Equivalent Quantum-Efficiencies of Photographic Emulsions

Radiobiological aspects of supralinear photographic emulsions.

Nuclear emulsions of the Ilford K series, exposed to X-rays from 15 to 150 kVp and systematically underdeveloped, exhibit supralinear blackness--exposure curves ranging from 1- to 4-hit in character, and whose shape is the same at all excitation voltages. Processing can be so adjusted that the curve shape is well represented by the alpha--beta model, and matches an experimental dose--response c...

Conversion Yields of Some Photographic Emulsions and Related Factors

A method is presented for the determination of the effective average projected grain diameter (d^) using visual analysis of enlargements of Kodak Tri-X Pan and Kodak Royal-X Pan emulsions. Each was exposed to three light sources of color temperatures 6100°K, 2850°K, and 2040°K, and was developed in Kodak developers HC-110, DK-50, and D-19 for 5, 8, 12, and 20 minutes at 68°F. For 5to 20-minute ...

Mechanical equivalent of quantum heat engines.

Quantum heat engines employ as working agents multilevel systems instead of classical gases. We show that under some conditions quantum heat engines are equivalent to a series of reservoirs at different altitudes containing balls of various weights. A cycle consists of picking up at random a ball from one reservoir and carrying it to the next, thereby performing or absorbing some work. In parti...

Barrier-width dependence of quantum efficiencies of GaN/Al x Ga 1x N multiple quantum wells

Comparison of the quantum efficiencies of interwell and intrawell radiative transitions in quantum cascade lasers

A theoretical study has been made to compare the quantum efficiencies of interwell and intrawell radiative transitions in quantum cascade lasers based on AlxGa1 xAs/GaAs technology. Radiative and non-radiative intersubband transition rates were calculated for a range of temperatures between 4 K and 300 K at an applied electric field of 4 kVcm 1 for structures designed to emit in both mid-infrar...