The reaction 36S(p, γ)37Cl: (II). Lifetimes,spins and parities of 37Cl levels

Analysis of the γ-ray angular distributions measured at 16 ³⁶S(p, γ)³⁷Cl resonances yields the spins and/or parities of 21 bound states of ³⁷Cl in addition to the resonance spins. Among the latter are four $\text{J =}\text{1}\text{2}$ resonances. For several other bound states the possible spins have been restricted. Multipolarity mixing ratios have been deduced from the same data. Lifetimes (or lifetime limits) of 29 bound states have been deduced from DSA measurements.This extensive experimental information allows a comparison with the results of a shell-model calculation for both the even- and odd-parity states of ³⁷Cl. In this calculation either zero, one or two particles are promoted from the 2s_{$\text{1}\text{2}$} or 1d_{$\text{3}\text{2}$} to the 1f_{$\text{7}\text{2}$} or 2p_{$\text{3}\text{2}$} subshells. Up to an excitation energy of about 5 MeV a one-to-one correspondence is found between experimental and calculated levels.     

Sub-barrier fusion of35, 37Cl+58, 64Ni evidence of effects of proton transfer channels

Sub-barrier fusion excitation functions of^35,37Cl+^58,64Ni have been measured. They are discussed in comparison to similar data of^34,36S+^58,64Ni with the aim of revealing the influence of coupled proton transfer channels. Using the simplified coupled channel code CCFUS, differences in the effects of inelastic channels are eliminated in an approximative manner to stress the differences in the effects of transfer channels. Signatures of positiveQ-value transfer channels coupled to fusion are clearly identified.     

Study of the36Cl(n,p)36S reaction in the neutron energy range up to 10 keV

The³⁶Cl(n,p)³⁶S reaction cross-section was measured by the time-of-flight method in the IBR-30 pulsed reactor of the JINR. The measured cross-section shows three not previously observed neutron resonances with energies E_n = 1.3; 3.5 and 8.2 keV for which the parameters A_p=gΓ_nΓ_p/Γ: 0.07 ±0.01; 0.08 + 0.03 and 1.7 + 0.3 eV were determined, respectively. Comparison of these results with the excited states obtained by the³⁶S(p, γ)³⁷Cl reaction made possible a more exact determination of the scale energy of the³⁷Cl nucleus excited states.     

Further experimental study of fast fission with the Cl + Au system

The onset of fast fission was investigated with the Cl + Au system. The mass distribution of the fragments and the fusion cross sections were determined at six different bombarding energies. It turns out that the width of the symmetric component of the mass distribution increases strongly with the critical angular momentum. This could be related with the disappearance of the fission barrier due to centrifugal effects. A semi-static model is developed and the results are compared with the experimental data. In this framework, the observed broadening of the mass distribution can be attributed to the presence of the fast fission phenomenon.     

Isotope effects in the temperature dependence of the pure quadrupole resonance spectra of Cl35 and Cl37 in trichloracetic acid

Elastic and thermoeleastic constants, abrasive hardness and indentation hardness were measured on AgClO₃, NaClO₃ and NaBrO₃. The differences in the elastic behaviour of AgClO₃ and NaClO₃ correspond to those of AgCl and NaCl. They agree with similar effects in isotypic crystal groups if main group elements are replaced by subgroup elements. The mechanical properties of these three crystals are in a close relationship to those of NaCl.     

Second-forbidden beta-decay and the effect of (V+A)- andS-interaction admixtures:36Cl

The shapefactor, the logft-value, the electron longitudinal polarization and the distribution of electrons emitted from oriented nuclei of³⁶Cl have been calculated by applying two different nuclear models. Firstly a pure 1d_3/2→1d_3/2 transition has been considered. Secondly a more refined shell model of thes-d shell configuration space has been taken into account. It is shown that there is no great influence of the shell model version to the observables, that the observables depend strongly on the relativistic nuclear matrix elements, that the so-called “two parameter equation” for the shapefactor cannot be used in the case of³⁶Cl and that there is no larger sensitivity of (V+A) admixtures to the electron longitudinal polarization than normally found in allowed decays. Comparisons with the existing experimental data are made.     

Effect of entrance channel parameters on the fusion of two heavy ions: Excitation functions of reaction products in16O +66Zn and37Cl +45Sc reactions

Excitation functions of reaction products formed in¹⁶O +⁶⁶Zn and³⁷Cl +⁴⁵Sc systems, leading to the same compound nucleus,⁸²Sr, were measured using recoil-catcher technique and off-line γ-ray spectrometry. The contribution of non-compound processes like transfer and incomplete fusion (ICF) reactions to the cross-sections of different evaporation residues were delineated by comparing the experimental data with the predictions of Monte Carlo simulation code PACE2. The results show that non-compound processes become a significant fraction of the total reaction cross-section in¹⁶O +⁶⁶ systems in the beam energy range studied, while³⁷Cl +⁴⁵Sc gives mainly compound nucleus products. The mass asymmetry dependence of the fusion and non-compound cross-sections have been analysed in terms of the static fusion model and sum rule model     

Interpretation of predissociation in the V′=3 level ofB 3Π0+ state of I35Cl and I37Cl

The observed oscillatory linewidths of theV′=3 level ofB ³Π₀₊ state of I³⁵Cl and I³⁷Cl are explained as due to heterogeneous predissociation caused by the crossing of an unstableZ ¹Π state. The crossing point and the slopes of the curves have been fixed to predict the observed linewidths.     

