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Experiments on Searching for the Heaviest Elements

Experiments on Searching for the Heaviest Elements. Kosuke Morita Superheavy Element Laboratory RIKEN Nishina Center, RIKEN. 共同研究者 collaborators. K. Morimoto RIKEN H. Haba RIKEN A. Yoneda RIKEN D. Kaji RIKEN T. Ichikawa RIKEN H. Kikunaga RIKEN T. Akiyama RIKEN, Saitama U.

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Experiments on Searching for the Heaviest Elements

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  1. Experiments on Searching for the Heaviest Elements Kosuke Morita Superheavy Element Laboratory RIKEN Nishina Center, RIKEN International Nuclear Physics Conference 2007

  2. 共同研究者 collaborators K. Morimoto RIKEN H. Haba RIKEN A. Yoneda RIKEN D. Kaji RIKEN T. Ichikawa RIKEN H. Kikunaga RIKEN T. Akiyama RIKEN, Saitama U. N. Sato RIKEN, Tohoku U. A. Yoshida RIKEN T. Suda RIKEN T. Ohnishi RIKEN K. Rituparna TRIUMF K. Katori RIKEN E. Ideguchi CNS Univ. of Tokyo T. Yamagichi Saitama U. S. Goto Niigata U. H. Kudo Niigata U. A. Ozawa Univ. of Tsukuba K. Sueki Univ. of Tsukuba H. Koura JAEA F. Tokanai Yamagata U. Y-.L. Zhao IHEP/Beijing H.-S. Xu IMP/Lanzhou RNC Superheavy Element Laboratory International Nuclear Physics Conference 2007

  3. one end of nuclear chart‘84 120 119 118 117 116 115 SHE 114 113 112 266 Rg 265 264 Ds 261 262 Mt 259 263 261 260 Hs 258 261 260 262 Bh 257 262 258 259 260 261 262 Sg Db Rf 184 162 a-decay A Spontaneous fission A b+ or EC decay A International Nuclear Physics Conference 2007

  4. one end of nuclear chart2007 294 120 119 290 291 292 293 118 287 288 117 286 287 288 289 290 116 278 283 284 115 SHE 285 286 283 284 277 282 114 279 280 274 272 113 279 273 282 269 270 271 281 112 275 266 276 Rg 268 270 278 270 271 265 275 264 269 266 267 Ds 264 261 262 266 267 271 272 265 Mt 259 263 271 261 264 260 265 266 262 Hs 258 261 267 259 260 262 268 263 Bh 257 262 263 267 268 258 259 260 261 261 262 Sg Db Rf 184 162 a-decay A Spontaneous fission A b+ or EC decay A International Nuclear Physics Conference 2007

  5. 113 278 284 283 277 112 286 283 282 285 284 272 Rg 280 274 272 279 271 269 279 273 271 Ds 270 281 282 273 268 Mt 268 270 276 275 266 cold fusion reaction 265 269 265 264 278 267 269 275 270 266 Hs 271 269 264 262 261 264 266 272 271 265 Bh 261 263 266 Sg 262 265 261 258 260 259 263 271 265 261 260 262 260 262 263 259 258 255 257 256 268 Db 267 258 261 259 48Ca induced reactions 260 257 261 259 262 253 257 254 255 256 267 268 Rf 258 257 259 260 253 256 252 254 255 256 262 261 Lr 252 253 254 256 258 255 257 253 250 251 253 252 254 253 262 255 259 No 260 252 253 250 254 256 251 255 257 247 248 250 249 251 258 259 260 252 Md 244 248 252 257 245 249 253 246 250 254 247 251 255 258 246 244 256 259 247 248 Fm 257 253 254 245 255 246 248 252 249 250 256 247 251 Es 248 244 250 249 251 253 252 255 245 247 246 254 Cf 244 245 248 243 246 247 249 250 251 hot fusion reaction Bk 242 250 244 249 251 243 247 248 245 246 Cm 241 244 246 242 243 245 247 Am 244 246 241 242 243 245 247 240 Pu 239 240 244 241 242 243 neutron capture + b-decay Np 239 240 242 238 U 162 150 International Nuclear Physics Conference 2007

  6. 272Rg 14 chains 278113 271Ds 14 chains 265Hs 10 chains Reactions studied at GARIS 116 176 115 114 113 112 277112 2 chains 111 Ds Mt 170 Hs Bh Sg Db Rf 162 a Lr SF No b+ or EC Md b- Fm Es New ! Cf 152 International Nuclear Physics Conference 2007

