifnerová, L. & Štursa, J. [Show all 8 contributors for this article] (2023). Fast on-line dissolution of KCl aerosol particulates for liquid-phase chemistry with homologues of superheavy elements. Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 1055. doi: 10.1016/j.nima.2023.168500. Full text in Research Archive
• Bartl, Pavel; Běhal, R; Matlocha, T; Němec, Mojmír; Šváb, P & Zach, Václav [Show all 10 contributors for this article] (2023). MARGE — a new ModulAr Robotic Gas-jet targEt system for chemistry studies with homologues of superheavy elements. Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 1052. doi: 10.1016/j.nima.2023.168280. Full text in Research Archive
• Nedkvitne, Eirik Nøst; Eriksen, Dag Øistein & Omtvedt, Jon Petter (2023). Grade and Tonnage Comparison of Anthropogenic Raw Materials and Ores for Cu, Zn, and Pb Recovery. Resources. 12(3). doi: 10.3390/resources12030033. Full text in Research Archive Show summary

  Primary metal production operates with large tonnages and takes advantage of economies of scale. Metal recycled from low-value waste streams, competing in the same global metal market as primary production, will be more competitive by also taking advantage of up-scaling. However, an overview of metal tonnages in low-value waste streams to see upscaling potential needs to be provided in the literature. In response, this study provides estimates of copper, zinc, and lead metal tonnages in waste incineration ash—A major waste stream going to landfills. Metal concentrations and tonnages are compared to tonnages and concentration grades found in ores. Copper, zinc, and lead concentration averages are about 3–5 times lower in ash compared to the worldwide average head grade of ores. Tonnages of metal in the ash generated from waste incineration in European countries bordering the Baltic and the North Sea are about 1/3 of mining metal output from Sweden, a leading mining country in the region. Therefore, incineration ash should be considered a significant potential Cu, Zn, and Pb metal source.

• Salina, Olga Nikolaevna; Grønås, Terje; Pottgießer, Vivien; Němec, Mojmír; Vahlbruch, Jan-Willem & Walther, Clemens [Show all 7 contributors for this article] (2022). RoboLab: providing remote access to a physical radiochemistry laboratory for teaching and training. Journal of Radioanalytical and Nuclear Chemistry. ISSN 0236-5731. doi: 10.1007/s10967-022-08589-3. Full text in Research Archive Show summary

  Abstract RoboLab enables students to perform real radiochemistry experiments without being physically present in a laboratory. Remotely controlled experiments are accessed through a web interface to a physical laboratory. The laboratory equipment is interfaced to a computer that both controls the equipment and provides feedback to the web user. A generic software template, using a cloud service, was developed to facilitate easy communication between the web browser and the control system. The sixth and most recent RoboLab, aiming at the production and measurement of 234m Pa (T 1/2  = 1.16 min), has been successfully developed and implemented using this template.

• Yakushev, A.; Lens, L.; Düllmann, Ch. E.; Khuyagbaatar, J.; Jäger, E. & Krier, J. [Show all 59 contributors for this article] (2022). On the adsorption and reactivity of element 114, flerovium. Frontiers in Chemistry. 10. doi: 10.3389/fchem.2022.976635. Full text in Research Archive Show summary

  Flerovium (Fl, element 114) is the heaviest element chemically studied so far. To date, its interaction with gold was investigated in two gas-solid chromatography experiments, which reported two different types of interaction, however, each based on the level of a few registered atoms only. Whereas noble-gas-like properties were suggested from the first experiment, the second one pointed at a volatile-metal-like character. Here, we present further experimental data on adsorption studies of Fl on silicon oxide and gold surfaces, accounting for the inhomogeneous nature of the surface, as it was used in the experiment and analyzed as part of the reported studies. We confirm that Fl is highly volatile and the least reactive member of group 14. Our experimental observations suggest that Fl exhibits lower reactivity towards Au than the volatile metal Hg, but higher reactivity than the noble gas Rn.

• Krupp, Dominik; Düllmann, Christoph E.; Lens, Lotte; Omtvedt, Jon Petter; Yakushev, Alexander & Scherer, Ulrich W. (2021). Speeding up liquid-phase heavy element chemistry: Development of a vacuum to liquid transfer chamber (VLTC). Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 1011. doi: 10.1016/j.nima.2021.165486. Full text in Research Archive
• Espegren, Fredrik; Kärkelä, Teemu; Pasi, Anna-Elina; Tapper, Unto; Kučera, Jan & Lerum, Hans Vigeland [Show all 8 contributors for this article] (2021). Tellurium transport in the RCS under conditions relevant for severe nuclear accidents. Progress in nuclear energy (New series). ISSN 0149-1970. 139, p. 1–12. doi: 10.1016/j.pnucene.2021.103815. Full text in Research Archive
• Tereshatov, Evgeny E.; Semelova, Miroslava; Čubová, Kateřina; Bartl, Pavel; Nemec, Mojmir & Stursa, Jan [Show all 10 contributors for this article] (2021). Valence states of cyclotron-produced thallium. New Journal of Chemistry. ISSN 1144-0546. 45(7), p. 3377–3381. doi: 10.1039/d0nj05198e. Full text in Research Archive
• Kucera, Jan; Pasi, Anna-Elina; Espergen, Fredrik; Kärkelä, Teemu; Lerum, Hans Vigeland & Omtvedt, Jon Petter [Show all 7 contributors for this article] (2020). Tellurium determination by three modes of instrumental neutron activation analysis in aerosol filters and trap solutions for the simulation of a severe nuclear accident. Microchemical Journal. ISSN 0026-265X. doi: 10.1016/j.microc.2020.105139. Full text in Research Archive
• Lerum, Hans Vigeland; Sand, Svetlana; Eriksen, Dag Øistein; Wibetoe, Grethe & Omtvedt, Jon Petter (2020). Comparison of single‑phase and two‑phase measurements in extraction, separation and back‑extraction of Cd, Zn and Co from a multi‑element matrix using Aliquat 336. Journal of Radioanalytical and Nuclear Chemistry. ISSN 0236-5731. 324, p. 1203–1214. doi: 10.1007/s10967-020-07168-8. Full text in Research Archive
• Khuyagbaatar, Jadambaa; Yakushev, Alexander; Düllmann, Ch. E.; Ackermann, Dieter; Andersson, Lise-Lotte & Asai, Masato [Show all 71 contributors for this article] (2020). Search for elements 119 and 120. Physical Review C. ISSN 2469-9985. 102(6). doi: 10.1103/PhysRevC.102.064602. Full text in Research Archive Show summary

  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.

