Cross sections for 68Ge production in natural- and enriched-germanium targets irradiated with protons of energy 100 MeV and background in experiments devoted to searches for the 2β0ν decay of 76Ge

The rate of ⁶⁸Ge production at sea level under the effect of the nuclear component of cosmic rays is calculated. The calculation is based on the experimental values of the cross sections for ⁶⁸Ge production in natural- and enriched-germanium targets (enrichment in ⁷⁶Ge) irradiated with high-energy protons. The background from the decays of ⁶⁸Ge can be a serious problem in new-generation experiments devoted to searches for the 2β0ν decay of ⁷⁶Ge.     

偶偶Ge和Se同位素核的形变HF态及负宇称带研究

将具有负宇称的fp轨道空间扩大到包含具有正宇称的1g_9/2轨道,采用修正的表面δ相互作用,对⁶⁴Ge,⁶⁶Ge,⁶⁸Ge,⁷⁰Se,⁷²Se和⁷⁴Se等6个偶偶核做了形变HF计算.得到了基态和一些激发态的解.同时,还用近似角动量投影形变Hartree-Fock(PDHF)方法,对⁶⁴Ge和⁷⁴Se进行了能谱计算,得到其正、负宇称带的解,计算结果与实验谱基本一致.     

原子核的反常宇称能谱研究

将具有负宇称的 fp 空间扩大到包含1g9/2 轨道, 采用修正的表面相互作用(MSDI), 对64Ge, 66Ge, 68Ge, 70Se, 72Se, 74Se, 76Kr 和 78Kr等偶偶核作了形变Hartree Fock计算, 得到了基态和一些激发态的解. 同时, 还用近似角动量投影形变Hartree Fock（PDHF）方法对偶偶核64Ge, 74Se和奇A核79Kr进行了能谱计算, 得到其正、 负宇称带的解, 计算结果与实验谱基本一致.Using modified surface delta interaction, enlarging the fp configuration space to include the 1g9/2 orbit with the abnormal parity, the deformed Hartree Fock calculations for the eight nuclei: 64Ge, 66Ge, 68Ge, 70Se, 72Se , 74Se, 76Kr and 78Kr are performed. The ground state and some particle hole excited configurations are obtained. The approximate angular momentum projected deformed Hartree Fock (PDHF) method is applied to even even nuclei 64Ge and 74Se and odd A nuclus 79Kr. Both of their normal and abnormal parity bands are obtained. The calculated energy spectra are consistent well with experimental spectra.     

Rate of germanium-isotope production by background processes in the SAGE experiment

Data on a direct determination of systematic uncertainties caused by the background production of germanium isotopes in the radiochemical SAGE experiment measuring the solar-neutrino flux are analyzed. The result obtained for the rate of ⁶⁸Ge production is 6.5(1±1.0) times greater than the expected one; the rate of ⁶⁹Ge production does not exceed preliminary estimates. The above result for ⁶⁸Ge corresponds to the systematic uncertainty that is caused by the interaction of cosmic-ray muons and which is equal to 5.8% (4.5 SNU) at a solar-neutrino-capture rate of 77.0 SNU. An experiment is proposed that would test the effect of cosmic-ray muon influence on the SAGE systematic uncertainty and which would be performed at the location of the underground scintillation telescope facilities of the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences).     

Formation of zero-dimensional hole states during molecular-beam epitaxy of Ge on Si (100)

The characteristic features of electronic spectra in Ge/Si (100) heterostructures obtained by molecular-beam epitaxy are investigated by capacitance spectroscopy. It is observed that the self-organization of a Ge film into an island film when the effective germanium thickness exceeds six monolayers is accompanied by the appearance of hole bound states, which can be attributed to size quantization and the Coulomb interaction of carriers in the array of Ge quantum dots. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 2, 125–130 (25 July 1998)     

Precise mass measurement of 68Se, a waiting-point nuclide along the rp process

Mass measurements of 68Ge, 68As, and 68Se have been obtained with the Canadian Penning Trap mass spectrometer. The results determine the mass excess of 68Se as -54 232(19) keV, the first measurement with a precision and reliability sufficient to address the light-curve and energy output of x-ray bursts as well as the abundances of the elements synthesized. Under typical conditions used for modeling x-ray bursts, 68Se is found to cause a significant delay in the rp process nucleosynthesis.     

