1. 2007/6/5 International Nuclear Physics Conference 2007 1 Experiments on Searching for the Heaviest Elements Kosuke Morita Superheavy Element Laboratory RIKEN Nishina Center, RIKEN

2. 2007/6/5 International Nuclear Physics Conference 2007 2 共同研究者 collaborators K. MorimotoRIKEN H. HabaRIKEN A. YonedaRIKEN D. KajiRIKEN T. IchikawaRIKEN H. KikunagaRIKEN T. AkiyamaRIKEN, Saitama U. N. SatoRIKEN, Tohoku U. A. YoshidaRIKEN T. SudaRIKEN T. OhnishiRIKEN K. Rituparna TRIUMF K. KatoriRIKEN E. IdeguchiCNS Univ. of Tokyo T. YamagichiSaitama U. S. Goto Niigata U. H. Kudo Niigata U. A. OzawaUniv. of Tsukuba K. Sueki Univ. of Tsukuba H. KouraJAEA F. TokanaiYamagata U. Y-.L. ZhaoIHEP/Beijing H.-S. XuIMP/Lanzhou RNC Superheavy Element Laboratory

3. 2007/6/5 International Nuclear Physics Conference 2007 3 120 119 118 117 116 115 114 113 112 Rg Ds Mt Hs Bh Sg Db Rf 162 184 262 266 265 264 262 261 260 259 258 257 258260259 260 261 262 263 262 261 SHE A A A  -decay Spontaneous fission  + or EC decay one end of nuclear chart ‘84

4. 2007/6/5 International Nuclear Physics Conference 2007 4 120 119 118 117 116 115 114 113 112 Rg Ds Mt Hs Bh Sg Db Rf 162 184 262 266 265 264 262 261 260 259 258 257 258260259 260 261 262 263 262 261 263 265266 267266 259 264 269270271 267 266 262 272 268 269 270271 277 278 273 274 261 270 265 263 264 267 268 271 272 271 275 276 275 279 280 279 278 281 284 285 286 282 283 284 283 287 288 289 290 286 287 288 290 291 292 293 294 SHE A A A  -decay Spontaneous fission  + or EC decay one end of nuclear chart 2007

5. 2007/6/5 International Nuclear Physics Conference 2007 5 Hs Bh Sg Db Rf Lr No Md Fm Es Cf Bk Cm Am Pu Np U Rg Ds Mt 238 239 240 241242243 244 240242 240 241242243 244 247 245 246 248 245 246 247 246 247 242243 244 247248 249 250 251 248 249 250 251 249 250 251 253 252 254 255 256 257 255 254253 245 243 244 241 255 254 253 252 251 250 249 248 247 246 245 244 252 251 250 249 248 247 246 245 247 246 245 244 246 245 244 243 242 255 254 253 252 251 250 257 256 255 254 253 252 257 256 258 257 259 258 260 261 259 258 260 261 260 246 244 248 247 250 252 251 247 249 248 253 255 254 250 252 251 253 255 254 252 256 253 255 254 256 257 255 256 257 258 259 260 261 262 264 265 267 266 269 270 271 266 262 272 268 277 262 273 261 273 269 265 266 270 271 262 263 261 260 259 258 259 262 260 259 262 258 259 265 256 257 278 274 270 266 262 272 268 264 260 256 271 269 263 259 253 265 261 257 253 113 112 271 272 267 268 275 276 279 280 278 281 282 283 284 282285 284 286 150 162 neutron capture +  -decay cold fusion reaction hot fusion reaction 48Ca induced reactions

6. 2007/6/5 International Nuclear Physics Conference 2007 6 116 115 114 113 112 111 Ds Mt Hs Bh Sg Db Rf Lr No Md Es Cf Fm 162 152  SF  + or EC -- 170 176 Reactions studied at GARIS 265 Hs 10 chains 277 112 2 chains 271 Ds 14 chains 272 Rg 14 chains 278 113 New ! 208 Pb( 58 Fe, n) 265 Hs 208 Pb( 64 Ni, n) 271 Ds 209 Bi( 64 Ni, n) 272 Rg 208 Pb( 70 Zn, n) 277 112 209 Bi( 70 Zn, n) 278 113

