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The $^{174}$Yb($^{29}$Si,5n) reaction at 148 MeV with thin targets was used to populate high-angular momentum states in $^{198}$Po. Resulting $gamma$ rays were observed with Gammasphere. A weakly-populated superdeformed band of 10 $gamma$-ray transitions was found and has been assigned to $^{198}$Po. This is the first observation of a SD band in the $A approx 190$ region in a nucleus with $Z > 83$. The ${cal J}^{(2)}$ of the new band is very similar to those of the yrast SD bands in $^{194}$Hg and $^{196}$Pb. The intensity profile suggests that this band is populated through states close to where the SD band crosses the yrast line and the angular momentum at which the fission process dominates.
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Low lying states of $^{198}$Hg have been investigated via $^{197}$Au($^{7}$Li, $ alpha $2n$ gamma $)$ ^{198} $Hg reaction at E$ _{text{beam}} $ = 33 MeV and 38 MeV and the members of $ gamma $-vibrational band have been identified. Results are compared with the systematic of this mass region and found in agreement. Observed band structures have been interpreted using the theoretical framework of microscopic triaxial projected shell model (TPSM) approach and it is shown that TPSM results are in fair agreement with the observed energies.
A superdeformed (SD) band has been identified in a non - alpha - conjugate nucleus 35Cl. It crosses the negative parity ground band above 11/2- and becomes the yrast at 15/2-. Lifetimes of all relevant states have been measured to follow the evolution of collectivity. Enhanced B(E2), B(E1) values as well as energetics provide evidences for superdeformation and existence of parity doublet cluster structure in an odd-A nucleus for the first time in A = 40 region. Large scale shell model calculations assign (sd)16(pf)3 as the origin of these states. Calculated spectroscopic factors correlate the SD states in 35Cl to those in 36Ar.
Results of a comparative analysis of the $^{214}$Po ($T_{1/2}= 163.47pm0.03$ $mu$s), $^{213}$Po ($T_{1/2}=3.705 pm 0.001$ $mu$s) and $^{212}$Po ($T_{1/2}=294.09pm0.07$ ns) half-life annular variation parameters are presented. It is shown that two independent sequential sets of the $^{214}$Po $tau$-values $(tauequiv T_{1/2})$ obtained in the spaced laboratories can be described by sinusoidal functions. The sinusoid curve with amplitude $A=(5.0 pm1.5) cdot 10^{-4}$, period $omega=(365pm 8)$ days, and phase $phi=(170 pm 7)$ days approximates the set of $^{214}$Po $tau$ values obtained at BNO INR RAS during the $sim$973 days starting on January 4, 2012. The function approximates a set of $tau$-values with a time duration of $sim1460$ days obtained at the KhNU has an amplitude $A=(4.9pm1.8)cdot10^{-4}$, a period $omega= (377pm13)$ days and a phase $phi=(77pm10)$ days. The $^{213}$Po $tau$-value set with a time duration of $sim1700$ days can be described by a sinusoidal function with an amplitude $A=(3.9pm1.2)cdot10^{-4}$, a period $omega= (370pm13)$ days and a phase $phi=(130pm9)$ days. The $^{212}$Po $tau$-value set with a time duration of $sim670$ days can be described by a sinusoidal function with an amplitude $A=(7.5pm1.6)cdot10^{-4}$, a period $omega= (375pm13)$ days and a phase $phi=(40pm10)$ days.
High-spin states in the doubly-odd $^{198}$Bi nucleus have been studied by using the $^{185,187}$Re($^{16}$O, xn) reactions at the beam energy of 112.5 MeV. $gamma-gamma$ coincidence were measured by using the INGA array with 15 Compton suppressed clover HPGe detectors. The observed levels have been assigned definite spin-parity. The high spin structure is grouped into three bands (B1, B2 and B3), of which two (B1 and B2) exhibit the properties of magnetic rotation (MR). Tilted axis cranking calculations were carried out to explain the MR bands having large multi-quasiparticle configurations. The calculated results explain the bands B1 and B2 very nicely, confirming the shears mechanism and suggest a crossing of two MR bands in both the cases. The crossing is from 6-qp to 8-qp in band B1 and from 4-qp to 6-qp in band B2, a very rare finding. A semiclassical model has also been used to obtain the particle-hole interaction strengths for the bands B1 and B2, below the band crossing.
Prompt, in-beam $gamma$ rays following the reaction $^{170}$Yb + 142 MeV $^{28}$Si were measured at the ATLAS facility using 10 Compton-suppressed Ge detectors and the Fragment Mass Analyzer. Transitions in $^{194}$Po were identified and placed using $gamma$-ray singles and coincidence data gated on the mass of the evaporation residues. A level spectrum up to J$approx$10$hbar$ was established. The structure of $^{194}$Po is more collective than that observed in the heavier polonium isotopes and indicates that the structure has started to evolve towards the more collective nature expected for deformed nuclei.
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