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Structural Evolution in the ( N,Z,I p ) Coordinate Frame for A~100

Structural Evolution in the ( N,Z,I p ) Coordinate Frame for A~100. Paddy Regan* Dept. of Physics University of Surrey,UK E-mail : p.regan@surrey.ac.uk * partially supported by WNSL-Yale Flint and Science Development Fund. Sr-Mo region ‘famous’ for dramatic collapse in I p =2 + energy

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Structural Evolution in the ( N,Z,I p ) Coordinate Frame for A~100

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  1. Structural Evolution in the (N,Z,Ip) Coordinate Frame for A~100 Paddy Regan* Dept. of Physics University of Surrey,UK E-mail: p.regan@surrey.ac.uk *partially supported by WNSL-Yale Flint and Science Development Fund

  2. Sr-Mo region ‘famous’ for dramatic collapse in Ip=2+ energy going from N=58 to N=60

  3. Explanation by Federman & Pittel in terms of quadrupole deformation ‘driving’ T=0 (pn) interaction. Particularly noticeable for protons and neutron orbitals with large spatial overlaps (e.g., Spin Orbit Partners such as p g9/2 and n g7/2 in A~100)

  4. Other aspects ? Correlation between deformation & population of ‘deformation aligned’, low-W h11/2 neutron intruder orbitals. Classic ‘chicken and egg’. Does population of orbital ‘cause’ deformation or is deformation there from the core and thus h11/2 orbital lies closer to the Fermi Surface ? How does this situation evolve with spin ?

  5. 82 1h11/2 50 [550]1/2- 1g9/2 Alignment (rotational picture at least) driven by Coriolis interaction on high-j, low-W orbitals (ie. ones with large jx on collective rotation axis. Vcor = -jx.w eg. nh11/2 [550]1/2 ‘intruder’ FS for N~57, b2~0.15->0.2 jx [541]3/2-

  6. = 101Mo, new data, see later

  7. Alignments and rotational motion in ‘vibrational’ 106Cd (Z=48, N=58), PHR et al. Nucl. Phys. A586 (1995) p351

  8. Detailed spectroscopy allowed by investigating gamma-decay sequences from high-spin states. YRASTBALL allows triples to show band-like structures in 101Ru. see A.D.Yamamoto et al., Phys. Rev. C66 (2002) 024302

  9. TRS calculations for 101Ru by F.R. Xu (Bejing) for different parity (and signature) configs. A.D.Yamamoto et al. Phys. Rev. C66 (2002) 024302 g b2 w=0.2MeV w=0.3MeV w=0.4MeV w=0.6MeV

  10. Crossing and alignments well reproduced by CSM, although AHVs see PHR et al., Phys. Rev. C68 (2003) 044313

  11. PHR, Beausang, Zamfir, Casten, Zhang et al., Phys. Rev. Lett. 90 (2003) 152502

  12. PHR, Beausang, Zamfir, Casten, Zhang et al., Phys. Rev. Lett. 90 (2003) 152502

  13. PHR, Beausang, Zamfir, Casten, Zhang et al., Phys. Rev. Lett. 90 (2003) 152502

  14. Vibrator-Rotator phase change is a feature of near stable (green) A~100. ‘Rotational alignment’ can be a crossing between quasi-vibrational GSB & deformed rotational sequence. (stiffening of potential by population of high-j, equatorial (h11/2) orbitals). PHR, Beausang, Zamfir, Casten, Zhang et al., Phys. Rev. Lett. 90 (2003) 152502

  15. Ge TLF beam qtlf,ftlf qblf,fblf BLF Simon et al., Nucl. Inst. Meth. A452, 205 (2000) Rochester Group TOF ~5-10 ns. ns-ms isomers can de-excite in be stopped byCHICO position detector. Delayed gs can still be viewed by GAMMASPHERE.

  16. z x q1 q2 f1 f2 y

  17. {180}{429,616,772,891} 891 772 616 429 180 delayed coincs with prompt 429, 616, 772 & 891 keV total, DIC prompts delayed Use ‘isomer gating’ to identify h11/2 band in N=59, 101Mo.

  18. See PHR, Yamamoto, Beausang, Zamfir, Casten, Zhang et al., AIP Conf. Proc. 656 (2002) p422 ‘Weak Coupling’ Eg/(I-j) E-GOS extension for odd-A Suggests 11/2- band is an anharmonic vibrator or g-soft rotor? seems to work ok for +ve parity bands though

  19. Wheldon suggested extension of E-GOS by ‘renormalising’ the rotational energies at the bandhead. If the band-head spin of a sequence is given by j then substituting I-j in place of I, one obtains,

  20. Even-Even yrast sequences and odd-A +ve parity only show rotational behaviour after (nh11/2 )2 crossing…. seems to work ok, nh11/2 bands now look like rotors,

  21. Even simpler to just take Eg (I->!-2) / I for odd-A e.g., R = [ Eg (15/2- ->11/2-) / (11/2) ]

  22. Other signatures of (perfect) vibrators and rotors State lifetimes, i.e., B(E2) values and selection rules (eg. Dn=1).

  23. Need to measure lifetimes B(E2) values of yrast stretched E2 decays in N=58 isotones (best cases) + h11/2 bands in N=57 isotones. RDM measurements in 103,4Pd, 105,6Cd due Aug. 2004 at Yale to ‘prove’ vibrator-to-rotor picture. ( Frauendorf’s ‘tidal wave’ picture is similar).

  24. From Dudek et al., Phys. Rev. Lett. 59 (1987) p1405 Single particle spectra (for minimised LDM energy at spin 60 hbar) shows distinct gaps for b2~0.4 at Z=42, N=58 (100Mo). Note these are the homologs of A~80 SD (N=42) and A~130 SD (Z=58)

  25. SD (b2=0.4) minimum • predicted in 100Mo to • become yrast around • spins 25-30 h. • ‘Doubly-Magic’ SD • shell gaps at • (Z=42, N=58) = 100Mo. J. Skalski et al.,Nucl. Phys. A617 (1997) p282 DIC Pb + Mo proposal to Be submitted to upcoming GAMMASPHERE PAC (deadline 26th April!)

  26. Acknowledgments P.H. Regan1,2, C. Wheldon1,3,A.D. Yamamoto1,2, S. Ashley1, P. Mumby-Croft1, D. Seaborne1, C.Y. Wu4, A.O. Macchiavelli5, D. Cline4, J.F. Smith6, R.S. Chakrawarthy6, M. Cromaz5, P. Fallon5, S.J. Freeman6, W. Gelletly1, A. Görgen5, A. Hayes4, H. Hua4, S.D. Langdown1,2, I.Y. Lee5, C.J. Pearson1, Zs. Podolyák1, R. Teng4, J.J. Valiente-Dobón1, 1University of Surrey, UK 2Wright Nuclear Structure Laboratory, Yale University, USA 3HMI, Berlin, Germany 4Nuclear Structure Research Laboratory, University of Rochester, USA 5Nuclear Science Division, Lawrence Berkeley National Laboratory, USA 6Department of Physics and Astronomy ,The University of Manchester, UK E-GOS story, PHR, Con Beausang, Victor Zamfir, Rick Casten, Jing-Ye Zhang Money from…EPSRC (UK) , DOE (USA) , NSF (USA), Yale Flint-Science Development Funds

  27. International Conference On NUclear STructure, Astrophysics & Reactions University of Surrey, Guildford, UK5-8 January 2005 http://www.ph.surrey.ac.uk/cnrp/nustar05

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