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61.
Ohne Zusammenfassung
Uebersetzung von H. Brehm (Dresden). 相似文献
62.
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64.
The absorption spectra and the characteristic emission and excitation spectra of CsI:Na bulk crystals at temperatures between 300 K and 4.2 K are reported. Localized exciton energies were calculated by considering a Born-Haber cycle. The results were compared with the experimental results and the origins of the absorption bands were identified. The characteristic emission spectrum consists of two bands, one peaking around 4200 Å, the other around 3800 Å. The corresponding excitation spectra show that this emission is due to the recombination of a relaxed exciton which was created by transferring an electron from an iodine ion to a substitutional sodium ion in an otherwise perfect CsI lattice. 相似文献
65.
Huang C Lu W Zhou M Clayton CE Joshi C Mori WB Muggli P Deng S Oz E Katsouleas T Hogan MJ Blumenfeld I Decker FJ Ischebeck R Iverson RH Kirby NA Walz D 《Physical review letters》2007,99(25):255001
The electron hosing instability in the blow-out regime of plasma-wakefield acceleration is investigated using a linear perturbation theory about the electron blow-out trajectory in Lu et al. [in Phys. Rev. Lett. 96, 165002 (2006)10.1103/PhysRevLett.96.165002]. The growth of the instability is found to be affected by the beam parameters unlike in the standard theory Whittum et al. [Phys. Rev. Lett. 67, 991 (1991)10.1103/PhysRevLett.67.991] which is strictly valid for preformed channels. Particle-in-cell simulations agree with this new theory, which predicts less hosing growth than found by the hosing theory of Whittum et al. 相似文献
66.
Cation tracer diffusion coefficients were measured in pure NaF crystals in the intrinsic ionic conductivity range (876–970 °C). The results can be rationalized satisfactorily in terms of contributions to the observed Na tracer diffusivities arising from both free vacancies and neutral vacancy pairs, the latter contribution amounting to about 53 per cent of the total Na diffusion at the highest measuring temperature. The best-fit defect parameters derived in an earlier conductivity study [21] from this laboratory on similar NaF crystals give for the free vacancy contribution Dv*(Na) = 4·25 exp (?2·21 eV/kT) cm2s?1. A combination of these Dv*(Na) values with the present diffusion data yields for the vacancy-pair contribution Dp*(Na) = 1·15 × 108exp (?4·04 eV/kT) cm2s?1. Comparison of the present findings with published values of the anion tracer diffusion coefficient in NaF showed that Dp* (F) is 2·3 to 4·4 times larger than Dp*(Na) over the temperature range of our observations, the difference between the two contributions increasing with decreasing temperature. When approximate account is taken of the temperature-dependence of the two pair correlation factors, this last result indicates that the anion jumps into the vacancy pair occur with a higher frequency, and increasingly so at lower temperatures, than do those involving the cations. 相似文献
67.
Clayton Antunes Martin Jesuí Vergílio Visentainer Cláudio Celestino de Oliveira Makoto Matsushita Nilson Evelázio de Souza 《Analytical sciences》2006,22(4):631-633
This study examined the concentration (mg/g) of trans polyunsaturated fatty acid (TPFA) in five soybean oil brands by gas-liquid chromatography. Tricosanoic acid methyl ester was used as the internal standard. All samples analyzed presented trans 18:2 fatty and trans 18:3 acids in detectable amounts. The concentration of TPFA ranged from 5.8 to 30.2 mg/g, with a mean concentration value of 18.4 mg/g. Trans 18:3 fatty acids had the highest TPFA group concentrations, which ranged from 3.9 to 16.3 mg/g. The main isomer of this group presented the 9c, 12c, 15t configuration. For trans 18:2 fatty acids, concentrations ranged from 1.9 to 14.0 mg/g with a mean value of 8.1 mg/g. Alpha-linolenic acid (all cis) concentrations ranged from 30.7 to 60.6 mg/g and their degree of isomerization ranged from 6.0 to 31.5, indicating that the deodorization process varies from one producer to another. From per capita consumption of soybean oil brands in Brazil and their TPFA concentrations, it is possible to conclude that their contribution to the average TPFA intake per person in Brazil is 0.4 g/d. 相似文献
68.
R. Pfaff B. M. Young W. Benenson J. Clayton D. J. Morrissey N. A. Orr T. Reposeur M. Thoennessen J. A. Winger 《Zeitschrift für Physik A Hadrons and Nuclei》1993,347(1):67-70
A comparison has been made between the production of high energy (E γ≧30 MeV)γ rays from the bombardment of124Sn and112Sn targets withE/A= 10 MeV12C ions. The results are well explained by then-p bremsstrahlung model and do not indicate the need for any new processes. 相似文献
69.
C.P. Bust J.R. Carter W.W. Neale J.G. Rushbrooke D.R. Ward R.E. Ansorge B.Y. Oh M. Pratap G. Sionakides G.A. Smith J. Whitmore R. Raja L. Voyvodic 《Nuclear Physics B》1978,140(3):409-422
We have investigated the reactions . The final state is dominated by diffractive production of a system which shows a strong tendency to form . The process is also observed in this reaction, indicating an energy dependence of s?1.5±0.1. The channel shows less single diffraction, and has a doubly diffractive component consistent with pomeron factorization. Strong Δ++(Δ++) production is agoain seen, but in contrast to the channel we also observe considerable ?0 production. 相似文献
70.
Katsouleas T.C. Clayton C.E. Serafini L. Pellegrini C. Joshi C. Dawson J. Castellano P. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1996,24(2):443-447
A technique for producing ultra-short electron bunches (e.g., ⩽100 fs) from a continuous electron beam using a short plasma wave section and a drift space is explored. The bunches are a fraction of a plasma wavelength long and are spaced by a plasma wavelength, making them of interest for injection into plasma accelerators or for driving a klystron-like structure to produce infrared radiation 相似文献