• Haba, H.; Fan, F.; Kaji, D.; Kasamatsu, Y.; Kikunaga, H. & Komori, Yukiko [Show all 31 contributors for this article] (2020). Production of Bh 266 in the Cm 248 (Na 23,5n) Bh 266 reaction and its decay properties. Physical Review C. ISSN 2469-9985. 102(2). doi: 10.1103/PhysRevC.102.024625. Full text in Research Archive Show summary

  The nuclide 266Bh was produced in the 248Cm(23Na,5n)266Bh reaction at beam energies of 125.9, 130.6, and 135.3 MeV. Decay properties of 266Bh were investigated with a rotating wheel apparatus for α and spontaneous fission (SF) spectrometry under low background conditions attained by a gas-jet transport system coupled to the RIKEN gas-filled recoil ion separator. Based on genetically correlated α−α and α-SF decay chains, a total of 23 chains were assigned to 266Bh and its daughter nuclide 262Db and granddaughter 258Lr. The half-life of 266Bh was measured to be T1/2=10.0+2.6−1.7s which is an order of magnitude longer than the literature data. The α-particle energies of 266Bh disperse widely in the range of Eα=8.62–9.40MeV. The maximum production cross section for the 248Cm(23Na,5n)266Bh reaction was determined to be σ=57±14 pb at 130.6 MeV, whereas the upper limit for the 248Cm(23Na,4n)267Bh reaction was σ≤14 pb at 121.2 MeV. These cross sections are discussed by comparing with the literature data as well as the theoretical calculations.

• Lerum, Hans Vigeland; Andersen, Niels Højmark; Eriksen, Dag Øistein; Hansen, Eddy Walther & Omtvedt, Jon Petter (2020). NMR study of the influence and interplay of water, HCl and LiCl with the extraction agent Aliquat 336 dissolved in toluene. Journal of Molecular Liquids. ISSN 0167-7322. 317. doi: 10.1016/j.molliq.2020.114160. Full text in Research Archive
• Skarnemark, Gunnar; Malmbeck, Rikard; Johansson, Jan Marcus; Omtvedt, Jon Petter; Trautmann, Norbert G. & Ödegaard-Jensen, Arvid [Show all 7 contributors for this article] (2019). SIMSISAK - a Method to Model Nuclide Transport in the SISAK System. Solvent extraction and ion exchange. ISSN 0736-6299. 37(3-4), p. 232–244. doi: 10.1080/07366299.2019.1639358. Full text in Research Archive Show summary

  A computer model that calculates the transport yield of a nuclide through an arbitrary SISAK experimental set-up has been developed. The model is intended to be used for two types of calculations connected to chemical studies of the heaviest elements. If the production cross section and the nuclide half-life are known, it can be used to estimate the number of decay events to be expected at the detection site. Consequently, if the number of atoms decaying in the detection cells is known, it can be used to estimate the production cross section or the half-life, provided that one of these properties is known.

• Khuyagbaatar, Jadambaa; Yakushev, Alexander; Düllmann, Christoph E.; Ackermann, Dieter; Andersson, Lise-lotte & Asai, Masato [Show all 72 contributors for this article] (2019). Fusion reaction Ca-48+Bk-249 leading to formation of the element Ts (Z=117). Physical Review C. ISSN 2469-9985. doi: 10.1103/PhysRevC.99.054306. Full text in Research Archive Show summary

  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.

• Lens, Lotte; Yakushev, Alexander; Düllmann, Christoph E.; Asai, Masato; Ballof, Jochen & Block, Michael [Show all 53 contributors for this article] (2018). Online chemical adsorption studies of Hg, Tl, and Pb on SiO2 and Au surfaces in preparation for chemical investigations on Cn, Nh, and Fl at TASCA. Radiochimica Acta. ISSN 0033-8230. 106(12), p. 949–962. doi: 10.1515/ract-2017-2914. Full text in Research Archive
• Cubova, Katerina; Semelova, Miroslava; Nemec, Mojmir; John, Jan; Milacic, Juraj & Omtvedt, Jon Petter [Show all 7 contributors for this article] (2018). Extraction of thallium and indium isotopes as the homologues of nihonium into the ionic liquids. Journal of Radioanalytical and Nuclear Chemistry. ISSN 0236-5731. doi: 10.1007/s10967-018-6270-x. Full text in Research Archive
• Lerum, Hans Vigeland; Andersen, Niels Højmark; Eriksen, Dag Øistein; Hansen, Eddy Walther; Petersen, Dirk & Wibetoe, Grethe [Show all 7 contributors for this article] (2018). Study of Cadmium Extraction with Aliquat 336 from Highly Saline Solutions. Journal of Solution Chemistry. ISSN 0095-9782. 47(8), p. 1395–1417. doi: 10.1007/s10953-018-0795-z. Full text in Research Archive
• Nitto, Antonio Di; Khuyagbaatar, Jadambaa; Ackermann, Dieter; Andersson, Lise-Lotte; Badura, Eugen & Block, Michael [Show all 64 contributors for this article] (2018). Study of non-fusion products in the 50Ti+249Cf reaction. Physics Letters B. ISSN 0370-2693. 784, p. 199–205. doi: 10.1016/j.physletb.2018.07.058. Full text in Research Archive Show summary

  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.

• Såmark-Roth, Anton; Sarmiento, Luis G.; Rudolph, Dirk; Ljungberg, Jimmy; Carlsson, B. Gillis & Fahlander, Claes [Show all 48 contributors for this article] (2018). Low-lying states in 219Ra and 215Rn: Sampling microsecond α -decaying nuclei. Physical Review C. ISSN 2469-9985. 98:044307(4), p. 1–11. doi: 10.1103/PhysRevC.98.044307. Full text in Research Archive
• Forsberg, Ulrika; Rudolph, D; Andersson, LL; Nitto, A Di; Dullmann, Ch E & Fahlander, C [Show all 54 contributors for this article] (2016). Recoil-α-fission and recoil-α-α-fission events observed in the reaction 48Ca + 243Am. Nuclear Physics A. ISSN 0375-9474. 953, p. 117–138. doi: 10.1016/j.nuclphysa.2016.04.025. Full text in Research Archive
• Ooe, Kazuhiro; Abdo, Mohamed Fathy Attallah; Asai, M; Goto, N; Gupta, Nalinava Sen & Haba, H. [Show all 33 contributors for this article] (2015). Development of a new continuous dissolution apparatus with a hydrophobic membrane for superheavy element chemistry. Journal of Radioanalytical and Nuclear Chemistry. ISSN 0236-5731. 303(2), p. 1317–1320. doi: 10.1007/s10967-014-3469-3. Full text in Research Archive Show summary

  A new technique for continuous dissolution of nuclear reaction products transported by a gas-jet system was developed for superheavy element (SHE) chemistry. In this technique, a hydrophobic membrane is utilized to separate an aqueous phase from the gas phase. With this technique, the dissolution efficiencies of short-lived radionuclides of 91m,93mMo and 176W were measured. Yields of more than 80 % were observed for short-lived radionuclides at aqueous-phase flow rates of 0.1–0.4 mL/s. The gas flow-rate had no influence on the dissolution efficiency within the studied flow range of 1.0–2.0 L/min. These results show that this technique is applicable for on-line chemical studies of SHEs in the liquid phase.

