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High spin states in 136,137 La, 148 Ce and 105 Mo

High spin states in 136,137 La, 148 Ce and 105 Mo. S. J. Zhu 1 , Y. J. Chen 1 , M. L. Li 1 , H. B. Ding 1 . , J. H. Hamilton 2 , A. V. Ramayya 2 , J. K. Hwang 2 , X. S. Dong 1 , U. Y. Nan 1 , L. H. Zhu 3 , S. X. Wen 3 , X. G. Wu 3.

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High spin states in 136,137 La, 148 Ce and 105 Mo

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  1. High spin states in 136,137La,148Ce and 105Mo

  2. S. J. Zhu1, Y. J. Chen1, M. L. Li1, H. B. Ding1., J. H. Hamilton2, A. V. Ramayya2, J. K. Hwang2, X. S. Dong1, U. Y. Nan1,L. H. Zhu3, S. X. Wen3, X. G. Wu3 1 Department of Physics, Tsinghua University, Beijing 100084, People’s Republic of China 2 Department of Physics, Vanderbilt University, U.S.A 3 China Institute of Atomic Energy, Beijing, 102413, People’s Republic of China

  3. I. INTRODUCTION • II. EXPERIMETAL METHODS • III. RESULTS AND DISCUSSION • IV. SUMMARY

  4. I. INTRODUCTION 136,137La 148Ce 60 62 64 66 68 105Mo

  5. A. A=135 Region:136La (Z=57, N= 79) 137La (Z=56, N=80) N: near N=82 magic number, stronger single-particle character. At the high spin states, look for collective bands: prolate bands, oblate bands

  6. The shape driving effect : E.S.Paul et al. PRL,58, 984(1987)

  7. B. A=140 neutron-rich Region: 148Ce: Searching for octupole deformation.

  8. C. A=110 neutron-rich Region: 105Mo: odd-A nucleus: Searching for two- phonon vibrational- rotation bands.

  9. II. EXPERIMETAL METHODS A. 136La:130Te(11B, 5n), beam: 60 MeV 137La: 130Te(11B, 4n) , beam: 50 MeV CIAE HI-13 tandem accelerator 50106 coincidence events

  10. CIAE In-Beam Gamma-ray detectors

  11. B. 148Ce, 105Mo: measure the prompt -rays from spontaneous fission of 252Cf. • Lawrence Berkeley National Laboratory • GAMMASPERE Detector Array 105 Compton-Suppressed Ge Detectors • 252Cf Source • Total of 5.7×1011 triple- and higher-fold -- coincidence events(in cube) • Radware software package to analyze data

  12. III. RESULTS AND DISCUSSION A. 136La: E.W.Cybulska et al. Acta Phys. Pol.B32, 929 (1999).

  13. Old: (8+) h11/2h11/2 systematic

  14. Bands(2) and (3): oblate(=-60). １.stronger △I=1transitions, ２.no signature splitting, ３. different moments of inertia from plolate. Band (2): • Band (3): Band (2)

  15. B. 137La: ↑New!

  16. Band (1): collective backbending

  17. 0.40 MeV 0.48 MeV Neutron routhian Proton routhian

  18. Band (3): oblate band (~-60) 带(３)———扁椭带

  19. C. 148Ce: Theoretical prediction: When N,Z=34, 56, 88, 132, a pair of single particle orbitals with N=1, l=3, j=3 closes to each other, octupole element Y30 is very strong, strong octupole correlations occur.

  20. Z=56, N=88, around A=144 neutron-rich region, octupole deformation discovered. Using simplex quantum numbers to express For even A nuclei, S= +1, Ip=0+, 1-, 2+, 3-, 4+, 5-, ….. S= -1, Ip=0-, 1+, 2-, 3+, 4-, 5+, ….. For odd A nuclei, S= +i, Ip=1/2+, 3/2-, 5/2+, 7/2-, 9/2+, 11/2-, ….. S= -1, Ip=1/2-, 3/2+, 5/2-, 7/2+, 9/2-, 11/2 +, …..

  21. Experimental structure: • Two I=2 band structures with positive and negative parities respectively. •  Strong B(E1) transitions between two opposite parity bands.

  22. Z=56: 140Ba, 141Xe, 142Ba, 143Ba, 144Ba, 145Ba, 146Ba Z=57: 145La, 147La Z=58: 144Ce, 146Ce Look for the Double octupole bands s= i in Odd-A nuclei :143,145Ba, 145La (our group)

  23. S.J.Zhu et al., Phys. Rev. C60 (1999) 051304.

  24. S=+i S=-i S.J.Zhu et al., Phys. Rev. C59 (1999) 1316.

  25. s= 1in even-A nuclei, No identified. S=+1 S=+1 S=+1

  26. B(E1)/B(E2) s=+1: ~ 0.8210-6 fm-2 s=-1: ~ 1.5110-6 fm-2

  27. C. 105Mo: Search for: collective bands:  vibrational- rotational bands one- phonon  vibrational- rotational bands: Mo: 104,106Mo, 108,110,112Ru two- phonon  vibrational- rotational bands: 104,106Mo

  28. -Vibration -Vibration

  29. 1- 1- 2- 2-

  30. In odd-A nuclei, look for 2- two- phonon  vibrational- rotational band is difficult, 105Mo?

  31.  5/2+[413]  5/2-[532] 1-  3/2+[411] 2- 1/2+[411]

  32. yrast 1- 2- yrast 1- yrast 1- 2- 2-

  33. Others: 108,110,112Ru 1-, 2- Two-quasiparticle bands Chiral doublet bands?

  34. 1- 2-

  35. 1- 2-

  36. 1- 2-

  37. III. SUMMARY We have investigeted: * A=135 region 136,137La, Yrast band (prolate) and oblate bands. Band crossing and signature inversion. * A=140 region 148Ce The s=i double octupole bands. * A=100 region 105Mo, 108,110,112Ru One phonon - band Two phonon - band

  38. THE END THANKS!

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