Rotational bands in the rare-earth proton emitters and neighboring nuclei Darek Seweryniak Argonne National Laboratory PROCON Rotational landscape in the rare- earth region. 2.Recoil-Decay Tagging. 3.Excited states in the proton emitters 147 Tm, 141 Ho and 131 Eu. 4.Particle-Rotor calculations. 5.GAMMASPHERE+  Ball+nWall. 6.Excited in 143 Ho and neighboring nuclei. 7.Summary and outlook.

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

Proton drip line 131 Eu 141 Ho 147 Tm

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

Strong coupling Coupling to the deformation axis: K is a good quantum number j precesses around the symmetry axis Coriolis introduces K-mixing signature splitting  4 and  enhances K-mixing R j K K K+1 K+2 K+3 K+1 K+2 K+3 K+4  K=1 Coriolis mixing K+4 E2 M1 E2 K-bandK+1 band

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

Recoil-Decay Tagging Prompt  rays Recoils Implants  and p decays GAMMASPHERE Spatial and time correlations in the DSSD

Excited states in 147 Tm p (h 11/2 )p (d 3/2 ) 620 |  |=0.13 GS data - 4 hours Aye-ball data

141 Ho spectra

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

Particle-Rotor Model Input  Tri-axial Rotor  Woods-Saxon potential with the universal set of parameters  Coriolis attenuation factor 0.85  Proton pairing strength MeV  Moments of inertia adjusted to the 2+ energy in the daughter nucleus Coriolis matrix elements are attenuated by the pairing factor: u 1 u 2 +v 1 v 2

 =  =0 o -(-20 o )  =100-90%  =100-90%   =0-(-0.06) 7/2 - 9/2 - 11/2 - 13/2 - 15/2 -  = exp  =0.29,  4 =0,  =0 o PR model sensitivity

141 Ho Particle-Rotor calculations Best fit:  2 =0.25 E(2 + )=190 keV  4 =-0.06  =-10 o Another fit:  2 =0.29 E(2 + )=140 keV  4 =-0.06  =-20 o

Total Routhian Surface Calculations  =0.25 MeV  =0.05 MeV  =0.15 MeV  =0.35 MeV 141 Ho is  soft and develops triaxiality at higher angular momentum

131 Eu spectra M1 E2 h 11/2 band

131 Eu level scheme 5/2 + [413] or 3/2 + [411] ground state? 3/2 + [411] band in 159 Tb 94 after A 5/3 scaling gives: /2+ 5/2+ 9/2+ 5/2 + [413] band in 159 Eu 96 after A 5/3 scaling gives: /2+ 5/2+ 9/2+ We observe 72 keV and 105 keV. Low energy transitions present in the spectrum suggest the 3/2+[411] assignment

Population of proton rich nuclei along the proton drip-line Z= Hf 153 Lu 152 Lu 151 Lu 150 Yb 149 Tm 148 Tm 147 Tm 150 Lu 146 Tm 146 Er 145 Tm 145 Ho 144 Ho 143 Ho 142 Ho 141 Ho 140 Ho 144 Dy 143 Dy 142 Dy 141 Dy 140 Dy 139 Dy 143 Tb 142 Tb 141 Tb 140 Tb 139 Tb 138 Tb 142 Gd 141 Gd 140 Gd 139 Gd 138 Gd 137 Gd 141 Eu 140 Eu 139 Eu 138 Eu 137 Eu 136 Eu CN 136 Gd CN pp ppp pp N= Eu 131 Eu … 50  b 300 nb500 mb 1 out of 10 million  rays! 5b5b 100 mb p

GAMMASPHERE  Ball+nWall p,  n 54 Fe  P  n   Ball - 96 CsI nWall 30 NE Mo

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

143 Ho level scheme 143 Ho(p1n2) Ho 11/2 - 15/2 - 19/2 - 23/2 -

 E(2 +,0) and  E(15/2 -,11/2 - ) systematics 149 Tm 148 Tm 147 Tm 146 Tm 146 Er 145 Tm 145 Ho 144 Ho 143 Ho 142 Ho 141 Ho 140 Ho 144 Dy 143 Dy 142 Dy 141 Dy 140 Dy 139 Dy 143 Tb 142 Tb 141 Tb 140 Tb 139 Tb 138 Tb 142 Gd 141 Gd 140 Gd 139 Gd 138 Gd 137 Gd 141 Eu 140 Eu 139 Eu 138 Eu 137 Eu 136 Eu Er 144 Er Tm similar to 143 Ho!

Summary 1.Studies of excited states proved to be a very useful source of complementary information on proton emitters. 2.Ground state band in 147 Tm confirmed and extended. 3.Lower  2 deformation in 141 Ho,  4 and  important. Single –particle configurations in agreement with adiabatic decay-rate calculations. 4.Rotational bands in 131 Eu observed. Fine structure confirmed. The 3/2+[411] assignment is favored. 5.The h 11/2 band in 143 Ho observed, more to come ….

Outlook 1. 1.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 117 La or 145 Tm GAMMASPHERE+  Ball+nWall will allow to fill up considerably the gap between the stability line and the proton drip line Other methods such as RDT using  - delayed proton emitters or isomer studies could also contribute.