• John, Jan; Lehto, Jukka; Koivula, Teija & Omtvedt, Jon Petter (2015). Cooperation in education and training in nuclear- and radiochemistry in Europe. Journal of Radioanalytical and Nuclear Chemistry. ISSN 0236-5731. 304(1), p. 459–466. doi: 10.1007/s10967-014-3624-x. Full text in Research Archive Show summary

  The motivation, history and status of coordination of education and training in nuclear- and radiochemistry in Europe are reviewed. The achievements of the Euratom FP7 project “Cooperation In education in Nuclear CHemistry (CINCH)” are described. Attention is paid to the results of the survey of universities teaching nuclear chemistry and their respective curricula evaluation, to the plan to introduce the EuroMaster in nuclear- and radiochemistry quality label recognized and guaranteed by the European Association for Chemical and Molecular Sciences (EuCheMS), and to CINCH NucWik—an interactive database proposed and implemented as an open structure in the form of a “Wiki”.

• Toyoshima, A.; Ooe, K.; Miyashita, S.; Asai, M; Abdo, Mohamed Fathy Attallah & Goto, N [Show all 33 contributors for this article] (2015). Chemical studies of Mo and W in preparation of a seaborgium (Sg) reduction experiment using MDG, FEC, and SISAK. Journal of Radioanalytical and Nuclear Chemistry. ISSN 0236-5731. 303(2), p. 1169–1172. doi: 10.1007/s10967-014-3438-x. Full text in Research Archive Show summary

  The extraction and reduction behavior of Mo and W, lighter homologs of Sg, was studied in continuous on-line experiments at the JAEA tandem accelerator to develop a new chemistry assembly consisting of a membrane degasser (MDG), a flow electrolytic column (FEC), and the continuous liquid–liquid extraction apparatus (SISAK). Extraction yields of Mo and W from 0.1 M HCl/0.9 M LiCl into 4-isopropyltropolone (hinokitiol, HT) in toluene were investigated. In the reduction experiment, Mo(VI) was successfully reduced to a lower oxidation state while W(VI) showed no reduction under the given conditions.

• Rudolph, Dirk; Forsberg, Ulrika; Golubev, Pavel; Sarmiento, Luis G.; Yakushev, Alexander & Andersson, Lise-Lotte [Show all 51 contributors for this article] (2015). Selected spectroscopic results on element 115 decay chains. Journal of Radioanalytical and Nuclear Chemistry. ISSN 0236-5731. 303(2), p. 1185–1190. doi: 10.1007/s10967-014-3445-y. Full text in Research Archive Show summary

  Thirty correlated α-decay chains were observed in an experiment studying the fusion-evaporation reaction 48Ca + 243Am at the GSI Helmholtzzentrum für 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 α-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.

