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CHEMICAL IDENTIFICATION of the element Db as decay product of the element 115

CHEMICAL IDENTIFICATION of the element Db as decay product of the element 115 in the 48 Ca + 243 Am reaction. The 97 th session of the JINR Scientific Council, 20-21 January 2005. CHART of the NUCLIDES. R. 288. 115. a. 1. 10.46 MeV. 125 ms. 284. 113. a. 2. 10. MeV.

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CHEMICAL IDENTIFICATION of the element Db as decay product of the element 115

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  1. CHEMICAL IDENTIFICATION of the elementDb as decay product of the element 115 in the 48Ca + 243Am reaction The 97th session of the JINR Scientific Council, 20-21 January 2005

  2. CHART of the NUCLIDES

  3. R 288 115 a 1 10.46 MeV 125 ms 284 113 a 2 10. MeV 00 0.69 s 28 0 111 a 3 9.75 MeV 5.2 s 276 Mt a 4 9.71 MeV 1.03 s 272 Bh a 5 9.02 MeV 14.14 s 268 Db SF Yu. Oganessian et al., 205 MeV Phys. Rev. C 69, 021601(R) 2004 23.1 hr Decay of 268 Db observed with Dubna Gas-filled Recoil Separator in 243Am + 48Ca Reaction EL = 248 MeV

  4. 5 3n 243Am + 48Ca 288115 268Db -6 -1.6 3.1017 / day - 1-2 event Dmitriev S., Oganessian Yu., Itkis M., TAN 03, November 16-20, 2003, Napa, California

  5. CHEMICAL IDENTIFICATION of the elementDb as decay product of the element 115 in the 48Ca + 243Am reaction June 2004, FLNR, DUBNA FLNR JINR (Dubna, Russia) PSI,University of Bern(Switzerland) IPN (Orsay, France) LLNL (Livermore, USA)

  6. Electronic ground-state configuration: [Rn] 5d146d37s2 – group 5 elem. Periodic Table (Nb – Ta – Db) What we know about aqueous phase chemistry of Db? Db is adsorbed on glass surface from nitric acid (like Nb and Ta) Db is not extract from 3.8 M HNO3 / HF into MIBK (Db  Ta, Db  Nb) HCl, HF – Aliquat 336 system HCl  Pa > Nb Db > Ta HF  Db  Nb  Ta >> Pa [DbF7]2- HF – Dowex50 (Cation-exchange) System Ac+3(kd104); NbF2- 7 CHEMICAL IDENTIFICATION of the Db

  7. EXPERIMENT SCHEME

  8. OUTLINE of the EXPERIMENT • Irradiation of 243Am-target with 48Ca-ions (accumulation of the EVR by copper catcher) • Removal of a Catcher from the target system and its transportation to the Radio.Chem.Lab. • Cleaning of the catcher surface from 243Am-aerosol particles by a cotton saturated with C2H5OH • Taking off thin layer of Cu (7-10 100150 mg Cu) on the micro-lathe • Dissolution of the Cu-cuttings in HNO3 conc. • Addition of the La3+ (0.7 mg), tracers (92mNb, 177Ta, 167Tm, 169Yb) and carriers Nb, Ta (1 g) • Precipitation of La(OH)3 by NH4OH (La, Nb, Ta, Db, Ac – precipitate; Cu-solution) – 3 times (Nb, Ta 99%) • Dissolution of the La(OH)3 in 2M HNO3 • Sorbtion of La, Ac, Nb, Ta, Db on Dowex 50 (cation-exchange resin) • Elution of group 5 elements (Nb, Ta, Db) with 2 ml 1M HF • Evaporation of the solution to 0.1 ml • Pipetting of the 0.1 ml solution on a PE-foil (40mkg/cm2) - 3 hr (92mNb  855%) (177Ta  75  5%)

  9. 48Ca + 243Am 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3,4.1018 15 events

  10. sample 9 (3 . 1017) - SSD on the catcher surface • (without chemistry) • 2 tracks/ day ( 72 days) • Kseparation ≈ 105 (preliminary experiments with tracers) ≥ 8.103 ( samples) • SF (Actinides, incl. 264Lr) < 0.1 % 252Cf and 254Cf 254Cf - 60,5 d (SF) (0,31% - α) 252Cf - 2,645 y (α) (3,09%- SF)

  11. Number of neutrons registered by 3He detectors per SF-decay (without taking into account the detector efficiency)

  12. The Periodic Table

  13. CHART of the NUCLIDES

  14. 5 3n 243Am + 48Ca 288115 268Db

  15. Conclusion • The properties of the isotope 268Db produced in the decay chain of element 115 using the gas-filled recoil separator agree by all measured parameters with the data of the present chemical experiment on the determination of its atomic number. • The decay chain of element 115 synthesized in the reaction 243Am+48Ca consists of 5 sequential -transitions resulting in the formation of the long-lived nucleus of element 105 leading to spontaneous fission. A hypothesis of the possible -decay of the Db nucleus has been totally rejected by the conditions of chemical separation of the reaction products in this experiment. • Thus, the data from the present experiment are the independent evidence for the synthesis of element 115 as well as element 113 in the reaction 243Am+48Ca

  16. 5 3n 243Am + 48Ca 288115  268Db (Chemistry – X Db) 105 MS IS + DbCl5Db  A = 268 (5 group, A = 268) 268Db 288115 105 FUTURE EXPERIMENTS • Determination of the mass of Super Heavy Nuclei MASHA Off-line

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