THE ROTATION ALIGNMENT EFFECTS OF g9/2 PROTON PAIR AND NEUTRON PAIR IN 68Ge

Using the HFB cranking model, the RAL effect of g_9/2 proton pair and neutron pair for three forking phenomenon in ⁶⁸Ge is studied. Calculations show that two backbending of three forking in ⁶⁸Ge are mainly caused by rotation alignment of g_9/2 proton pair and neutron pair.     

High spin states in66,68Ge

High spin states of^66,68Ge have been investigated at the FN Tandem accelerator of the University of Köln via the reactions⁴⁰Ca(³²S,2p,4p)^66,68Ge at a beam energy of 100 MeV and⁵⁸Ni(¹⁶O,2p)⁶⁸Ge at 65 MeV. The OSIRIS spectrometer with 12 escape suppressed Ge detectors was used to measure coincidences and -ray angular distributions. In⁶⁶Ge (⁶⁸Ge) 33 (22) new levels were found and 63 (62) new -transitions were placed in the level scheme. Both nuclei show a rather complicated but similar excitation pattern, ruled by the interplay of quasiparticle and collective degrees of freedom. The results are compared to the recently published EXVAM calculations for⁶⁸Ge.Supported by German BMFT under contract No. 06 OK 143.     

Room temperature oxidation of Cu(3)Ge films grown on Si and Si(1-x)Ge(x) substrates

Room temperature oxidation of Cu3Ge films grown on Si, Si(0.85)Ge(0.15) and Si(0.52)Ge(0.48) substrates, respectively, at a temperature of 200-300 degrees C was studied using transmission electron microscopy (TEM) in conjunction with energy dispersive spectrometry (EDS) and scanning electron microscopy (SEM). For Cu(3)Ge films grown at 200 degrees C and subsequently exposed in air for 1 week oxide protrusions and oxide networks appeared in the film surface and grain boundaries of Cu(3)Ge, respectively. At room temperature O from air and Si from the substrate, diffused along the grain boundaries of Cu(3)Ge to react with Cu(3)Ge grains, initiating the Cu(3)Si-catalyzed oxidation. Cu(3)Ge films are superior to Cu(3)(Si(1-x)Gex) films in retarding Cu(3)Si-catalyzed oxidation. Annealing at 300 degrees C allowed Si diffusion from the substrate into the Cu(3)Ge overlayer to form Cu(3)(Si(1-x)Gex), enhancing the Cu(3)Si-catalyzed oxidation rate. In the present study, Cu(3)Ge films grown on Si(0.52)Ge(0.48) at 200 degrees C show the best resistance to room temperature oxidation because higher Ge concentration in the substrate and lower temperature annealing can more effectively retard Si diffusion from the substrate into the Cu(3)Ge overlayer, and hence reduce the Cu(3)Si-catalyzed oxidation rate.     

Ge(SiO2)n团簇结构和电子性质的密度泛函理论研究

采用密度泛函理论中的广义梯度近似(GGA)对Ge(SiO2)n (n = 1—7)团簇的几何构型进行优化,并对能量、频率和电子性质进行了计算。 结果表明,Ge(SiO2)n的最低能量结构是在(SiO2)n端位O原子以及近邻端位O原子的Si原子上吸附一个Ge原子优化得到;随着锗原子数的增加,增加的锗原子易与原来的锗原子形成锗团簇。掺杂锗原子后团簇的能隙比(SiO2)n团簇的能隙小,当多个Ge原子掺杂到(SiO2)3团簇时,其能隙随着Ge原子个数的增加出现了振荡,Gem(SiO2)3的能隙从可见光区到近红外光区变化。二阶能量差分、分裂能表明Ge(SiO2)2和Ge(SiO2)5团簇是稳定的。     

