Multinucleon transfer reactions have been used, for the first time, to populate high-spin bands of alternating parity states in 218,220,222 Rn and 222,224,226 Ra. The behavior of the angular momentum alignment with rotational frequency for the Rn isotopes is very different when compared with Ra and Th isotopes with N ഠ 134, indicating a transition from octupole vibrational to stable octupole deformation. Throughout the measured spin range the values of jD 0 ͞Q 0 j remain constant for 222 Ra and 226 Ra and have a very small value for 224 Ra, suggesting that the charge and mass distributions are not affected appreciably by rotations. [S0031-9007(97)02928-1] PACS numbers: 21.10. Re, 23.20.Lv, 25.70.Gh, 27.90. + b Of all nuclear species, radium (Z 88) and thorium (Z 90) isotopes with N ഠ 134 show the best evidence for octupole instability in their ground state [1-3]. These nuclei have low-lying negative-parity states and relatively strong B͑E1͒ values for the transitions between the bands of opposite parity; for the single case of 226 Ra large B͑E3͒ values have been measured consistent with its interpretation as a rotating pear shape [4]. The inaccessibility of these nuclei has, however, meant that there are large gaps in our knowledge of octupole effects in heavy nuclei. Comprehensive measurements of the high-spin behavior of the yrast octupole band exist only for the isotopes of thorium. For the radium isotopes such measurements are available for the weakly quadrupole coupled 218,220 Ra and the strongly coupled 226 Ra. There is only a limited amount of data on 224 Ra and virtually no information exists for 222 Ra. The scarce data do, however, suggest cancellation effects for the electric dipole moment for 224 Ra [5] which do not occur in the thorium isotopes. This effect is not properly established as the spin-dependent behavior for 222 Ra has not yet been measured. There are almost no data on the octupole structures for the radon isotopes. Systematic measurement of the variation of angular momentum with rotational frequency of the octupole bands should provide an insight into the nature of the strength of the octupole interactions in these nuclei.In order to populate the nuclei of interest the properties of multinucleon transfer reactions have been exploited. Previously, yields have been mapped out following the bombardment of a thick 232 Th target with various projectiles [6]. As the reaction 136 Xe 1 232 Th offered the largest yield for radon and radium isotopes with N ഠ 134, this reaction was chosen in order to make spectroscopic measurements of the heavy products.High-spin states in 218,220,222 Rn and 222,224,226 Ra were simultaneously populated following multinucleon transfer between 136 Xe and 232 Th. The 136 Xe projectile was accelerated to an energy of 833 MeV by the 88 in. cyclotron at Lawrence Berkeley National Laboratory. This bombarded a 232 Th target of thickness 36 mg͞cm 2 . Deexcitation gamma rays emitted from reaction products were collected for 49 h with the Gammasphere spectrometer which cons...

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An in-beam study of excited states in the transfermium nucleus 252 No has been performed using the recoil separator RITU together with the JUROSPHERE II array at the University of Jyväskylä. This is the second transfermium nucleus studied in an in-beam experiment. Levels up to spin 20 were populated and compared to levels in 254 No. An upbend is seen at a frequency of 200 keV/ប corresponding to spin 16. We also use an improved systematics to connect the energy of the lowest 2 ϩ state with its half-life and find that the deformation of both 252,254 No is slightly larger than previously assumed.

Prompt and delayed ␥ rays from 191,193 Bi have been identified using the recoil-decay tagging, isomer tagging, and recoil gating techniques, resulting in extensive level schemes for both nuclei. Excitation energies of the isomeric 13/ 2 + states have been established and oblate strongly coupled bands built on them have been observed. The nearly spherical 9 / 2 − ground-state bands appear to be crossed by more oblate-deformed lowlying structures. The properties of the bands feeding the 1 / 2 + intruder states indicate some structural change between 193 Bi and 191 Bi. The deformation associated with each of these states has been extracted from total Routhian surface calculations which also reveal the development of prolate minima with decreasing neutron number. B͑M1͒ / B͑E2͒ ratios have been measured for the observed strongly coupled bands in order to resolve the intrinsic excitations. The observed quasiparticle structures in 193 Bi and high-spin isomers both in 193 Bi and 191 Bi are interpreted based on the coupling of the odd proton to the even-even Pb core.