7. 2007/6/5 International Nuclear Physics Conference 2007 7 Cross sections 100 102104106108110112114 Atomic Number 1b1b 1nb 10nb 100nb 100pb 10pb 1pb 0.1pb 208 Pb, 209 Bi(HI,1n) reaction RIKEN

8. 2007/6/5 International Nuclear Physics Conference 2007 8 Yield – Cross section (sensitivity) Y =  ×T × B ×  typical value Yevent rate/s  cross sectioncm 2 10 -36 1 p-barn Ttarget thickness/cm 2 1.3×10 18 450  g/cm 2 Bbeam intensity/s4×10 12 0.65 particle  A  efficiency0.8 Y= 4×10 -6 /s → 1 event/3days

9. 2007/6/5 International Nuclear Physics Conference 2007 9 select the nuclei of our interest from the unwanted then transport to the detector chamber Experimental setup 標的（金属薄膜） incident ion beam （粒子の流れ） イオン源 加速器 分離装置 (separator) 検出器 (detectors) nucl. reaction remove electrons from neutral atoms accelerate ions using electric field information of energies or positions of incoming ions and their decay particles are transform to electric signal 18GHz ECR ion-source 理研 original RFQ-Linac GARIS

10. 2007/6/5 International Nuclear Physics Conference 2007 10

11. 2007/6/5 International Nuclear Physics Conference 2007 11 RILAC Facility 18GHz ECR Ion Source RFQ-Linac CSM Acc. Tanks RILAC Acc. Tanks GARIS Beam Energy Monitor

12. 2007/6/5 International Nuclear Physics Conference 2007 12 beam Differential pumping section D1 Bending angle45 degree Pole gap150 mm Radius of central ray1200 mm Maximum field1.54 T Q1, Q2 Pole length500 mm Bore radius150 mm Maximum field gradient5.2 T/m D2 Bending angle10 degree Pole gap160 mm Pole length400 mm Maximum Field1.04 T MagnificationX-0.76 Y-1.99 Dispersion0.97 cm/% Total length5760 mm Acceptance  ±68 mrad  ±57 mrad  12.2 msr Rotating Target r150 mm  2000 rpm RIKEN Gas-filled Recoil Separator GARIS D1 Q1 Q2 D2

13. 2007/6/5 International Nuclear Physics Conference 2007 13 MCP1 MCP2 SSD box PSD ions Focal Plane Detectors

14. 2007/6/5 International Nuclear Physics Conference 2007 14

15. 2007/6/5 International Nuclear Physics Conference 2007 15 period2004/4/2 ～ 2004/5/24 Beam Energy346 MeV at target half depth Total Dose4.4x10 18 Target Thickness450 μg/cm 2 number of events2  0.44 +0.59 -0.29 pb Irradiation time693 Hours(28.9 Days) Beam Intensity1.76x10 12 /s(0.3 p-  A) Counting rate ～ 1 cps Experimental condition 208 Pb( 70 Zn, n) 277 112 J. Phys. Soc. Jpn., Vol. 76, No. 4, p.043201(2007)

16. 2007/6/5 International Nuclear Physics Conference 2007 16 277 112 273 Ds 269 Hs 265 Sg 261 Rf CN 11.09 ± 0.07 MeV 1.10 ms 23.57 mm 11.14 ± 0.04 MeV 0.52 ms 23.45 mm 9.17 ± 0.04 MeV 14.19 s 23.34 mm 8.71 ± 0.04 MeV 23.02 s 23.45 mm 197.3 MeV 2.97 s 23.41 mm 34.42 MeV 23.33 mm 16-April-2004 E ( 70 Zn) = 349.5 MeV Observed events at RIKEN in 208 Pb + 70 Zn reaction 277 112 273 Ds 269 Hs 265 Sg 261 Rf CN 11.32 ± 0.04 MeV 1.22 ms 18.31 mm 11.15±0.07MeV (2 nd trig. PSD+SSD) 39.9  s 20.18 mm 9.25 ± 0.07 MeV(PSD+SSD) 0.270 s 19.03 mm 8.70 ± 0.04 MeV 79.9 s 18.05 mm 156.3 MeV 8.3 s 18.50 mm 35.13 MeV 18.45 mm 22-May-2004 E ( 70 Zn) = 349.5 MeV Strip #8Strip #11

