The quadrupole moments of Zn and Cd isotopes—an update

The nuclear quadrupole moments of ¹¹¹*Cd (245 keV state) and ⁶⁷Zn were determined from the quadrupole coupling constants and lattice parameters of the metals at low temperature. The required electric field gradients were obtained with density functional calculations employing the WIEN2k code. The resultant numbers, 0.765(15) and 0.151(4) b, are in line with the previously used values but considerably more precise. Calculations for various other solids confirm the results, with less accuracy, however.     

The quadrupole moments of Cd and Zn isotopes - an apology

In 2010 we presented an update of the nuclear quadrupole moments (Q) for the Cd and Zn isotopes, based essentially on straightforward density functional (DF) calculations (H. Haas and J.G. Correia, Hyperfine Interact 198, 133–137 (2010)). It has been apparent for some years that the standard DF procedure obviously fails, however, to reproduce the known electric-field gradient (EFG) for various systems, typical cases being Cu₂O, As and Sb, and the solid halogens. Recently a cure for this deficiency has been found in the hybrid DF technique. This method is now applied to solid Cd and Zn, and the resultant quadrupole moments are about 15 % smaller than in our earlier report. Also nuclear systematics, using the recently revised values of Q for the long-lived 11/2 isomers in¹¹¹Cd to¹²⁹Cd, together with earlier PAD data for^107,109Cd, leads to the same conclusion. In addition, EFG calculations for the cadmium dimethyl molecule further support the new values: Q(¹¹¹Cd, 5/2⁺) = .683(20) b, Q(⁶⁷Zn, gs) = .132(5) b. This implies, that the value for the atomic EFG in the \(^{3}\textit {P}_{1}\) state of Zn must be revised, as it has been for Cd.     

Cross sections of multiparticle photonuclear reactions with <Superscript>203, 205</Superscript>Tl isotopes

An experiment on the irradiation of the natural mixture of ^203,205Tl isotopes by the bremsstrahlung beam of pulsed racetrack microtron RTM-70 (Skobeltsyn Institute of Nuclear Physics, Moscow State University) at an electron energy of 67.7 MeV was performed. The yields and integral cross sections of multiparticle photonuclear reactions with ^203,205Tl isotopes were measured.     

The decay of110mAg to110Cd

The gamma-ray spectrum of the decay of^110mAg has been measured with the Ge(Li) detectors. A total of 32 gamma rays associated with the decay of^110mAg have been observed and their intensities determined. A number of gamma-ray transitions have not been observed previously. The K-electron internal conversion coefficients were found from the relative gamma intensities used in conjunction with published K-conversion electron intensities.It is proposed that the level scheme of¹¹⁰Cd has new levels at 1410·4, 1443·2 and 2237·7 keV in addition to the previously known levels. The spins and parities of the new levels are discussed.The author wishes to express her gratitude to Professor V. Petrílka for his permanent support and to Mr. J. Lipták and Mr. J. Vrzal for valuable assistance and discussions.     

Copper ion induced reactions on110-108-106Cd,109-107Ag and110Pd. new rhenium,osmium and iridium isotopes

By⁶³Cu induced reactions on¹¹⁰Cd,¹⁰⁸Cd,¹⁰⁶Cd,¹⁰⁹Ag,¹⁰⁷Ag and¹¹⁰Pd targets, new isotopes were searched in the Ir, Os, Re region. Cross bombardments and excitation function measurements were used to identify newα emitting isotopes:¹⁷⁰Ir (E _α = 6.01 ±0.01 MeV?T _1/2=1.1±0.2s),¹⁶⁹Ir (E _α =6.11±0.01 MeV?T _1/2=0.4±0.1 s),¹⁶⁸Ir (E _α =6.22±0.02 MeV,¹⁶⁸Os (E _α =5.66±0.01 MeV?T _1/2=1.9±0.1 s),¹⁶⁷Os (E _α =5.84 ±0.01MeV ?T ^1/2=0.65±0.15s),¹⁶⁶Os (E _α =6.00±0.02 MeV?T _1/2=0.3 ±0.1 s),¹⁶⁵Os (E _α =6.20±0.02 MeV),¹⁶⁹Re (E _α =5.05±0.01 MeV),¹⁶⁸Re (5.26±0.01 MeV?T ^1/2=5.5 ±0.5 s). Theα-decay measurements are compared to theQ _α values obtained from different mass predictions.     

锌、镉和汞二价负离子团簇的结构和芳香性研究

采用密度泛函理论,在B3PW91/LANL2DZ水平上对二价阴离子Zn2-n、Cd2-n和Hg2-n(n=3~7)团簇的稳定结构、芳香性和电子结构进行了研究.研究结果表明:锌、镉和汞团簇的二价阴离子随着n增大其稳定性依次减弱.对于锌团簇来说,当n为奇数时具有较强芳香性,当n为偶数时芳香性较弱或呈现反芳香性,镉团簇和汞团簇的芳香性随着n值增大逐渐减小并最终向反芳香性转变.     

