共查询到19条相似文献,搜索用时 140 毫秒
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在壳模型的基础上系统研究了146Gd区A=147-153核的Gamow-Teller跃迁.这些相对146Gd核心为粒子态的核唯一的β允许衰变道为π1h11/2→v1h9/2的Gamow-Teller跃迁.计算结果表明,实验的约化几率B(GT)与计算的B(GT)比较,存在一个阻塞因子γ2,即γ2=Bexp(GT)/Bcal(GT)=0.17±0.05. 相似文献
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M.萨哈伊 朱胜江 甘翠云 朱凌燕 杨利明 许瑞清 全明吉 姜卓 张征 J.H.Hamilton A.V.Ramayya B.R.S.Babu J.K.Hwang W.C.Ma J.Komicki J.D.Cole R.Aryaeinejad M.W.Dirgert J.O.Rasmussen M.A 《中国物理 C》2000,24(11):1018-1023
通过对252Cf自发裂变产生的瞬发γ谱的测量,对丰中子奇A核145,147Ce的高自旋态进行了研究,首次识别了145Ce的集体带结构,扩展了147Ce的集体带结构,扩展了147Ce的能级,并新识别了3个边带,粒子–转子模型的计算指出,145,147Ce的晕带可能来自于νi13/2轨道的耦合,145Ce基态起源于(νh9/2νf7/2)组态混合,而147Ce基态则起源于νh9/2轨道.在这两个核中未观测到明显的八极形变带,然而,在147Ce中观测到的一个边带,可能显露出八极关联的迹象. 相似文献
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通过融合蒸发反应144Nd(19F,5n)布居了双奇核158Tm的高自旋态. 扩展了原来已知的带结构, 并建立了一条新转动带. 通过与相邻核的比较, 讨论158Tm核中两条四准粒子带的内禀组态, 并分别指定为πh11/2\otimes νh9/2(α=+1/2)\otimes (νi13/2)2和πh11/2\otimes νh9/2(α=-1/2)\otimes (νi13/2)2
组态. 建立在πh11/2\otimes νi13/2组态上的转动带被观测到呈现持续旋称反转现象, 而前述的两条高自旋区的
四准粒子转动带也呈旋称反转. 对这两种类型的旋称反转现象的可能机制进行了简单而定性的讨论. 相似文献
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丰中子核145,147La的八极形变 总被引:1,自引:1,他引:0
朱胜江 王牧歌 朱凌燕 李明 甘翠云 杨利明 萨哈伊 朴秀日 邓景康 龙桂鲁 J.H.Hamilton A.V.Ramayya B.R.S.Babu J.K.Hwang W.C.Ma J.Komicki J.D.Cole R.Aryaeinejad M.W.Drigert J.O.Rasmussen 《中国物理 C》2000,24(5):418-425
通过对252Cf自发裂变产生的瞬发γ谱的实验研究,建立与扩展了丰中子核145,147La的高自旋态能级图,最高自旋态达到(41/2+)与(43/2-).测得的交叉相联的相反宇称带及带间的强化E1跃迁说明在145,147La中形成强的八极形变.对145La的研究表明,具有轴对称形状的四极形变与具有反演不对称形状的八极形变在同一核中产生共存与竞争.在πh11/2带中观测到的带交叉位于ω≈0.26—0.30MeV附近,由推转壳模型计算表明,它是由一对i13/2中子的顺排所引起的. 相似文献
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质量数在160-180核区形变双奇核高自旋态实验研究 总被引:1,自引:0,他引:1
基于在160-180核区形变双奇核高自旋态研究中所取得的研究结果和最近几年陆续发表的双奇核高自旋态核谱学数据,系统地考察和研究了πh11/2⊙νi13/2强耦合带和πh9/2⊙νi13/2半退耦带旋称反转的特征和规律.指出182,184Au核素的πh13/2⊙νi13/2半退耦带也可能出现旋称反转;有限的实验数据似乎支持这一观点.首次在双奇核178,180Ir的πh11/2⊙νi13/2强耦合带中发现了低转频下的逐渐顺排现象;在178Ir核中发现了回弯频率反常超前.这些反常现象可能与核形变(或中子对力)的组态依赖性有关. 相似文献
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骆鹏 张玉虎 周小红 柳敏良 郭应祥 刘忠 雷相国 宋立涛 郑勇 王华磊 于海萍 谢成营 马英君 Y.Sasaki K.Yamada H.Ohshima 《中国物理 C》2004,28(5):495-501
利用在束γ谱实验技术,通过128Te(10B,3n)135La反应研究了135La的高自旋态.基于γγ符合关系、γ射线的相对强度和各向异性度的测量结果,建立了135La的能级纲图.在hω≈0.40MeV附近,观测到基于πh11/2质子轨道上的负宇称带的带交叉.比较N=78同中子素链能级结构的系统性,认为该带交叉是由一对h11/2准质子发生转动顺排造成的.在高自旋态处,观测到具有很强M1跃迁、Signature劈裂很小的ΔI=1负宇称带,根据系统性认为该带是建立在πh11/2(νh11/2)2组态上的γ≈–60°的扁椭球形变带. 相似文献
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LIU Ying WU Xiao-Guang ZHU Li-Hua LI Guang-Sheng HE Chuang-Ye LI Xue-Qin PAN Bo HAO Xin LI Li-Hua WANG Zhi-Min LI Zhong-Yu XU Qiang 《中国物理C(英文版)》2009,33(Z1)
The high spin states of 129Ce have been populated via heavy-ion fusion evaporation reaction 96Mo (37C1, 1p3n) 129Ce. The γ-γ coincidence and intensity balance used to measure the B(M1; I→I-1)/B(E2; I→I-2) (the probability ratio of the dipole and quadrupole transition) in v7/2[523] rotational band of 129Ce. And the energy splitting (Δe') has been got through the experimental Routhians. The lifetimes and quadrupole moments Qt have been extracted from the lineshape analyses using DSAM. The deformation of the v7/2[523] rotational band of 129Ce was extracted from the Qt and moment of inertia JRR. 相似文献
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G. S. Li Z. Y. Dai S. X. Wen S. G. Li P. K. Weng L. K. Zhang G. J. Yuan C. X. Yang 《Zeitschrift für Physik A Hadrons and Nuclei》1986,356(2):119-123
