Present status of the heaviest elements study using GARIS at RIKEN

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1 Present status of the heaviest elements study using GARIS at RIKEN Kosuke Morita Superheavy Element Laboratory RIKEN Nishina Center for Accelerator Based Science 2006/9/29 TASCA06 Garching,, Germany 1

2 Reactions studied at GARIS 265 Hs 10 chains Hs Bh Sg Db Rf Lr No Md Fm Es Cf Ds 14 chains Mt 111 Ds chains chains New! α SF β+ or EC β chains 2006/9/29 TASCA06 Garching,, Germany 2

3 Yield Cross section (sensitivity) Y = σ T B ε typical value Y event rate /s σ cross section cm p-barn T target thickness /cm mg/cm 2 B beam intensity /s particle ma ε efficiency 0.8 Y= /s 1 event/3days/p-barn 2006/9/29 TASCA06 Garching,, Germany 3

4 RILAC Facility CSM Acc. Tanks RILAC Acc. Tanks δv/v ~ ±0.1 % Beam Energy Monitor RFQ-Linac 18GHz ECR Ion Source GARIS Exp. room for chemistry 2006/9/29 TASCA06 Garching,, Germany 4

5 RIKEN Gas-filled Recoil Separator GARIS beam Rotating Target r 150 mm ω 2000 rpm Differential pumping section D1 Bending angle Pole gap Radius of central ray Maximum field Q1, Q2 Pole length Bore radius Maximum field gradient D2 Bending angle Pole gap Pole length Maximum Field 45 degree 150 mm 1200 mm 1.54 T 500 mm 150 mm 5.2 T/m 10 degree 160 mm 400 mm 1.04 T D1 Q1 Q2 D2 Magnification Dispersion Total length Acceptance X Y θ φ Ω cm/% 5760 mm ±68 mrad ±57 mrad 12.2 msr 2006/9/29 TASCA06 Garching,, Germany 5

6 Focal Plane Detectors PSD ions MCP1 MCP2 SSD box 2006/9/29 TASCA06 Garching,, Germany 6

7 Performance of detection system Energy / MeV 209 Bi TOF-energy spectrum Bi+ 64 Ni reaction (Main.033,( strip 13) Beam-like particles Target-like particles Counts per 10 kev ER-α correlation analysis Total Total [ ROI = 8-12MeV ] 0.5 cps 2.4x10-2 cps Anti-coincidence with TOF detectors 1.8x10-3 cps TOF / ns Lr ER-α correlation ( P=+/( =+/-1 1 mm, τ=30 s) 260 Db 264 Bh 268 Mt Light charged particles Energy / MeV 2006/9/29 TASCA06 Garching,, Germany 7

8 209 Bi + 70 Zn n 23-July :55 (JST) 262 Db α 266 Bh 1 st chain α 9.08 MeV (PSD) s mm 270 Mt α α MeV (PSD+SSD) ms mm MeV TOF ns mm CN MeV (PSD) 344 μs mm MeV (PSD+SSD) ms mm 262 Db α 266 Bh α 9.77 MeV (PSD) 1.31 s mm 270 Mt α MeV (escape) 1.63 s mm α MeV TOF ns mm CN MeV (PSD) 4.93 ms mm =11.31 MeV (PSD+SSD) 34.3 ms mm σ = 31 fb 2 nd chain 2-April :18 (JST) MeV(PSD) MeV(PSD) 2006/9/29 s.f s TASCA06 s.f s Garching,, Germany mm mm

9 Observed events at RIKEN in 208 Pb + 70 Zn reaction 16-April-2004 E ( 70 Zn) = MeV 273 Ds Strip #8 Strip # MeV mm CN ± 0.07 MeV 1.10 ms mm 273 Ds MeV mm CN ± 0.04 MeV 1.22 ms mm 269 Hs ± 0.04 MeV 0.52 ms mm 269 Hs 11.15±0.07MeV (2 nd trig. PSD+SSD) 39.9 µs mm 265 Sg 9.17 ± 0.04 MeV s mm 265 Sg 9.25 ± 0.07 MeV(PSD+SSD) s mm 261 Rf 8.71 ± 0.04 MeV s mm 261 Rf 8.70 ± 0.04 MeV 79.9 s mm 22-May-2004 E ( 70 Zn) = MeV MeV MeV /9/29 s 8.3 s TASCA06 Garching,, Germany mm mm

