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11.
L. K. Kostov W. Andrejtscheff L. G. Kostova A. Dewald K. O. Zell P. von Brentano 《Zeitschrift für Physik A Hadrons and Nuclei》1974,355(2):179-184
The lifetimes of several negative-parity states in 126,130Xe and 132Ba have been determined by means of the generalized centroid-shift method. The reactions 124,128Te(α, 2n) and 122Sn(13C, 3n) have been used. Following results were obtained: T1/2(2758 keV) = 1.3 ± 0.2 ns in 126Xe, T1/2 (2060 keV) = 0.20 ± 0.10 ns, T1/2 (2104 keV) = 0.50 ± 0.10 ns, T1/2 (2376 keV) = 0.30 ± 0.10 ns and T1/2 (2973 keV) = 4.6 ± 0.4 ns in 130Xe as well as T 1/2(2120 keV) = 0.40 ?0.10 +0.20 ns in 132Ba. A systematics of the B(E2; 7 1 ? ? 5 1 ? ) values in the N = 76 nuclei is presented. Electric dipole and quadrupole transition rates are discussed in terms of octupole and quadrupole collectivity. The structure of the 5 1 ? and 7 1 ? states is considered. Nuclear reactions: 124,128Te(α, 2n), E = 26 MeV, 122Sn (13C, 3n), E = 53 MeV; measured E{gg}, I{gg}, γ-r.f. Deduced T1/2, B(σL) in 126,130Xe and 132Ba. Ge detectors. Generalized centroid-shift analysis. 相似文献
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W. Andrejtscheff L.K. Kostov L.G. Kostova P. Petkov M. Senba N. Tsoupas Z.Z. Ding C. Tuniz 《Nuclear Physics A》1985,445(3):515-533
By the in-beam application of the generalized centroid shift method, nanosecond half-lives have been determined for the first time: in using the reaction , in using the reaction (16 O, αp), in using the reaction (16O,2np), in and in using the reaction P(α, xn). Some known nanosecond isomers in different nuclei produced as by-products have also been detected. In the nuclei investigated far away from closed shells with complex wave functions, M1 transitions are considered which would be l-forbidden in the pure shell model. A retarded transition in 91 Nb is considered as proceeding between possible multiparticle-hole configurations. 相似文献
13.
Wolfgang Gaberl Plamen Kostov Michael Hofbauer Horst Zimmermann 《Optical and Quantum Electronics》2014,46(10):1269-1275
A noise model for phototransistors in open base configuration is presented. The model was developed from the noise measurements on four different phototransistor designs. The extracted current gains from the noise model were verified by measured current gains from Gummel measurements. Furthermore the current noise spectral density was modeled and compared with the noise measurements. A difference of less than 12 % in the current gain was achieved. In addition to the extracted current gains also the most dominant shot noise terms including their values of each phototransistor are extracted. 相似文献
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Cheriha Hassen Gati Yousra Kostov Vladimir Petrov 《Lithuanian Mathematical Journal》2020,60(4):456-469
Lithuanian Mathematical Journal - For sequences of d + 1 signs + and ? beginning with a + and having exactly two variations of sign, we give some sufficient conditions for the (non)existence... 相似文献
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Two coexisting adsorption states of molecularly adsorbed acetylene on the Si(001)-(2 x 1) surface have been identified by a combined study based on the high-resolution electron energy loss spectroscopy and density functional computations. Seven possible adsorbate-substrate structures are considered theoretically including their full vibrational analysis. Based on a significantly enhanced experimental resolution, the assignment of 15 C2H2- and C2D2-derived vibrational modes identifies a dominant di-sigma bonded molecule adsorbed on top of a single Si-Si dimer. Additionally there is clear evidence for a second minority species which is di-sigma bonded between two Si-Si dimers within the same dimer row (end-bridge geometry). The possible symmetries of the adsorbate complexes are discussed based on the specular and off-specular vibrational measurements. They suggest lower than ideal C(2v) and C(s) symmetries for on-top and end-bridge species, respectively. At low coverages the symmetry reductions might be lifted. 相似文献
17.
Glasses in the MoO3-CuO-PbO system are obtained at high cooling rates (104-105 K/s) and characterized using X-ray diffraction (XRD), differential thermal analysis (DTA), infrared (IR) and X-ray photoelectron spectroscopy (XPS). Two glass formation regions are determined: one with compositions having a high MoO3 content (50-80 mol%) and the other in the PbO-rich compositions (65-80 mol%). In the region of MoO3-rich compositions the building units of the amorphous network are МоО6, МоО4 and CuO4 groups. For these high MoO3 contents and respectively low PbO concentrations, the lead oxide is supposed to act as a network modifier while at high content PbO is found to be the main glass network former. In latter case the structure of glasses is formed by chains of PbOn (n = 3, 4) polyhedra, between which there are isolated MoO4 and CuO4 complexes. IR and XPS data reveal the existence of Mo-O-Mo, Mo-O-Me(Me’) (where Me = Cu2+, Cu1+ and Me’ = Pb) and Me(Me’)-O-Me(Me’) bonds in the amorphous network. Surprising result is found for low PbO content (10 mol%) where the lead oxide acts as glass network modifier: the actual MoO3 content drops strongly which is accompanied with a significant increase of the actual CuO content with respect to their nominal MoO3-CuO composition. Such effect is not observed in PbO-rich composition (70 mol%) where PbO has a role of network former. 相似文献
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As labor costs become more expensive, less labor-intensive disposable devices have become more ubiquitous. Similarly, the disposable optical pH sensor developed in our lab could provide a convenient yet cost-effective way for pH sensing in processes that require stringent pH control. This optical pH sensor is prepared in uniform individual lots of 100–200 sensors per lot. Calibration is accomplished on a few randomly selected sensors out of each lot. We show that all others in the same lot can then be used directly without requiring individual calibration. In this paper, a calibration model is derived to include all the factors that affect the signal of the disposable sensor. Experimental results show that the derived calibration model fits the experimental data. The readings of 28 randomly selected disposable sensors with 4 sensors from each of the 7 lots show an error less than 0.1 pH units in the useful sensing range of the sensor. The calibration model indicates that if further improvement on precision is desired, more uniform porous material and more advanced coating techniques will be required. When it comes to the effects of the varying coasters, house-made low-cost fluorometers, the variability in the brightness ratio of the blue-to-violet LEDs is the primary reason for the lack of precision. Other factors like LED light intensity distribution, optical properties of the filters and electronics also contribute to the coaster-to-coaster difference, but to a lesser extent. Two different methods for correcting the instrument variations were introduced. After correction, the collective reading errors for all the tested instruments were reduced to less than 0.2 pH units within the sensor's useful sensing range. Based on this result, our lab is currently implementing further improvements in modifying the coasters to equalize the ratios of blue-to-violet LED brightness. 相似文献
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