~(187)Pt的高自旋态能级结构

利用在束γ谱学技术和173Yb(18O,4n)熔合蒸发反应研究了187Pt的高自旋态能级结构.实验观测到基于νi13/2,ν7/2-[503],νi213/2νj,ν3/2-[512]和ν1/2-[521]组态的转动带,并且利用推转壳模型对这些转动带的性质进行了解释.总Routhian面计算表明:νi13/2转动带具有显著的负γ形变;负宇称带具有近似长椭球的形变.通过比较带内B(M1)/B(E2)比率的实验值和由Dnau和Frauendorf半经典公式得到的理论值,发现ν7/2-[503]转动带在低转动频率下的带交叉是由一对h9/2质子顺排引起的.

~(187)Pt的转动带性质研究

利用在束γ谱学技术和173Yb(18O,4n)熔合蒸发反应研究了187Pt的高自旋态能级结构．建立了包括3个转动带的187Pt高自旋态能级纲图．基于187Pt周围核结构的系统学和比较带内B(M1)／B(E2)比率的实验值和理论值,建议上述3个转动带的组态分别为11／2+[615],7／2-[503]和1／2-[521]．对各转动带的带交叉频率、顺排增益、旋称劈裂等进行了讨论．

~(179)Pt转动带性质的研究

利用能量为 16 4— 180MeV的3 5Cl束流 ,通过14 9Sm(3 5Cl,p4n)反应研究了179Pt的高自旋态能级结构 .进行了γ射线的激发函数、X γ和γ γ t符合测量 ,建立了基于 1 2 -[5 2 1],5 2 -[5 12 ]和7 2 + [6 33]组态的 3个转动带 .实验上观测到 1 2 -[5 2 1]带在ω =0 2 7MeV附近顺排角动量突然增大 ,且 7 2 + [6 33]带具有较大的旋称劈裂 .通过比较奇APt同位素和179Pt的同中子素能级结构的系统性 ,对相关现象进行了分析和讨论 .

Prolate and oblate shape coexistence in Pt-188

A standard in-beam gamma-spectroscopy experiment for Pt-188 is performed via the Yb-176(O-18, 6n) reaction at beam energies of 88 and 95 MeV, and the level scheme for (188) Pt is established. Prolate and oblate shape coexistence has been demonstrated to occur in Pt-188 by applying the projected shell model. The rotation alignment of i(13/2) neutrons drives the yrast sequence changing suddenly from prolate to oblate shape at angular momentum 10th, indicating likely a new type of shape phase transition along the yrast line in Pt-188.

High-spin structure in Pt-187

High-spin states in Pt-187 were studied via the Yb-173(O-18, 4n) reaction. Rotational bands based on the vi(13/2), v7/2(-)[503], vi(13/2)(2)vj, v3/2(-)[512] and v1/2(-)[521] configurations were observed, and interpreted within the framework of the cranked shell model. The TRS calculations show that the vi(13/2) band has an appreciable negative gamma deformation, and the negative-parity bands tend to have a near prolate shape with small positive gamma values. Experimental values of B(M1)/B(E2) ratios have been extracted and compared with theoretical values from the semi-classical Donau and Frauendof approach, strongly suggesting a low frequency pi h(9/2) alignment in the v7/2(-)[503] band.

High-spin states in Pt-190

The level structure of Pt-190 has been studied experimentally using the Yb-176 (O-18, 4n) reaction at beam energies of 88 and 95 MeV. gamma-gamma-t coincidence measurements were carried out. Based on the analysis of gamma-gamma coincidence relationships, the level scheme of Pt-190 is extended to high-spin states. A new structure built on the 3413.6 keV 14(+) state has been observed, and the vi(13/2)(-2) vh(9/2)(-1) vj (j = p(3/2) or f(5/2)) configuration is tentatively assigned to it.

Band properties of the transitional nucleus Pt-187

High-spin states in Pt-187 have been studied experimentally using the Yb-173(O-18, 4n) reaction at beam energies of 78 and 85 MeV. The previously known bands based on the nu i(13/2),nu 7/2(-)[503], and nu i(13/2)(2)nu j configurations have been extended to high-spin states, and new rotational bands associated with the nu 3/2(-)[512] and nu 1/2(-)[521] Nilsson orbits have been identified. The total Routhian surface calculations indicate that the transitional nucleus Pt-187 is very soft with respect to beta and gamma deformations. The band properties, such as level spacings, band crossing frequencies, alignment gains, and signature splittings, have been compared with the systematics observed in neighboring nuclei and have been interpreted within the framework of the cranked shell model. The rotational bands show different band crossing frequencies, which can be explained by the alignment either of i(13/2) neutrons or of h(9/2) protons. Importantly, evidence is presented for a pi h(9/2) alignment at very low frequency in the nu 7/2(-)[503] band. The proton nature of the band crossing is strongly suggested by comparing the measured B(M1;I -> I-1)/B(E2;I -> I-2) ratios with the theoretical values from the semiclassical Donau and Frauendof approach.

Quasiparticle nature of rotational bands in Pt-187

The high-spin states in Pt-187 have been studied experimentally by means of in-beam gamma-ray spectroscopy techniques via the Yb-173(O-18, 4n) fusion-evaporation reaction. The high-spin level scheme of Pt-187 has been established, including three rotational bands. Based on the systematics of level structure in neighboring nuclei and by comparing the experimental and theoretical B(M1)/B(E2) ratios, configurations of 11/2+ [615], 7/2(-)[5031 and 1/2(-)[521] have been proposed for the three rotational bands, respectively. Band properties of band crossing frequency, alignment gain and signature splitting have been discussed.

Band properties of the transitional nucleus Pt-189

High-spin states in Pt-189 have been studied with the in-beam gamma-spectroscopy method via the Yb-176(O-18, 5n) reaction at beam energies of 88 MeV and 95 MeV. A new level scheme of Pt-189 has been established. Rotational bands based on the upsilon i(13/2)(-1), upsilon f(5/2)(p(3/2)) and upsilon i(13/2)(-2)upsilon f(p(3/2)) configurations, as well as several structures with irregular level spacings, have been observed. Properties of rotational bands have been analyzed in the framework of triaxial particle-rotor model. A gamma similar to -30 degrees triaxial shape and a near prolate shape have been proposed to the upsilon i(13/2)(-1) and uf(5/2)(p(3/2)) bands, respectively. Two Delta I=2 transition sequences with similar energies have been observed, and they have been proposed to be associated with the upsilon i(13/2)(-1)upsilon f(5/2)(p(3/2)) configuration. According to the relevant Nilsson orbitals, the bands built on the upsilon i(13/2)(-1)upsilon f(5/2)(p(3/2)) configuration could be interpreted as a pair of pseudo-spin partner.