Abstract: A detecting system capable of simultaneously detecting radioactive emissions from a multiplicity of samples uses a sample holder containing a multiplicity of receiving zones and a multiplicity of drift chambers corresponding respectively to each receiving zone and also having one or more apertures. An array of cathodes is disposed transversely to an array of anodes and the crossing points corresponds to the apertures. There is also a structure that eliminates cross talk between the chambers. This structure is arranged so that a potential difference can be applied across the sample holder which in turn creates a field within the drift chambers in order to improve the detection gain of the detector head assembly.

Abstract: Apparatus for monitoring the dielectric composition of articles, particularly articles such as blisterpacks and laminated boards. The apparatus comprises an amplifying circuit including a capacitor between the electrodes (1, 3) of which an article (22) is moved in use. The gain of the amplifying circuit varies with the capacitance of the capacitor so that the amplifying circuit provides an output signal, the peak value of the output signal varying with the dielectric constant of the article (22) between the capacitor electrodes (1, 3). Typically the amplifying circuit includes an operational amplifier (9) the non-inverting input (10) of which is connected to a ground potential (6) and the inverting input (8) is connected to one electrode (3) of the capacitor. A feedback loop (11) is applied between the output (14) of the operational amplifier (9) and the inverting input (8) of the operational amplifier to force the inverting input to the same potential as the non-inverting input.

Abstract: A detecting head assembly provides output signals relating to individual ionizing events due to radioactive decay of material in a medium such as a radiochromatogram or electrophoretogram. The detecting head assembly comprises a scanning head which includes an ionization chamber comprising two spaced detecting electrodes each including an array of spaced conductors. The conductors extend transversely of one another to provide a plurality of conductor crossing points. A mask having a plurality of radiation transmissive zones or apertures is supported relative to the detecting electrodes such that said zones or apertures respectively correspond with the conductor crossing points.