Über den Ionennachweis mit Photoplatten

Abstract

Part I. The transparency curve, produced by ions of 10 - 100 keV, can be described by T=Ts+(1-Ts) T = transparency, Ts = transparency at saturation, e = photographic sensitivity, N = number of ions incident per unit area, V = parameter of the size-frequency distribution of the AgBr grain impact areas. The equation is derived from basic principles by suitably modifying Kinoshita’s assumptions 1. Agreement with experimental curves is demonstrated. Part II. The shape of the transparency curve (T vs. log of ion density) was investigated for several developers at various developing temperatures and developing times, for the improved Ilford Q2 emulsion. Plates were exposed with 28 keV Kr+-ions. For short developing times, only those grains are developed which have been struck by r and more ions, r in the order of 50. With increasing developing time, r tends towards 1. This statistical effect, observed for all developers, is superimposed by two developer-dependent effects: in regions of high density of developable grains, the developing action is hampered by local consumption of developer reagents; furthermore, some developers result in a superposition of curves of very different values of r: the transparency curves appear “flatter” than those demanded by theory. Part III. The consideration of background fog necessitates the differentiation of two types of background: a fog due to light quanta or plate storage, and a surface fog due to particles with limited penetration depth into the emulsion. Equations are derived correcting measured transparencies for both types of background. Background fog reduces the photographic sensitivity. A theoretical equation gives the loss of photographic sensitivity for ion-produced fog. A similar equation is valid for light- and plate storageproduced fog; it then contains a parameter which has to be determined experimentally. Agreement with experiment is demonstrated. Part IV. Grain size and grain density of Ilford Q2 emulsions are determined from photometric measurements of statistical fluctuations of the blackening for various developing conditions. For most developers, the grain density increases with increasing developing time, the grain size remaining constant. The maximum attainable precision of photometer transparency and ion current density measurements for a given line area is stated.