The detection efficiency, or sensitivity, of a neutron detector material such as of Si, SiC, amorphous Si, GaAs, or diamond is substantially increased by forming one or more cavities, or holes, in its surface. A neutron reactive material such as of elemental, or any compound of, .sup.10 B, .sup.6 Li, .sup.6 LiF, U, or Gd is deposited on the surface of the detector material so as to be disposed within the cavities therein. The portions of the neutron reactive material extending into the detector material substantially increase the probability of an energetic neutron reaction product in the form of a charged particle being directed into and detected by the neutron detector material.

Neutron detectors, advanced detector process techniques and advanced compound film designs have greatly increased neutron-detection efficiency. One embodiment of the detectors utilizes a semiconductor wafer with a matrix of spaced cavities filled with one or more types of neutron reactive material such as .sup.10B or .sup.6LiF. The cavities are etched into both the front and back surfaces of the device such that the cavities from one side surround the cavities from the other side. The cavities may be etched via holes or etched slots or trenches. In another embodiment, the cavities are different-sized and the smaller cavities extend into the wafer from the lower surfaces of the larger cavities. In a third embodiment, multiple layers of different neutron-responsive material are formed on one or more sides of the wafer. The new devices operate at room temperature, are compact, rugged, and reliable in design.

A detector for detection of ionizing radiation, and an apparatus for use in planar beam radiography, including such a detector. The detector includes a chamber filled with an ionizable gas. First and second electrode arrangements are provided in the chamber with a space therebetween. The space includes a conversion volume, an electron avalanche amplification unit arranged in the chamber, and at least one arrangement of read-out elements for detection of electron avalanches. To reduce the effect of possible spark discharges in the chamber, at least one of the first and second electrode arrangements includes a resistive material having a surface facing the other electrode arrangement.

A radiation detector includes a new and sensitive radiation sensor. The sensor includes a photo conductor cell. A substantially transparent cone optically coupled to the photo conductor cell, and a first layer of phosphor material coated onto the transparent cone. The layer of metal is then coated onto the phosphor material. This combination provides a sensitive and compact sensor construction. A bias light is further included to improve the sensitivity of the sensor. Signals sent by the sensor and evaluated by a microprocessor result in the transmission of predetermined audible sounds.

A solid-state thermal neutron detector comprises: a layered structure that includes; an electrically insulating substrate; a first electrode affixed to the substrate; a neutron-reactive layer affixed to and in ohmic contact with the first electrode; and a second electrode affixed to and in ohmic contact with the neutron-reactive layer; a voltage source electrically coupled to the first and second electrodes; and an electrical current detector electrically coupled in series between the layered structure and the voltage source.