1. 1 CNS summer school 2002 The RI-Beam Factory and Recent Development in Superheavy Elements Search at RIKEN ◆ Brief introduction to the RI Beam Factory ◆ Confirmation of 271 [110] and discovery of a new transuranium isotope 234 Bk Isao Tanihata RIKEN

2. 2 CNS summer school 2002 RIBF is a multi-disciplinary facility ◆ Nuclear Physics ◆ Nuclear Astrophysics ◆ Atomic Physics ◆ Material Science ◆ Nuclear Chemistry ◆ Biology ◆ Medicine ◆ Nuclear Power

3. 3 CNS summer school 2002 Nuclear Physics ◆ Probe the limit of nuclear existence and to understand the basic physics of the nuclear landscape ■ Exploration of the limit of existence Drip-line nuclei Nuclei outside the drip lines Superheavy nuclei ■ Magic numbers far from the stability ■ Study of unbalanced nuclear matter and the role of isospin ◆ Explore the new forms and dynamics of nuclei ■ Neutron skins & halos Also excitations and correlation ■ Exotic shapes ◆ Testing of the Standard model and fundamental symmetries and conservation laws

4. 4 CNS summer school 2002 Nuclear Astrophysics ◆ Provide the basic data of nuclear astrophysics ■ Big bang nucleosynthesis ■ The CNO cycle to the rp-process ■ Alpha-rich freeze out ■ The r-process ■ Equation of state of asymmetric matter and neutron stars ■ Highly ionized atoms of unstable nuclei ■ Remarks The measurement and the analysis of the nuclei far from stability will provide new test benches for theoretical nuclear models. This should allow one to reformulate these models in a more general form. Hence, the predictive power of these models, when applied to unknown nuclei for nuclear astrophysics applications, will be greatly increased.

5. 5 CNS summer school 2002 Bird Eye View of RIBF 2005

6. 6 CNS summer school 2002 The Beam Delivering Method ◆ AVF cyclotron --> will become free ■ CNS/RIKEN ◆ Present facility --> primary and secondary beam from ISR ◆ BigRIPS --> two experimental beam lines ◆ MUSES --> ACR, DSR

7. 7 CNS summer school 2002 Accelerator Scheme Accelerators ECR18 RILAC CMS RRCfRC IRC SRC RFQ linac

8. 8 CNS summer school 2002 Primary Beam Energy @RIBF 1 pµA for all elements With fRC

9. 9 CNS summer school 2002 IRC Sector magnet

10. 10 CNS summer school 2002 SRC design

11. 11 CNS summer school 2002 ECRIS-18

12. 12 CNS summer school 2002 ECRIS-18 Beam Intensity

13. 13 CNS summer school 2002 RI Beam Separators (Big-RIPS)

14. 14 CNS summer school 2002 Production Target

15. 15 CNS summer school 2002 R.T. Test Result

16. 16 CNS summer school 2002 Rotating Target Extension ◆ Changing target thickness in one rotation ■ 6000 rpm -> 1 rotation = 10 ms -> 10˚=0.27 ms ■ Control of 0.3 ms is possible! ■ 3mm/30cm diameter= 0.57

17. 17 CNS summer school 2002 Experimental Room

18. 18 CNS summer school 2002 Secondary Beam Intensities

19. 19 CNS summer school 2002 Doubly Magic Nuclei Intensity

20. 20 CNS summer school 2002 Search for Superheavy Elements Confirmation in different laboratories is essential!

21. 21 CNS summer school 2002 Advantage of RIKEN Yield =  x T x I x   = 10 -36 cm 2 (1pb) T = 5x10 17 /cm 2 I = 6x10 12 /s (1 particle  A)  = 0.3 Y = 9x10 -7 events/s 2.3 /month ◆ Heavy Element Search ■ High-intensity beam from high-performance accelerator ■ High-performance recoil separator ◆ Accelerator complex in RIKEN ■ ECR ion source + RFQ Linac + RILAC + CSM ■ Highest Energy5.8AMeV ■ Highest Intensity10 particle  A ◆ Gas-filled Recoil Separator GARIS ■ Velocity & Charge -state focusing ■ A large acceptance

22. 22 CNS summer school 2002 Ring Cyclotron GARIS ECR+RFQ+RILAC + CSM CSM(Charge State Multiplier) ECR ion source RILAC(RIken Linear ACcelerator) 284. WE-Heraeus-Seminar 2002/08/08

23. 23 CNS summer school 2002 GARIS

24. 24 CNS summer school 2002 GARIS target with Beam Target and Beam in He gas

25. 25 CNS summer school 2002 Principle of GARIS ◆ Magnetic rigidity ◆ is independent from ◆ the velocity of a nucleus. Vacuum q c -1 q c q c +1 gas

26. 26 CNS summer school 2002 GARIS Detector

27. 27 CNS summer school 2002 2 71 [110] by 208 Pb( 64 Ni,n) 271 [110]

28. 28 CNS summer school 2002 271 [110] Summary Reaction 208 Pb( 64 Ni,1n) 271 [110] Target 208 Pb 230  g/cm 2 Efficiency0.76 Counting rate of PSD2/s (@ 0.4 p  A) Beam energy311.2 MeV Total beam dose8.8x10 17 Event number1 Cross section2.3 pb Beam energy314.2 MeV Total beam dose6.3x10 17 Event number2 Cross section6.3 pb T(1/2) = 12.9 ms

29. 29 CNS summer school 2002 Collaborators: K. MoritaRIKEN K. MorimotoRIKEN D. KajiRIKEN, Niigata U. And many others

30. 30 CNS summer school 2002 New Isotope of Bk ◆ 197 Au( 40 Ar,3n) 234 Bk ■ Beam energy at 196.9 and 188.4 MeV ■ 1.5~2.5 particle µA ◆ 9  -chain events have been observed.

31. 31 CNS summer school 2002 234 Bk  chains

32. 32 CNS summer school 2002 Decay chain of 234 Bk

33. 33 CNS summer school 2002 Comparison of  -decay Q-value ◆ KUTY is the mass formula with shell energies on a spherical- basis, ◆ TUYY is the mass formula with an empirical shell term, ◆ FRDM is the finite- range-droplet model and folded-Yukawa single-particle potential, and ◆ HFBCS is to be based on the Hartree- Fock+BCS method with the MSk7 Skyrmeforce.

34. 34 CNS summer school 2002 SHE search is running at full speed