[en] The nuclei in mass region A ∼190 are well known for the prolate-oblate shape co-existence/transition phenomena. The shape coexistence phenomena has been observed in nuclei like Hg and Tl of this mass region. The calculations done for Pt nuclei in indicate a smooth shape change from prolate deformed "1"8"6Pt to nearly spherical "2"0"2"-"2"0"4 Pt through the region of triaxially deformed "1"8"8"-"1"9"8Pt and slightly oblate "2"0"0Pt. In these calculations, a change of shape from prolate to oblate is expected at A = 188. In recent high spin spectroscopic investigations, significant amount of reduced prolate collectivity has been observed in "1"8"8Pt. The level lifetimes provide valuable information about the nuclear shape and also the shape change with increase in spin along a band. So, to get clear signature of prolate to oblate shape inversion in Pt nuclei near A = 190, it is required to perform lifetime measurements. With this objective, the RDM lifetime measurements of high spin states have been done for various even-even Pt isotopes with masss A ≤ 186 over the years. The results obtained in these measurements are very encouraging and do indicate changing nuclear structure for Pt-isotopes with increasing mass at low spins. A gradual increase in B(E2) values upto 4"+ state and near constant nature there after in "1"8"8Pt, contrary to the other light neighboring Pt nuclei tends to indicate the volatile nature of deformation in Pt nuclei near A ∼ 190 which needs further theoretical investigations. (author)

No abstract available

[en] From the low-lying spectroscopic properties, it appears that "1"8"6Pt is a transitional nucleus. In fact, the previous studies on the level structure of "1"8"6Pt suggests that this nucleus is extremely γ soft and there are evidences for the presence of co-existing prolate, oblate and tri-axial band structures. The shape-coexistence feature in Pt-isotopes has been of primary interest for many years. Extensive theoretical calculations have been carried out to understand the underlying feature. One debating issue persists: whether the intruder states play a major role in the shape evolution of Pt-isotopes or the same can be understood without invoking the intruder states

[en] Relativistic mean field theory with the NL3 force is used to produce potential energy surfaces (PESs) for a series of isotopes suggested as exhibiting critical point symmetries. Relatively flat PESs are obtained for nuclei showing the E(5) symmetry, whereas in nuclei corresponding to the X(5) case, PESs with a bump are obtained. The PESs corresponding to the Pt chain of isotopes suggest a transition from prolate to oblate shapes at ¹⁸⁶Pt

[en] The study of F-spin multiplets within the neutron-proton interacting boson model is reviewed, the mechanism of F-spin multiplets is classified in detail. Furthermore, the results are presented, and the new probable mechanism is reported here

[en] Complete text of publication follows. The on-line nuclear orientation technique was used to study the structures of ¹⁸⁶Pt populated following the decay of ¹⁸⁶Au (T_1/2 = 10.7 min). The orientation of gold nuclei was produced using the hyperfine field in a ferromagnetic host at a low temperature (∼ 15 mK) which was achieved in a ³He-⁴He dilution refrigerator. The directional distributions of γ-rays were measured by high resolution Ge(Li) detectors. With these measurements unique spin-parity assignments were made to most of the populated levels in ¹⁸⁶Pt and the multipole mixing ratios of many mixed transitions were obtained. The structure of ¹⁸⁶Pt was examined using the neutron-proton interacting boson approximation (IBA-2). The energy levels were fitted, and the mixing ratios of some selected transitions were calculated and compared with the experimental results. The set of model parameters indicates that ¹⁸⁶Pt has a structure intermediate between the γ-soft, O(6), and rotational, SU(3), limits of the IBA. (author)

No abstract available

[en] "1"8"6Pt was tested in the framework of IBM-1 and the X(3) model. The results show that "1"8"6Pt is located close to the shape phase transition point, but the B(E2) values little agree with the X(3) model. The shape evolution in the yrast states of "1"8"6Pt is also discussed in detail. TRS calculation exhibits a flat bottomed potential at low spin states, but a relatively deep minimum at high spin states. It suggests that a shape evolution from vibrational mode to rotational mode happens in "1"8"6Pt. The result is in agreement with the E-GOS calculation. (authors)

[en] The low temperature nuclear orientation facility KOOL was used for a systematical study of the very neutron-deficient Au isotopes where the on-line technique is compulsory due to the short lifetimes involved. The measurement of the magnetic moment of the 4.6 min ¹⁸⁹Au 11/2^- isomer, a preliminary result on the same state in tsub(1/2) = 0.9 sec ¹⁹¹Au and the moment value of the tsub(1/2) = 10.7 min ¹⁸⁶Au 3^- ground state is reported. Several spins and mixing ratios in ¹⁸⁹Pt, ¹⁸⁶Pt and ¹⁹¹Au have been determined as well

No abstract available