Anregung von Zinkoxyd durch langsame Elektronen

Under excitation with monochromatic electrons luminescence of a ZnO phosphor starts with a screen voltage of 2.8 volts (contactpotential 2.4 v) i.e. with an impact energy of 0.4 eV. A flattening was found in the rise of the fluorescence for screen voltages between 7 and 10 volts. This can be considered as an interaction of the incoming electron with the lattice electrons. The quantum efficiency of electrons having an energy of 10 eV was about one light quantum per 200 electrons. The work function of ZnO was found to be 4 eV.     

Messung der durch ein Quermagnetfeld erzeugten Gasströmung in einem wandstabilisierten Niederstrombogen

The conductivity of a liquid metal is calculated by a Greenwood-Peierls-formula. For the two-electron Green's function a Bethe-Salpeter-equation is derived and approximately solved. The solution, satisfying Ward-identities, gives an extension of Ziman's formula to higher order perturbation theory. Special higher order terms are discussed showing an unusual dependence on the structure factor.     

Untersuchung des Niveauschemas von Nb93 durch Messung der Gammastrahlung nach der inelastischen Streuung schneller Neutronen

Fast neutrons from a nanosecond-pulsedD(d, n)He³ neutron source were scattered from Nb⁹³. The gamma spectrum arising from inelastic scattering was measured in a high resolution Ge(Li)-spectrometer. In order to obtain low background a time gate technique was used. About 44 gamma lines could be found between 150 keV and 2.2 MeV in the single spectrum. In addition gamma-gamma-coincidences were investigated with a NaJ- and a Ge(Li)-detector. By these means it was possible to identify almost all gamma transitions and to receive a nearly complete level scheme of Nb⁹³ up to 2.2 MeV. The experimental cross sections for the population of the levels by the (n, n′)-reaction were compared with the results of the Hauser-Feshbach theory using the optical model transmission coefficients of Lindner and Meldner. From this and from the observed gamma transitions proposals for spin- and parity-assignments of the energy levels are given.     

Ein experimenteller Beitrag zu der durch langsame Primärelektronen ausgelösten Sekundärelektronenemission

The energy distribution of secondary electrons emitted from a highly degassed polycristalline Pt surface was investigated as a function of low energy (V _p ) primary electrons 5<V _p <150eV. The measurements were carried out in an UHV of better than 10^?10 mm Hg. The dependence of the numberN _S ^(Ev) of secondary electrons of a fixed energyE _v (3<E _v <12eV) on the energyV _p of the primaries (=isochromates) is studied. A lot of observations can be detected:

1. I.
   The exit depth of true secondary electrons is strongly dependent of their energy.     
   
   

Messung der von Elektronenlawinen erzeugten Raumladungsfelder mittels einer Sondenlawine

The electrical fields due to the space charge of positive ions in a plane-parallel discharge gap are measured by means of an electron avalanche. The measurements were made in a N₂-CH₄ gas mixture (5% CH₄) at a total pressure of 210 Torr (20 °C) in a 3 cm gap, at a voltage UD (static breakdown potential). The positive ions are produced by electron avalanches, which are released from a broad area by an UV flash at the cathode. The ions so produced drift towards the cathode with a drift velocity v₊. After a timeT the probe avalanche is started by a second UV flash in the symmetry axis of the charge distribution. From its temporal growth, which is given by the relation\(i_s (t) \sim \delta v\_\exp \left( {\int\limits_0^t {\alpha v\_dt} } \right)\), one can evaluate the space charge field E(z) of the positive ions. The measured fields are in good agreement with those predicted by calculations.     

Messung kohärenter Streulängen durch Kleinwinkelstreuung von Neutronen im Schwerkraft-Refraktometer

Using the small angle scattering of neutrons by a “Christiansen-Filter”, a mixture of a grained powder with a liquid, it has been possible to determine the scattering amplitude of powders and liquids with an error within ± 1% or lower. By measurements with Tungsten-powder and mixtures of the liquids C₂Cl₄ and C₆H₅Cl and with mixtures of heavy and light water we got the scattering amplitudes of the bound atoms: Deuteruma=(6.70 ± 0.05) f and Tungstena=(4.77 ± 0.05) f.     

Untersuchung der γ-Strahlung bei Einfang thermischer Neutronen in Nd143 mit der Summen-Koinzidenzmethode

Zeitschrift für Physik A Hadrons and nuclei - 2 two-step cascades from the capturing state to the groundstate of Nd144 and 6 two-step cascades from the capturing state to the 0,69 MeV excited...