1. Triple-Humped Fission Barrier and Clusterization in the Actinide Region
A. Krasznahorkay
Inst. of Nucl. Res. of the Hungarian Acad. of Sci. (ATOMKI) Debrecen, Hungary

2. Experimental results:
Introduction
Resonant tunneling
Experimental methods
Experimental results:
Superdeformed (SD) bands in 240Pu
Hyperdeformed (HD) bands in 234U and in 236U
On the shape of the potential barriers
Mass distributions for 236U and for 233Th
Clustering effects
Summary and conclusion

3. Triple humped fission barrier

4. Nuclear fission paths

5. Resonant tunneling through the fission barrier
Eres  E*,
()  J,K

6. The best energy regions for studying the SD and HD states
Howard, Möller, ADNDT 25 (1980) 218
Cwiok et al., PLB 322 (1994) 304

7. Cyclotron laboratory in ATOMKI, Debrecen

8. The split-pole magnetic spectrometer in ATOMKI

9. Experimental setup for studying fission (transmission) resonances in ATOMKI (Debrecen)

10. Low-pressure position sensitive avalanche counters

11. Experimental setup for studying fission resonances in Garching (Germany)

12. Experimental results for 240Pu

13. SD rotational bands in 240Pu

14. Previous results for 234U P.G. Goldstone et al., PRC 18 (1978) 1706
J. Blons et al., NP A477 (1988) 21
A. Krasznahorkay et al., PRL 80 (1998) 2073

15. Reanalized angular distributions

16. Comparison of the results obtained for 234U

17. Recent results for 234U
A. Krasznahorkay et al., Phys. Lett B 461 (1999) 15

18. Results of the fitting

19. Previous results for 236U Krasznahorkay et al., PRL 80
(1998) 2073
P.G. Goldstone et al., PRC 18 (1978) 1706

20. Angular distribution of the 5.4 MeV band in 236U

21. Recent results for 236U

22. Fitting the fission resonances in 236U
Not SD but HD bands !!!

23. On the depth of the third minimum
Calculations with the back shifted Fermi-gas model

24. Determination of the height of the inner barrier
Lower and higher limits 
EA= 5.15 ± 0.20 MeV
hA = 1.2 MeV
Exp. Data from Goerlach diploma thesis, Univ. MPI Heidelberg (1978), unpublished

25. On the height of the fission barriers
History of the 3. Minimum
Möller … PLB 40 (1972) 329
Blons … PRL 41 (1978) 1282
(Howard, Möller, ADNDT 25 (1980) 218 )
Cwiok … PLB 322 (1994) 304

26. Nuclear molecules

27. Clusterization in 234U

28. The shape of 236U in the third minimum

29. Setup for TOF measurements

30. On the width of the mass distribution of 236U

31. Mass distribution measurements with a double ionization chamber
C. Budtz-Jörgensen et al., NIM A258 (1987) 209

32. On the width of the mass distributions of 233Th
Target: ThO mg/cm2, diameter 4 cm
Neutrons from 7Li(p,n) at ATOMKI then in Karlsruhe, =1.8*106 n/cm2, one week exp.

33. TKE-mass distribution correlations
A=100 A=132
Cold fission
Compact fission

34. TKE-mass correlations in the decay of the HD resonance in 233Th

35. Summary and conclusions
Fission resonances  SD and HD states
Density of the HD states  depth of the 3rd minimum
Appearence of the HD resonances + isomer population probability  EA
The ˝Th anomaly˝ has been solved.
Mass distribution from the decay of the HD states  heavy clusterization