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  • 1
    ISSN: 1434-601X
    Keywords: 23.40.Hc ; 21.10.Dr ; 29.30.Kv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The new proton-rich nucleus104Sn was produced in a50Cr(58Ni, 2p2n)104Sn reaction. Its half-life was measured to be 21±1s. From a newly established partial decay scheme, aQ EC value of 4,000 −300 +650 keV was estimated. The resulting mass excess value for104Sn, combined with decay energies for α and proton emission, leads to mass excess values for the nuclei108Te,109I,112Xe, and113Cs. These mass values are compared to predictions of mass formulae.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-601X
    Keywords: 23.40.Hc ; 21.10.Dr ; 21.10.Pc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract For the first time, detailed decay-spectroscopic investigations were performed for the very neutron-deficientN=50 nuclide98Cd. The98Cd activity was produced in spallation reactions between 600 MeV protons and a natural tin target, yielding a98Cd beam intensity of 10 to 60 atoms/s at the collector of the ISOLDE massseparator. By means ofγ-ray and conversion-electron spectroscopy, 19 transitions were found to follow the β+/EC decay98Cd→98Ag. The transitions at 61 and 107 keV were shown to beM1(+E2) andE2, respectively, and the98Cd half-life was measured as 9.2±0.3 s. TheQ EC value of98Cd is determined semiempirically and is compared to model predictions together with the measuredQ EC values of the neighbouring cadmium isotopes100,102Cd and theN=50 isotones92Mo,94Ru, and96Pd, taken from the literature. The newly established decay scheme of98Cd includes 9 excited states of98Ag. Four states at 1691, 1861, 2164, and 2544 keV are directly fed by 0+ → 1+ Gamow-Teller beta transitions with a summed strength of 3.5 −0.7 +0.8 . This value corresponds to 25±5% of the strength predicted for the GT transformation of a g9/2 proton (in98Cd) into a g7/2 neutron (in98Ag) by the extreme single-particle shell model. The GT-strength splitting and quenching, observed for98Cd, are compared with the corresponding data for lighter even-even N=50 isotones, and are discussed with reference to the predictions of more sophisticated nuclear models. We find that only in some cases it is possible to explain qualitatively the observed GT strength distribution and its total magnitude without renormalizing the free-neutron value of the axial-vector coupling constant.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-601X
    Keywords: 23.40.Hc ; 21.10.Dr ; 21.10.Pc ; 27.60.+j ; 29.30.Kv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract With the use of the58Ni+50Cr fusion-evaporation reaction and chemically selective on-line mass separation, the EC/β + decay of104Sn was studied byγ-ray and conversionelectron spectroscopy. In the course of these studies, a new 15.7-s isomeric state of104In was observed. Reinvestigation of theβ-decays of the two heavier even isotopes of tin, produced in the58Ni+58Ni reaction and mass separated without chemical discrimination, brought new information on the decay of106Sn and108Sn. The QEC values of104Sn,106Sn and108Sn were determined to be 4550 −250 +300 keV, 3200±100 keV and 〈 2270 keV, respectively. In the data analysis, the emphasis is put on the identification of the 0+ → 1+ Gamow-Tellerβ transitions and determination of their strengths. For104−110Sn, the total Gamow-Teller strengths are measured to be 20% to 30% of that predicted by the single-particle shell model with the inclusion of pairing correlations and core polarization. Predictions of the decay properties of the as yet unobserved102Sn and100Sn are made.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 332 (1989), S. 275-284 
    ISSN: 1434-601X
    Keywords: 23.40.Hc ; 21.10.Dr ; 27.60.+j ; 29.30.Kv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Neutron-deficient isotopes of cadmium were produced in thep(600 MeV)+natSn spallation reaction. The ISOLDE facility provided mass-separated beams of these isotopes. The production yield was 103 to 104 atoms/s for100Cd and roughly two orders of magnitude less for98Cd. The properties of the100Cd→100Ag decay were studied in detail by X-ray,γ-ray and conversion electron spectroscopy. Forty nineγ-transitions were assigned to this decay, and all but five of them were placed in the decay scheme. The half-life was determined to be 49.1±0.5 s. TheQ EC value of 3890±70 keV was deduced from a comparison of experimental and theoreticalβ +/(EC+β + probability ratios. Seven 0+→1+ Gamow-Teller transitions with log ft values between 3.5 and 4.9 were identified. The total (summed) strength is about five times smaller than predicted by the shell model for the transformation of ag 9/2 proton into ag 7/2 neutron. The quenching of the Gamow-Teller strength and other questions of nuclear structure are discussed for the100Cd decay. The properties of98Cd are inferred by extrapolation of104,102,100Cd data, and some preliminary experimental results on98Cd decay are presented.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 329 (1988), S. 267-273 
    ISSN: 1434-601X
    Keywords: 21.10.Dr ; 21.60.Cs ; 23.40.Hc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Selected properties of the Gamow-Teller beta decay of even nuclei near100Sn have been studied. Two theoretical models were used: a self-consistent Hartree-Fock-Bogolyubov approach with the Skyrme interaction and a shell-correction model with a Woods-Saxon average field and monopole pairing residual interaction. Calculations reproduce fairly well both theQ EC values and the average energies of theI π=1+ states fed directly in the decay. It is shown that the observed energy splitting between the 1+ states cannot be associated with a stable deformation of a final doubly-odd nucleus. The calculated pairing factors are used to estimate the 0+ → 1+ GT transition strength in the neighbourhood of doubly-magic 50 100 Sn50.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-601X
