Theoretical study of fusion reactions 32S + 94,96Zr and 40Ca + 94,96Zr and quadrupole deformation of 94Zr

The dynamic coupling effects on fusion cross sections for reactions~(32)S + ~(94,96)Zr and ~(40)Ca + ~(94,96)Zr are studied with the universal fusion function formalism and an empirical coupled channel(ECC) model. An examination of the reduced fusion functions shows that the total effect of couplings to inelastic excitations and neutron transfer channels on fusion in ~(32)S +~(94)Zr(~(40)Ca +~(94)Zr) is almost the same as that in ~(32)S +~(96)Zr(~(40)Ca +~(96)Zr). The enhancements of the fusion cross section at sub-barrier energies due to inelastic channel coupling and neutron transfer channel coupling are evaluated separately by using the ECC model. The results show that effect of couplings to inelastic excitations channels in the reactions with94 Zr as target should be similar as that in the reactions with ~(96) Zr as target. This implies that the quadrupole deformation parameters β_2of ~(94)Zr and~(96) Zr should be similar to each other.However, β_2 's predicted from the finite-range droplet model, which are used in the ECC model, are quite different. Experiments on~(48) Ca +~(94)Zr or~(36) S +~(94)Zr are suggested to solve the puzzling issue concerning β_2for~(94)Zr.     

Intermediate mechanisms in fission-like fragmentation in the 32S + 59Co and 32S + 63Cu reactions

The fission-like fragmentation of the ³²S + ⁵⁹Co and ³²S + ⁶³Cu composite systems has been studied at incident energies E/A ≈ (4–5) MeV/nucleon. Mass, energy and angular distributions of the fission-like fragments were obtained from time-of-flight measurements. The mean total kinetic energies of the fragments are found to be fully relaxed, whereas a strong angular dependence is observed in the mass distributions. The data are interpreted in terms of a dynamical model based on the transport theory.     

The submillimeter wave spectrum of 32S16O2, 32S16O2(ν2), and 34S16O2

Extensive new measurements in the region 400–1000 GHz have been made on ³²S¹⁶O₂, ³²S¹⁶O₂(ν₂), and ³⁴S¹⁶O₂. These measurements represent almost a threefold extension in the frequency region for which high-resolution microwave data are available. These data have been combined with the previously available microwave data for this analysis. The results, when extrapolated into the far infrared, compare favorably with recent results obtained from high-resolution FIR spectroscopy.     

One-neutron transfer contribution to the elastic 32 S+ 32S scattering at Einc = 91.3 MeV

The elastic scattering differential cross section for ³²S incident on ³³S at E_inc = 91.3 MeV has been measured. The observed backward oscillations are successfully described by explicit inclusion of a parity-dependent term in the real potential for the optical-model calculations of the elastic scattering. To investigate possible sources of the parity-dependent term, the backward oscillations were also interpreted as being produced by the interference between the elastic amplitude and the one-neutron elastic one-step transfer process.     

Element distributions for the reactions32S+100Mo,32S+93Nb and28Si+93Nb near the coulomb barrier

The element distributions for the reactions³²S+¹⁰⁰Mo,³²S+⁹³Nb, and²⁸Si+⁹³Nb have been measured atE/B～1.4. The correlations between the first moment of the measured distributions and TKEL are consistent with the predictions of the liquid drop potential energy surfaces showing the charge equilibration of the dinuclear systems. The measured second moments are compared with a recent systematics.     

Multifragmentation study on 30 AMeV32S+58Ni

In a multidetector experiment on 26 or 30 AMeV³²S+⁵⁸Ni, up to four coincident heavier or intermediate-mass fragments were observed. One of these occasionally has the characteristics of a projectile-like fragment, up to three may be attributed to the decay of the heavy reaction product. Taking the velocity of the fragments as a measure of the heavy-product excitation energy, one finds evaporation, fission and multifragmentation to follow one another with rising excitation. Model simulations of sequential decay with up to two binary fissions and, alternatively, of simultaneous statistical multifragmentation were performed for comparison with experimental distributions of mass, velocity and (for events with three slow intermediate-mass fragments) relative azimuthal angle. Though in the three-fragment events indications of simultaneous multifragmentation are present, the sequential binary decay predominates. Evaporated protons and α particles detected in coincidence have a mean multiplicity growing with excitation energy, while the temperature governing the spectra has a plateau with a value of about 5.5 MeV.     

Microwave spectrum of the32S17O radical. Magnetic hyperfine structure and quadrupole coupling constants

Summary The millimetre wave spectrum of the³²S¹⁷O free radical has been observed and analysed. The fine- and hyperfine-structure parameters have been determined. Ther ^s andr ^m structures have been also determined.

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Riassunto è stato osservato ed analizzato lo spettro millimetrico del radicale libero³²S¹⁷O. Sono stati determinati i parametri di struttura fine ed iperfine e le strutturer ^s er ^m.

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Резюме Наблюдался д проведен анализ спектра миллиметровых волн свободного радикала³²З¹⁷О. Определены параметры тонкой и сверхтонкой структуры. Также определены структурыr ^s иr ^m.

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To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.

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The supporting organizations are the CNR and the M.P.I.     