锌、镉和汞二价负离子团簇的结构和芳香性研究

采用密度泛函理论,在B3PW91/LANL2DZ水平上对二价阴离子Znn2-、Cdn2-和Hgn2- (n=3—7)团簇的稳定结构、芳香性和电子结构进行了研究.研究结果表明:锌、镉和汞团簇的二价阴离子随着n增大其稳定性依次减弱.对于锌团簇来说,当n为奇数时具有较强芳香性,当n为偶数时芳香性较弱或呈现反芳香性,镉团簇和汞团簇的芳香性随着n值增大逐渐减小并最终向反芳香性转变.     

A simple explanation of the sign and magnitude of quadrupole moments in even-A Fe,Zn, Cd,Te and Hg isotopes

Coupling valence-shell protons (cluster) to the vibrational field gives the sign and magnitude of quadrupole moments in Fe, Zn, Cd, Te and Hg as a consequence of the shell structure. Competition of contributions of the available valence proton configurations determines the sign and magnitude of the quadrupole moment of two-proton clusters. The field-induced polarization effect always leads to an enhancement of the cluster quadrupole moment.     

Skyrme-Hartree-Fock approach to Cd,Sn and Te isotopes

The ground state properties of Cd, Sn and Te isotopes are investigated in the framework of the Skyrme-Hartree-Fock theory using the normal force parameters SKI2 plus density-dependent pairing correlations and new force parameters SKI4 which has a generalized spin-orbit term [P. G. Reinhard and H. Flocard, Nucl. Phys. A 584 (1995) 467]. The theoretical results agree well with experimental data of binding energies and matter root-mean-square radii of charge distributions. Both parameter sets are also successful in reproducing the experimental law of isotope shifts in Cd and Sn elements. The behavior of isotope shifts in Te elements is predicted. We have made detailed comparison and discussion on the numerical results and given an explanation for the cause of above success.     

Skyrme-hartree-fock approach to Cd,Sn and Te isotopes

The ground state properties of Cd, Sn and Te isotopes are investigated in the framework of the Skyrme-Hartree-Fock theory using the normal force parameters SKI2 plus density-dependent pairing correlations and new force parameters SKI4 which has a generalized spin-orbit term [P. G. Reinhard and H. Flocard, Nucl. Phys. A 584 (1995) 467]. The theoretical results agree well with experimental data of binding energies and matter root-mean-square radii of charge distributions. Both parameter sets are also successful in reproducing the experimental law of isotope shifts in Cd and Sn elements. The behavior of isotope shifts in Te elements is predicted. We have made detailed comparison and discussion on the numerical results and given an explanation for the cause of above success.     

Collective properties of neutron-rich Ru, Pd, and Cd isotopes

Collective properties of neutron-rich Ru, Pd, and Cd isotopes are reviewed, combining the original results from the IGISOL β-decay experiments with recent experimental and theoretical progress. The transitional nature of Ru and Pd nuclei is discussed via the low-lying level systematics, including the low-lying 0^?+? states. Although the role of an anharmonic quadrupole vibrator in Cd nuclei was recently questioned, level systematics for the three-phonon quintuplet in ^116,118,120Cd are presented, and an outlook of the spectroscopic methods for the level lifetime or B(E2) values is given.     

The 206, 204Pb(p, α)203, 201Tl reactions at 35 MeV

The ²⁰⁶Pb(p, α)²⁰³Tl and ²⁰⁴Pb(p, α)²⁰¹Tl reactions have been studied using 35 MeV protons. For both ²⁰³Tl and ²⁰¹Tl approximately 50 levels with excitation energies up to 4.0 MeV were identified and angular distributions of most of these states were measured. Cluster-model DWBA calculations were shown to produce excellent fits to the measured angular distributions. Using these calculations high-spin $\text{(j ≧}\text{15}\text{2}\text{)}$ states were found in both nuclei. The strengths, energies, and number of high-spin states excited in ²⁰¹Tl and ²⁰³Tl are compared with those observed in ²⁰⁵Tl in a previous study.     

The cross sections of the proton nuclear reactions on Cd isotopes

The cross sections for the (p, n) and the (p, 2n) reactions on Cd isotopes have been measured by the stacked foil technique and the activation method at proton energies between 3 and 18?MeV. The results have been compared with the calculations accounting for equilibrium and pre-equilibrium emissions.     

In-beam studies of203, 205Bi and shell-model features of odd-a bismuth isotopes

States in^{203, 205}Bi are populated using the reaction^{203, 205}Tl(³He,3n). Theπi _13/2 single-proton states and all the members of thev(2 ₁ ⁺ )?π h _9/2 quintuplet are identified in both nuclei. The half-lives of the isomericJ ^π=21/2⁺ states in both isotopes are measured and found to be 90±7 ns and 100±6 ns, and from these values suggestions for the half-lives of the previously reportedJ ^π=25/2⁺ isomers are made. The structures of the multiplets of the formv(Pb)?π h _9/2 are calculated in the framework of the shell model and it is shown that the main features can be derived from theπ?v ^?1 effective interaction. The wave functions of the 4 ₁ ⁺ and 4 ₀ ⁺ states in^{202, 204}pb are deduced indirectly from the calculation in^{203, 205}Bi.     

