Comparative quadrupole moments of triaxial superdeformed states in 163, 164, 165Lu

Average transition quadrupole moments in the yrast triaxial superdeformed bands of ¹⁶³Lu, ¹⁶⁴Lu and ¹⁶⁵Lu were determined in a Doppler-shift attenuation-method experiment. Fractional Doppler shifts were determined in γ-ray coincidence spectra measured with the Gammasphere array. The transition quadrupole moments derived from these data show a decrease from ¹⁶³Lu to ¹⁶⁵Lu which is not predicted by total-energy surface calculations. Received: 12 August 2002 / Accepted: 23 October 2002 / Published online: 10 December 2002 RID="a" ID="a"e-mail: schoenwa@iskp.uni-bonn.de Communicated by D. Schwalm     

New experimental results in proton radioactivity

A review of experimental data obtained recently on proton-radioactive nuclei is presented. The highlights include the observation of fine structure in proton emission, for the decays of ¹³¹Eu, ¹⁴⁵Tm and ¹⁴⁶Tm, and the studies of the excited states in proton-emitting nuclei. The observation limits are extended to few nanobarns cross-sections ( ¹⁴⁰Ho, ¹⁶⁴Ir and ¹³⁰Eu) and few microsecond half-lives (e.g., ¹⁴⁵Tm). Measured decay properties for thirty-nine proton-emitting ground and isomeric states contributed to the understanding of nuclear masses and evolution of single-particle states at and beyond the proton drip line. Experimental results have stimulated new theoretical approaches to proton emission and the structure of unbound narrow resonance states. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: rykaczew@phy.ornl.gov     

In-beam studies of very neutron-deficient heavy nuclei

The JYFL gas-filled recoil separator RITU, combined with Ge detector arrays and a SACRED magnetic solenoid spectrometer, has been successfully employed in recoil-decay-tagging (RDT) experiments in order to probe structures of very neutron-deficient heavy nuclei. The present contribution focuses on the light Pb region where the new data extend the systematics of shape-coexisting yrast states towards the proton dripline. Similarities between band structures and their relation to possible multi-particle multi-hole intruder excitations will be discussed. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: rauno.julin@phys.jyu.fi     

Fragen der molekularen Systemorganisation,II. Solvatochrome Komplexe

Several mixed complexes, such as Fe(phen)₂(CN)₂ are subject to variations in color, according to the acceptor properties of the molecular environment. The charge transfer band is gradually shifted to decreasing wave length of the absorption maximum, as the acceptor number of the solution is increased. Likewise, the charge transfer band of the copper(II)-complex with tetramethyl-ethylenediamine and acetylacetonate as ligands is shifted to greater wave length as the donor number of the solution is increased, thus providing evidence for gradual changes from the planar into octahedral arrangement. All complexes have in common that their coordination centre is hard enough to respond to changes of an essentially hard environment and soft enough to redistribute any changes in charge density over the whole system in such ways that the basic characteristics of the complex molecule under consideration is retained. The charge density pattern around the coordination centre, which is at the same time an integral part of the molecular outer regions, appears to retain locally a nearly invariant charge density. The redistribution of the charge density pattern appears to be subject to the regulating actions around the coordination centre. This is therefore considered as representing the highest hierarchic level, to which the charge densities in all other boundary areas are subordinated. Reorganization of the charge density pattern is performed due to the mobilities of the -electron systems under control of the said superordinated levels. The lowest hierarchic level seems to be represented by the charge density areas along the structural framework, which provides the static boundary conditions for the more highly developed dynamic properties of the higher levels.

     

Experimental verification of the optimal tuning of a tunable vibration neutralizer for global vibration control

A theoretical method has been previously proposed by the authors to optimize a tunable vibration neutralizer for global vibration control. However, experimental verification of the tuning method has yet to be presented. This paper aims to do this. It is shown that by using the proposed optimization method, the tunable vibration neutralizer can be as effective as an active control device in reducing global vibration of a structure. One particularly interesting finding is that although the vibration neutralizer is a passive device which is incapable of supplying energy to a system, it appears to be as effective as active control in reducing the global vibration of a structure, even in the frequency range where the control device is required to supply energy.     