17. 2007/6/5 International Nuclear Physics Conference 2007 17 277 112 273 Ds 269 Hs 265 Sg 261 Rf 257 No 253 Fm CN 11.45 MeV 280  s 17.85 mm 11.08 MeV 110  s 17.77 mm 9.23 MeV 19.7 s 17.81 mm 4.60 MeV 7.4 s 17.57 mm 8.52 MeV 4.7 s 17.96 mm 8.34 MeV 15.0 s 17.91 mm 32.04 MeV 18.06 mm 277 112 273 Ds 269 Hs 265 Sg 261 Rf CN 11.17 MeV 1406  s 26.03 mm 11.20 MeV 310  s 26.01 mm 9.18 MeV 22.0 s 26.16 mm 0.2 MeV 18.8 s 27.33 mm 153 MeV 14.5 s 26.70 mm 24.09 MeV 26.06 mm 09-Feb-1996 E( 70 Zn) = 343.8 MeV 05-May-2000 E ( 70 Zn) = 346.1 MeV Observed events at GSI in 208 Pb + 70 Zn reaction

18. 2007/6/5 International Nuclear Physics Conference 2007 18 ref. 1Hofmann S. et al., Z. Phys. A354, 229 (1996) 208 Pb + 70 Zn → 277 112 + n 2Hofmann S. and M ü nzenberg G., Rev. Mod. Phys. 72, 733 (2000) 208 Pb + 70 Zn → 277 112 + n 3present 208 Pb + 70 Zn → 277 112 + n 4present 208 Pb + 70 Zn → 277 112 + n 5Lazarev Yu. A. et al., Phys. Rev. C54, 620 (1996) 244 Pu + 34 S → 273 Ds + 5n 6Lazarev Yu. A. et al., Phys. Rev. C62, 064307(2000) 244 Pu + 22 Ne → 261 Rf + 5n GSIRIKENFLNR ref.123456 277 11211.4511.1711.09±.0711.32±.04 0.28 ms1.41 ms1.10 ms1.22 ms 273 Ds11.0811.2011.14±.0411.15±.0711.35 0.11 ms0.31 ms0.52 ms0.04 ms0.39 ms 269 Hs9.239.189.17±.049.25±.07 19.7 s22.0 s14.2 s0.27 s 265 Sg4.600.208.71±.048.70±.048.63 74.0 s18.8 s23.0 s79.9 s158 s 261 Rf8.521531971568.30±0.06 4.70 s14.5 s2.97 s8.30 s54 +8 -4 s 257 No8.348.228.24, 8.34 15.0 s384 s17 s

19. 2007/6/5 International Nuclear Physics Conference 2007 19 10  s 1ms 0.1s 10s 1000s 277 112  = 1.0 ms 273 Ds  = 0.24 ms 269 Hs  = 14 s 265 Sg  = 32 s 261 Rf  = 7.6 s T_decay/s RIKEN GSI N=165 N=163 N=161 N=159 N=157

20. 2007/6/5 International Nuclear Physics Conference 2007 20 0.25 14 1.0 32 7.6 277 112 273 Ds 269 Hs 265 Sg 261 Rf ms +0.25 -0.08 s +14 -5 ms +1.0 -0.3 s +32 -11 s +7.6 -2.5 0.69ms +0.69 -0.23 9.7s +9.7 -3.2 0.17ms +0.17 -0.06 22s +22 -8 5.3s +5.3 -1.8  T 1/2