Lifetime measurements of the high spin states in the yrast band of 128Ce were performed using the Doppler shift attenuation method in connection with the reaction 100Ru(32S, 2p2n) 128Ce at incident energy of 141 MeV. In the vicinity of the band crossing, the previously reported anomalously high B(E2) value was not observed. The gross behavior of the normalized transition strength is approximate to symmetric rotor. It is confirmed that the trend of increase in collectivity with decreasing neutron number, which was indicated in the previous studies on 130, 132, 134Ce, continues in 128Ce. The value of quadrupole deformation parameter β2 deduced from the measured lifetimes is in good agreement with the theoretical calculation using a cranking model based on a non-axially deformed Woods-Saxon potential. 相似文献
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G. S. Li Z. Y. Dai S. X. Wen S. G. Li P. K. Weng L. K. Zhang G. J. Yuan C. X. Yang 《Zeitschrift für Physik A Hadrons and Nuclei》1996,356(1):119-123
Lifetime measurements of the high spin states in the yrast band of128Ce were performed using the Doppler shift attenuation method in connection with the reaction100Ru(32S, 2p2n)128Ce at incident energy of 141 MeV. In the vicinity of the band crossing, the previously reported anomalously highB(E2) value was not observed. The gross behavior of the normalized transition strength is approximate to symmetric rotor. It is confirmed that the trend of increase in collectivity with decreasing neutron number, which was indicated in the previous studies on130,132,134Ce, continues in128Ce. The value of quadrupole deformation parameterβ 2 deduced from the measured lifetimes is in good agreement with the theoretical calculation using a cranking model based on a non-axially deformed Woods-Saxon potential. 相似文献
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Seweryniak D Blank B Carpenter MP Davids CN Davinson T Freeman SJ Hammond N Hoteling N Janssens RV Khoo TL Liu Z Mukherjee G Robinson A Scholey C Sinha S Shergur J Starosta K Walters WB Woehr A Woods PJ 《Physical review letters》2007,99(8):082502
Gamma rays deexciting states in the proton emitter 145Tm were observed using the recoil-decay tagging method. The 145Tm ground-state rotational band was found to exhibit the properties expected for an h{11/2} proton decoupled band. In addition, coincidences between protons feeding the 2{+} state in 144Er and the 2{+}-->0{+} gamma-ray transition were detected, the first measurement of this kind, leading to a more precise value for the 2{+} excitation energy of 329(1) keV. Calculations with the particle-rotor model and the core quasiparticle coupling model indicate that the properties of the pi{11/2} band and the proton-decay rates in 145Tm are consistent with the presence of triaxiality with an asymmetry parameter gamma approximately 20 degrees . 相似文献
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采用基于密度泛函理论加U的计算方法,研究了Ce和O空位单(共)掺杂锐钛矿相TiO_2的电子结构和光吸收性质.计算结果表明,Ce和O空位共掺杂TiO_2的带隙中出现了杂质能级,且带隙窄化为2.67 eV,明显比纯TiO_2和Ce,O空位单掺杂TiO_2的要小,因而可提高TiO_2对可见光的响应能力,使TiO_2的光吸收范围增加.光吸收谱显示,掺杂后TiO_2的光吸收边发生了显著红移;在400.0—677.1 nm的可见光区,共掺杂体系的光吸收强度显著高于纯TiO_2和Ce单掺杂TiO_2,而略低于O空位单掺杂TiO_2.此外,Ce掺杂TiO_2中引入O空位后,TiO_2的导带边从-0.27 eV变化为-0.32 eV,这表明TiO_2的导带边的还原能力得到了加强.计算结果为Ce和O空位共掺杂TiO_2在可见光光解水方面的进一步研究提供了有力的理论依据. 相似文献