• Langrock, Gert; Wiehl, Norbert; Kling, Hans-Otto; Mendel, Matthias; Nähler, Andrea & Tharun, Udo [Show all 11 contributors for this article] (2015). Digital liquid-scintillation counting and effective pulse-shape discrimination with artificial neural networks. Radiochimica Acta. ISSN 0033-8230. 103(1), p. 15–25. doi: 10.1515/ract-2014-2281. Full text in Research Archive
• Rudolph, D; Forsberg, U; Golubev, P; Sarmiento, LG; Yakushev, A & Andersson, L [Show all 51 contributors for this article] (2014). Alpha-photon coincidence spectroscopy along element 115 decay chains. Acta Physica Polonica B. ISSN 0587-4254. 45(2), p. 263–272. doi: 10.5506/APhysPolB.45.263. Full text in Research Archive
• Yakushev, Alexander; Gates, Jacklyn M.; Türler, Andreas; Schädel, Matthias; Düllmann, Christoph Emanuel & Ackermann, Dieter [Show all 44 contributors for this article] (2014). Superheavy element flerovium (Element 114) is a volatile metal. Inorganic Chemistry. ISSN 0020-1669. 53(3), p. 1624–1629. doi: 10.1021/ic4026766. Full text in Research Archive
• Khuyagbaatar, Jadambaa; Yakushev, A; Dullmann, CE; Ackermann, D; Andersson, LL & Asai, M [Show all 72 contributors for this article] (2014). Ca 48 + Bk 249 fusion reaction leading to element Z=117: Long-lived α -decaying Db 270 and discovery of Lr 266. Physical Review Letters. ISSN 0031-9007. 112:172501(17). doi: 10.1103/PhysRevLett.112.172501. Full text in Research Archive
• Rudolph, Dirk; Forsberg, U; Golubev, P; Sarmiento, LG; Yakushev, A & Andersson, LL [Show all 51 contributors for this article] (2013). Spectroscopy of Element 115 Decay Chains. Physical Review Letters. ISSN 0031-9007. 111(11:112502). doi: 10.1103/PhysRevLett.111.112502. Full text in Research Archive
• Forsberg, U; Golubev, P.; Sarmiento, L.G.; Jeppsson, J.; Rudolph, D. & Andersson, L.-L. [Show all 33 contributors for this article] (2012). FIRST EXPERIMENT AT TASCA TOWARDS X-RAY FINGERPRINTING OF ELEMENT 115 DECAY CHAINS. Acta Physica Polonica B. ISSN 0587-4254. 43(2), p. 305–311. doi: 10.5506/APhysPolB.43.305. Full text in Research Archive
• Usoltsev, I; Eichler, R; Dressler, R; Piguet, D; Wittwer, D & Türler, Andreas [Show all 10 contributors for this article] (2012). Preparation of Pd-based intermetallic targets for high intensity irradiations. Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 691, p. 5–9. doi: 10.1016/j.nima.2012.06.060. Full text in Research Archive
• Even, Julia; Ballof, J; Brüchle, Willy; Buda, R. A.; Düllmann, Christoph E. & Eberhardt, Klaus [Show all 34 contributors for this article] (2011). The recoil transfer chamber — An interface to connect the physical preseparator TASCA with chemistry and counting setups. Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 638(1), p. 157–164. doi: 10.1016/j.nima.2011.02.053. Full text in Research Archive
• Gupta, Nalinava Sen; Wragg, David; Tilset, Mats & Omtvedt, Jon Petter (2011). 4,7,13,18-Tetraoxa-1,10-diazoniabicyclo[ 8.5.5]icosane bis(hexafluoridophosphate). Acta Crystallographica Section E: Structure Reports Online. 67. doi: 10.1107/S1600536811025992. Full text in Research Archive
• Gupta, Nalinava Sen; Wragg, David; Tilset, Mats & Omtvedt, Jon Petter (2011). 4,7,13,18-Tetraoxa-1,10-diazoniabicyclo[8.5.5]icosane hexafluoridosilicate. Acta Crystallographica Section E: Structure Reports Online. 67. doi: 10.1107/S1600536811026006. Full text in Research Archive
• Gates, Jacklyn; Düllmann, Christoph E.; Omtvedt, Jon Petter; Yakushev, A; Turler, A & Eberhardt, K [Show all 48 contributors for this article] (2011). First superheavy element experiments at the GSI recoil separator TASCA: The production and decay of element 114 in the Pu-244(Ca-48,3-4n) reaction. Physical Review C. Nuclear Physics. ISSN 0556-2813. 83(5). doi: 10.1103/PhysRevC.83.054618. Full text in Research Archive
• Graeger, Reimar; Ackermann, Dieter; Chelnokov, M; Chepigin, V; Düllmann, Christoph E. & Dvorak, Jan [Show all 30 contributors for this article] (2010). Experimental study of the U-238(S-36,3-5n)(269-271)Hs reaction leading to the observation of (270)Hs. Physical Review C. Nuclear Physics. ISSN 0556-2813. 81(6). doi: 10.1103/PhysRevC.81.061601. Full text in Research Archive
• Düllmann, Christoph E.; Schädel, Matthias; Yakushev, Alexander; Türler, Andreas; Eberhardt, Klaus & Kratz, Jens v. [Show all 45 contributors for this article] (2010). Production and Decay of Element 114: High Cross Sections and the New Nucleus (277)Hs. Physical Review Letters. ISSN 0031-9007. 104(25). doi: 10.1103/PhysRevLett.104.252701. Full text in Research Archive
• Samadani, Fereshteh; Alstad, Jorolf; Bjørnstad, Tor; Stavsetra, Liv & Omtvedt, Jon Petter (2010). Development of a SISAK extraction system for chemical studies of element 108, hassium. Radiochimica Acta. ISSN 0033-8230. 98(12), p. 757–764. doi: 10.1524/ract.2010.1787. Full text in Research Archive
• Omtvedt, Jon Petter (2009). Laboratorieøvelser som fjernundervisning - Erfaringer fra utvikling av det fjernstyrte laboratoriumet RoboLab. In Koch, Susanne Anette Kjekshus (Eds.), Ringer i vann. Lenge leve fleksibel læring ved Universitetet i Oslo. Universitetet i Oslo. ISSN 9788299740739. p. 49–58. Full text in Research Archive
• Zheng, Li; Alstad, Jorolf; Bjørnstad, Tor; Polakova, Darina; Stavsetra, Liv & Omtvedt, Jon Petter (2008). Extraction of Nb and Ta, homolgues of Db, from sulphuric acid solutions with TOA in toluene using SISAK. Radiochimica Acta. ISSN 0033-8230. 96. doi: 10.1524/ract.2008.1463. Full text in Research Archive
• Omtvedt, Jon Petter; Alstad, Jorolf; Bjørnstad, Tor; Düllmann, Christoph E.; Gregorich, Kenneth E. & Hoffman, Darleane C. [Show all 15 contributors for this article] (2007). Chemical properties of the transactinide elements studied in liquid phase with SISAK. European Physical Journal D : Atomic, Molecular and Optical Physics. ISSN 1434-6060. 45(1), p. 91–97. doi: 10.1140/epjd/e2007-00214-6. Full text in Research Archive
• Pershina, V; Polakova, Darina & Omtvedt, Jon Petter (2006). Theoretical predictions of complex formation of group-4 elements Zr, Hf, and Rf in H2SO4 solutions. Radiochimica Acta. ISSN 0033-8230. 94, p. 407–414. Full text in Research Archive
• Omtvedt, Jon Petter; Alstad, Jorolf; Bjørnstad, Tor; Düllmann, Christoph E.; Folden, C. M. & Gregorich, Kenneth E. [Show all 14 contributors for this article] (2006). SISAK Liquid-Liquid Extraction Studies of Rutherfordium and Future Plans to Study Heavier Transactinides. In May, I.; Alvares, R. & Bryan, N. (Ed.), Recent Advances in Actinide Science. Royal Society of Chemistry (RSC) Publishing. ISSN 9780854046782. p. 278–280. Full text in Research Archive Show summary

  Actinide elements and their chemistry have a significant number of applications. Bringing together contributions from the leading experts in the field, Recent Advances in Actinide Science covers six main topics; Analysis, the environment and biotransformations Coordination and organometallic chemistry Heavy elements Nuclear fuels, materials and waste forms Separations and solution chemistry Spectroscopy, magnetism and superconductivity Covering a wide range of research from pure academic studies to applied industrial science and technology, this book distils the knowledge and achievements gained in actinide science over the last four years. This high level book is aimed at researchers, both industrial and academic, and provides a comprehensive overview of the current status of actinide science.

• Polakova, Darina; Alstad, Jorolf; Bjørnstad, Tor; Skarnemark, Gunnar; Stavsetra, Liv & Sudowe, Ralf [Show all 10 contributors for this article] (2006). Development of a System for Chemical Studies of Rutherfordium by Liquid-Liquid Extraction From Sulphuric Acid Solutions with SISAK. In May, I.; Alvares, R. & Bryan, N. (Ed.), Recent Advances in Actinide Science. Royal Society of Chemistry (RSC) Publishing. ISSN 9780854046782. p. 281–283. Full text in Research Archive Show summary

  Actinide elements and their chemistry have a significant number of applications. Bringing together contributions from the leading experts in the field, Recent Advances in Actinide Science covers six main topics; Analysis, the environment and biotransformations Coordination and organometallic chemistry Heavy elements Nuclear fuels, materials and waste forms Separations and solution chemistry Spectroscopy, magnetism and superconductivity Covering a wide range of research from pure academic studies to applied industrial science and technology, this book distils the knowledge and achievements gained in actinide science over the last four years. This high level book is aimed at researchers, both industrial and academic, and provides a comprehensive overview of the current status of actinide science.

