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The structure of Tc nuclei is extended to the more neutron-rich regions based on measurements of prompt gamma rays from the spontaneous fission of 252Cf at Gammasphere. The level scheme of N=67 neutron-rich (Z=43) 110Tc is established for the first time and that of 111Tc is expanded. The ground-state band of 111Tc reaches the band-crossing region and the new observation of the weakly populated alpha = -1/2 member of the band provides important information of signature splitting. The systematics of band crossings in the isotopic and isotonic chains and a CSM calculation suggest that the band crossing of the gs band of 111Tc is due to alignment of a pair of h11/2 neutrons. The best fit to signature splitting, branching ratios, and excitations of the ground-state band of 111Tc by RTRP model calculations result in a shape of epsilon2 = 0.32 and gamma = -26 deg. for this nucleus. Its triaxiality is larger than that of 107Tc, to indicate increasing triaxiality with increasing neutron number. The identification of the weakly-populated "K+2 satellite" band provides strong evidence for the large triaxiality of 111Tc. In 110Tc the four lowest-lying levels observed are very similar to those in 108Tc. At an excitation of 478.9 keV above the lowest state observed, ten states of a delta I = 1 band are observed. This band is very analogous to the delta I = 1 bands in 106,108Tc, but it has greater signature splitting at higher spins.

New level schems of Y and Nb isotopes are proposed based on measurements of prompt gamma rays from 252Cf fission at Gammasphere. Shape trends regarding triaxiality and quadrupole deformations are studied.

Using Gammasphere data on prompt gamma rays from spontaneous fission of 252Cf, we propose energy-level schemes for 110,111,112, & 113Rh (Z=45). The fission-gamma data complement earlier studies of others on beta decay of fission products in that prompt fission gammas mainly populate yrast or near-yrast levels, while beta decay populates lower-spin levels. For the odd-A rhodium nuclei studied here, their ground bands and collective sidebands are compared with model calculations using triaxial-shaped nucleus with one odd quasi-proton. The energies and E2 transition rates are best fit by a shape slightly to the prolate side of maximum triaxiality, namely, gamma = 28 deg. The model calculations also show a K=1/2+ band with energies not in good agreement with a corresponding exerimental band. The experimental 1/2+ band is regarded as an intruder band from a prolate-driving proton orbital 1/2[431] above the Z=50 closed shell. This intruder band, seen in other odd-A Rh isotopes, is probably more deformed and prolate and would not be expected to be fit at the same triaxial shape parameter as the 7/2+ ground band. We observe a band-crossing (backbending) in the odd-A ground bands above spins of about 21/2. The odd-odd nuclei 110 and 112 Rh show mainly a single band with no backbending up to higherfrequency than the backbend in the odd-A isotopes. It is concluded that the backbend is due to alignment of a pair of h11/2 neutrons.

Using Gammasphere data on prompt gamma rays from spontaneous fission of 252Cf, we propose energy-level schemes for 110,111,112, & 113Rh (Z=45). The fission-gamma data complement earlier studies of others on beta decay of fission products in that prompt fission gammas mainly populate yrast or near-yrast levels, while beta decay populates lower-spin levels. For the odd-A rhodium nuclei studied here, their ground bands and collective sidebands are compared with model calculations using triaxial-shaped nucleus with one odd quasi-proton. The energies and E2 transition rates are best fit by a shape slightly to the prolate side of maximum triaxiality, namely, gamma = 28 deg. The model calculations also show a K=1/2+ band with energies not in good agreement with a corresponding exerimental band. The experimental 1/2+ band is regarded as an intruder band from a prolate-driving proton orbital 1/2[431] above the Z=50 closed shell. This intruder band, seen in other odd-A Rh isotopes, is probably more deformed and prolate and would not be expected to be fit at the same triaxial shape parameter as the 7/2+ ground band. We observe a band-crossing (backbending) in the odd-A ground bands above spins of about 21/2. The odd-odd nuclei 110 and 112 Rh show mainly a single band with no backbending up to higherfrequency than the backbend in the odd-A isotopes. It is concluded that the backbend is due to alignment of a pair of h11/2 neutrons.

We report the experimental confirmation of the production of element110. In the bombardment of a 208Pb target with a 309~;MeV 64Ni beam, we have observed two chains of time- and position-correlated events. Each chain consisted of the implantation of an evaporation residue followed by the emission of alpha-particles. We attribute these two chains to the decay of 271-110 produced with a cross section of 8.3 (+11/-5.3)pb.

