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Spectroscopy of exotic nuclei Lecture 4

Spectroscopy of exotic nuclei Lecture 4. Superheavy Elements ( continued ) Shape coexistence. „Cold“ Fusion. „Cold“ Fusion . medium heavy projectile on doubly magic target 208 Pb low excitation energy of Compund nucleus Evaporation of single neutron.

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Spectroscopy of exotic nuclei Lecture 4

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  1. SpectroscopyofexoticnucleiLecture 4 Superheavy Elements (continued) Shape coexistence R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  2. „Cold“ Fusion „Cold“ Fusion • medium heavy projectile on doubly magic target 208Pb • low excitation energy of Compund nucleus • Evaporation of single neutron Low excitation energy results from shell closure of target nucleus R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  3. SHIP Experiment at GSI Darmstadt Time of flight detectors Maximal: 0.3 particle mA = 2.1012pps Position sensitive focal plane detector Beam stop Magnetic dipole Target wheel Electric dipole Magnetic quadrupole R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  4. Decay of 265Hs (Z=108) a-Energies Z 266 263 264 265 267 269 Hs Hs Hs Hs Hs Hs Hs 108 0.45 ms 0.8ms 1.7ms 2.3 ms ? 59 ms  9.3 s Hassium a a a a a ,sf a a a Bh 267 266 262 264 260 261 Bh Bh Bh Bh Bh Bh 107 » 17 s » 1s 11.8 ms 440 ms 102ms 8ms ? Bohrium a a a a a a a 259 260 261 262 263 265 266 Sg 258 Sg Sg Sg Sg Sg Sg Sg Sg 106 1.4s 6.9 ms 0.48 s 7.4 s 21 s 2.9 ms 3.6 ms 0.23 s 0.3s 0.9s a ,sf a ,ec Seaborgium sf a sf a ,sf? a ,sf? a a ,sf? Db 255 256 257 258 Db 260 Db Db 262 263 261 Db Db Db Db Db 105 160 4.4 s 1.5 s 1.8 s 34 s 27 s 1.6 s 2.6 s 1.3 s Dubnium a ,sf a ,ec/sf? a ,sf a ,ec/sf? a ,sf a ,sf a ,ec a ,sf Rf Rf 257 258 259 260 261 262 253 254 255 256 Rf Rf Rf Rf Rf Rf Rf Rf Rf 78 s 1.4s 23 s 6.1 s 2.1s 48 s 13 ms 3.1 s 21 ms 0.8s 1.4s 4.7s 47ms Ruther- fordium a ,sf a a ,sf a ,sf sf, a sf sf sf sf sf a ,ec a ,ec sf 150 152 154 156 158 N a-decay Spont.anneous fission EC-decay • Successive decay must happen at same position • a-energies must coincide with known decay energies R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  5. Gas-filledseparator • Magnetic field region filled with ~ 1 Torr He Gas • Heavy ion leaves target with charge distribution • Scattering of ion with gas (velocity of bound electrons) •  charge exchange reactions •  narrow charge distribution around average charge state • higher acceptance compared to vacuum system since only few charge states are accepted in vacuum system • in first order magnetic rigidity B is independent of velocity since average charge state depends on velocity •  large acceptance • BUT • - Low mass resolution • - Low background reduction B = 0.0227 A v/v0 q-1 q = v/v0Z1/3 R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  6. Dubna gas-filledseparator R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  7. Hot Fusion Hot Fusion • light projectile onto actinide target è neutron rich isotope • high excitation energy of compound nucleus •  Evaporation of several neutrons Probability for „survival“ of compound nucleus: each evaporation of a neutron is in competition with fission R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  8. Nuclearchartoftransactinides in 2008 • “Problems” of Dubna results: • decays often end in unknown isotopes • short decay chains • long correlation times 294118 118 292 291116 293116 290116 116 116 116 » 33 ms a 288115 287115 115 289 287 288 286114 114 114 114 114 114 »5 s »2 s »20 s a a a 282113 283113 284113 278113 113 176 Copernicium (Cp) Suggestion: 283 284 285 277 282112 112 112 112 112 112 112  3 min »10 s »10 min 194ms 277ms Roentgenium (Rg) sf a a a a 272 274Rg 278Rg 279Rg 280Rg 111 174 111 1.5 ms a Darmstadtium (Ds) 269 270 271 279Ds 273 267 280 281 110 110 110 110 110 110 110 110 170 m s 1.1ms 56 ms ? 0.1ms 6 ms »7 s »1 min 76 ms 118ms sf a a a a a a a a a 274Mt 275Mt 276Mt 266 268 270Mt Mt Mt Mt 172 109 170 1.7 ms 70 ms Meitnerium a a 275Hs 277 270Hs 271Hs 266 263 264 265 267 269 Hs Hs Hs Hs Hs Hs Hs Hs 108 »10min hot fusion 0.45 ms 0.8ms 1.7ms 2.3 ms ? 59 ms  9.3 s Hassium a a a a sf a ,sf a a a Bh 267 270Bh 271Bh 272Bh 266 262 264 260 261 Bh Bh Bh Bh Bh Bh 107 168 166 » 17 s » 1s 11.8 ms 440 ms Z 102ms 8ms ? Bohrium a a a a a a a 271Sg 267Sg 259 260 261 262 263 265 266 Sg 258 Sg Sg Sg Sg Sg Sg Sg Sg 106 1.4s 6.9 ms 0.48 s 7.4 s 21 s 2.9 ms 3.6 ms 0.23 s 0.3s 0.9s a ,sf a ,ec Seaborgium sf a sf a ,sf? a ,sf? a a ,sf? 266Db 267Db 268Db 259Db Db 255 256 257 258 Db 260 Db Db 262 263 261 Db Db Db Db Db 105 160 164 4.4 s 1.5 s 1.8 s 34 s 27 s 1.6 s 2.6 s 1.3 s Dubnium a ,sf a ,ec/sf? a ,sf a ,ec/sf? a ,sf a ,sf a ,ec a ,sf 267Rf Rf Rf 257 258 259 260 261 262 263Rf 253 254 255 256 Rf Rf Rf Rf Rf Rf Rf Rf Rf 162 78 s 1.4s 23 s 6.1 s 2.1s 48 s 13 ms 3.1 s 21 ms 0.8s 1.4s 4.7s 47ms Ruther- fordium a ,sf a a ,sf a ,sf sf, a sf sf sf sf sf a ,ec a ,ec sf 150 152 154 156 158 N New elements/isotopes since 2001 A-decay Spont. fission EC-decay R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  9. Cross-sections D. Ackermann R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  10. 48Ca + 238U → 286112* - Summary D. Ackermann Independent confirmation of Dubna result !! R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  11. Spectroscopy of 254No 48Ca + 208Pb Cross section: ~500 nb (large due to doubly magic projectile and target nuclei) R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  12. Gamma spectroscopy of 254No at RITU JUROGAM R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  13. Identificationof254No througha-decay 26 MeV 40 MeV Implantation 15 MeV 55 MeV Alpha decay R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  14. Rotational spectra in 254No Gamma rays of nuclei at target position!!! In coincidence with detected recoils In coincidence with alpha decay transitions of 254No decay chain R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  15. SACRED Conversion electrons guided by Solenoid magnet to segmented Si Detector R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  16. Confirmationofdeformationof254No R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  17. Chemistry of SHE Situation as of one century ago Periodic Table of the Elements R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  18. Does Hs behavelike Os? R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4 A. Türler, RCM, TUM

