169Re的转动带结构研究

利用在束γ谱学方法,通过反应¹⁴⁴Sm(²⁸Si,1p3n)¹⁶⁹Re研究了¹⁶⁹Re的激发态能级结构.实验进行了X-γ符合、γ-γ符合、DCO系数和带内B(M1)/B(E2)比率测量.基于这些测量,建立了组态为π9/2^－[514]的强耦合带和组态为π1/2^－[541]的退耦合带.通过比较¹⁶⁹Re的转动带与邻近奇质子核已知转动带的结构和B(M1)/B(E2)比率,指定了¹⁶⁹Re转动带的组态.实验观测到π9/2^－[514]和π1/2^－[541]转动带的中子AB带交叉的转动频率分别为0.23和0.27MeV.着重讨论了¹⁶⁹Re转动带的中子AB带交叉频率、转动角动量顺排和旋称劈列等,并讨论了奇ARe核转动带结构的系统性     

双奇核172Re高自旋态转动带结构实验研究

利用重离子熔合蒸发反应¹⁴⁹Sm(²⁷Al,4nγ)¹⁷²Re布居了形变双奇核¹⁷²Re的高自旋态,用12套带有BGO反康普顿抑制的高纯锗探测器阵列进行了在束γ实验测量,首次建立了形变双奇核¹⁷²Re由3个转动带构成的高自旋态能级纲图.研究和讨论了3个转动带的结构特征,基于已有的高自旋态核结构知识并通过系统学比较和分析指出它们的准粒子组态分别为πh_11/2⊙νi_13/2,πh_9/2⊙νi_13/2和π1/2^－[541]⊙ν1/2^－[521].发现前两个转动带在自旋小于18.5h时其转动能级呈现反常的旋称劈裂.     

双奇核170Ta的转动带结构

用能量为105MeV的¹⁶O束流,通过¹⁵⁹Tb(¹⁶O,5nγ)¹⁷⁰Ta反应研究了¹⁷⁰Ta的高自旋态,观察到¹⁷⁰Ta的3个转动带,其中一个耦合带和一个半退耦带中的非优先ΔI=2转动系列是由本工作发现的.文中还讨论了这些转动带可能的准粒子组态.     

奇奇核170Ta高自旋态及旋称反转研究

用97MeV的¹⁹F束通过¹⁵⁵Gd(¹⁹F,4n)¹⁷⁰Ta反应布居了奇奇核¹⁷⁰Ta的高自旋态,将¹⁷⁰Ta的3个转动带推向了更高的自旋态,并观测到了半退耦带的旋称反转点,将其自旋值定在了19.5h.首次比较系统地总结了稀土区半退耦带的旋称反转系统规律,并比较了该核区半退耦带与晕带的系统性差异,特别是这两个带在能量劈裂程度上存在着系统性差异.从这一现象出发,探讨了半退耦带与晕带旋称反转系统性差异的成因,指出p-n剩余相互作用在这一现象中起着非常重要的作用.     

187Pt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.     

179Pt转动带性质的研究

利用能量为164—180MeV的³⁵Cl束流,通过¹⁴⁹Sm(³⁵Cl,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γγt符合测量,建立了基于12^－[521],52^－[512]和72⁺[633]组态的3个转动带.实验上观测到12^－[521]带在hω=0.27MeV附近顺排角动量突然增大,且72⁺[633]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.     

形变双奇核178Ir转动带能级的旋称反转

利用¹⁵²Sm(³¹P,5nγ)¹⁷⁸Ir反应产生并研究了双奇核¹⁷⁸Ir的高自旋态.实验中进行了¹⁷⁸Ir核的在束γ测量,包括γ射线的激发函数测量、X–γ和γ–γ符合测量.首次建立了双奇核¹⁷⁸Ir基于πh_9/2νi_13/2和πh_11/2νi_13/2准粒子组态上的转动带能级纲图.发现在低自旋区,两个转动带能级均出现旋称反转.对此核区半退耦带的旋称反转作了简要的分析和讨论.     

A=80区奇奇核的晕带能谱计算

采用二准粒子加轴对称转子模型,研究了A=80区部分奇奇核的晕带能谱,理论计算结果准确地再现了每个核的signature反转,并与实验值符合相当好- 关键词：     

双奇核176Ir转动带的旋称反转

利用¹⁴⁹Sm(³¹P,4nγ)反应,通过γ射线的激发函数测量、X-γ和γ-γ符合测量研究了双奇核¹⁷⁶Ir的高自旋态.首次建立了双奇核¹⁷⁶Ir由4个转动带构成的能级纲图.依据从实验数据中提取出的带内B(M1)/B(E2)值与理论计算值的比较,以及相邻双奇核的带结构特征,给出了转动带的准粒子组态.基于本实验建立起的带间跃迁和在I=18h处观测到的旋称交叉,指出¹⁷⁶Ir核基于πh_9/2⊙νi_13/2和πi_13/2⊙νi_13/2组态的两个转动带在低自旋时出现旋称反转现象.     