New level schemes of $^{141}$Ba and $^{139}$Xe are proposed from the analyses of spontaneous-fission gamma data from our $^{252}$Cf spontaneous fission Gammasphere runs of 1995 and 2000. By analogy with the N = 85 even-odd isotones $^{149}$Gd, $^{147}$Sm, and $^{145}$Nd, spins and parities were assigned to the observed excited states in $^{141}$Ba and $^{139}$Xe. It appears that spherical shell model neutron excitations plus octupolephonons are an appropriate basis at the lower end of the bands. Going to higher spins it is clear that the soft rotor involving valence protons as well as neutrons becomes increasingly important in the configurations. Level systematics in the N = 85 even-odd isotones from Gd(Z=64) through Te(Z=52), are discussed. The excitation systematics and smooth trends of the analogous levels support the spin and parity assignment for excited levels observed in $^{141}$Ba and $^{139}$Xe. The level systematics and the comparison with neighboring even-even isotopes indicate that quadrupole and octupole collectivity play roles in $^{141}$Ba and $^{139}$Xe. From Gd(Z=64) through Te(Z=52), increasing excitation energies of the 13/2$^{+}$ states and lowering relative intensities of the positive parity bands in the N = 85 even-odd isotones may indicate that the octupole strength is becoming weaker for the isotones when approaching the Z = 50 closed shell.

A fundamental question in nuclear physics is what combinations of neutrons and protons can make up a nucleus. Many hundreds of exotic neutron-rich isotopes have never been observed; the limit [...]

In bombardments of 248Cm with 143.7–146.8 MeV 26Mg ions the nuclides 269Hs and presumably 270Hs were produced. After chemical isolation, Hs atoms were identified by observing genetically linked nuclear-decay chains. Three chains originating from 269Hs confirmed the decay properties observed previously in the decay of 277112. Two chains exhibited the characteristics expected for the new nuclide 270Hs, which was predicted to be a deformed ‘doubly magic’ nucleus. From the measured Eα = 9.16+0.07-0.03 MeV an α-decay half-life of 3.6+0.8-1.4 s was estimated. [ABSTRACT FROM AUTHOR]

Investigates the chemical separation and characterization of only seven detected atoms of hassium in the fusion reaction between magnesium and curium. Enthalpy of adsorption; Chemical properties of hassium; Seven nuclear decay chains originating from hassium isotopes; Thermochromatogram of hassium oxide and osmium oxide.

Abstract: Two new neutron-deficient isotopes, 60Ge and 64Se, were observed for the first time. They were produced by projectile fragmentation of a 140-MeV/nucleon 78Kr primary beam on a beryllium target. The secondary fragments were unambiguously identified after separation in the A1900 fragment separator. The nucleus 60Ge corresponds to the heaviest isotone of the neutron shell and it is most likely the last isotone to be observed. Lower limits of 110 and 180 ns were extracted for the half-life of 60Ge and 64Se, respectively. No events of 59Ga or 63As have been observed, providing very strong evidence that these nuclei are unbound with respect to proton emission. This non-observation implies an upper limit for the half-life of 43 ns for 59Ga and 63As. [Copyright &y& Elsevier]

Abstract: The fast liquid–liquid extraction system SISAK with continuous liquid scintillation detection was coupled to the Berkeley Gas-filled Separator to enable studies of the chemical properties of -decaying transactinide elements. The preseparated transactinide 257Rf (4.7s), was transported via a He/KCl-jet directly into the scintillation solution. This permitted the first unambiguous detection of transactinide atoms by the means of the -liquid scintillation detectors of the SISAK-system. During the experiment, 89 257Rf atoms were observed. The type of events observed correspond well with the expectations based on half-lives, decay branches and transport- and hold-up times. The successful result of this experiment demonstrates that the system is well fitted for count-rates of 1–2 atoms/h and half-lives of a few seconds. [Copyright &y& Elsevier]

The regions around the doubly magic nuclei 100Sn and 78Ni are of great interest from a nuclear structure standpoint. These nuclei also play a key role in the astrophysical rp- and r-processes, respectively. Recently, nuclei in these regions were studied at the Coupled Cyclotron Facility at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. [Copyright &y& Elsevier]