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  • 1980-1984  (7)
  • 1
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Cross sections for the reactionse + e −→e + e − (Bhabha scattering) ande + e −→γγ are measured for center-of-mass (c.m.) energies $$\sqrt s $$ between 12.0 and 34.6 GeV. The results agree with the predictions of Quantum Electrodynamics (QED) and the cut-off parameters are determined. From Bhabha scattering at the highest energy, $$\left\langle {\sqrt s } \right\rangle = 34.6 GeV$$ , the 1 δ limits 0.12〈sin2 ϑ w 〈0.38 are obtained for the weak mixing angle. The higher order (α3) QED processese + e −→e + e −γ ande + e −→γγγ are also studied and are found to agree with the α3 QED predictions. A search for excited electrons is carried out by investigating the (e ±γ) invariant mass distribution in the reactione + e −→e + e −γ.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The mean charged multiplicity as well as its distribution has been measured as a function of c.m. energy in the reactione + e −→hadrons. Fragmentation models are compared with the data. After applying radiative corrections the mean charged multiplicity is measured to be 8.4±0.3±0.6 at 12 GeV, 13.1±0.3±0.6 at 30 GeV and 13.6±0.3±0.6 at 35 GeV. The ratio of mean charged multiplicity to the dispersion (〈N ch〉/D ch) is almost constant in the energy range studied, indicating KNO scaling of the charged multiplicity. The inclusive differential cross sections(dσ/dx p ) shows scaling violation in the highx p region (x p 〉0.15). The absolute value of the scaling violation is consistent with the result of 2nd order QCD calculations. The production of neutral kaons has been investigated by identifying the decayK S 0 →π+π−. The production probability for a strange quark relative to that of au ord quark in the fragmentation, γ s , has been determined to be 0.27±0.03±0.05 averaged over c.m. energies from 12 to 35 GeV. Momentum spectra for neutral kaons are presented and are compared with model predictions.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Energy-energy-correlations (EEC) have been measured with the JADE detector at c.m. energies of 14 GeV, 22 GeV and in the region 29 GeV〈E cm〈36 GeV. Corrected results are presented of EEC and their asymmetry, which can be directly compared to theoretical predictions. At 〈E cm〉=34 GeV a comparison with second order QCD predictions yields good agreement for the string model fragmentation resulting in a value of the strong coupling constant α s =0.165±0.01 (stat.). The independent fragmentation models, which yield values of α s between 0.10 and 0.15 depending on the treatment of energy and momentum conservation and of the gluon splitting, do not provide a satisfactory description of the data over the full angular range.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A search has been made for new particles with chargeQ=2/3, 1, 4/3, 5/3 produced ine + e −-reactions at PETRA. The energy range wasE cm=27–35 GeV. No such particles were found. Upper limits for the cross-section depending on the assumed mass and production spectrum are given. ForQ=2/3 quarks with mass less than 12 GeV/c 2, upper limits $${{\sigma \left( {q\bar q} \right)} \mathord{\left/ {\vphantom {{\sigma \left( {q\bar q} \right)} {\sigma \left( {\mu \mu } \right)}}} \right. \kern-\nulldelimiterspace} {\sigma \left( {\mu \mu } \right)}} \leqq 10^{ - 2} $$ (90% C.L.) are obtained both for inclusive and exclusive production. For the lifetime of theB-meson (m B =5GeV/c 2) an upper limit τ≦2×10−9s is obtained.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have studied the distribution of particles within and between jets of 3-jet final states produced in the reactione + e −→hadrons at c.m. energies of 22 GeV and 29–36.4 GeV. The lowest energy jet shows distributions of transverse momenta, particle flow, and energy flow which differ significantly from those of the other two jets and from jets of 2-jet events atE cm=14 GeV. First order QCD calculations with subsequent fragmentation of quarks and gluons into hadrons indicate that the lowest energy jet has the largest probability of originating from a gluon. To reproduce the observed differences in an independent parton fragmentation model, the secondary quarks of a gluon jet have to have higher transverse momenta and lower parallel momenta than those of a quark jet. The particle densities between the jets as well as the correlation of transverse and longitudinal momenta of the particles within the jets favour models with fragmentation along the colour axes.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1871-4528
    Keywords: reduzierende Zucker ; Standort ; Jahr ; Niederschlagsmenge ; Züchtung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary Eleven potato cultivars were grown at four sites (Gross Lüsewitz, Tützpatz, Vollenschier, Vellahn) from 1974 to 1981 and the tendency to form sugars during storage at 4°C was determined with healthy graded (40–60 mm) tubers. Reducing sugar content was determined colorimetrically on three occasions: 1) immediately after harvest, 2) after 4–8 weeks storage at 12°C and 10 weeks at 4°C, 3) after a further 10 weeks at 4°C. Analysis of variance showed that sugar development was influenced significantly by cultivar, site and year (Table 1). Cultivars differed considerably for increases in reducing sugars during the first 10 weeks storage at 4°C (Table 2). Correlation coefficients could be derived between the sugar contents at each of the sampling dates, although no definite prediction could be made from the values immediately after harvesting about the expected sugar contents of each of the genotypes. The site and above all the year influenced both the absolute content of reducing sugars at each date and the increase in sugar formation (Tables 3 and 4). The effect of year and to some extent also the site differences could be attributed to meteorological phenomena: day temperature and amount of precipitation. High day temperatures and low levels of precipitation during the growing period produced low reducing sugar contents, while precipitation during or after flowering determined the absolute value and increase of reducing sugars during storage at 4°C. From the variance components, the proportion attributable to the genetic component was estimated to be ≧91% and therefore definite advances should be expected through breeding. Preliminary results are presented.