179Au的1/2[660](πi13/2)转动带

利用能量为164—180MeV的³⁵Cl束流,通过重离子核反应¹⁴⁹Sm(³⁵Cl,5n)研究了¹⁷⁹Au的高自旋态能级结构.实验进行了γ射线的激发函数、X-γ和γ-γ-t符合测量.基于对实验测量结果的分析,首次建立了¹⁷⁹Au的1/2[660](πi_13/2)转动带.结合已有的实验数据,着重讨论了奇AAu核中1/2[660](πi_13/2)转动带的带头激发能随中子数的变化     

双奇核~(170)Re高自旋转动带分析(英文)

通过重离子熔合蒸发反应142Nd(32S,1p3nγ)170Re布居了缺中子双奇核170Re的高自旋激发态,识别出了该核的一条转动带并建议了其组态为πh1/2 νi13/2。基于对同中子素能级系统性、旋称反转系统性、带内B(M1)/B(E2)、准粒子Routhians、动力学转动惯量和Total Routhian Surface(TRS)等带结构特征的详细分析和讨论,进一步确认了对A=170核区目前最缺中子双奇核高自旋转动带组态、宇称和自旋值的指定。     

Rotational Bands in Odd-Odd 174Re

High spin states in ¹⁷⁴Re have been studied via the ¹⁵⁹Tb (²⁰Ne, 5nγ) ¹⁷⁴Re reaction through excitation function, X-γ and γ-γ coincidence measurements. A stretched E2 cascade has been identified and assigned to be the doubly decoupled band band on the л1/2^－[541]⊙v1/2^－[521] configuration. Other two bands with semidecoupled and strongly coupled characters have been found and their quasiparticle configurations are qualitatively discussed.     

Observation of High-j Two-Quasiparticle Bands in Odd-Odd ^174Re

High spin states in ^174Re have been investigated via the ^152Sm （^27 Al, 5nγ） ^174Re reaction. Gamma-ray excitation functions, x-γ and γ-γ coincidences have been measured. Two rotational bands built on the πh9/2 × vi13/2 and πh11/2 × vi13/2 configurations have been identified and extended up to high-spin states. The relative spin and parity of the band levels have been unambiguously fixed due to observations of several inter-band transitions. Both the bands show the low-spin signature inversion, which is consistent with systematic expectations for the high-j two-quasiparticle bands in the A = 170 mass region.     

Description of the Superdeformed Bands of the Odd-Odd Nuclei in A ～ 150 Region

With the supersymmetry scheme including many-body interactions, the global property and the △I ＝ 4bifurcation in the superdeformed (SD) bands of odd-odd nuclei in A ～ 150 mass region are investigated systematically.Good results for the γ-ray energies, the dynamical moments of inertia, and energy differences △ Eγ - △ Erefγ are obtained.It shows that this approach is quite powerful in describing not only the SD bands in even-even and odd-A nuclei butalso those in odd-odd nuclei in the mass region.     

A=160号区部分奇奇核的晕带能谱计算

将奇核轴对称转子加准粒子模型推广到奇奇核的情况,考虑了在奇奇核的基矢空间中计及模型的质子—中子相互作用项,方法用于A=160号区多个实际核的计算,所得结果均与实验值定性相符.文中还对奇奇核Signature反转的一种可能的机制进行了讨论.     

Description of Chiral Doublet Bands in Odd-Odd Cs Isotopes

Properties of the chair doublet bands of the odd-odd Cs isotopes built on the πh11/2× vh11/2 configuration are investigated systematically within the supersymmetry scheme including many-body interactions and possessing the SO（5）（or SU（5）） symmetry on the rotational symmetry. Quantitatively good results of the energy spectra, the energy staggering parameter as a function of the spin are obtained. The calculation shows that the stronger competition between the pairing and anti-pairing effects and the SU（3） symmetry broking more seriously exist in the stable chiral structure.     

Description of Chiral Doublet Bands in Odd-Odd Cs Isotopes

Properties of the chair doublet bands of the odd-odd Cs isotopes built on the π h_11/2 \otimes ν h_11/2 configuration are investigated systematicallywithin the supersymmetry scheme including many-body interactions andpossessing the SO(5)(or SU(5)) symmetry on the rotational symmetry.Quantitatively good results of the energy spectra, the energy staggering parameter as a function of the spin are obtained. The calculation shows that the stronger competition between the pairing and anti-pairing effects and the SU(3) symmetry broking more seriously exist in the stable chiral structure.     

Search for decoupled bands in Odd-Odd 174Re

An effort has been made to search for the decoupled bands in odd-odd ¹⁷⁴Re via the ¹⁵⁹Tb(²⁰Ne,5n γ)¹⁷⁴Re reaction through excitation functions, K x-γ and γ-γ coincidence measurements. The doubly decoupled band and the semidecoupled one have been found in this work. Their quasiparticle configurations are proposed to be π1/2⁻[541] ⊗ν1/2⁻[521] and π1/2⁻[541] ⊗νi _13/2, respectively, according to the characteristics of band structures in this mass region. Another band with strongly coupled character is also reported. Received: 23 November 1999 / Revised version: 5 January 2000