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Synthesis of superheavy elements at FLNR

PASIFICHEM 2010, 18 December 2010, Honolulu, Hawaii, USA. Synthesis of superheavy elements at FLNR. S. DMITRIEV Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, 141980, Russia e-mail: dmitriev@jinr.ru. Cn.

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Synthesis of superheavy elements at FLNR

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  1. PASIFICHEM 2010, 18 December 2010, Honolulu, Hawaii, USA Synthesis of superheavy elements at FLNR S. DMITRIEV Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, 141980, Russia e-mail: dmitriev@jinr.ru

  2. Cn

  3. Cold & hot fusion cross sections fusion survival SHE

  4. ACCELERATORS ISOTOPE ENRICHMENT TARGET TECHNOLOGY NEW RECOIL SEPARATOR REACTOR REGIME Efforts focused on the synthesis of SHE New ECR-ion source (GANIL, JINR) Enrichment up to 68-70% (Lesnoy) 48Ca technology of the target preparation – 0.3mg/cm2 Separation and detection of superheavy nuclei New separator & detectors (Dubna, Livermore) isotope enrichment 98-99% S-2 separator (Sarov) New target matter isotope production high flux reactors (Oak Ridge, Dimitrovgrad)

  5. FLNR U400 cyclotron

  6. Experimental Setup v (A=48) = 0.11 c q = 16.5+ v (A=288) = 0.017 c q = 6.2+

  7. Total detection efficiency: for α-particles…………..83% for SF-fragment…….~ 100% for both fragments……..42% Focal plane detector

  8. Number of observed decay chains Element 118 3 Element 116 26 Element 115 4 Element 114 43 Element 113 2 Element 112 8

  9. fusion survival SHE Cold & hot fusion cross sections

  10. Relatively long half-lives of isotopes of elements 104-116 produced in the reactions with 48Ca and chemical properties of SHE predicted theoretically permit new experiments aimed at: • the chemical identification of SHE (268Db) • study of their chemical properties (112,114), • determination of masses of the SHE isotopes

  11. Number of observed decay chains Element 118 3 Element 116 26 Element 115 4 Element 114 43 Element 113 2 Element 112 8

  12. The Bk-249 was produced at ORNL (USA) by irradiation: of Cm and Am targets for approximately 250 days by thermal-neutron flux of 2.5  1015neutrons/cm²·s in the HFIR (High Flux Isotope Reactor).  Irradiation ends December 2008

  13. 249Bk was produced at High Flux Reactor in Oak-Ridge………...March 09, 2009 22 mg of pure 249Bk was shipped to Moscow……………................June 20, 2009 Arrived at Dimitrovgrad (Russia) for target preparation……………..July 01, 2009 Experiment have started at Dubna…………….....................................July 27, 2009

  14. Target Target 310 μg/cm2 BkO2 on 1.5 μm-Ti foil ω = 1700 rpm 6 cm2 Yu. Oganessian 2010 600 120 mm target-making June 2009

  15. Dubna Gas-Filled Recoil Separator Dubna Gas-Filled Recoil Separator Experimental technique Yu. Oganessian 2010 Transmission for: EVR 35-40% target-like 10-4-10-7 projectile-like 10-15-10-17 Registration efficiency: for α-particles 87% for SF single fragment 100% two fragments ≈ 40% beam 48Ca target 249Bk Experiment was started July 272009

