15 January 1998 Ž . Physics Letters B 417 1998 13–19 Lifetimes of yrast and excited superdeformed states in 150 Gd: effect of particle-hole excitations on the deformation C.W. Beausang a,b , P. Fallon c , D.E. Appelbe a , S. Aztalos c , R.M. Clark c , S. Clarke a , B. Cederwall c,d , M.A. Deleplanque c , R.M. Diamond c , S. Erturk a , ¨ W. Kelly e , I.Y. Lee c , A.O. Macchaivelli c , D.C. Patterson b , M.B. Smith a , F.S. Stephens c , P.J. Twin a , A.N. Wilson b a OliÕer Lodge Laboratory, UniÕersity of LiÕerpool, UK b Wright Nuclear Structure Laboratory, Yale UniÕersity, USA c Nuclear Science DiÕision, Lawrence Berkeley Laboratory, USA d Royal Institute of Technology, Stockholm, Sweden e Iowa State UniÕersity, USA Received 16 July 1997; revised 22 September 1997 Editor: J.P. Schiffer Abstract The quadrupole moments and deformations have been measured for six superdeformed bands in 150 Gd. The results indicate evidence for deformation driving properties of both the high-N intruder and also low-N natural parity states at the superdeformed Fermi surface. Several new transitions have been identified and placed in the low spin non-yrast portion of one of the SD bands. q 1998 Published by Elsevier Science B.V. Ž . Superdeformed SD states at high angular mo- mentum have been well established in many nuclei wx in the mass 150 region 1 . The yrast SD states are normally classified in terms of the occupation of several high-N intruder orbitals, N s 6 for protons Ž and N s 7 for neutrons N being the principal oscil- . lator quantum number . The structure of excited SD states, and the rotational bands built upon then, usually involves the occupation of different numbers of intruder orbitals through particle-hole excitations either from a high-N intruder to a low-N natural parity state, or vice versa. The natural parity states near the SD Fermi surface usually have low angular momenta and small rotational alignments and, subse- quently, are not particularly sensitive to the nuclear rotation. The intruder orbitals, on the other hand, are very sensitive to the rotation and, in addition, each intruder state is affected differently by the rotation. Hence the variation in the dynamic moment of iner- Ž Ž2. . Ž . tia J from band to band or nucleus to nucleus reflects the different intruder configurations. For this reason, SD bands with the same intruder configura- tion are often observed to have similar J Ž2. mo- ments of inertia and, depending on the detailed coupling of the low-N natural-parity orbital to the SD core, may have identical relationships between their gamma-ray energies. While the J Ž2. moment of inertia is affected mostly by the intruder-orbital occupation, both the high-N intruders and low-N natural-parity states af- 0370-2693r98r$19.00 q 1998 Published by Elsevier Science B.V. All rights reserved. Ž . PII S0370-2693 97 01347-6