  7. 208Pb,209Bi(HI,1n) reaction 1mb 100nb RIKEN 10nb 1nb 100pb 10pb 1pb 0.1pb 102 104 106 108 110 112 114 100 Atomic Number Cross sections International Nuclear Physics Conference 2007

  8. Yield – Cross section (sensitivity) Y = s×T × B × e Y= 4×10-6 /s → 1 event/3days International Nuclear Physics Conference 2007

  9. 分離装置(separator) Experimental setup nucl. reaction select the nuclei of our interest from the unwanted then transport to the detector chamber incident ion beam （粒子の流れ） GARIS 標的（金属薄膜） 加速器 検出器(detectors) accelerate ions using electric field information of energies or positions of incoming ions and their decay particles are transform to electric signal RFQ-Linac イオン源 remove electrons from neutral atoms 理研original International Nuclear Physics Conference 2007 18GHz ECR ion-source

  10. International Nuclear Physics Conference 2007

  11. Beam Energy Monitor GARIS RILAC Facility CSMAcc. Tanks RILAC Acc. Tanks RFQ-Linac 18GHz ECR Ion Source International Nuclear Physics Conference 2007

  12. RIKEN Gas-filled Recoil Separator GARIS beam Differential pumping section D1 Q1 Q2 D2 International Nuclear Physics Conference 2007

  13. PSD SSD box MCP2 ions MCP1 Focal Plane Detectors International Nuclear Physics Conference 2007

  14. International Nuclear Physics Conference 2007

  15. Experimental condition 208Pb(70Zn, n)277112 period 2004/4/2 ～ 2004/5/24 Beam Energy 346 MeV at target half depth Total Dose 4.4x1018 Target Thickness 450 μg/cm2 number of events 2 s0.44+0.59-0.29 pb Irradiation time 693 Hours (28.9 Days) Beam Intensity 1.76x1012 /s (0.3 p-mA) Counting rate ～1 cps J. Phys. Soc. Jpn., Vol. 76, No. 4, p.043201(2007) International Nuclear Physics Conference 2007

  16. Observed events at RIKEN in 208Pb + 70Zn reaction Strip #8 Strip #11 34.42 MeV 23.33 mm 35.13 MeV 18.45 mm 277112 CN 277112 CN 16-April-2004 E (70Zn) = 349.5 MeV 11.09 ± 0.07 MeV 1.10 ms 23.57 mm 11.32 ± 0.04 MeV 1.22 ms 18.31 mm 273Ds 273Ds 11.14 ± 0.04 MeV 0.52 ms 23.45 mm 11.15±0.07MeV (2nd trig. PSD+SSD) 39.9 ms 20.18 mm 269Hs 269Hs 9.17 ± 0.04 MeV 14.19 s 23.34 mm 9.25 ± 0.07 MeV(PSD+SSD) 0.270 s 19.03 mm 265Sg 265Sg 8.71 ± 0.04 MeV 23.02 s 23.45 mm 8.70 ± 0.04 MeV 79.9 s 18.05 mm 261Rf 261Rf 22-May-2004 E (70Zn) = 349.5 MeV 197.3 MeV 2.97 s 23.41 mm 156.3 MeV 8.3 s 18.50 mm International Nuclear Physics Conference 2007

  17. 32.04 MeV 18.06 mm 277112 CN Observed events at GSI in 208Pb + 70Zn reaction 11.45 MeV 280 ms 17.85 mm 24.09 MeV 26.06 mm 273Ds 277112 CN 09-Feb-1996 E(70Zn) = 343.8 MeV 11.08 MeV 110 ms 17.77 mm 11.17 MeV 1406 ms 26.03 mm 269Hs 273Ds 9.23 MeV 19.7 s 17.81 mm 11.20 MeV 310 ms 26.01 mm 265Sg 269Hs 4.60 MeV 7.4 s 17.57 mm 9.18 MeV 22.0 s 26.16 mm 261Rf 265Sg 8.52 MeV 4.7 s 17.96 mm 0.2 MeV 18.8 s 27.33 mm 257No 261Rf 05-May-2000 E (70Zn) = 346.1 MeV 8.34 MeV 15.0 s 17.91 mm 153 MeV 14.5 s 26.70 mm 253Fm International Nuclear Physics Conference 2007

  18. International Nuclear Physics Conference 2007

  19. N=165 277112 t = 1.0 ms N=163 273Ds t = 0.24 ms RIKEN N=161 GSI 269Hs t = 14 s N=159 265Sg t = 32 s N=157 261Rf t = 7.6 s 10ms 1000s 1ms 0.1s 10s International Nuclear Physics Conference 2007 T_decay/s

