The Secretary of State for Industry in Her Britannic Majesty's

Alan G Roddie

Julian G Edwards

A photon drag detector having a block of semi-conductor material with two opposite faces through one of which a beam of radiation can enter and from the other of which it can emerge; spaced end electrodes in contact with said block, one adjacent to each of said opposite faces; at least two intermediate electrodes in contact with said block, arranged intermediate and spaced from said end electrodes and spaced from each other; and an impedance connecting said end electrodes; whereby the change in sensitivity of the detector with the position of the beam in the said block can be made small. The block of semi-conductor material is typically bar shaped with the opposite faces substantially parallel end faces of the bar. The bar is conveniently cylindrical. The electrodes are preferably ring electrodes, embracing the block and parallel with the planes of the opposite faces. The semi-conductor may be P-doped germanium of about 30 ohm centimeter resistivity, and the impedance may be a resistance in the range from about 100 to about 400 ohm.

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Isleworth, United Kingdom

Alan G Roddie