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Rotational bands in the rare-earth proton emitters and neighboring nuclei

Rotational bands in the rare-earth proton emitters and neighboring nuclei. Rotational landscape in the rare-earth region. Recoil-Decay Tagging. Excited states in the proton emitters 147 Tm, 141 Ho and 131 Eu. Particle-Rotor calculations. GAMMASPHERE+ m Ball+nWall.

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Rotational bands in the rare-earth proton emitters and neighboring nuclei

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  1. Rotational bands in the rare-earth proton emitters and neighboring nuclei • Rotational landscape in the rare-earth region. • Recoil-Decay Tagging. • Excited states in the proton emitters 147Tm,141Ho and 131Eu. • Particle-Rotor calculations. • GAMMASPHERE+mBall+nWall. • Excited in 143Ho and neighboring nuclei. • Summary and outlook. Darek Seweryniak Argonne National Laboratory PROCON-2003

  2. Collaboration D.Seweryniak, C.N.Davids, M.P.Carpenter, S.Freeman, A.Heinz, G.Mukherjee, A.Sonzogni, J.J.Uusitalo, R.V.F.Janssens, T.L.Khoo, F.G.Kondev, T.Lauritsen, C.J.Lister, G.L.Poli, P.Reiter, I.Wiedenhoever Argonne National Laboratory P.J. Woods, T. Davinson University of Edinburgh J.J. Ressler, J. Shergur, W.B. Walters University of Maryland J.A. Cizewski, K.Y. Ding, N. Fotiades Rutgers University

  3. Proton drip line 147Tm 141Ho 131Eu

  4. Nilsson diagram 147Tm 141Ho 135Tb 145Ho? 131Eu

  5. j R K Strong coupling Coupling to the deformation axis: K+4 K+4 M1 E2 K+3 K+3 K+2 E2 K+2 K+1 K+1 K K-band K+1 band DK=1 Coriolis mixing • K is a good quantum number • j precesses around the symmetry axis • Coriolis introduces K-mixing • signature splitting • b4 and g enhances K-mixing

  6. j R a Rotational coupling Coupling to the rotational axis: j+6 E2 j+4 j+2 j StrongCoriolis interaction • j precesses around the rotational axis • energies similar as in the gs band in the daughter • small deformation, high-j, low-K

  7. Recoil-Decay Tagging GAMMASPHERE Prompt g rays Recoils Implants a and p decays Spatial and time correlations in the DSSD

  8. Excited states in 147Tm |b|=0.13 620 Aye-ball data p (h11/2) p (d3/2) GS data - 4 hours

  9. 141Ho spectra

  10. 141Ho level scheme b=0.25(4) Harris formula Unexpectedly large signature splitting! p 7/2-[523] p ½+[411] D. Seweryniak et al., PRL C86(2001)1458

  11. Particle-Rotor Model Input • Tri-axial Rotor • Woods-Saxon potential with the universal set of parameters • Coriolis attenuation factor 0.85 • Proton pairing strength 0.136 MeV • Moments of inertia adjusted to the 2+ energy in the daughter nucleus Coriolis matrix elements are attenuated by the pairing factor: u1u2+v1v2

  12. PR model sensitivity 15/2- 13/2- 11/2- 9/2- 7/2- g=0o-(-20o) D=100-90% x=100-90% b4=0-(-0.06) b=0.25-0.31 E(2+)=180-200 b=0.29, b4=0, g=0o exp

  13. 141Ho Particle-Rotor calculations Another fit: b2=0.29 E(2+)=140 keV b4=-0.06 g=-20o Best fit: b2=0.25 E(2+)=190 keV b4=-0.06 g=-10o

  14. Total Routhian Surface Calculations w=0.05 MeV w=0.15 MeV w=0.25 MeV w=0.35 MeV 141Ho is g soft and develops triaxiality at higher angular momentum

  15. h11/2band M1 E2 M1 131Eu spectra

  16. 5/2+[413] band in 159Eu96 after A5/3 scaling gives: 9/2+ 134 237 7/2+ 104 5/2+ 131Eu level scheme 5/2+[413] or 3/2+[411] ground state? 3/2+[411] band in 159Tb94 after A5/3 scaling gives: 9/2+ 105 189 7/2+ 72 5/2+ We observe 72 keV and 105 keV. Low energy transitions present in the spectrum suggest the 3/2+[411] assignment

  17. 136Eu 137Gd 138Tb 138Gd 137Eu 139Tb 138Eu 140Tb 139Gd 139Eu 141Tb 140Gd 141Gd 142Tb 140Eu 143Tb 142Gd 141Eu Population of proton rich nuclei along the proton drip-line N=82 154Hf Z=72 CN 150Lu 151Lu 152Lu 153Lu p p 150Yb CN 145Tm 146Tm 147Tm 148Tm 149Tm p p p 146Er 300 nb 500 mb CN 140Ho 141Ho 142Ho 143Ho 144Ho 145Ho p p 50mb 139Dy 140Dy 141Dy 142Dy 143Dy 144Dy 5mb CN 100 mb 136Gd CN … 131Eu 135Eu p 1 out of 10 million g rays!

  18. GAMMASPHEREmBall+nWall a P g mBall - 96 CsI p,a 54Fe 92Mo n nWall 30 NE203 g n http://wunmr.wustl.edu/~dgs/mball/

  19. Gamma spectra 143Tb(3p) 143Dy(2p1n) 142Dy(2p2n) 63Zn(2p1n) on C

  20. 143Ho level scheme 143Ho(p1n2) 23/2- 663 19/2- 508 15/2- 318 11/2- 143Ho

  21. 145Tm 146Tm 147Tm 148Tm 149Tm 464 144Er 145Er 146Er 137Gd 138Tb 136Eu 137Eu 138Gd 139Tb 138Eu 140Tb 139Gd 140Gd 139Eu 141Tb 140Eu 141Gd 142Tb 143Tb 142Gd 141Eu 140Ho 141Ho 142Ho 143Ho 144Ho 145Ho 169 318 487 139Dy 140Dy 141Dy 142Dy 143Dy 144Dy 203 316 493 307 521 221 329 515 273 323 526 DE(2+,0) and DE(15/2-,11/2-)systematics 145Tm similar to 143Ho!

  22. Summary • Studies of excited states proved to be a very useful source of complementary information on proton emitters. • Ground state band in 147Tm confirmed and extended. • Lower b2 deformation in 141Ho, b4 and g important. Single –particle configurations in agreement with adiabatic decay-rate calculations. • Rotational bands in 131Eu observed. Fine structure confirmed. The 3/2+[411] assignment is favored. • The h11/2 band in 143Ho observed, more to come ….

  23. Outlook • Recent upgrades of the FMA implantation station and GAMMASPHERE promise next successful RDT campaign. • GAMMASPHERE+FMA will allow to study excited states in other, recently discovered deformed proton emitters such as 117La or 145Tm. • GAMMASPHERE+mBall+nWall will allow to fill up considerably the gap between the stability line and the proton drip line. • Other methods such as RDT using b-delayed proton emitters or isomer studies could also contribute.

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