Studium der Herstellung von Emulsionen für ionisierende Strahlung

Zusammenfassung In der vorliegenden Arbeit werden einige Faktoren besprochen, von denen die Empfindlichkeit besonderer Emulsionen für die ionisierende Strahlung abhängt. Es wurde die Rezeptur für die Zubereitung dieser Emulsionen angegeben. Mit Emulsionen des angeführten Typs wurden Gelatinesorten mit verschiederter photochemischer Aktivität mit nachträglicher chemischer Sensibilisation ausprobiert. Es wurde ein neuer kräftiger Sensibilisator nuklearer Emulsionen gefunden.     

Bestimmung der Wirkungsquerschnitte für die Kleinstwinkelstreuung von Elektronen

Cross sections for small angle scattering of electrons are determined from the absolute measurements of the foregoing paper.Lenz's approximation of the cross sections proves to be valid but in a very limited angular range for most elements. Deviations from results calculated withLenz's theory can be ascribed to this reason in all in vestigated cases. Determination of the cross sections shows that the Thomas-Fermi-Dirac-model describes small angle scattering much better than is commonly assumed, disregarding a very small range near the angle 0 into which but a very small portion of the electrons is scattered.Lenz's method, however, yields only in special cases the correct cross sections and must not be as commonly used as is general practice.     

Aussagen der Theorie von Kraichnan für die isotrope hydromagnetische Turbulenz

The theory ofKraichnan is applied to quasi-stationary isotropic hydromagnetic turbulence. The average infinitesimal-impulse-response functionsg(k, τ), g _m (k, τ) and the time-correlationsr(k, τ), r _m (k, τ) are evaluated by the non-local direct-interaction approximation within the inertial range. For the range of ohmic but no viscous dissipation it is found that the magnetic energy spectrumE _m (k) obeys aE(k)k ^?2-law in accordance with results ofGolitsyn andMoffatt.     

Eine Bestimmung der effektiven Zustandsdichte des Bandes für überschüssige Defektelektronen in Anthrazen

Steady-state space-charge-limited current measurements were used to obtain the effective density of states in the band appropriate to excess hole motion in anthracene. Since the energetic trap density decreases exponentially with the energy distance from the band, the traps are filled by the space charge up to a certain quasi Fermi level. The thermal activation energy of the current should be a kind of spatial avarage of this level. This energy was measured and used to calculate the effective density of states. The result, 4·10²¹ cm^?3, is close to the double molecular density which is 8,4·10²¹ cm^?3. Further, a discussion on traps is given in an appendix.