Chronology of particle emission from the E/A=61 MeV 36Ar+27Al reaction

The emission time chronology of neutrons, protons, and deuterons from the E/A=61 MeV 36Ar+27Al reaction is deduced from two-particle correlation functions.     

The reaction 36S(p,γ)37Cl: (I). Excitation energies and γ-ray branchings of bound states deduced from resonances in the range Ep = 500–2000 keV

Yield curves of the reaction ³⁶S(p, γ)³⁷Cl have been measured over the range E_p = 500–2000 keV with a highly enriched (81%) ³⁶S target. Proton energies, with a precision of typically 0.3 keV, and strengths are presented for the nearly 200 observed resonances. Several previously reported resonances, among which the well-known $\text{J}{}^{\mathrm{\pi }}\text{=}\text{7}\text{2}{}^{\mathrm{?}}\text{, E}{}_{\mathrm{p}}\text{= 1887}\text{keV}$ analogue resonance, are proven to be multiplets.At 75 selected resonances in the ranges E_p = 500–1200 and 1800–2000 keV the decay schemes have been studied. These measurements also provide rather detailed information on the γ-ray branching ratios of more than 50 bound states of which the majority has not been observed previously. Precision excitation energies have been determined; for the levels with E_x < 5 MeV the median uncertainty amounts to 30 ppm. The reaction Q-value is Q = 8386.34 ± 0.23 keV.These precision data invalidate several previous spin and parity assignments to low-lying bound states of ³⁷Cl. They also provide a basis for the lifetime measurements and spin and parity assignments to be discussed in the following paper.     

Prompt light particle emission in the 36Ar + 58Ni reaction at 95 MeV/nucleon

The prompt component at intermediate velocity of light charged particles is investigated. An improved coalescence model coupled to the intra-nuclear cascade code ISABEL is used to obtain light complex particle energy spectra and multiplicities as a function of impact parameter. The results are compared with experimental data from the ³⁶Ar + ⁵⁸Ni experiment at 95 MeV/nucleon, performed with the INDRA 4π detection system. The calculated prompt component is found to rather well reproduce proton spectra. For complex light charged particles the calculated components well populate the high energy part of spectra. Prompt emission can therefore explain the large transverse energies experimentally observed at mid-rapidity. Received: 27 July 2000 / Accepted: 20 November 2000     

Polarized absorption spectra of Co2+ in Na2Cd3Cl8 single crystals

Summary The polarized optical absorption spectra of Na₂Cd₃Cl₈: Co²⁺ in the range of 15 000 to 40 000 cm⁻¹ down to 15 K are reported. The Co²⁺ ion is found to occupy the Cd²⁺ sites in octahedral geometry and the spectra are interpreted satisfactorily in terms of a cubic ligand field model including spin-orbit coupling. The observed crystal field spectra are well reproduced withB=745 cm⁻¹,C=3410 cm⁻¹,Dq=700 cm⁻¹ and ζ (spin-orbit interaction) =520 cm⁻¹. No spectral evidence for tetragonal distortion is observed.     

HX+2(X=Cl,Br)离子的密度函数理论(DFT)研究

选取密度泛函方法,采取6-311++G(2df,2pd)基组对单态HCl+2和HBr+2离子进行了理论计算.考虑到HF+2离子中D∞h结构可独立存在的事实,文中首次对HCl+2和HBr+2离子的包含D∞h在内的四种可能几何构型进行了优化计算;求得了Cl2与Br2的质子亲和能及Cl-ClH+与Br-BrH+的键分离能,丰富和完善了对HCl+2的理论计算,并对HBr+2离子存在的可能性进行了计算研究,结果预言HBr+2单态中Cs结构为其平衡结构.最后给出了HCl+2和HBr+2的热化学数据、力常数等数值,并给出了基态HBr+2离子的离解通道,从而给出其完全离解时的离解能,为该离子的分析势能函数的推导准备了必需的理论数据.     

Competition between the fusion-fission and deep-inelastic orbiting mechanisms in the35Cl +12C reaction

The binary decay properties of the⁴⁷V nucleus, produced in the³⁵Cl +¹²C reaction, have been investigated at the³⁵Cl bombarding energiesE _lab = 180 and 200 MeV by means of a kinematical coincidence technique. Binary reaction products show full energy equilibration and a characteristic 1/sin(θ _cm) angular distribution. The elemental distribution of the fully-damped products is asymmetric, similar to what has previously been observed in the decay of the⁵⁶Ni nucleus. Comparison with theoretical model predictions suggests the occurrence of a fusion-fission rather than orbiting process. Moreover the calculations performed using the Extended Hauser-Feshbach Method reproduce well the experimental fission yields. A general discussion of orbiting and fusionfission experimental data of light heavy-ion systems is presented in the framework of the calculated number of available open channels for these systems.     

Simultaneous measurements of the release of atomic sodium, particle diameter and particle temperature for a single burning coal particle

The temporal history of the release of volatile alkali species during coal combustion is a significant, but poorly understood factor in the fouling and corrosion of heat transfer surfaces within industrial coal-fired boilers. We present new results of the simultaneous measurement of particle temperature, particle size and the atomic sodium concentration in the plume of a burning coal particle. During the char phase, the sodium concentration in the plume was found to be linearly dependent on the inverse of particle diameter, but during the ash phase the sodium concentration was found to decay exponentially with decreasing particle temperature. The centreline decay of Na within the plume above the burning particle consists of one region controlled by a first order chemical reaction and a second region controlled by diffusion.