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High-spin levels in 129, 131Ce have been produced by the reactions 116, 118Sn(16O, 3n) 129, 131Ce and studied by in-beam γ-ray spectroscopic techniques. Two strongly populated band structures are observed. The odd-parity levels based on a state constitute a system explained in the triaxial-rotor-plus-particle model as the result of the coupling of an neutron-hole to a prolate-type triaxial core. The even-parity band built on a state corresponds to collective excitations associated with a neutron-hole in the shell. Backbending effect observed in the yrast cascade is discussed. 相似文献
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A classification of nuclear states according to the non-compact Lie algebra Sp(4, R) is investigated. This model strikes a compromise between the Sp(6, R) and Sp(2, R) models and furnishes a practical, yet algebraically simple means for selecting those shell-model core excitations which are needed for the development of quadrupole collectivity in rotational bands of deformed nuclei. Applications to rotational bands in 24Mg and 16O, including shell-model excitations with excitation energies up to 10?ω, show that the core excitations needed to fit observed E2 rates in these nuclei are too large to be treated by perturbation theory. Despite this, a definite symplectic band structure emerges. The nature of the core excitations is very simple, so that it may be feasible to incorporate such symplectic excitation structures into more detailed shell-model calculations. 相似文献
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Excited states of the137Ce,139Ce,139Nd and141Nd nuclei have been studied using the138Ba(α, 5nγ)137Ce,138Ba(3He, 4nγ)137Ce,138Ba(α, 3nγ)139Ce,140Ce(α, 5nγ)139Nd,140Ce(3He,4nγ)139Nd,140Ce(α, 3nγ)141Nd and142Ce(α, 5nγ)141Nd reactions. Singlesγ-ray spectra,γ —γ coincidence spectra, angular distributions and time distributions ofγ-rays with respect to beam pulses have been measured. Gamma transitions between excited states with spin values up to 21/2, 23/2 or 25/2 have been observed. Isomeric states with T1/2=70 ns have been observed in139Ce at 2631.5 keV (19/2) and in141Nd probably at 2952.0 keV (19/2). The level structure observed in the nuclei studied can be explained if the neutron-holes are coupled to the doubly even core excitations. The coupling of theh 11/2 neutron-hole with the 2+, 4+ and 3? collective excitations are calculated in terms of the weak and intermediate coupling models. The intermediate coupling results seem to be in better agreement with the experimental data. The energies of theree-particle states, being the result of the coupling of theh 11/2 neutron-hole with the two-proton excitations in the core, are well reproduced in the calculations when empirical values of the two-body interaction matrix elements were used. 相似文献
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ZHU ShengJiang GAN CuiYun ZHU LingYan YANG LiMing XU RuiQing JON MyonGil JIANG Zhuo ZHANG Zheng 《中国物理C(英文版)》2000,24(11):1018-1023
Through study of the prompt r-rays emitted in the spontaneous fission of 252Cf, high spin states of neutron-rich odd-A 145,147Ce nuclei have been investigated. The levels in 147Ce have been extended. A collective band in 145Ce have been identified for the first time. The results from the particle rotor model calculations indicate that the yrast bands in 145Ce and 147Ce originate from vi13/2 orbital coupling and the ground states of 145Ce and 147Ce originate from (vh9/2,vf7/2) and vh9/2 configiration, respectively. No obvious octupole deformation was observed in these two isotopes, but a side band obtained in 147Ce may show some octupole correlations. 相似文献