21. 2007/6/5 International Nuclear Physics Conference 2007 21 period2003/9/5 ～ 2006/5/15 Beam Energy5.03 AMeV 348 MeV at target half depth Total Dose6.2x10 19 Target Thickness1.3x10 18 /cm 2 (0.45 mg/cm 2 )  _GARIS0.8  (2-ev.)3.1x10 -38 cm 2 31 +40 -20 fb Irradiation time5776 Hours(241 Days) Beam Intensity3.0x10 12 /s(0.5 p-  A) Summary of 209 Bi + 70 Zn experiment J. Phys. Soc. Jpn., Vol. 76, No. 4, p.045001(2007) J. Phys. Soc. Jpn., Vol. 73, No. 10, p.2593(2004)

22. 2007/6/5 International Nuclear Physics Conference 2007 22 yearstartstophours /days dose/sum [x 10 19 ]  [fb] error+error- 20039/512/291389/57.91.24/1.2475.3(upper limit) 20047/88/2526/21.90.51/1.755513045 20051/201/2372/3.00.07/1.825212043 3/234/22650/27.10.71/2.537510049 5/195/2148/2.00.05/2.58749848 8/78/25386/16.10.45/3.03638340 9/710/20937/39.01.17/4.20455929 11/2512/15469/19.50.63/4.83395125 20063/145/151300/54.21.37/6.20314020 5776/241 Total 2 events 20044/25/24694/28.90.44440590290 Z=112 Z=113

23. 2007/6/5 International Nuclear Physics Conference 2007 23 Masses of Beams & Targets Audi & Wapstra, Nucl. Phys A565, 1 (1993) Masses of Compound Nuclei Myers & Swiatecki, Nucl. Phys. A601, 141 (1996) Calculated threshold of fission after 1n emission 5 10 15 20 Ex of C.N. (MeV) 20 10 4 2 1 0.5 0.3 0.2 0.1  (pb) 272 Ds 273 111 278 112 279 113

24. 2007/6/5 International Nuclear Physics Conference 2007 24 SnSn (A – n) + n A B + T B + T + Ecm SnSn saddle point Deformation BfBf Second chance fission sreshold saddle point Deformation Energy diagram of 1n emission Ecm Ex(CN)

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26. 2007/6/5 International Nuclear Physics Conference 2007 26 278 113 274 111 270 Mt 266 Bh CN 11.68 MeV (PSD) 344 μs 30.49 mm 11.15 MeV 6.149+5.003 (PSD+SSD) 9.260 ms 30.40 mm 10.03 MeV 1.136+8.894(PSD+SSD) 7.163 ms 29.79 mm 9.08 MeV (PSD) 2.469 s 30.91 mm 36.75 MeV TOF 44.61 ns 30.33 mm 23-July-2004 18:55 (JST)     1 st chain 262 Db 204.05 MeV(PSD) 40.9 s 30.25 mm 278 113 274 111 270 Mt 266 Bh CN 11.52 MeV (PSD) 4.93 ms 30.16 mm 0.88+10.43=11.31 MeV (PSD+SSD) 34.3 ms 29.61 mm 2.32 MeV (escape) 1.63 s 29.45 mm 9.77 MeV (PSD) 1.31 s 29.65 mm 36.47 MeV TOF 45.69 ns 30.08 mm 2-April-2005 2:18 (JST) 209 Bi + 70 Zn → 278 113 + n     262 Db 192.32 MeV(PSD) 0.787 s 30.47 mm 2 nd chain s.f.  = 31 fb

27. 2007/6/5 International Nuclear Physics Conference 2007 27 10  s 1ms 0.1s 10s 1000s 278 113  = 2.6 ms 274 Rg  = 21.8 ms 270 Mt  = 0.82 s 266 Bh  = 1.89 s 262 Db  = 20.8 s T_decay/s RIKEN N=165 N=163 N=161 N=159 N=157