The distance dependence and spatial distribution of the molecular quadrupole moments of P2, S2 and Cl2

The quadrupole moments (Θ) of the molecules P₂, S₂ and Cl₂ have been computed at the SCF, CASSCF and CASSCF + 1 + 2 levels of theory, using augmented correlation consistent basis sets. The convergence of Θ as a function of basis set and level of theory is discussed. The variation of Θ from the separated atoms to the equilibrium region is reported. Θ is written as the sum of a sigma and pi contribution, and inaccuracies in the SCF values for P₂ and S₂ are due to the poor representation of the pi system in the SCF theory. A reference state dependent quadrupole moment density, - ½(3cos² θ- 1)r ²δη(r; R), is defined whose integral is the mole2 cular quadrupole moment, and the spatial distributions of the density and its relationship to the density difference δη(r; R) are examined.     

H2S和H2S+的振动光谱和电子能谱计算

本文基于MOLPRO软件包使用从头算方法计算了星际分子H₂S及其阳离子H₂S⁺的势能面及光电子能谱.首先,在(U)CCSD/cc-pVQZ理论水平下获取了H₂S沿法线坐标展开的势能面,势能面直观描述了不同振动模式耦合对分子能量变化的影响,S-H键的非对称伸缩振动和面内弯曲振动共同作用使得系统势能变化范围明显变大.振动多组态相互作用方法被用来计算非谐振动频率和振动光谱,计算结果显示,倍频和组合频之间出现了强烈的费米共振,使得相应波段处的红外强度显著增强.最后,使用拉曼波函数和收缩不变Krylov子空间方法首次计算了H₂SΧ¹A₁→H₂S⁺ X²B₁的光电子能谱.此项研究有助于进一步理解星际分子的内部结构,并为实验研究及星际观测提供参考.     

Two distinct quasifission modes in the 32S + 232Th reaction

Comprehensive fission measurements, including mass-angle distributions, for the reaction of 32S with the prolate deformed nucleus 232Th at near-barrier energies show two distinct components in both mass and angle; surprisingly, both have characteristics of quasifission. Their relative probabilities vary rapidly with the ratio of the beam energy to the capture barrier, suggesting a relationship with deformation aligned (sub-barrier), or antialigned (above-barrier), configurations at contact.     

16O+16O molecular structure and superdeformation in 32S

The molecular structure with the ¹⁶O+¹⁶O configuration in ³²S and the superdeformed structure in ³²S are discussed from the viewpoint of the cluster model.     

近垒能区32S+90,96Zr势垒分布的研究

精确测量了³²S+^90,96Zr两系统的背角准弹散射激发函数, 总体误差小于1%, 从中分别抽取了它们的势垒分布, 对比观测到³²S+⁹⁶Zr的势垒结构扁平且向低能区展宽, 这种 势垒可导致在垒下能区该体系的熔合截面的大大增强. ³²S+⁹⁶Zr与³²S+⁹⁰Zr相比 存在较强的中子转移反应, 且转移Q值为正. ³²S+⁹⁶Zr势垒的扁平结构可能是中子转移道耦合所致, 这会导致³²S+⁹⁶Zr垒下熔合截面大的增强.     

The g-factor and the electric quadrupole moment of the 7/2+ isomer in125Xe

The time differential perturbed angular distribution method (PAD) was used to measure theg-factor and the electric quadrupole interaction in a Cd single crystal for thet _1/2=140 ns,I ^π=7/2⁺ isomer in¹²⁵Xe. Theg-factor isg=+0.264(10) and the quadrupole coupling constante ² Qq/h=122.1 (6) MHz at 552 K. The lifetime of theI ^π=11/2⁺ state was measured to beτ=11.3 (1.1) ps by the recoil distance method (RDM). From an analysis of the spectroscopic data using the triaxial-rotor-plus-particle (TRPP) model the quadrupole moment of the 7/2⁺ isomer is deduced to beQ=1.40 (15) b yielding an electric field gradient (efg)eq=3.6(4)·10¹⁷ V/cm² for XeCd.     

Electric quadrupole moments of neutron-rich nuclei 32Al and 31Al

The electric quadrupole moments for the ground states of ³²Al and ³¹Al have been measured by the β ray-detected nuclear quadrupole resonance method. Spin-polarized ³²Al and ³¹Al nuclei were obtained from the fragmentation of ⁴⁰Ar projectiles at E/A?=?95 MeV/nucleon, and were implanted in a single crystal α-Al₂O₃ stopper. The measured Q moment of ³²Al, |Q(³²Al)|?=?24(2) mb, is in good agreement with a conventional shell-model calculation with a full sd model space and empirical effective charges, while that of ³¹Al is considerably smaller than the sd calculations.     

Angular momentum alignment in the reaction154Sm+214 MeV32S

Angular momentum alignment in the reaction¹⁵⁴Sm+214 MeV³²S has been investigated using discrete-lineγ-ray techniques. The anisotropies of stretchedE2 transitions from the target-like fragments reach approximately three at the largest energy losses, implying rather strong alignment. The results are compared with the predictions of a simple model.     

Determination of the quadrupole ratio Q3+/Q2+ in172sYb

Statistically perturbed angular correlations of¹⁶⁰Dy and¹⁷²Yb have been time differentially investigated in liquid sources. As solvents we used ethylalcohol and concentrated hydrochloric acid at various temperatures. From our results we have calculated the ratio of the spectroscopic quadrupole moments of the 2⁺ rotational and the 3⁺ isomeric level in¹⁷²Yb asQ ³⁺/Q ²⁺=1.33±0.14.     

Isomer shift and quadrupole splitting of the 2+-rotational state in174Yb

The change of the charge radius and the quadrupole moment of the 2⁺-rotational state of¹⁷⁴Yb are determined from Mössbauer measurements. Comparison with¹⁷⁰Yb reveals slightly increasing rigidity at constant equilibrium deformation if two neutron pairs are added. Theoretical predictions are discussed, in connection with additional experimental data.