10 ref Ds 269 Hs 265 Sg 261 Rf 257 No GSI RIKEN FLNR ± ± ms 1.41 ms 1.10 ms 1.22 ms ± ± ms 0.31 ms 0.52 ms 0.04 ms 0.39 ms ± ± s 22.0 s 14.2 s 0.27 s ± ± s 18.8 s 23.0 s 79.9 s 158 s ± s 14.5 s 2.97 s 8.30 s s , s 384 s 17 s ref Hofmann S. et al., Z. Phys. A354, 229 (1996) Hofmann S. and Münzenberg G., Rev. Mod. Phys. 72, 733 (2000) present present Lazarev Yu. A. et al., Phys. Rev. C54, 620 (1996) Lazarev Yu. A. et al., Phys. Rev. C62, (2000) 208 Pb + 70 Zn n 208 Pb + 70 Zn n 208 Pb + 70 Zn n 208 Pb + 70 Zn n 244 Pu + 34 S 273 Ds + 5n 244 Pu + 22 Ne 261 Rf + 5n 2006/9/29 TASCA06 Garching,, Germany 10

11 3.2. Chemistry system coupled to a recoil separator Open new frontiers in SHE chemistry Gas-jet transport system coupled to GARIS in collaboration with the TASCA community at GSI (TransActinide Separator and Chemistry Apparatus) Haba et al Chemical experiments under extremely low background conditions Stable and high gas-jet transport efficiency Chemical reactions with a large variety of chemical reagents RIKEN GARIS Gas-jet transport system Differential pumping section Primary beam Evaporation residues Beam stopper Gas inlet Rotating target Focal plane Mylar window SHE nuclides He gas (with aerosol) Teflon capillary Chemistry apparatus Elastic scattering monitor D1 Q1 Q2 D2 10 cm 2006/9/ TASCA06 2 Garching, m, Germany 11

12 PSD spectrum Rn α spectrum of 255 No Beam Off Transmition eff. = 5.7 = 1.91 Tm 255 No Ra isotopes Counts / 20 kev ,213 Ra counts / 4800sec No E / kev Magnetic field / kgauss Experimental condition Reaction: 238 U( 22 Ne, 5n) 255 No, 90nb Ra isotopes and its daughter were observed. Beam energy: MeV nat Pt( 22 Ne, xn)ra reaction Recoil energy: 9.6 MeV Beam intensity: 4 pμa But these isotopes can be separated by GARIS Magnetic rigidity: Tm system at Bρ = 1.91 Tm 2006/9/29 He pressure: 38 Pa TASCA06 Garching,, Germany 12

13 Transmission efficiency of GARIS transmission (%) U+ 22 Ne 255 No+5n 5.6% 265 Hs 208 Pb 204 Fr 245 Fm 209 Bi 255 Lr 254 No: 208 Pb+ 48 Ca 254 No+2n v/v 0 (137β) 2006/9/29 TASCA06 Garching,, Germany 13

14 Positional Distribution at Focal Plane P(He) = 67 Pa (0.5Torr) L = 500 cm Position (mm) Bi(.0.11AMeV) Pb(0.26AMeV) simulation simulation 2006/9/29 TASCA06 Garching,, Germany 14

15 x 1/ e = n coll θ av l 2 l 3 2 n coll = l ρ σ eff l : total _ length σeff : effective _ cross _ section ρ : numver _ decsity _ of _ gas _ atom θ av : averaged _ deflection _ angel _ of _ one _ collision 2006/9/29 TASCA06 Garching,, Germany 15

16 NN2003 at Moscow 18Jun2003 projectile target recoil compound nucleus system 208 Pb + 58 Fe 208 Pb + 64 Ni 208 Pb + 70 Zn E MeV β Bρ Tm E MeV β Bρ Tm E MeV β Bρ Tm energy separator velocity separator gas-filled separator Ep/Ecn Er/Ecn βp/ p/βcn βr/ r/βcn Bρp/B p/bρcn Bρr/B r/bρcn /9/29 TASCA06 Garching,, Germany 16

17 RIBF in Future GARIS_new 2006/9/29 TASCA06 Garching,, Germany 17

18 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. RNC Superheavy Element Laboratory 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 2006/9/29 TASCA06 Garching,, Germany 18

19 young powers! 2006/9/29 TASCA06 Garching,, Germany 19

20 Thank you for your attention. address: 2006/9/29 TASCA06 Garching,, Germany 21