28. 2007/6/5 International Nuclear Physics Conference 2007 28 10  s 1ms 0.1s 10s 1000s 277 112  = 1.0 ms 273 Ds  = 0.24 ms 269 Hs  = 14 s 265 Sg  = 32 s 261 Rf  = 7.6 s T_decay/s RIKEN GSI N=165 N=163 N=161 N=159 N=157

29. 2007/6/5 International Nuclear Physics Conference 2007 29 252 Md ← 256 Lr ← 260 Db ← 264 Bh ← 268 Mt ← 272 111  =5.5ms  =30ms  =1.3s  =2.2s  =27s α３ α３ α５α５ α４ α４ α２ α２ α１α１ (sec) α１α１ α１α１ α２α２ α２α２ α３α３ α３α３ α４α４ α４α４ α５α５ α５α５  =27s Journal of Physical Society of Japan (JPSJ) Vol. 73, (2004) 1738 - 1744

30. 2007/6/5 International Nuclear Physics Conference 2007 30 Hindrance Factor (T exp /T calc ) Systematics by Viola & Seaborg a=1.81040, b=-21.7199, c=-0.26488, d=-28.1319 by Smolanczuk, Phys. Rev. C56(1997)812 112 Ds Hs Sg Rf 113 Rg Mt Bh neutron number 166 164162 160158 0.1 156 1 10 100 1000

31. 2007/6/5 International Nuclear Physics Conference 2007 31 Summary I 208 Pb( 58 Fe,n) 265 Hs, 208 Pb( 64 Ni,n) 271 Ds, 209Bi Pb( 64 Ni,n) 272 Rg, 208 Pb( 70 Zn,n) 277 112, and 209 Bi( 70 Zn,n) 278 113 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

32. 2007/6/5 International Nuclear Physics Conference 2007 32 Summary II 278 113 was produced by 209 Bi( 70 Zn,n) reaction. 278 113(  )→ 274 Rg(  )→ 270 Mt(  )→ 266 Bh(  )→ 262 Db(SF) Identification was based on –connected to the known decays 266 Bh(  )→ 262 Db(SF) –reaction energy systematics –cross section systematics Z & A of 278 113 are largest ones among the isotopes whose Z & A were determined experimentally.

33. 2007/6/5 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

34. 2007/6/5 International Nuclear Physics Conference 2007 34 Thank you for your attention.

35. 2007/6/5 International Nuclear Physics Conference 2007 35

36. 2007/6/5 International Nuclear Physics Conference 2007 36 1)Searching for the new elemets Z=113cont. 209 Bi + 70 Zn → 278 113 + n Z=114start 208 Pb + 76 Ge → 283 114 + n Z=115start 209 Bi + 76 Ge → 284 115 + n ??? Z=120start 238 U + 64 Ni → 299 120 + 3n GARIS upgrade cf. DUBNA 244 Pu + 58 Fe → 299 120 + 3n

37. 2007/6/5 International Nuclear Physics Conference 2007 37 Calculated by Wladek Swiatecki Dec. 2005

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40. 2007/6/5 International Nuclear Physics Conference 2007 40 2)Spectroscopic study of the heaviest elements 113 278 111 274 Mt 270 Bh 266 Bh 265 α 線 γ 線の同時測定による励起状態の研究

41. 2007/6/5 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??

42. 2007/6/5 International Nuclear Physics Conference 2007 42 4)New Detector for SHE Search Independent Identifications of A & Z from decay-chain High resolution  E measurement High resolution total-E detection ??

43. 2007/6/5 International Nuclear Physics Conference 2007 43 RILAC + GARIS + Chemistry AVF + newGARIS + Chemistry as a research center of Heavy Element’s Science in Asia

44. 2007/6/5 International Nuclear Physics Conference 2007 44 young powers!

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46. 2007/6/5 International Nuclear Physics Conference 2007 46 Rotating Target  = 300 mm,  = 3000 rpm