  19. In-Situ Volatilization and On-line detection (IVO) 26Mg-beam rotating Vacuum window 248Cm target N2(liq.) cooling thermostat (-20°C) PFA-teflon capillary He/O2 He/O2 2x 36 PIN-diodes 269,270Hs oven SiO2-column Recoilchamber (i.D. 4 mm) (600°C) HsO4deposition -20 °C -170 °C 0 40 cm R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  20. Shape coexistence R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  21. Predictions of superheavy nuclei without shell correction with shell corrections Existence of superheavy nuclei 2nd minium at large deformation (superdeformation / shape coexistence) Strutinsky, Nuclear Physics A95 1967 R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  22. Shape coexistence in 152Dy Oblate ND Minimum SD Minimum SD statesbecomeyrastat I » 60ħ Prolate ND Minimum R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  23. High spin spectroscopy EUROBALL Population of nuclei at high angular momentum in Fusion-Evaporation-Reaction R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  24. Shape coexistence in 152Dy linking transitions unknown R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  25. Superdeformation Superdeformation Nucleiwithlongtoshort Axis ratioof» 2:1 Around250 superdeformedbands havebeenobserved Low-spin superdeformed states are at high energies with respect to ground state R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  26. Shape isomerism around 74Kr M. Bender et al., PRC 74, 024312 (2006) Adopted from A. Görgen R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  27. Electron conversion spectroscopy R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  28. Isotope shifts in Hg strongly prolate deformed b =-0.1 b= 0.25-0.28 weakly oblate deformed collinearlaserspekctroscopy b =-0.17 Isotope shift (IS) ofatomictransitions Meansquarechargeradius<r2> R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  29. Shape coexistence in 186Pb 0p-0h 4p-4h 2p-2h Protonen-Konfigurationen • M(186Pb) ~ 174 GeV/c2 • Subtle balance of nuclear forces leads to competition on the 1 MeV level (6∙10-6) A. Andreyev et al., Nature 405, 430 (2000) R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  30. SHIP velocity filter at GSI R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  31. Shape coexistence in 186Pb – a-Spectra prolate oblate spherical Reduced a-width d2: Measure for creation of a-particle in the nucleus Û p-h configuration Large overlap: (only protons) |Po;2p-0h> ® |Pb;0p-0h> |Po;4p-2h> ® |Pb;2p-2h> analogy: spectroscopic factors A. Andreyev et al., Nature 405, 430 (2000) “Penetration”-factor P depends on shape! R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  32. Shape coexistence in the light Hg nuclei R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  33. Plunger + Ritu@Jyväskylä JUROGAM Ge-array ~ 4% efficiency He at 1-2 mbar Q Q D Q RITU separator ~ 30% recoil eff. beam T. Grahn et al., PR L97 (2006) 062501 T. Grahn et al., PRC80 (2009) 014324 target C- foil R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  34. Lifetime measurement in 180Hg T. Grahn et al., PRC 80, 014324 (2009) R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  35. Coulex of 184,186,188Hg at REX-ISOLDE Online spectrum Target: 120Sn 367 keV 21+01+ 184Hg 41+ 22+ 21+ 02+ 287 keV 41+21+ 535 keV 22+01+ 01+ Aim: - Measure E2 transitionand diagonal matrixelements deformations R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4 P. Butler et al.

  36. Superheavy elements Shell quenchingby diffuse surface Isospin competition and symmetry Neutron Skins New shellgapsthrough residual interaction Soft collectivemodes Halos Nuclear Structure at the extremes Shape coexistence Cluster R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

  37. Thank you for your attention!! R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 4

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