• Zheng, Li; Alstad, Jorolf; Bjørnstad, Tor; Polakova, Darina; Stavsetra, Liv & Omtvedt, Jon Petter (2006). Influence of KCl on the Extraction of Rutherfordium Homologues Hafnium and Zirconium From Sulphuric Acid with Tri-Octylamine in Toluene. In May, I.; Alvares, R. & Bryan, N. (Ed.), Recent Advances in Actinide Science. Royal Society of Chemistry (RSC) Publishing. ISSN 9780854046782. p. 284–286. Full text in Research Archive Show summary

  Actinide elements and their chemistry have a significant number of applications. Bringing together contributions from the leading experts in the field, Recent Advances in Actinide Science covers six main topics; Analysis, the environment and biotransformations Coordination and organometallic chemistry Heavy elements Nuclear fuels, materials and waste forms Separations and solution chemistry Spectroscopy, magnetism and superconductivity Covering a wide range of research from pure academic studies to applied industrial science and technology, this book distils the knowledge and achievements gained in actinide science over the last four years. This high level book is aimed at researchers, both industrial and academic, and provides a comprehensive overview of the current status of actinide science.

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• Lehrum, Hans Vigeland; Andersen, Niels Højmark; Eriksen, Dag Øistein; Hansen, Eddy Walther & Omtvedt, Jon Petter (2020). NMR Studies of Aliquat 336 in toluene after contact with saline solutions - Determination of ionic content. Full text in Research Archive
• Lerum, Hans V.; Sand, Svetlana; Eriksen, Dag Øistein; Hansen, Eddy Walther; Wibetoe, Grethe & Omtvedt, Jon Petter (2018). Determination of Distribution Ratios in Liquid-liquid Extraction of Hydrometallurgical Process Solutions using ICP-MS and Radiotracer Techniques. Full text in Research Archive
• Lerum, Hans Vigeland; Bouzga, Aud Mjærum; Jørgensen, Sissel; Petersen, Dirk; Eriksen, Dag Øistein & Hansen, Eddy Walther [Show all 8 contributors for this article] (2016). Study of cadmium extraction from aqueous solutions with high chloride concentration using radiotracer and NMR. Full text in Research Archive
• Lerum, Hans Vigeland; Bouzga, Aud Mjærum; Jørgensen, Sissel; Petersen, Dirk; Eriksen, Dag Øistein & Hansen, Eddy Walther [Show all 8 contributors for this article] (2016). LIQUID-LIQUID EXTRACTION OF CADMIUM CHLORIDE COMPLEXES STUDIED BY NMR. Full text in Research Archive
• John, Jan; Retegan, Teodora; Lehto, Jukka; Omtvedt, Jon Petter & Skipperud, Lindis (2016). CINCH–II Project – A Milestone in the Coordination of Education and Training in Nuclear- and Radiochemistry in Europe. Full text in Research Archive
• Retegan, Teodora; Ekeberg, Christian; John, Jan; Cuba, Vaclav; Nemec, Mojmir & Lehto, Jukka [Show all 14 contributors for this article] (2015). Cooperation in Education and Training in Nuclear and Radiochemistry in Europe – A Continuous Process. Full text in Research Archive
• John, Jan; Cuba, Vaclav; Nemec, Mojmir; Retegan, Teodora; Ekeberg, Christian & Lehto, Jukka [Show all 16 contributors for this article] (2014). Cooperation in Education and Training in Nuclear- and Radiochemistry in Europe. Full text in Research Archive
• John, Jan; Retegan, Teodora; Lehto, Jukka; Omtvedt, Jon Petter & Skipperud, Lindis (2013). CINCH-II: Next step in the coordination of education in nuclear and radiochemistry in Europe. Full text in Research Archive
• John, Jan; Retegan, Teodora; Lehto, Jukka; Koivula, Teija; Scully, Paul J. & Walther, Clemens [Show all 13 contributors for this article] (2013). Next step in the coordination of education in nuclear and radiochemistry in Europe. Full text in Research Archive
• John, Jan; Vaclav, Cuba; Nemec, Mojmir; Retegan, Teodora; Ekeberg, Christian & Lehto, Jukka [Show all 14 contributors for this article] (2013). Coordination of Education in Nuclear And Radiochemistry In Europe. Full text in Research Archive
• Wærsted, Frøydis Meen; Omtvedt, Jon Petter; Wibetoe, Grethe & Vogt, Rolf David (2013). The role of particles and phosphorus bound to particles in eutrophication. Full text in Research Archive
• Bjørnstad, Tor; Eriksen, Dag Øystein & Omtvedt, Jon Petter (2013). Radiochemistry and hydrometallurgy - two synergetic fields. Full text in Research Archive
• Omtvedt, Jon Petter; Alstad, Jorolf; Bjørnstad, Tor; Dullmann, C.E.; Gregorich, K.E. & Gupta, N.S. [Show all 11 contributors for this article] (2010). Superheavy Element Chemistry with SISAK. Full text in Research Archive
• Omtvedt, Jon Petter (2008). Thorium og kjernekraft - trenger Norge slik kompetanse? Full text in Research Archive
• Omtvedt, Jon Petter (2008). Kjernekraft fra thorium. Full text in Research Archive
• Omtvedt, Jon Petter (2008). Recent developments in automated liquid-liquid extraction studies of transactinide elements. Full text in Research Archive Show summary

  Liquid-liquid extraction (LLE) studies of Rf (Z=104), after physical preseparation with the Berkeley Gas-filled Separator, were performed. Based on the experience gained in these successful experiments, the computer controlled SISAK LLE system has been improved and developed further in order to be able to study transactinide elements heavier than Rf. In particular, the transfer from the recoil transfer chamber (RTC) (which transfer the recoils from the separator to a aerosol seeded gas-jet) to the chemistry apparatus and the acquisition system for the liquid scintillation detectors have been improved. The results from the RTC developments will be presented together with other improvements made to the SISAK centrifuge system and liquid-scintillation detectors.

• Omtvedt, Jon Petter (2008). Hvordan får vi energi fra thorium? Naturfag. ISSN 1504-4564. 1, p. 28–32. Full text in Research Archive Show summary

  Denne artikkelen er skrevet med tanke på å gi grunnleggende informasjon om kjerneenergiverk som benytter thorium som brennstoff. Målet er at læreren skal forstå de viktigste mulighetene og begrensningene på en slik måte at hun/han kan formidle dette videre. Artikkelen vil ikke diskutere for eller imot kjerneenergiverk, den diskusjonen overlates til andre fora. Det er forfatterens håp at artikkelen vil bidra til at både tilhengere og motstandere av kjerneenergi kan diskutere med utgangspunkt i et tryggere faglig grunnlag og dermed heve debattens kvalitet og verdi.