  16. 0.3% First run: from July 27 to October 23, 2009 Beam dose: 2.4·1019

  17. str.#10, 09:40 Aug.20, 2009 11.89 MeV 293 str.#10, 15.20 mm 12:28 Sep.10, 2009 117 a str.#10, 1 13.87 MeV 04:50 Sep.18, 2009 10.99 MeV 293 289 22.70 mm 17.01 ms 117 str.#8, 115 a a 13.51 MeV 15.02 mm 294 1 2 04:23 Oct.17, 2009 17.17 mm a 11.14 MeV missing 117 a 289 285 7.89 ms 1 9.96 MeV 294 115 a a 113 23.16 mm 11.08 MeV 22.04 mm (6.64 +4.44) 290 3 2 117 a 4.6 ms a missing 1 115 9.72 MeV a 281 285 17.19 mm str.#10, 10.91 MeV 2 16.17 s 290 113 a 01:37 Oct.23, 2009 Rg 15.40 mm 53.01 ms 10.34 MeV 3 286 115 a 122.16 mm 0.017 s 9.52 MeV (8.98 +0.54) 9.36 MeV 2 281 113 a 203.3 MeV SF 294 17.41 mm 2.22 s 13.23 mm 3 10.25 MeV 40.19 s Rg 117 286 a 9.71 MeV 0.51 s (9.17 +0.54) 14.86 mm 282 1 113 a 1.16 s 22.20 mm 11.00 MeV 3 Rg SF 291.9 MeV (184.8 +7.1) . -6 290 N= 6 10 20.24 ms 9.79 MeV 4.25 s ran 282 115 a 22.67 mm 13.33 mm 0.24 s SF 204.8 MeV (180.0 +24.8) 2 Rg 22.09 mm 12.03 s 10.27 MeV (9.03+1.24) . -3 N= 1 10 286 16.45 mm ran 0.42 s 189.4 MeV(153 +36) SF 113 a 10.90 mm 76.56 s -5 . 3 N= 1 10 ran 23.19 mm 9.48 MeV 282 13.49 s Rg . -11 23.59 mm 3 10 N= ran SF 194.0 MeV 76.56 s 23.19 mm . -11 3 10 N= ran Ex=39 MeV Beam dose: 2.4·1019

  18. 4n 297 117 Ex=39 MeV Ex=35 MeV Beam dose: 2.0·1019

  19. Synthesis of a new element with atomic number Z=117 Yu. Ts. Oganessian,1) F. Sh. Abdullin,1) P. D. Bailey,2) D. E. Benker,2) M. E. Bennett,3)S N. Dmitriev,1) J. G. Ezold,2) J. H. Hamilton,4) R. A. Henderson,5) M. G. Itkis,1) Yu. V. Lobanov,1) A. N. Mezentsev,1) K. J. Moody,5)S. L. Nelson,5) A.N. Polyakov,1) C. E. Porter,2) A. V. Ramayya,4) F. D. Riley,2) J. B. Roberto,2) M. A. Ryabinin,6)K. P. Rykaczewski,2) R. N. Sagaidak,1) D. A. Shaughnessy,5) I.V. Shirokovsky,1) M. A. Stoyer,5)V. G. Subbotin,1)R. Sudowe,3)A. M. Sukhov,1) Yu. S. Tsyganov,1) V. K. Utyonkov,1) A. A. Voinov,1) G. K. Vostokin,1) and P. A. Wilk5) 1Joint Institute for Nuclear Research, RU-141980 Dubna, RF 2Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA 3University of Nevada Las Vegas, Las Vegas, NV 89154, USA 4Vanderbilt University, Nashville, TN 37235, USA 5Lawrence Livemore National Laboratory, Livermore, CA 94551, USA 6Research Institute of Atomic Reactors, RU-433510 Dimitrovgrad, RF (Dated: April 1, 2010) The discovery of a new chemical element with atomic number Z=117 is reported. The isotopes 293117 and 294117 were produced in fusion reactions between 48Ca and 249Bk. Decay chains involvingeleven new nuclei were identified by means of the Dubna Gas Filled Recoil Separator. The measureddecay properties show a strong rise of stability for heavier isotopes with Z≥111, validating theconcept of the long sought island of enhanced stability for super-heavy nuclei

  20. Yu. Oganessian 2010 Decay properties of the nuclei in the decay chains of Z=117 isotopes

  21. CHEMISTRY OF THE 113 ELEMENT Target (249 Bk; 0,5 mg/cm2) (4) SiO2- Ta 800°C Au - 113 16 pairs 2.5m 1 L/min He/Ar (70/30)