    Keywords: 23.40.Hc ; 21.10.Dr ; 21.10.Pc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Within the framework of a systematic study of 0+→1+ Β-transitions in the100Sn region, the decay of the neutrondeficient isotope102Cd was investigated. This isotope was produced in16O+92Mo and58Ni+50Cr heavy-ion reactions and in proton-induced spallation ofnatSn, and mass-separated samples were prepared by means of the GSI and the ISOLDE on-line mass separators, respectively. Observations of X-rays,γ-rays, and conversion-electrons studies have led to an improved102Cd→102Ag decay scheme which includes six 0+→1+ Gamow-Teller transitions. The half-life of102Cd was redetermined with higher accuracy to be 345±8 s. Using a Si(Li)-BGO-Ge spectrometer, theΒ + endpoint energy of the main decay component was measured, yielding aQ EC value of 2587±8 keV. This very small uncertainty ofQ EC, combined with the improved knowledge of half-life and decay scheme, allows an accurate determination of the observed Gamow-Teller decay strengthB Σ (GT)=1.513±0.055 for102Cd. This result is discussed in comparison with predictions from model calculations.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-601X
    Keywords: 21.10.−k ; 23.40.Hc ; 27.60,+j
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The EC/β+-decay of the odd-odd nucleus100Ag was studied by means of total absorptionγ-ray spectrometry. Most of the Gamow-Teller strength was found to be concentrated at an excitation energy of 5.6 MeV in100Pd, the FWHM of this resonance being 1.5 MeV. The measured strength distribution which is interpreted within the BCS approximation as being due to the dominant population of four-quasiparticle excitations, resembles the distribution predicted by an advanced shell-model calculation for the98Ag →98Cd decay.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In theories of the minor phase (domain) formation in polyblends rendered as emulsions it is usually assumed that the size and shape of the domains are the result of melt viscosity effects (Taylor, Wu) or viscoelasticity effects (VanOene, Elmendorp) being balanced by interfacial tension. This assumption would predict a monotonic decrease of the domain size to a final limiting size with increasing energy of mixing. However, a systematic study of the dependence of domain morphology on industrial mixing processes which was carried out on a “model” LDPE/PS (2/1) mixture and the related polyalloy (i.e., the same mixture with a corresponding block copolymer as compatibilizer) does not support this expectation. Doirain size was found to go through a minimum as mixing energy was increased. A similar minimum was seen in data on specific volume of the melt vs. mixing energy, which indicates a correlation between melt specific volume and domain size. Calculation of the approximate surface area of the domains using a simple model of domain shape indicated that total interfacial energy in the polyblend and/or polyalloy is a trivial part of the mixing energy introduced. These calculations also indicated that if compatibilizer was located entirely at the interface, the surface layer would have a thickness of about 90 nm. Some micrographs seem to show such a surface layer. We propose that an abrasion mechanism is responsible for the early stage of the dispersion process, and that the final domain size may be controlled by a dispersion-coalescence equilibrium. This is compared with the theories of final particle size proposed by VanOene and Wu.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 617-624 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper details some of the immediate findings for phase morphology formation and persistence in an industrial melt mixing of a polyblend/alloy (‘PB’/‘PBA’). Estimation of the minor phase domain size in a polyblend is feasible if the viscoelasticity functions, interfacial tension of the component-polymers, and the mixing process shear stress level are available. Clusters of domains are formed in the mixer (following streamlines). During steady flow in capillaries the clusters are forming rings which result from the flow velocity profile. Quantitative description of the clusters requires an expansion of image analysis software to account for the interdomain spacing in the clusters, as well as for their pattern. The on-line rheometry was found useful for monitoring coalescence and the effectiveness of the compatibilizer: higher “stiffness” of the PAB melt compared with that of PB shows up in measurements of complex viscosity and modulus. Further study is required, however, for correlating domain spacing and the real time rheometry data (esp. the relaxation spectrum plateau [13]). Finally, the study of phase morphology for the “model” polyblend provides an insight into the melt deformation history in an industrial mixer. It is expected that the distribution of domain sizes would correlate with the pass frequency in the mixing blocks [41], stress distribution in the extruder, and coalescence of the dispersed (“minor”) phase.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 618-626 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Particular rheology compositions (PRC) so far observed for blends of polyolefins are confirmed with composition dependence of melt elasticity and viscosity functions for polypropylene/rubbers and blends of other commercial polymers. Particular morphology at PRC was indirectly ascertained from the composition dependence of specific volume, vT-compositions for which the maximum vT observed are those of minimum viscoelasticity. Direct evidence from scanning electron microscopy (SEM) indicates that the disperse morphology undergoes distinct change at PRC: from uniform into bimodal, with coarser core. Rubber rich mixtures display stratified texture confirming that the melt elasticity ratio (Van Oene's) criterion for disperse/stratified morphology transition is valid in case of polypropylene/rubber blends. For a set of polymers of given melt elasticity ratios and at a composition ratio, static and rotational distributive mixers generate polyblends differing significantly in the melt rheology - morphology interaction.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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