1. Preparation of gas-chemistry of Dubnium at IMP Z. Qin, J.S. Guo, X.L. Wu, H.J.Ding, W.X.Huang, Z.G. Gan, Institute of Modern Physics, Chinese Academy of Sciences,

2. content 1. Study of Transactinides by rotating wheel. 2. Preparation of Gas-chemistry for SHE.

3. ? 241 Am( 22 Ne, 4n) 259 Db ? Partial chart of nuclide 243 Am( 26 Mg, 4n) 265 Bh

4. Energy constant: K ~ 70 (E k ~6-7MeV/A) Intensity: ~ 3×10 13 pps (C-Ne) ~ 5×10 12 pps (Mg-Ar) SFC: Sector Focusing Cyclotron, HIRFL

5. 22 Ne 241 Am Fusion 263 Db* 259 Db Hot fusion reaction

6. 0.8 µA 118 MeV 22 Ne 5+ Improved Rotating Wheel system Transportation time≈ 0.3 s efficiency ≈ 50% He-NaCl-jet 241 Am(910  g/cm 2 ) + Al(1.7mg/cm 2 ) NaCl 259 Db Recoil chamber A-1 A-2 B-1 C-1 A-3 B-2 D-1 B-3 D-3 C-2 D-2 C-3

7. 259 Db  -spectrum of the reaction 22 Ne + 241 Am 255 Lr

8. Decay-curve of 258,259 Db and their daughter 254,255 Lr 258 Db E  = 9.08, 9.17, 9.30 MeV T 1/2 = 4.3±1.1s 254 Lr E  = 8.46 MeV T 1/2 = 13.4±4.2s, 258 Db T 1/2 = 4.3±1.4s

9. 241 Am( 22 Ne,4~5n) 258,259 Db 258 Db 4.4 s 4n 5n 9.17 9.08 9.01 9.47 8.46 8.41 8.37 8.41 259 Db 0.5 s 254 Lr 13 s 255 Lr 21 s Z.G. Gan, Z.Qin, H.M. Fan, et al., Eur. Phys. J., A10(2001)21

10. Rotating Multi-detector Arrays( ROMA)

11.  -spectrum of the reaction 26 Mg + 243 Am at energy of 168 MeV

12. Paren t  1 / keV t 1 / ms Daught er  2 / keV t 2 / ms Grand- daught er  3 / keV t 3 / ms 265 Bh 92681736 261 Db 90064860 265 Bh 93001015 261 Db 8924224 257 Lr 89054639 265 Bh 9219574 261 Db 89211898 257 Lr 88871405 265 Bh 9274193 261 Db 89185834 265 Bh 92221140 261 Db 8942436 265 Bh 91791933 261 Db 89021523 265 Bh 92452547 261 Db 88691608 265 Bh 91991334 261 Db 89273480 264 Bh 9440555 260 Db 89882686 264 Bh 95012770 260 Db 90851378 264 Bh 95241203 260 Db 9003259 264 Bh 94812321 260 Db 9098975  -  correlation events observed from 243 Am( 26 Mg,4~5n) 264,265 Bh

13. 243 Am( 26 Mg,4~5n) 264,265 Bh Z.G. Gan, J.S.Guo, X.L.Wu, Z.Qin, et al., Eur. Phys. J., A20(2004)385 264 Bh 1 s 4n 5n 9.48 9.62 9.24 9.04 9.07 9.12 8.93 265 Bh 0.9 s 260 Db 1.5 s 261 Db 1.8 s 257 Lr 0.65 s 8.86 8.80 Q  = 9.38 MeV RMF calculation Q  = 9.41 MeV

14. 22 Ne+ 249 Bk 271 Bh* Berkeley, PRL, 85 (2000)2697 Beam: 300 particle nA Energy: 117, 123 MeV Time: 62h Dose: 4×10 17 One Events of 266 Bh: E  =9.29 MeV life-time:0.87s

15. Preliminary!! 278 113 274 Rg 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 1 st chain July 23, 2004 18:55 (JST) Morita et al.:JPSJ 73, 2593 (2004). α α α α 262 Db 204.05 MeV(PSD) 40.9 s 30.25 mm 278 113 274 Rg 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 nd chain April 2, 2005 2:18 (JST) Decay chains of 278 113 α α α α 262 Db 192.32 MeV(PSD) 0.787 s 30.47 mm SF σ = 39 +53 -25 fb 209 Bi + 70 Zn → 278 113 + n

16. HIVAP calculation

17. Beam energy: 162 MeV 26 Mg 8+ Beam energy: 162 MeV 26 Mg 8+ Beam intensity: 2 e  A Target: 1.2 mg/cm 2 243 Am Transport efficiency: 50% Detector efficiency: 30% Stepping time: Mother Mode:4s, Daughter Mode:60s Irradiation time: 200h Experiment condition

18.  -spectrum of the reaction 26 Mg + 243 Am at energy of 162 MeV

19.  -  correlation events observed from 243 Am( 26 Mg,3n) 266 Bh Event No.E  1 /MeV  t 1 /s E  2 /MeV  t 2 /s E  1 /MeV  t 3 /s 18.9891.138.45933.62 29.1280.888.67633.84 39.0710.798.60434.14 48.9590.518.54229.238.6415.07 -  correlation energy window: 8.5-10 MeV Daughter life-time window: 20-60s

20. 243 Am( 26 Mg,3n) 266 Bh 266 Bh ~0.9 s 262 Db 34 s 258 Lr 4 s 9.04 8.45 8.53 8.67 8.60 8.62 8.57 8.65

21. LBL RIKEN 1 st RIKEN 2 nd This work E  (MeV) 9.29 9.08 9.77 9.04 Lifetime (s) 0.87 2.469 1.31 0.9 Decay properties of 266 Bh

22. Comparison of Q  value from the experiment with Macro-micro Model

24. Production of Dubnium: 243 Am( 20 Ne, 4~5n) 258, 259 Db 258 Db: T 1/2 = 4.4s, E  = 9.17, 9.08, 9.01 MeV Carrier gas: He/KBr Reaction gas: HBr Gas-chemistry: OLGA-III Detection: Rotating wheel system

25. On-line gas chemistry Apparatus OLGA-III

26. Summary 1. Two new isotopes of 259 Db and 265 Bh were synthesized 2.The known isotope of 266 Bh was studied, and E  close to the RIKEN first chain. 3. Db gas chemistry is under going.

27. Thank you for attention