  22. Capillary length from target chamber to detector system is 2.5 m

  23. 16 pairs of gold covered detectors

  24. 48Ca + 249Bk Target 249Bk (0.5 mg∙cm-2) natNd (30 μg∙cm-2) 48Ca Emid. target = 252 MeV I ~ 9 eμA Irradiation: - 18.04.2010 – 31.05.2010; target I - 3.5 1018 ; target II - 5.6 1018 9.1∙1018

  25. Alpha and SF spectra

  26. 112 ms 45 ms 297 294 117 117 α1 10.81(10) MeV 11.00 MeV 0.023 s 1.0 s 290 E* = 35 MeV 1 event 115 α2 9.95(40) MeV 10.23 MeV 28.3 s 16 s 3n 3n 286 249Bk + 48Ca 249Bk + 48Ca 113 294 294 α3 117 117 α1 α1 9.63(10) MeV 9.56 MeV 0.74 s 8.1 s 282 290 290 Rg 115 115 α2 α4 α2 9.00(10) MeV 9.43 MeV 286 286 Bot. 8 11.0 s 13 s 278 113 113 α3 α3 Mt α5 9.62 MeV Bot. 8 Top 4 282 282 9.55(19) MeV 9.14 MeV Rg Rg 1.3 min 7.4 min α4 α4 274 Bh 8.89 MeV 64.90 s 9.01 MeV 1.85min α6 278 Bot. 8 278 Mt Mt 8.80(10) MeV 8.43 MeV α5 α5 270 9.52 MeV 6.49 s Db 274 Bot. 8 274 Bot. 4 preliminary Bh Bh α6 α6 8.77 MeV 13.59 min 8.64 MeV <1.42min SF 270 270 Db Db TKE = 219(5) MeV 33.4h SF SF 101.0 + 89.1 MeV 79.25 h 98.6 + 88.5 MeV 64.61h DGFRS 04 May 2010 10:05:4616 May 2010 02:29:54 Bk-target I Bk-target II 26

  27. 112 ms 45 ms 297 294 117 117 α1 10.81(10) MeV 11.00 MeV 0.023 s 1.0 s 290 115 α2 3n 249Bk + 48Ca 9.95(40) MeV 10.23 MeV 294 28.3 s 16 s 286 117 113 α3 α1 9.63(10) MeV 9.56 MeV 0.74 s 8.1 s 282 Rg α4 290 9.00(10) MeV 9.43 MeV 115 11.0 s 13 s 278 α2 Mt α5 9.55(19) MeV 9.14 MeV 1.3 min 7.4 min Bot. 8 274 286 Bh 113 α6 α3 8.80(10) MeV 8.43 MeV 270 9.62 MeV Db Bot. 8 282 SF Rg α4 TKE = 219(5) MeV 33.4h 8.89 MeV 64.90 s Bot. 8 278 Mt α5 9.52 MeV 6.49 s Bot. 8 274 Bh α6 8.77 MeV 13.59 min 270 Db SF 101.0 + 89.1 MeV 79.25 h 3n 249Bk + 48Ca 294 117 α1 290 115 α2 286 113 α3 Top 4 282 Rg α4 9.01 MeV 1.85min 278 Mt α5 Bot. 4 274 Bh α6 8.64 MeV <1.42min 270 Db SF 98.6 + 88.5 MeV 64.61h E* = 35 MeV 1 event preliminary DGFRS 04 May 2010 10:05:4616 May 2010 02:29:54 Bk-target I Bk-target II 27