  20. t T1/2 277112 1.0 +1.0 ms 0.69 +0.69 ms -0.3 -0.23 273Ds 0.25 +0.25 ms 0.17 +0.17 ms -0.08 -0.06 269Hs 14 +14 s 9.7 +9.7 s -5 -3.2 265Sg 32 +32 s 22 +22 s -11 -8 261Rf 7.6 +7.6 s 5.3 +5.3 s -2.5 -1.8 International Nuclear Physics Conference 2007

  21. Summary of 209Bi + 70Zn experiment period 2003/9/5 ～ 2006/5/15 Beam Energy 5.03 AMeV 348 MeV at target half depth Total Dose 6.2x1019 Target Thickness 1.3x1018 /cm2 (0.45 mg/cm2) e_GARIS 0.8 s(2-ev.) 3.1x10-38 cm2 31 +40-20 fb Irradiation time 5776 Hours (241 Days) Beam Intensity 3.0x1012 /s (0.5 p-mA) J. Phys. Soc. Jpn., Vol. 73, No. 10, p.2593(2004) J. Phys. Soc. Jpn., Vol. 76, No. 4, p.045001(2007) International Nuclear Physics Conference 2007

  22. 5776/241 2 events Total Z=113 Z=112 International Nuclear Physics Conference 2007

  23. 20 272Ds 10 273111 4 2 s (pb) 278112 1 0.5 279113 0.3 0.2 0.1 5 10 15 20 Ex of C.N. (MeV) Calculated threshold of fission after 1n emission Masses of Beams & Targets Audi & Wapstra, Nucl. Phys A565, 1 (1993) Masses of Compound Nuclei Myers & Swiatecki, Nucl. Phys. A601, 141 (1996) International Nuclear Physics Conference 2007

  24. B + T + Ecm Sn Second chance fission sreshold Ex(CN) (A – n) + n Sn saddle point Bf Deformation A saddle point Deformation Ecm Energy diagram of 1n emission B + T International Nuclear Physics Conference 2007

  25. International Nuclear Physics Conference 2007

  26. 36.75 MeV TOF 44.61 ns 30.33 mm 36.47 MeV TOF 45.69 ns 30.08 mm 209Bi + 70Zn → 278113 + n 278113 CN 278113 CN a a 1st chain 11.68 MeV (PSD) 344μs 30.49 mm 11.52 MeV (PSD) 4.93ms 30.16 mm 23-July-2004 18:55 (JST) 274111 274111 a a 11.15 MeV 6.149+5.003 (PSD+SSD) 9.260 ms 30.40 mm 0.88+10.43=11.31 MeV (PSD+SSD) 34.3 ms 29.61 mm 270Mt 270Mt a a 10.03 MeV 1.136+8.894(PSD+SSD) 7.163 ms 29.79 mm 2.32 MeV (escape) 1.63 s 29.45 mm 266Bh 266Bh s = 31 fb a a 2nd chain 9.08 MeV (PSD) 2.469 s 30.91 mm 9.77 MeV (PSD) 1.31 s 29.65 mm 2-April-2005 2:18 (JST) 262Db 262Db 204.05 MeV(PSD) 40.9 s 30.25 mm 192.32 MeV(PSD) 0.787 s 30.47 mm International Nuclear Physics Conference 2007 s.f. s.f.

  27. N=165 278113 t = 2.6 ms N=163 274Rg t = 21.8 ms RIKEN N=161 270Mt t = 0.82 s N=159 266Bh t = 1.89 s N=157 262Db t = 20.8 s 10ms 1000s 1ms 0.1s 10s International Nuclear Physics Conference 2007 T_decay/s

  28. N=165 277112 t = 1.0 ms N=163 273Ds t = 0.24 ms RIKEN N=161 GSI 269Hs t = 14 s N=159 265Sg t = 32 s N=157 261Rf t = 7.6 s 10ms 1000s 1ms 0.1s 10s International Nuclear Physics Conference 2007 T_decay/s

  29. 5 5 a1 0 0 5 5 a2 0 0 Counts / 100 keV 5 5 Counts / bin a3 0 0 5 5 a4 a4 0 0 5 5 a5 a5 0 0 8 9 10 11 12 100ms 10ms 1s 100s 10000s E / MeV Tdecay α 252Md ← 256Lr ← 260Db ← 264Bh ← 268Mt ← 272111 α３ α５ α４ α２ α１ t=5.5ms α１ α１ α２ t=30ms α２ t=1.3s α３ α３ α４ α４ t=27s t=2.2s α５ t=27s α５ (sec) International Nuclear Physics Conference 2007 Journal of Physical Society of Japan (JPSJ) Vol. 73, (2004) 1738 - 1744