Measurement of parity admixtures in nuclear forces in180Hf,181Ta and203Tl

The parity mixing in nuclear states was studied by measuring the circular polarizationP of the γ-radiation emitted from unpolarized nuclei. The analyzer was a “radial transmission magnet” of high symmetry. With 4 NaI scintillation counters and the current integration method 4 independent results were obtained simultaneously. The polarimeter efficiency was determined via the Quadratic Compton effect. Studies of the polarized bremsstrahlung with¹⁷⁰Tm,¹⁷⁷Lu and¹⁹⁸Au sources served as tests for the calculated corrections due to the bremsstrahlung effect. Our results for the circular polarization are:P=?(2.0±0.4) · 10^?3 for the 501 keV transition in¹⁸⁰Hf,p=+(1±4) · 10^?6 for the 482 keV transition in¹⁸¹Ta andP=+(1±7) · 10^?6 for the 279 keV transition in²⁰³Tl. Thus, in the case of¹⁸⁰Hf, the existence of the parity mixing in nuclear states was confirmed.     

Theory of the effects of nuclear structure on internal conversion in Tl203

The Fermi-liquid method is applied to consider the effects of the strong interaction on the penetration matrix element for the conversion transition in Tl²⁰³. The theoretical value agrees well with experiment.We are indebted to M. A. Listengarten for discussions.     

Internal conversion coefficients and penetration effect for the 279 keV transition in203Tl

The internal conversion process of theM1+E 2 mixed 279 keVγ-ray transition in the decay of²⁰³Hg has been reinvestigated. The emission rate of theK-shell internal conversion electrons was determined with an electron X-ray coincidence measurement using a magneticΒ-spectrometer and a Si(Li) detector of high energy resolution. Conversion electron ratios were obtained from electron spectra recorded as a function of momentum. The disintegration rate has been taken from measurements with a calibrated NaI(Tl)γ-ray spectrometer. Following results have been deduced: α=0.2279±0.0024, α _K =0.1653±0.0017, α _L =0.0475±0.0013,K/(L+M+?)=2.64±0.03,K/L=3.48±0.12,L/(M+N+ ?)=3.14±0.12. On the basis of the experimental results on theK-shell internal conversion coefficient,α _k , and the conversion ratioK/(L+M+?) the penetration effect on the internal conversion of theM1 part and the mixing ratio,δ ², of the 279 keVγ-ray transition in²⁰³Tl have been studied. Calculations were made using Hager and Seltzer's formalism and their theoretical internal conversion coefficients. The results are consistent with a mixing ratio ofδ ²=1.32±0.11 and a penetration parameter ofλ=6.8 ±0.8.     

Investigation of new neutron-rich gold isotopes203Au and205Au

Using a²⁰⁸Pb beam of the UNILAC accelerator at GSI we produced the new isotopes²⁰³Au and²⁰⁵Au and identified them by measuring their-decay properties. Their half-lives were found to be 60(6)s and 31(2)s, respectively, and theQ-value of²⁰³Au was determined to beQ =2040(60)keV. Nuclear structure information of^203,205Hg was derived from this measurement. Furthermore, production cross-sections of^203,205Au are given and compared to those obtained in other experiments.This work has been supported by the Federal Ministry for Research and Technology (BMFT) under contract number 06 Gö 451-1/2     

不同掺杂Zn0.95Cd0.05 Te〈110〉单晶的THz辐射特性研究

利用太赫兹(THz)时域光谱技术研究了不同掺杂的Zno95Cd0.05Te<110〉单晶产生THz辐射的特性.实验发现,当晶体的直流电阻率ρ＞102 Ω·cm时,晶体产生THz辐射的效率随着晶体电阻率的增加而增加,但当电阻率ρ＞106Ω·cm时,晶体产生THz辐射的效率出现饱和甚至可能下降.光谱测量结果表明,此类晶体在THz波段的透过率基本上取决于其低频电阻率,但除了晶体对THz辐射的吸收这一因素外,其色散性质的变化对晶体的THz辐射性能也有重要的影响.因此,当ZnCdTe晶体用于THz辐射产生和探测时,仅仅用材料的Hall电阻率不能完全表征器件的性能.     

EFG sign for Sn in Zn,Cd, and Sb

Mössbauer spectroscopy on ion-implanted sources of¹¹⁹Cd in single-crystals was applied to study the electric field gradients (EFG) at¹¹⁹Sn in three non-cubic metals. The signs and magnitudes determined are in agreement with presently known systematics. The measured isomer shifts and the recoilless fractions are discussed.