Spectroscopy of the neutron-deficient nuclide 171Pt

The decay out of the πh _11/2νh _11/2 band to the known low-energy levels in ¹³²La was studied using the reaction ¹⁰⁰Mo + ³⁶S at 160 MeV beam energy. The low-energy level scheme has been further developed and unambiguous spin and parity values have been assigned to the levels connecting the band to the 6^- isomeric state. According to the new level scheme the spins in the πh _11/2νh _11/2 band are shifted up by one unit compared to the earlier tentative experimental values. The obtained new spins prove the existence of signature inversion in ¹³²La and give further support to the spin assignments made for the πh _11/2νh _11/2 bands in the neighbouring odd-odd La isotopes from level energy systematics. Received: 7 May 2002 / Accepted: 31 October 2002 / Published online: 17 January 2003 RID="a" ID="a"e-mail: timar@atomki.hu RID="b" ID="b"Present address: Dipartimento di Matematica e Fisica, Università di Camerino, via Madonna delle Carceri, I-62032 Camerino, Italy. Communicated by J. ?yst?     

Investigation of lifetimes in quadrupole bands of 142Gd

For a level scheme investigation of ¹⁴²Gd an experiment with the γ -spectrometer EUROBALLIII has been carried out and lifetimes have been measured with EUROBALL IV using the Doppler-shift attenuation method. The high-spin states have been populated in these experiments by means of the ⁹⁹Ru(⁴⁸Ti, 2p3n) reaction at a beam energy of 240MeV and the ¹¹⁴Sn(³²S, 2p2n) reaction at 160MeV, respectively. Reduced E2 transition probabilities B(E2) were determined for 15 members of four quadrupole bands. For the interpretation of the positive-parity even-spin quadrupole bands, calculations in the cranked Nilsson-Strutinsky as well as interacting boson models have been performed. From the former calculations it was concluded that the high-spin states of the (+ , 0)₁ band in ¹⁴²Gd represent a triaxial nucleus rotating around the longest principal axis.     

热超声倒装键合中换能杆末端多维振动的相关性研究

换能杆末端的振动情况对于超声键合机理的研究有着重要意义；换能杆末端的实际振动模式直接影响着芯片键合的质量。利用高精度非接触式激光多普勒测振仪采集了换能杆末端俯仰、水平、轴向振动速度，用相干函数方法分析了3个方向的相互耦合关系。分别对换能杆末端有未安装劈刀的情况做了比较，得出了在换能系统工作频率附近，换能杆末端轴向振速与水平、俯仰振速的相关程度。这对实际键合中，换能系统末端的劈刀安装长度的选择以及换能杆工作频率的选择有指导意义。     

多参考组态相互作用方法研究ZnHg低激发态(~1∏,~3∏)的势能曲线和解析势能函数

采用多参考组态相互作用方法计算了ZnHg二聚体两个低激发∏态(1∏,3∏)的原子间相互作用势能曲线.用Murrel-Sorbie函数拟合得到了相应的解析势能函数,并用其计算力常数,进而确定了光谱常数.所得结果与仅有的理论工作进行了比较.基于所得势能曲线,通过解分子中原子核运动的薛定谔方程预测了各电子态的振动能级.     

Spectroscopy of neutron-deficient nuclei around 36Ca

An experiment was performed to extend the knowledge of excited states in neutron-deficient Ca isotopes. In particular, the first excited state in ³⁶Ca was searched for to obtain information on the isospin dependence of the nucleon-nucleon interaction near the proton drip line from a comparison with its stable mirror nucleus, ³⁶S. The ³⁶Ca ions were produced using a two-step fragmentation technique with a ³⁷Ca secondary beam, and in-beam γ-rays were measured. First results are the energy of the first 2⁺ state in ³⁶Ca, E(2⁺)=3036(11) keV, and the cross section for the reaction ³⁷Ca → ³⁶Ca at 61.A MeV. In addition, the de-excitaion of the first 2⁺ state in ²⁸S has been observed.