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21.
22.
A. Breakstone C. D. Buchanan R. Campanini H. B. Crawley M. Dallavalle K. Doroba D. Drijard F. Fabbri A. Firestone H. G. Fischer H. Frehse W. Geist G. Giacomelli R. Gokieli M. Gorbics P. Hanke M. Heiden W. Herr E. E. Kluge J. W. Lamsa T. Lohse W. T. Meyer G. Mornacchi T. Nakada M. Panter A. Putzer K. Rauschnabel F. Rimondi R. Sosnowski M. Szczekowski O. Ullaland D. Wegener 《Zeitschrift fur Physik C Particles and Fields》1984,25(1):21-27
High energy proton-proton interactions yielding a single trigger particle with large transverse momentum give rise to a four-jet event structure with two transverse jets and two jets along the beam direction. The transverse jets are due to the fragmentation of point like scattered partons. It is shown that the quantum numbers of triggering charged pions and positive kaons are correlated with the flavour of the scattered parent parton; thus one can enhance data samples with a particular flavour of a scattered parton. The analysis, which is independent of detailed model calculations, exploits (a) the identification of the leading particles in the trigger jets (trigger particles), (b) the measurement of their relative production rates, (c) short range quantum number correlations within the trigger jets, and (d) long range correlations between leading particles from different jets. The data were obtained at \(\sqrt s \) =62 GeV with the Split Field Magnet detector at the CERN ISR. 相似文献
23.
X. Zhang I. Moerman C. Sys P. Demeester J. A. Crawley E. J. Thrush 《Journal of Crystal Growth》1997,170(1-4):83-87
Highly uniform AlGaAs/GaAs and InGaAs(P)/InP epitaxial layers have been grown in a vertical rotating susceptor MOVPE reactor capable of accommodating three 2′ wafers. The unique water-cooled “showerhead”-type injection distributor which is located 1.5 cm above the substrates ensures a uniform reactant distribution, resulting in uniform growth over a wide range of growth conditions. Periodic multilayer and single layer structures have been used to investigate the thickness and compositional uniformities. The thickness variations over a radial distance of 48 mm for three wafers grown in the same run are within ± 2% for both AlGaAs and InGaAs layers, resulting in a standard deviation of only 0.9%. The gallium concentration of an InGaAs layer varies from 46.88% to 47.01% over the same radial distance with the standard deviation of 0.043%. Measurements of InGaAsP layers grown onto 2′ InP wafers with different alloy compositions show good compositional uniformity yielding standard deviations within 4.4 nm in PL wavelength and 135 ppm in lattice mismatch over a 46 mm radial distance. 相似文献
24.
Valence and deep-lying neutron-hole strengths corresponding to orbits near and well below the Fermi surface have been observed in high-resolution studies of the 144, 148, 152Sm(3He, α) and of the 144, 148, 150, 152, 154Sm(p, d) reactions at 70 and 42 MeV bombarding energy, respectively. The explored excitation energy range was 28 MeV for the (3He, α) experiment and about 12 MeV in the (p, d) study. Complete angular distributions have been measured in both cases and the data was analyzed within the framework of the distorted waves Born approximation theory of direct reactions.For the neutron closed shell target (144Sm), in addition to the well-known fragmentation of the 2d and 1g valence-hole strength, a new bump observed around 7.6 MeV excitation energy is excited in both reactions. This structure corresponds to the 1g inner-hole strength in 143Sm and the analysis of the (3He, α) data suggests that more than 50% of the l = 4 strength can be found between 6 and 12 MeV. When one goes to the heavier Sm isotopes, the energy spacing between valence-hole states located above and just below the N = 82 shell decreases strongly and disappears in 151Sm as a result of increasing deformation.Combining good energy resolution and detailed analysis of the two reactions, rather complete spectroscopic information is obtained for the valence-hole strength distributions. With regard to inner-hole states, the energy spectra exhibit a narrow structure whose centroid energy decreases from 4.4 to 2.9 MeV when the mass number increases from A = 147 to A = 153. The main peak displays an asymmetric shape with an extremely large high-energy tail. The 1h hole strength is split into the Nilsson Orbitals. The narrow bumps are found to carry a large fraction of the l = 5 and l = 2 hole strengths in 147,149,151,152Sm isotopes. In the high-energy tail of the structures one observes overlapping and increasing spreading of the g, 2d and possibly 1g inner-hole strengths due to the disappearance of the N = 82 shell gap between N = 83 and N = 89 neutron numbers. The experimental hole strengths distributions are compared where possible to the predictions of the quasiparticle-phonon nuclear model or to the simple Nilsson model. 相似文献
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The (12C, 10Be) and (12C, 9Be) reactions on 58Ni were studied at 77 MeV. New levels were determined for both residual nuclei, 60Zn and 61Zn. For 61Zn, levels and a new ground state mass were also measured with the 64Zn(3He, 6He) reaction. A mass excess for 61Zn of ?56333±23 keV was obtained. Angular distributions for the 12C induced reactions are compared with finite range DWBA calculations and found to be insensitive to L? and J-transfer. 相似文献
27.
S. Crawley I. C. McNeill 《Journal of polymer science. Part A, Polymer chemistry》1978,16(10):2593-2606
The course of the chlorination reaction of cis-1,4-polybutadiene is dependent on the choice of solvent. When methylene chloride is used, a pure addition reaction of chlorine leads to a polymer with the structure of head-to-head, tail-to-tail PVC. The thermal stability of the head-to-head PVC polymer has been studied by thermal volatilization analysis, thermogravimetry, and evolved gas analysis for hydrogen chloride, and the changes in the ultraviolet (UV) spectrum of the polymer during degradation have been investigated. The head-to-head polymer has a lower threshold temperature of degradation than normal PVC, but reaches its maximum rate of degradation at a higher temperature for powder samples of the polymer under programmed heating conditions. Blends of head-to-head PVC with poly(methyl methacrylate) have also been degraded, and the presence of the head-to-head polymers, like that of normal PVC, results in depolymerization of the PMMA as soon as the dehydrochlorination reaction commences. The mechanism of degradation of head-to-head PVC is discussed. 相似文献
28.
29.
W. Morris B.Y. Oh D.L. Parker G.A. Smith J. Whitmore L. Voyvodic R. Walker R. Yaari E.W. Anderson H.B. Crawley W.J. Kernan F. Ogino R.G. Glasser D.G. Hill G. McClellan H.L. Price B. Sechi-Zorn G.A. Snow V.P. Kenney 《Physics letters. [Part B]》1975,56(4):395-399
Using new data from 100 interactions, we find the energy dependence of the invariant cross-section in the target fragmentation (central) region to be consistent with an behavior. The leading particle peak near x = + 1 exhibits a width in x which becomes smaller with increasing energy and an integrated cross section which is approximately energy independent. 相似文献
30.
Monica K LittleCharlene D Crawley 《Analytica chimica acta》2002,464(1):25-35
Antibody coupled capillary electrophoresis was employed in the pre-concentration and detection of atrazine at the parts per billion (ppb) level. A 1000-fold increase in detection has been demonstrated in the use of IgG anti-atrazine monoclonal antibodies for the analysis of atrazine in well water by capillary zone electrophoresis (CZE) with UV-VIS detection. These results were confirmed by an enzyme linked immunosorbent assay (ELISA) specific for atrazine. 相似文献