• Omtvedt, Jon Petter & Helgesen, Ole K. (2008). Spenning om thorium. [Journal]. Teknisk ukeblad. Full text in Research Archive
• Omtvedt, Jon Petter & Sæther, Jens Marius Sæther (2008). Klart for atomkamp på tinget. [Journal]. Dagsavisen. Full text in Research Archive
• Omtvedt, Jon Petter & Strande, Mona (2008). Norge må forske på kjernekraft. [Journal]. Teknisk ukeblad. Full text in Research Archive
• Jemterud, Torkild; Rose, Sunniva & Omtvedt, Jon Petter (2008). Verdt å vite 2008-12-19. [Radio]. NRK P2. Full text in Research Archive
• Stølen, Svein; Gorbitz, Carl Henrik; Omtvedt, Jon Petter & Ødegaard, Knut Jørgen Røed (2008). Verdt å vite spesial: Grunnstoffene og periodesystemet. [Radio]. NRK P2. Full text in Research Archive
• Opel, Karsten; Akermann, Dieter; Brüchle, Willy; Dressler, R; Düllmann, Christoph E. & Dvpral, K [Show all 21 contributors for this article] (2007). Recoil Transfer Chamber Design at TASCA. Full text in Research Archive
• Opel, Karsten & Omtvedt, Jon Petter (2007). New Control System for SISAK. Full text in Research Archive
• Omtvedt, Jon Petter (2007). Fast and continuous liquid-liquid extraction with the computer controlled SISAK system. Full text in Research Archive
• Samadani, Fereshteh & Omtvedt, Jon Petter (2007). Developing a SISAK extraction system for chemical study of element 108, hassium. Full text in Research Archive
• Vogt, Rolf David; Solomonova, Polina; Gjessing, Egil & Omtvedt, Jon Petter (2006). Preparative gel fractionation of NOM for ecological studies - The fate of mercury in aquatic ecosystems. Full text in Research Archive Show summary

  Forty years ago it was shown that dissolved humic substances (HS) in water could be separated into a number of different size fractions using the gel-matrix Sephadex (1). Since then a number of different techniques and methods have been introduced for the purpose to define and describe the physical properties and chemical composition of HS. During the last few decades the awareness of the ecological importance of this complicated organic matter has increased and it is realized that more knowledge on biological properties and biological functions of HS are needed. We have re-introduced preparative gel-filtration, in order to be able to learn more about the fate of micro pollutants in fresh-water ecosystems. Mercury (Hg) is an element of considerable health concern, mostly due to its global distribution and its bio-magnification potentials in water. The important role of HS both as carrier and as mediator of Hg transport from soil to the surface water is demonstrated by elevated Hg concentrations in humic-rich waters. The purpose of the work to be presented is to fractionate “Hg-spiked” dissolved natural organic matter (NOM), and to investigate the Hg distribution on the NOM in detail. The biological properties of the resulting fractions will later be studied in co-operation with ecologists.

• Omtvedt, Jon Petter; Alstad, Jorolf; Bjørnstad, Tor; Dullmann, C.E.; III, C.M. Folden & Gregorich, K.E. [Show all 15 contributors for this article] (2006). “Chemical Properties of the Transactinide Elements Studied in Liquid Phase with SISAK”, Full text in Research Archive
• Zheng, Li; Alstad, Jorolf; Bjørnstad, Tor; Polakova, Darina; Stavsetra, Liv & Omtvedt, Jon Petter (2006). ”Influence of KCl on the extraction of rutherfordium homologues hafnium and zirconium from sulphuric acid with tri-octylamine in toluene”, Full text in Research Archive
• Omtvedt, Jon Petter & Hammerfjeld, Jon R. (2006). Lagde verdens tyngste grunnstoff. [Journal]. Dagbladet.no. Full text in Research Archive
• Polakova, Darina; Alstad, Jorolf; Bjørnstad, Tor; Skarnemark, Gunnar; Stavsetra, Liv & Sudowe, Ralf [Show all 10 contributors for this article] (2005). Development of a System for Chemical Studies of Rutherfordium by Liquid‐Liquid Extraction from Sulphuric Acid Solutions with SISAK. Full text in Research Archive
• Polakova, Darina & Omtvedt, Jon Petter (2005). Liquid-Liquid Extraction of Rf from H2SO4 with TOA. Full text in Research Archive
• Zheng, Li & Omtvedt, Jon Petter (2005). Plans for Liquid-Liquid Extraction Studies of Dubnium. Full text in Research Archive
• Omtvedt, Jon Petter (2005). SISAK Liquid‐Liquid Extraction Studies of Rutherfordium and Future Plans to Study Heavier Transactinides. Full text in Research Archive
• Årnes, Silje Kathrine & Omtvedt, Jon Petter (2023). A Study on Metal Recovery from Ilmenite Mud Waste: Characterisation, Hydrochloric Acid Leaching, and Oxidation Roasting. Universitetet i Oslo. Full text in Research Archive
• Dirdal, Ragnhild Elise & Omtvedt, Jon Petter (2023). Selective Recovery of Copper from Municipal Solid Waste Incineration Bottom Ash. Universitetet i Oslo. Full text in Research Archive Show summary

  A hydrometallurgical process was investigated as a method to selectively recover copper from municipal solid waste incineration (MSWI) bottom ash. In Norway, bottom ash is mainly disposed of instead of being utilized. When landfilled, hazardous components, such as copper and zinc, can potentially be released to the environment and cause groundwater pollution. Therefore, extraction of copper and zinc would be a favorable solution for both disposal and utilization of bottom ash, as well as a potential source for secondary materials. In order to be economically feasible to recover metals from bottom ash, other metals and components probably need to be recovered as well. Acidic leaching solutions are most commonly used, however, alkaline solutions are generally more selective, less corrosive and have a lower reagent consumption according to previous studies. Ammonia-ammonium carbonate (AAC) is stated to be a suitable choice of leach solution for selective recovery of copper and zinc. The different substances of the AAC solution can be recovered, recombined and used in subsequent processing. In the present study, AAC leaching of bottom ash followed by a cementation procedure in order to selectively precipitate copper was investigated. Co-dissolution of zinc was also monitored during the study due to possible subsequent recovery based on procedures established in previous studies. MSWI bottom ash originating from different incineration plants in Norway was characterized and used in the study. The bottom ash was leached with an aqueous solution of ammonia (NH3) and ammonium carbonate ((NH4)2CO3). In order to efficiently extract copper from bottom ash, the AAC leaching procedure was optimized in terms of particle size, total ammonia concentration, leaching temperature, pulp density (solid/liquid ratio), and leaching time. The optimal leaching conditions were found to be 4.7 M, 60 C, 100 g bottom ash per liter leach solution and 180 minutes of leaching time, before the liquid and solid phases were separated. The pregnant leach solution (PLS) was quantitatively analyzed with inductively coupled plasma optical emission spectroscopy (ICP-OES). Extraction of more than 98 % of the copper from bottom ash was achieved. The copper was subsequently precipitated from the PLS by a cementation procedure with metallic zinc dust. After cementation, the PLS was quantitatively analyzed with ICP-OES and the solid residue was qualitatively analyzed using X-ray diffraction. More than 90% of copper was recovered from the PLS by cementation.