  28. Hg-185 DISTRIBUTION

  29. 21 ms 10 ms 112 ms 45 ms 297 297 293 294 117 117 117 117 α1 α1 288 115 11.03(8) MeV 11.26 MeV 10.81(10) MeV 11.00 MeV 0.023 s 1.0 s 0.32 s 0.22 s 290 289 115 115 10.46 MeV 87 ms α2 α2 3n 284 10.31(9) MeV 10.48 MeV 9.95(40) MeV 10.23 MeV 113 243Am + 48Ca 7.9 s 1.2 s 28.3 s 16 s 285 286 113 113 10.00 MeV 0.48 s α3 α3 280 α1 9.63(10) MeV 9.56 MeV 9.74(8) MeV 9.48(11) MeV 9.96 MeV Rg 0.74 s 8.1 s 281 282 Rg Rg 9.75 MeV 3.6s α4 276 Mt 9.00(10) MeV 9.43 MeV 11.0 s 13 s SF 278 α2 Mt 9.71 MeV 0.72s TKE = 218(5) MeV 38s α5 272 Bh 9.55(19) MeV 9.14 MeV 1.3 min 7.4 min 274 Bh 9.02 MeV 9.8 s α6 268 α3 8.80(10) MeV 8.43 MeV Db 270 Db SF TKE = 205(5) MeV 16 h SF α4 TKE = 219(5) MeV 33.4h α5 Chemistry of the Element 113 249Bk + 48Ca DGFRS

  30. Experimental program of 2011-2012 • Chemistry of 113 element (243Am + 48Ca) • Chemistry of 114 element (244Pu + 48Ca) • Mass number measurement of 112 - 114 elements • 242Pu(48Ca,3n)287114(0.5s,α) –> 283112(4 s) 243Am(48Ca,3n)–> 288115 (0.1 s, α) –> 284113(0.5 s)

  31. Introduction • MAss • Separator of • Heavy • Atoms General ion-optical parameters: Range of energy variation, kV 15-40 Range of Br variation, Tm 0.08-0.5 Mass acceptance, % +/-2.8 Angular acceptance, mrad +/-14 Diameter the ion source exit hole, mm 5.0 Horizontal magnification at F1/F2 0.39/0.68 Mass dispersion at F1/F2, mm/% 1.5/39.0 Linear mass resolution at F1 75 Mass resolution at F2 1150 The proposedsetup is a combination of the so-called ISOLmethod of synthesis and separation of radioactivenuclei with the classical method of mass analysis,allowing mass identification of the synthesizednuclides in the wide mass range.

  32. STATUS of the MASS-SPECTROMETER Mass-spectrometer MASHA at the beam line of the cyclotron U-400M

  33. FIRST EXPERIMENTS • Mass identification of 112 и 114 elements synthesizedat the reactions • 242Pu(48Ca,3n)287114(0.5 s) –> 283112(4 s) • Mass identification of 113elements synthesizedat the reaction • 243Am(48Ca,3n)288115 (0.1 s) →284113 (0.5 s)

  34. DRIBs-III 2010 -2016 • Creation of the new experimental hall (≈ 2600 м2) • Creation of high current heavy ion accelerator • Development and creation of next generation set-ups

  35. Gas-Filled Separator • ADVANTAGES: • presence of a gas – H2, He; • high energy and charge • acceptances; • additional target cooling • through convection; • low number of elements; • no high voltage. Ready time must be synchronized with the construction of the new experimental hall & accelerator

  36. NEW EXPERIMENTAL HALL

  37. a) b) c) d) a).Cumulative alpha spectrum from 16 pairs of detectors b). Cumulative spectrum of fission fragments from 16 pairs of detectors c). Cumulative alpha spectrum from 8th pair of detectors d). Cumulative spectrum of fission fragments from 8th pair of detectors

  38. a) b) c) d) a).Cumulative alpha spectrum from 16 pairs of detectors b). Cumulative spectrum of fission fragments from 16 pairs of detectors c). Cumulative alpha spectrum from 4th pair of detectors d). Cumulative spectrum of fission fragments from 4th pair of detectors

  39. Chromatographic deposition of 209At and 185Hg in the detector array at 0°C together with a standard Monte-Carlo simulation of the 209At deposition.

  40. The deposition of 185Hg compared to the deposition of 209At in the isothermal detector array at 0°C together with Monte-Carlo simulation of the depositions. The Hg deposition points to an efficient chromatographic gold surface the second part of the experiment.

  41. THANK YOU FOR YOUR TIME!

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