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J.H . Hamilton 1 , S. Hofmann 2 , and Y.T . Oganessian 3

THE IMPORTANCE OF CLOSED SHELL STRUCTURES IN THE SYNTHESIS OF SUPER HEAVY ELEMENTS . J.H . Hamilton 1 , S. Hofmann 2 , and Y.T . Oganessian 3 1 Vanderbilt University, 2 GSI 3 Joint Institute for Nuclear Research ISCHIA 2014. 102.

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J.H . Hamilton 1 , S. Hofmann 2 , and Y.T . Oganessian 3

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  1. THE IMPORTANCE OF CLOSED SHELL STRUCTURES IN THE SYNTHESIS OF SUPER HEAVY ELEMENTS J.H. Hamilton1,S. Hofmann2, and Y.T. Oganessian3 1VanderbiltUniversity,2GSI3Joint Institute for Nuclear Research ISCHIA 2014

  2. 102

  3. Calculated ground-state shell-correction energy, partial spontaneous fission (SF), and α-particle half-lives (Smolanczuk, Sobiczewski).

  4. 184 102

  5. X 117

  6. cold hot

  7. Velocity separator SHIP Ge Detectors Si Detectors SHIP: Separation time: 1 – 2 μs Transmission: 20 – 50 % Back ground: 10 – 50 Hz Energy resolution: 18 – 25 keV Position resolution 150 μm Dead time: 3 – 25 μs ToF Detectors 7.5° Magnet Target wheel Beam stop Magnets Electric field Quadrupoles Ion beam

  8. The Dubna gas-filled recoil separator DGFRS and detectors are shown.

  9. 20 96 94 20 92

  10. Experiment SHIP, June 24 – July 26, 2010 07-July-2010, 09:01 chain 5 21.0 MeV, 28 mm, strip 12 07-July-2010, 00:10 h chain 4 22 MeV, 24 mm, strip 15 02-July-2010, 01:52 h; chain 2 8.96 MeV, 10.4 mm, strip 4 292116 292116 292116 CN CN CN 1 1 1 ≈10.6 MeV (stop + box) 11.6 ms 2.75 MeV (escape) 3.3 ms 1.4 MeV (escape) 28.8 ms 288114 288114 288114 2 2 2 1.8 MeV (escape) 252 ms ≈10.0 MeV (stop + box) 72 ms 9.959 MeV 993 ms 284Cn 284Cn 284Cn 03-July-2010, 20:01 h; chain 3 18 MeV, 27.4 mm, strip 2 292116 CN sf sf sf 195 MeV, uncorrected 121 ms 185 MeV, uncorrected 25 ms 172 MeV, uncorrected 50 ms 1 10.624 MeV 76 s 288114 2 9.895 MeV 1.3 s 284Cn sf 197 MeV, uncorrected 269 ms 48Ca + 248Cm => 292116 + 4n

  11. black - experiment, blue – theory Note the good agreement of the macroscopic-microscopic calculated alpha energies (blue) and our experimental ones (black). Note a decay not SF as for 281Rg 70 days run

  12. Definitive evidence for elements 113, 115 in the reaction 243Am + 48Ca Two sets of experiments from November 2010 – February 2012. Five different beam energies were used.

  13. Since PRL 2012 27 28 2 3 4

  14. Cross bombardment check

  15. New 249Bk target for Dubna and GSI 2012, 2013 Dubna 48Ca + 249Bk 11 new events of 293117 and 3 new events of 294117. Totals 16 events of 293117 and 4 of 294117. One new 48Ca + 249Cf 294118 + 3n GSI 48Ca + 249Bk Confirmed 294117. 50Ti + 249Bk 296119 + 3n No events seen; s less than 70 femtob after 6 months.

  16. Alpha-Gamma Spectroscopy on 288115 22 chains (out of 30) of ours are compatible with the 31 chains (out of 37) associated with the 3n channel 288115 by Oganessianet al. 288115 288115 D. Rudolph et al., PRL 111 (2013) 112502 DGFRS TASCA 10.29-10.56 0.150( ) 10.33-10.58 0.171( ) s 42 28 43 28 276Mt 280Rg 276Mt 284113 272Bh 284113 268Db 268Db 272Bh 280Rg 9.97(5),9.81(7) 0.97( ) 9.10-10.11 0.81( ) s 25 17 23 15 9.09-9.87 3.6( ) 9.25-9.92 6.4( ) s 9 6 21 13 9.17-9.95 0.54( )/6( ) 9.43-9.89 0.75( ) s 25 15 8 2 14 9 8.73-9.15 12.0( ) 8.55-9.09 9.2( ) s 31 18 31 21 26( ) h (and γ rays!) 27( ) h 5 4 7 5 D. Rudolph, Lund University APSORC 13, Kanazawa, Japan, September 2013

  17. Partial half-lives for SF vs. N. solid symbols and crosses denote even-even, open symbols – even-odd nuclei. Solid lines are drawn through the experimental points of even-even nuclei. The dashed lines are calculated TSF(th) .

  18. Radioactive properties:(a) a-particle energies Qafor odd-Z nuclei agree with the systematics and have intermediate values between neighboring even-Z nuclei.(b) a-particle energies of the Z=107 and Z=109 isotopes as well as their behavior vs neutron number are in agreement with what is observed for the neighboring lighter previously known nuclei.(c) Decrease of Qa values with approaching N=184 magic number --increase of stability.

  19. Radioactive properties:increase of stability with approaching N=184 magic number

  20. 281111(N=170) lies in the “critical” region between the stabilizing effect of the N=162 and 184 neutron shells.

  21. The high hindrance caused by the odd proton does not save 281111(N=170) from SF because of the weakening of the above neutron shells. 282111(N=171) has an extra unpaired neutron that further hinders SF relative to alpha decay. Thus this nucleus undergoes alpha decay.

  22. s less than 70 femtob after 6 months at TASCA.

  23. Warmest best wishes for health and long life to Prof. Aldo Covello

  24. Thank you.

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