• Raskovic-Lovre, Zeljka; Omtvedt, Jon Petter & Eriksen, Dag Øistein (2019). Extraction of zinc from highly saline and acidic solutions. Universitetet i Oslo. Full text in Research Archive
• Rafique, Waqas; Riss, Patrick & Omtvedt, Jon Petter (2018). Synthesis of Fluorine-18 Labelled Radiotraces and Their Pre-Clinical and Clinical Characterization. Kjemisk institutt, Universitetet i Oslo. Full text in Research Archive Show summary

  Positron emission tomography (PET) is one of the most sensitive in vivo imaging techniques available to clinicians and researchers. It helps in understanding the biological interactions and mechanism of various diseases through use of radiolabelled compounds called radiotracers. Herein is described the development of facile radiolabelling approaches for straightforward access to 18F-labelled trifluoromethyl radiotracers. Direct nucleophilic radiofluorination of difluorovinyl precursors was achieved for 18F-trifluoromethylation of aliphatic compounds, and applied to the radiosynthesis of [18F]lansoprazole and N-methyl[18F]lansoprazole. The compounds were used to analyze the blood-brain barrier penetration in healthy persons and for the detection of tau-neurofibrillary tangles in Alzheimer’s patients. For 18F-trifluoromethylation of aromatic compounds, in situ synthesis of Cu[18F]CF3 was achieved and used in 18F-trifluoromethylation of iodo-arenes using a single vial one-step method. The procedure was applied for radiosynthesis of a derivative of AH7921, which is a sub-type selective mu-opioid receptor agonist. The developed procedures are applicable to available radiosynthesis hardware, and provide access to desired compounds within 40 minutes in high radiochemical yields. In addition, a series of new compounds were synthesized with aim to discover the new radioligands based on modifications to the lead compounds i.e. lansoprazole and AH7921. Several interesting candidates with good combination of affinity and selectivity were identified from each series, and radiolabelled with fluorine-18. The newly developed 18F-labelled compounds have good potential to provide the in vivo characterization of tau-neurofibrillary tangles and quantification of the opioid receptors using the PET imaging.

• Thorén, Masayo & Omtvedt, Jon Petter (2017). Assessment of a Potential Radiological Attack - Investigation of Scenarios Pertaining to Contamination of Infant Milk Formula. Universitetet i Oslo. Full text in Research Archive Show summary

  The purpose of this work is to systematically assess the consequences of a potential radiological attack on processed food in a production facility. Infant milk formula (IMF) is specifically chosen as the case of investigation. Three different radionuclides, 90Sr, 137Cs and 241Am, are chosen as sources of contamination for the assessment. The assessment of the consequences of an attack is limited to negative health effects, i.e. mortality or morbidity. It is found that a considerably large number of infants would potentially receive negative health effects due to ingestion of radionuclides in the contaminated IMF (depending on the activity used at the time of contamination, as well as the contamination scenario). However, in the case of contamination at mortality and morbidity level, the radioactivity from contaminated IMF is calculated to be detectable during its production phase. This is achieved using a NaI(Tl) detector on the outside of an IMF packaging (a can) during the production. In the case of contamination at permissible level, the detector would only alarm the abnormality for the 137Cs source. This investigation has also found that radioactive sources that are easily accessible to the general public are possible to use in such scenarios with some effect. This finding further encourages the related industries to practice preparedness against the possibility of contamination events using radioactive materials.

• Ræstad, Svein Harald; Omtvedt, Jon Petter; Wibetoe, Grethe & Eriksen, Dag Øystein (2017). Investigation of Leaching of Rare Earth Elements from Phosphate Rock with Nitric Acid using Neutron Activation. Universitetet i Oslo. Full text in Research Archive
• Lehto, Jukka; Omtvedt, Jon Petter; Popic, Jelena Mrdakovic; Nemec, Mojmir & Koivula, Teija (2015). Workshop on Nuclear Chemistry Education and Training in Europe, CINCH-II Deliverable D4.5. NMBU/CERAD. Full text in Research Archive
• Kristiansen, Håvard; Omtvedt, Jon Petter & Eriksen, Dag Øistein (2015). Radiochemical analysis of cadmium in nitric and phosphoric acid. Universitetet i Oslo. Full text in Research Archive
• Lerum, Hans Vigeland & Omtvedt, Jon Petter (2014). Preparations for a Reduction and Liquid-Liquid Separation Experiment for Element 106, Seaborgium. Universitetet i Oslo. Full text in Research Archive Show summary

  The purpose of this thesis was to check if it was possible to prepare a mechanical and chemical system that can reduce Seaborgium, element 106, and separate between the reduced and the oxidized state. To do this the liquid-liquid extraction system SISAK has been coupled to a flow electrolytic column, which is able to reduce single atoms. To overcome the high difference in flow rate between these two systems a membrane degasser has been utilized which managed to severely reduce the amount of fluid needed. Several extraction schemes have been tested. These had the goal that they should manage to strongly extract only one of the oxidation states. As a model for Sg experiments Mo and W have been used. During the work of this thesis it has been shown that it is possible to reduce and separate between two oxidation states of Mo. Furthermore, slight separation has been achieved for W in some systems. This have been done to model Sg in such a way that it is realistic to believe that Sg will behave in the same way. In addition a proof of concept has been achieved were the newly developed membrane degasser, the flow electrolytic column and the SISAK centrifuge have been coupled together. This managed to reduce enough Mo and separate between the reduced and oxidized Mo species at a flow rate of 0.2 mL/s and with the aquatic solution 0.1 M HCl + 0.9 M LiCl and an organic solution of 0.01 M hinokitiol in Toluene. Some kinetic studies have been performed at 0.2 mL/s flow rate with HDEHP as an extractant in toluene and an aquatic solution of 0.1 m H2SO4. Additionally retention on the carbon electrode is discussed. The work presented in this thesis have been performed as a part of a large collaboration between the nuclear chemistry group at the university of Oslo, Norway and between the superheavy element group in Tokai, Japan. An importan part of this work has therefore been to set up a working SISAK set-up in Tokai and a working flow electrolytic column in Oslo.