Research on High Spin States in 68Ge,65Ga and 67Ga

The high spin states in ⁶⁸Ge,⁶⁵Ga and ⁶⁷Ga were studied through in-beam gamma-ray spectroscopy experiment.The reaction ⁴⁶Ti(²⁵Mg,xpxn) was used with beam energy 68MeV.In ⁶⁸Ge the new multiplicity of band structures,the crossing transitions among the bands and a new band with possible big diformation were observed.The experiment results agree with a new microscopic model calculation (EXCITED FED VAMPIR).In ⁶⁵Ga and ⁶⁷Ga a few band structures with strong collectivity were observed and the new level schemes were given.     

石墨炉原子吸收法测定麦芽粉中的锗和硒

本文叙述了平台石墨炉原子吸收法测定麦芽粉中的锗和硒，采用Ｐｄ＋Ｎｉ和Ｐｄ基体改进剂，使锗和硒的灰化温度分别提高到１４００和１２００℃，有效地消除了基体干扰。方法特征量为３１ｐｇ（Ｇｅ）和２３ｐｇ（Ｓｅ），检出限为２８ｐｇＧｅ和６２ｐｇＳｅ（３σ）。对含２２￣１１０μｇ／ｇＧｅ和１８￣３５μｇ／ｇＳｅ的样品测定，相对标准偏差为Ｇｅ３．７￣５．６％（ｎ＝９），Ｓｅ４．３￣６．５％（ｎ＝９），回收率在９     

Ge/Pb/Si(111)生长中Ge原子沿团簇边缘扩散的三维Monte-Carlo模拟

用动态Monte-Carlo方法对Ge在单层表面活性剂Pb覆盖的Si(111)表面上沿团簇边缘扩散进行三维模拟.重点讨论Ge原子是否沿团簇边缘扩散,沿边缘扩散时的最大扩散步数及最近邻原子数对三维生长的影响,并计算薄膜表面粗糙度研究三维生长模式.模拟表明Ge沿团簇边缘扩散的行为对薄膜生长模式的影响很大,同时讨论了ES势对三维生长模式的影响.     

Ge在Ru(0001)表面上生长及其性质研究

报道Ge在Ru(0001)表面上生长以及相互作用行为的扫描隧道显微镜（STM）和x射线光电子能谱（XPS）研究. STM的实验结果表明Ge在Ru(0001)表面的生长呈典型的Stranski_Krastanov生长模式，Ge的覆盖度小于单原子层时呈层状生长，而从第二层开始呈岛状生长. XPS测量显示衬底Ru(0001)与Ge的相互作用很弱. Ru(0001)表面的Ru 3d5/2和Ru 3d3/2芯态结合能分别处于2798和2840 eV. 随着Ge的生长，到Ge层的厚度为20个单原子层，衬底Ru 3d芯态结合能减小了约02 eV，而Ge 3d芯态结合能从Ge低覆盖度时的289 eV增加到了290 eV，其相对位移约为01 eV. 关键词： Ge Ru表面 生长 相互作用     

Low-lying states and isospin excitation in the Ge isotopes

The level structure of 64-70Ge isotopes has been studied within the framework of the interacting boson model-3 (IBM-3). The symmetry character in the proton and neutron degrees of freedom of the energy levels has been investigated. The isospin excitation states (T>Tz) have been assigned for the 64Ge (N=Z) nucleus. Some intruder states in these nuclei have been suggested. The calculated energy levels and transition probabilities are in good agreement with recent experimental data. The study indicates that the Ge isotopes are in transition from γ-unstable to vibrational.     

