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

2007/6/5 International Nuclear Physics Conference 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

2007/6/5 International Nuclear Physics Conference Rg Ds Mt Hs Bh Sg Db Rf SHE A A A  -decay Spontaneous fission  + or EC decay one end of nuclear chart ‘84

2007/6/5 International Nuclear Physics Conference Rg Ds Mt Hs Bh Sg Db Rf SHE A A A  -decay Spontaneous fission  + or EC decay one end of nuclear chart 2007

2007/6/5 International Nuclear Physics Conference Hs Bh Sg Db Rf Lr No Md Fm Es Cf Bk Cm Am Pu Np U Rg Ds Mt neutron capture +  -decay cold fusion reaction hot fusion reaction 48Ca induced reactions

2007/6/5 International Nuclear Physics Conference Ds Mt Hs Bh Sg Db Rf Lr No Md Es Cf Fm  SF  + or EC - Reactions studied at GARIS 265 Hs 10 chains chains 271 Ds 14 chains 272 Rg 14 chains 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) Bi( 70 Zn, n)

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

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

2007/6/5 International Nuclear Physics Conference 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

2007/6/5 International Nuclear Physics Conference

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

2007/6/5 International Nuclear Physics Conference 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

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

2007/6/5 International Nuclear Physics Conference

2007/6/5 International Nuclear Physics Conference 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  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) J. Phys. Soc. Jpn., Vol. 76, No. 4, p (2007)

2007/6/5 International Nuclear Physics Conference Ds 269 Hs 265 Sg 261 Rf CN ± 0.07 MeV 1.10 ms mm ± 0.04 MeV 0.52 ms mm 9.17 ± 0.04 MeV s mm 8.71 ± 0.04 MeV s mm MeV 2.97 s mm MeV mm 16-April-2004 E ( 70 Zn) = MeV Observed events at RIKEN in 208 Pb + 70 Zn reaction Ds 269 Hs 265 Sg 261 Rf CN ± 0.04 MeV 1.22 ms mm 11.15±0.07MeV (2 nd trig. PSD+SSD) 39.9  s mm 9.25 ± 0.07 MeV(PSD+SSD) s mm 8.70 ± 0.04 MeV 79.9 s mm MeV 8.3 s mm MeV mm 22-May-2004 E ( 70 Zn) = MeV Strip #8Strip #11

2007/6/5 International Nuclear Physics Conference Ds 269 Hs 265 Sg 261 Rf 257 No 253 Fm CN MeV 280  s mm MeV 110  s mm 9.23 MeV 19.7 s mm 4.60 MeV 7.4 s mm 8.52 MeV 4.7 s mm 8.34 MeV 15.0 s mm MeV mm Ds 269 Hs 265 Sg 261 Rf CN MeV 1406  s mm MeV 310  s mm 9.18 MeV 22.0 s mm 0.2 MeV 18.8 s mm 153 MeV 14.5 s mm MeV mm 09-Feb-1996 E( 70 Zn) = MeV 05-May-2000 E ( 70 Zn) = MeV Observed events at GSI in 208 Pb + 70 Zn reaction

2007/6/5 International Nuclear Physics Conference ref. 1Hofmann S. et al., Z. Phys. A354, 229 (1996) 208 Pb + 70 Zn → n 2Hofmann S. and M ü nzenberg G., Rev. Mod. Phys. 72, 733 (2000) 208 Pb + 70 Zn → n 3present 208 Pb + 70 Zn → n 4present 208 Pb + 70 Zn → 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, (2000) 244 Pu + 22 Ne → 261 Rf + 5n GSIRIKENFLNR ref ± ± ms1.41 ms1.10 ms1.22 ms 273 Ds ± ± ms0.31 ms0.52 ms0.04 ms0.39 ms 269 Hs ± ± s22.0 s14.2 s0.27 s 265 Sg ± ± s18.8 s23.0 s79.9 s158 s 261 Rf ± s14.5 s2.97 s8.30 s s 257 No , s384 s17 s

2007/6/5 International Nuclear Physics Conference  s 1ms 0.1s 10s 1000s  = 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

2007/6/5 International Nuclear Physics Conference Ds 269 Hs 265 Sg 261 Rf ms s ms s s ms s ms s s  T 1/2

2007/6/5 International Nuclear Physics Conference 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.)3.1x cm 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 (2007) J. Phys. Soc. Jpn., Vol. 73, No. 10, p.2593(2004)

2007/6/5 International Nuclear Physics Conference yearstartstophours /days dose/sum [x ]  [fb] error+error /512/291389/ / (upper limit) 20047/88/2526/ / /201/2372/ / /234/22650/ / /195/2148/ / /78/25386/ / /710/20937/ / /2512/15469/ / /145/151300/ / /241 Total 2 events 20044/25/24694/ Z=112 Z=113

2007/6/5 International Nuclear Physics Conference 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 Ex of C.N. (MeV)  (pb) 272 Ds

2007/6/5 International Nuclear Physics Conference 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)

2007/6/5 International Nuclear Physics Conference

2007/6/5 International Nuclear Physics Conference Mt 266 Bh CN MeV (PSD) 344 μs mm MeV (PSD+SSD) ms mm MeV (PSD+SSD) ms mm 9.08 MeV (PSD) s mm MeV TOF ns mm 23-July :55 (JST)     1 st chain 262 Db MeV(PSD) 40.9 s mm Mt 266 Bh CN MeV (PSD) 4.93 ms mm =11.31 MeV (PSD+SSD) 34.3 ms mm 2.32 MeV (escape) 1.63 s mm 9.77 MeV (PSD) 1.31 s mm MeV TOF ns mm 2-April :18 (JST) 209 Bi + 70 Zn → n     262 Db MeV(PSD) s mm 2 nd chain s.f.  = 31 fb

2007/6/5 International Nuclear Physics Conference  s 1ms 0.1s 10s 1000s  = 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

2007/6/5 International Nuclear Physics Conference  s 1ms 0.1s 10s 1000s  = 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

2007/6/5 International Nuclear Physics Conference Md ← 256 Lr ← 260 Db ← 264 Bh ← 268 Mt ←  =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)

2007/6/5 International Nuclear Physics Conference Hindrance Factor (T exp /T calc ) Systematics by Viola & Seaborg a= , b= , c= , d= by Smolanczuk, Phys. Rev. C56(1997) Ds Hs Sg Rf 113 Rg Mt Bh neutron number

2007/6/5 International Nuclear Physics Conference 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) , and 209 Bi( 70 Zn,n) 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

2007/6/5 International Nuclear Physics Conference Summary II was produced by 209 Bi( 70 Zn,n) reaction (  )→ 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 are largest ones among the isotopes whose Z & A were determined experimentally.

2007/6/5 International Nuclear Physics Conference ・ 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

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

2007/6/5 International Nuclear Physics Conference

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

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

2007/6/5 International Nuclear Physics Conference

2007/6/5 International Nuclear Physics Conference

2007/6/5 International Nuclear Physics Conference )Spectroscopic study of the heaviest elements 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

2007/6/5 International Nuclear Physics Conference )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??

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

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

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

2007/6/5 International Nuclear Physics Conference

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