• Wærsted, Frøydis Meen; Vogt, Rolf David; Wibetoe, Grethe & Omtvedt, Jon Petter (2014). The Role of Particles and Phosphorus Bound to Particles in Eutrophication. Universitetet i Oslo. Full text in Research Archive
• Samadani, Fereshteh; Alstad, Jorolf; Schulz, Frøydis; Nilssen, Johannes; Omtvedt, Jon Petter & Ottesen, Heidi B. [Show all 23 contributors for this article] (2010). Pilot-Test Experiment with Os of a SISAK Setup for Hs-Chemistry Studies. GSI Helmholtzzentrum für Schwerionenforschung. Full text in Research Archive
• Samadani, Fereshteh; Omtvedt, Jon Petter & Bjørnstad, Tor (2010). Liquid Chemistry of Hassium Tetroxide using Osmium in Model Experiments with SISAK. Universitetet i Oslo. Full text in Research Archive
• Zheng, Li; Omtvedt, Jon Petter; Alstad, Jorolf & Bjørnstad, Tor (2007). Preparation for Liquid-Liquid Extraction Studies of Dubnium Using Homologue Models with the SISAK System. Universitetet i Oslo. Full text in Research Archive Show summary

  Tracers of Nb, Ta, and the pseudo-homologue Pa were used to model the chemical behaviour of dubnium in the development of suitable liquid-liquid extraction systems for the SISAK centrifuge system. Extraction from sulphuric acid solutions into trioctyl amine in toluene and into Aliquat 336 in toluene were investigated as chemical separation systems. Distribution ratios for the homologues and the protactinium tracer, 233Pa, were measured in batch experiments, whereas short-lived cyclotron-produced tracers of Nb and Ta were measured in on-line separations using the SISAK system. SISAK is an automated centrifuge system purpose built to perform fast liquid-liquid extractions of short-lived nuclei. The results establish the optimal conditions for a SISAK dubnium experiment to explore its chemical properties in solutions relating to those of niobium and tantalum. Addition of H2O2 to the Aliquat 336/H2SO4 system was investigated as part of this work. The addition suppresses the extraction of Nb. And also Ta, but to a lesser extent. This selective hydrogen peroxide complex formation might serve as the basis for an alternative way to investigate the complexing behaviour of Db. Part of the work presented here is from participation in a SISAK experiment on 257Rf. In this experiment the distribution ratio for extraction into trioctyl amine in toluene from sulphuric acid was determined. The practical experience gained from the Rf experiment was important to ensure that the liquid-liquid extraction system developed here for dubnium is realistic, and furthermore was invaluable in understanding all the necessary requirements and conditions for performing such a complex experiment. The Rf experiments used for the first time a two-step extraction procedure with direct detection of alpha activity in both organic phases. Consequently, the distribution ratio can be determined without knowledge of the amount of activity entering the SISAK system, thereby reducing the uncertainty in the distribution measurement significantly. Due to the high amounts of liquid consumed by the SISAK system during transactinide experiments, which typically lasts several days, recycling of chemicals is necessary. This results in build-up of KCl in the aqueous phase (from the KCl-aerosol particles used as carriers in the gas jet). Thus, in a separate study the influence of KCl on the distribution ratios for zirconium and hafnium was determined to be negligible for the 5-time recycling currently used for the aqueous phase. It can, however, become a problem if the aqueous phase is more extensively recycled.

• Düllmann, Christoph E.; ackermann, dieter; brüchle, willie; Hessberger, F. P.; Jäger, Egon & Khuyagbaatar, J [Show all 26 contributors for this article] (2007). TASCA Recoil Transfer Chamber Commissioning. 1. Small Image Mode. Univ. Mainz Jahresbericht 2006, Institut für Kernchemie. Full text in Research Archive
• Yakushev, Alexander; Dvorak, Jan; andrey, semchenkov; Türler, Andreas; ackermann, dieter & brüchle, willie [Show all 17 contributors for this article] (2007). Window Design for the TASCA Recoil Transfer Chamber (RTC). Jahresbericht 2006 Univ. Mainz, Institut für Kernchemie. Full text in Research Archive
• Semchenkov, Andrey; ackermann, dieter; Brüchle, W.; Düllmann, Christoph E.; Jäger, Egon & Schimpf, E [Show all 15 contributors for this article] (2007). First TASCA Commissioning Experiments in the Small Image Size Mode. Gesellschaft f¨ur Schwerionenforschung mbH (GSI). Full text in Research Archive
• pershina, valeria; Polakova, Darina & Omtvedt, Jon Petter (2007). Theoretical Predictions of Complex Formation of Group-4 Elements Zr, Hf, and Rf in H2SO4 Solutions - GSI report. Gesellschaft für Schwerionenforschung mbH (GSI). Full text in Research Archive
• Samadani, Fereshteh; Omtvedt, Jon Petter & Bjørnstad, Tor (2006). Developing a SISAK extraction system for studies of element 108, hassium. Universitetet i Oslo. Full text in Research Archive Show summary

  The SISAK (i.e. Short-lived Isotope Studied by the AKufve -technique) system was used for investigation of the reaction between osmium tetroxide and NaOH as a model for chemical study of hassium. The result was a two- stage extraction procedure. In the first extraction stage, OsO4 was extracted from NaOH solutions of different concentrations into toluene and the following equilibrium constants for the reaction of OsO4 and NaOH were obtained: K´= (2.35 ± 0.04) 104 for formation of Na[OsO4(OH)] and K″= 6 ±4 for formation of Na2[OsO4(OH)2] out of Na[OsO4(OH)]. The purpose of the second extraction stage was to transfer the activity from the aqueous phase into the organic phase in an efficient way. In order to fulfill this purpose the basic aqueous phase from the first extraction stage was acidified with HCl, HClO4 or H2SO4 and the activity was extracted into toluene either with or without tri-n-octylamine (TOA) as an extracting agent. The extraction efficiency in this stage was around 90% in both cases although there were indications that extraction with TOA had a somewhat higher distribution ratio. An attempt was also made to use Aliquat 336 as an extracting agent to transfer activity into the organic phase. This experiment showed that Aliquat 336 can extract the activity very efficiently. There was, however, a problem with the purity of the liquid phases.

• Stavsetra, Liv & Omtvedt, Jon Petter (2005). Achievements using the continuous SISAK alpha-liquid scintillation technique, and its application in detection of 257Rf atoms. Faculty of Mathematics and Natural Sciences. Full text in Research Archive

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