Structure of69Ge

The beta decay of⁶⁹As is reinvestigated. Its decay half-life is measured to be 15.1±0.3 m. Using beta, gamma and conversion electron spectroscopy techniques, a decay scheme comprising 68 transitions among 28 excited states in⁶⁹Ge is proposed. Spin-parity assignments are made to many states andB(M1) andB(E2) are deduced for some transitions. The structure thus obtained for⁶⁹Ge is compared with that from other works and discussed in the light of nuclear models.     

Calculation of astrophysical reaction rate of 82Ge(n,γ)83Ge

The neutron capture reaction on a neutron-rich near closed-shell nucleus 82Ge may play an important role in the r-process following the fallout from nuclear statistical equilibrium in core-collapse supernovae.By carrying out a DWBA analysis for the experimental angular distribution of 82Ge(d, p)83Ge reaction we obtain the single particle spectroscopic factors, S2,5/2 and S0,1/2 for the ground and first excited states of 83Ge=82Ge(⊕)n, respectively. And then these spectroscopic factors are used to calculate the direct capture cross sections for the 82Ge(n, γ)83Ge reaction at energies of astrophysical interest. The optical potential for neutron scattering on unstable nucleus 82Ge is not known experimentally. We employed a real folding potential which was calculated by using the proper 82Ge density distribution and an effective nucleon-nucleon force DDM3Y.The neutron capture reactions on neutron-rich closed-shell nuclei are expected to be dominated by the direct capture to bound states. We will show that the direct capture rates on these nuclei are sensitive to the structure of the low-lying states.     

SiH4 adsorption on SiGe(0 0 1)

The adsorption process of silane (SiH₄) on a SiGe(0 0 1) surface has been investigated by using infrared absorption spectroscopy in a multiple internal reflection geometry. We have observed that SiH₄ dissociatively adsorbs on a SiGe(0 0 1) surface at room temperature to generate Si and Ge hydrides. The dissociation of Si- and Ge-hydride species is found to strongly depend on the Ge concentration of the SiGe crystal. At a low Ge concentration of 9%, Si monohydride (SiH) and dihydride (SiH₂) are preferentially produced as compared to the higher Si hydride, SiH₃. At higher Ge concentrations of 19%, 36%, on the other hand, monohydrides of SiH and GeH and trihyderide SiH₃ are favorably generated at the initial stage of the adsorption. We interpret that when SiH₄ adsorbs on the SiGe surface, hydrogen atoms released from the SiH₄ molecule stick onto Ge or Si sites to produce Si or Ge monohydrides and the remaining fragments of -SiH₃ adsorb both on Si and Ge sites. The SiH₃ species is readily decomposed to lower hydrides of SiH and SiH₂ by releasing H atoms at low Ge concentrations of 0% and 9%, while the decomposition is suppressed by Ge in cases of 19% and 36%.     

Making and breaking covalent bonds across the magnetic transition in the giant magnetocaloric material Gd5(Si2Ge2)

A temperature-dependent, single crystal x-ray diffraction study of the giant magnetocaloric material, Gd5(Si2Ge2), across its Curie temperature (276 K) reveals that the simultaneous orthorhombic to monoclinic transition occurs by a shear mechanism in which the (Si, Ge)-(Si,Ge) dimers that are richer in Ge increase their distances by 0.859(3) A and lead to twinning. The structural transition changes the electronic structure, and provides an atomic-level model for the change in magnetic behavior with temperature in the Gd5(SixGe1-x)(4).     

Multidetector device for the detection of coincidences of charged particles and γ rays

A 4π position-sensitive, axisymmetrical assembly of Si-Au charged-particle detectors is proposed, implemented, and tested on a beam of heavy ions; the dimensions and structure of the device are conducive to the organization of coincidences of charged reaction products with discrete γ rays emitted by the daughter nucleus and registered by a system of ultrapure Ge detectors. First results are obtained from an investigation of the reaction ⁵⁸Ni(¹⁶O,α2pγ)⁶⁸Ge at E ₀=74.5 MeV. Zh. Tekh. Fiz. 68, 139–142 (April 1998)