Abstract: A series of improved electron multipliers is shown which are capable of reducing the number of bombardments per unit area. In the preferred embodiment, the inner channel is significantly increased in surface area over that surface area of present-day multipliers. Because the surface area is increased, for the same charge throughout, the number of electron bombardments per unit area is decreased. Since the number of bombardments per unit area is reduced, there is less degradation on the inner surface of the channel and hence the device lifetime is also increased.

Abstract: A segmented electron multiplier is disclosed with front and rear sections. The sections are specially designed so that the length of the rear section compared to the length of the front section is no less than 4:1. This permits multiple replacements of the rear section, after the multiplier wears out, without any unsatisfactory drop in the overall electrical gain produced by the repaired device. In the preferred embodiment, the front portion is a funnel having a tubular stem, and the rear portion is a straight tube with a cylindrical helical inner channel. The length-to-length split is 5:1, which theoretically permits up to six or seven replacements of the rear section before unsatisfactory gain occurs.

Abstract: A pressure sensor includes a resonator element (14) mounted on an optical fibre ferrule (11) whereby light signals for maintaining the resonator in a state of oscillation and for returning a modulated signal to a remote station are coupled to the resonator. The resonator is located in an evacuated cavity and is mounted on a flexible diaphragm whereby pressure changes may be detected as changes in the resonant frequency.