    Abstract: Résumé Pendant les années 1974 à 1981, 11 variétés de pommes de terre ont été cultivées dans 4 lieux (Gross Lüsewitz, Tützpatz, Vollenschier, Vellahn). Sur des tubercules sains, du calibre 40–60 mm, les sucres ont été analysés pendant la conservation à 4°C. La teneur en sucres réducteurs a été déterminée par la méthode colorimétrique aux périodes suivantes: 1) sitôt après la récolte, 2) après 4–8 semaines d'entreposage à 12°C suivie d'une conservation de 10 semaines à 4°C, 3) après 10 semaines supplémentaires de conservation à 4°C. II ressort de l'analyse de variance que la formation de sucre pendant la conservation ait été influencée de manière significative par la variété, le lieu de culture et l'année (tabl. 1). Entre les variétés des écarts importants dans la formation de sucres sont particulièrement observés pendant les 10 premières semaines de la conservation à 4°C (tabl. 2). Les corrélations entre taux de sucres aux différentes dates permettent de conclure qu'un dosage de sucres sitôt après la récolte ne donne pas une information fiable pour chaque génotype sur leur accumulation pendant la conservation. Le lieu et particulièrement l'année exercent une influence prédominante sur la formation de sucres (tabl. 3 et 4). L'influence de l'année ainsi que les différences entre lieux proviennent principalement des températures journalières et des précipitations. Les températures de jour élevées et de faibles précipitations pendant la période de végétation ont pour effet un taux de sucres bas à la récolte, tandis que les précipitations pendant la période de floraison et après la floraison déterminent le taux absolu de sucres ainsi que leur formation pendant la conservation à 4°C. L'estimation de la variance donne un effet génétique de≧91%, ce qui permet d'espérer d'importants progrès par la sélection. Les premiers résultats à ce sujet sont présentés dans ce travail.
    Notes: Zusammenfassung Achtjährige Untersuchungen zeigen, dass Sorte, Standort und Jahr einen signifikanten Einfluss auf die Neigung von Kartoffelknollen zur Zuckerbildung während mehrmonatiger Lagerung bei 4°C ausüben. Dabei ist das Jahr besonders in der zweiten Lagerphase (Januar–April) von entscheidender Bedeutung für das Ausmass der genetisch bedingten Zuckerbildung. Mittlere Tagestemperatur und Niederschlagsmenge während der gesamten Vegetationsdauer stehen in enger Beziehung zum Gehalt an reduzierenden Zuckern unmittelbar nach der Ernte, während die Niederschlagsmenge während und nach der Blüte die Neigung zur Zuckerbildung während der Lagerung eindeutig bestimmt. Die Varianzkomponentenschätzung ergab einen Anteil des genetischen Effekts von≥91% und lässt damit bei züchterischer Bearbeitung dieses Merkmals einen deutlichen Fortschritt erwarten.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The fraction of the total available energy carried by photons and the fraction carried by neutral particles of all types ine + e − multihadron final states have been measured at three centre-of-mass energies between 12 and 35 GeV. These fractions are approximately 27% and 37% with no strong dependence on centre-of-mass energy and the event topology. The neutrino energy fraction is estimated to be less than 10% at the 95% confidence level.
    Type of Medium: Electronic Resource
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