  30. Systematics by Viola & Seaborg a=1.81040, b=-21.7199, c=-0.26488, d=-28.1319 by Smolanczuk, Phys. Rev. C56(1997)812 1000 Rg Mt 100 Bh 113 10 Hindrance Factor (Texp/Tcalc) 112 Ds Hs 1 Sg Rf 0.1 156 166 162 164 158 160 neutron number International Nuclear Physics Conference 2007

  31. Summary I • 208Pb(58Fe,n)265Hs, 208Pb(64Ni,n)271Ds,209BiPb(64Ni,n)272Rg, 208Pb(70Zn,n)277112, and 209Bi(70Zn,n)278113 reactions have been studied. • Independent confirmations of synthesis of elements 108, 110, 111, and 112 • Optimum reaction energies for (HI,n) reactions were studied • New synthesis of an isotope of 113th element International Nuclear Physics Conference 2007

  32. Summary II • 278113 was produced by 209Bi(70Zn,n) reaction. • 278113(a)→274Rg(a)→270Mt(a)→266Bh(a)→262Db(SF) • Identification was based on • connected to the known decays 266Bh(a)→262Db(SF) • reaction energy systematics • cross section systematics • Z & A of 278113 are largest ones among the isotopes whose Z & A were determined experimentally. International Nuclear Physics Conference 2007

  33. ・Research in future ーScience of heavy elementsー 1)Searching for new elements 2)Spectroscopic study of heaviest elements 3)Chemistry of heaviest elements 4)Development of the new detectors for SHE study International Nuclear Physics Conference 2007

  34. Thank you for your attention. International Nuclear Physics Conference 2007

  35. International Nuclear Physics Conference 2007

  36. 1)Searching for the new elemets Z=113 cont. 209Bi + 70Zn → 278113 + n Z=114 start 208Pb + 76Ge → 283114 + n Z=115 start 209Bi + 76Ge → 284115 + n ??? Z=120 start 238U + 64Ni → 299120 + 3n GARIS upgrade cf. DUBNA 244Pu + 58Fe → 299120 + 3n International Nuclear Physics Conference 2007

  37. Calculated by Wladek Swiatecki Dec. 2005 International Nuclear Physics Conference 2007

  38. 122 308 305 121 120 302 299 208Pb+76Ge 119 118 294 293 296 117 116 293 292 291 290 238U+70Zn 115 287 288 283 284 114 286 287 288 289 290 238U+64Ni 113 278 283 284 112 277 282 284 285 286 283 238U+58Fe 111 272 274 279 280 110 271 279 281 282 273 109 268 270 275 276 108 265 267 278 272 275 269 107 264 266 272 106 263 261 265 271 105 260 262 267 268 232Th+40Ar 104 259 267 261 268 257 103 256 102 255 101 Z=120 N=184 Magic number? 100 99 98 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 International Nuclear Physics Conference 2007

  39. 122 308 305 121 120 302 299 119 118 294 293 296 117 116 293 292 291 290 115 287 288 283 284 114 286 287 288 289 290 113 278 283 284 112 277 282 284 285 286 283 111 272 274 279 280 110 271 279 281 282 273 109 268 270 275 276 108 265 267 278 272 275 269 107 264 266 272 106 263 261 265 271 105 260 262 267 268 104 259 267 261 268 257 103 256 102 255 101 100 99 98 International Nuclear Physics Conference 2007

  40. α線γ線の同時測定による励起状態の研究 113 278 111 274 Mt 270 2)Spectroscopic study of the heaviest elements Bh 266 Bh 265 International Nuclear Physics Conference 2007

  41. 3)Chemistry of the heaviest elements Using GARIS as a pre-separator for chemistry experiments excellent!! →Dr. Haba’s talk today New GARIS for ONLY Chemistry experiment use?? International Nuclear Physics Conference 2007

  42. 4)New Detector for SHE Search Independent Identifications of A & Z from decay-chain High resolution DE measurement High resolution total-E detection ?? International Nuclear Physics Conference 2007

  43. RILAC + GARIS + Chemistry AVF + newGARIS + Chemistry as a research center of Heavy Element’s Science in Asia International Nuclear Physics Conference 2007

  44. young powers! International Nuclear Physics Conference 2007

  45. International Nuclear Physics Conference 2007

  46. Rotating Target f = 300 mm, w = 3000 rpm International Nuclear Physics Conference 2007

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