Other

Debeers Industrial Diamond Division (Proprietary) Limited

Tenon Ltd.

Tom L Nam

Rex J Keddy

Shawn Araikum

Barbara L Jones

Geoffrey John Davies

Johan F Prins

Lesley Kay Hedges

Robert Charles Burns

Robert C Burns

Hendrik J Van Rijn

Paul J Fallon

Joanne F Schlimmer Nee Andrews

Jacques P Sellschop

The invention provides a method of detecting and monitoring ionizing radiation such as nuclear radiation. The method comprises providing a diamond radiation sensor element having a nitrogen concentration not exceeding 20 ppm and which is optimized for phosphorescent response, and exposing it to ionizing radiation. The resulting phosphorescent response of the sensor element is then monitored, typically over a period of at least 20 seconds. The invention extends to the sensor element itself, and to apparatus employing the sensor.

Diamond radiation detector element

The instant invention relates to a method and an apparatus of monitoring nuclear radiation. The method utilizes a diamond radiation sensor element having a nitrogen impurity concentration of less than 150 ppm. The sensor element is subjected to nuclear radiation, while being stimulated with light of a selected wavelength or range of wavelengths, preferably in the ultraviolet or near-ultraviolet range, resulting in light emissions from the sensor element. Typically, the sensor element is fixed to the end of an optical fibre, the far end of the fibre being used to channel stimulating light to the sensor element and to feed resultant light emissions from the sensor element to a photomultiplier tube.

Radiation probe

A neutron detector is formed from a layer of polycrystalline diamond which is deposited by a chemical vapor deposition process. The diamond material contains .sup.10 B as a dopant, in a concentration of 1,000 ppm or less. In one embodiment, the layer of diamond material is deposited on a supporting substrate. Advantageously, the substrate itself may comprise a layer of diamond material. In another embodiment, the substrate comprises a layer of conductive or semiconductive material. The diamond material is deposited on top of the substrate, with at least two regions in contact with the semiconductive material. A central portion of the semiconductive material is etched away, and electrical contacts are applied to the remaining portions of the semiconductive substrate. An advantage of the neutron detector of the invention is that the diamond layer is very thin, less than 50 .mu.m thick, so that the sensitivity of the detector to other radiation, particularly .gamma. radiation, is reduced.

Diamond neutron detector

Cubic boron nitride having an impurity profile as set out below has been found to exhibit excellent thermoluminescent properties with a high gamma radiation sensitivity and low light sensitivity:

Method of detecting or measuring nuclear radiation

The invention provides a scintillation detector for nuclear radiation which comprises a synthetic diamond having a nitrogen impurity concentration of 150 ppm or less. The detector has solvent (or oxides thereof) impurity concentrations of 1000 ppm or less, where the solvents are any of the following: Ni, Cu, Mn, Al or Cr, or combinations thereof. The detector has Fe and Co impurity concentrations of less than 10 ppm. A practical version of the detector includes an optical fibre and a photomultiplier tube, the optical fibre collecting light emitted by the diamond and channelling it to the photomultiplier tube.

Diamond scintillation detector

Nuclear radiation is detected by applying electrical contacts to a synthetic diamond having a nitrogen impurity concentration of 25 to 150 parts per million. An electrical circuit is connected to the contacts and applies a DC bias voltage across the diamond. When the diamond is subjected to nuclear radiation, a change in the current or voltage in the circuit occurs which corresponds to the radiation intensity. The nuclear radiation may be any kind of radiation. The contacts are preferably attached directly to the diamond and are ohmic in nature.

Synthetic diamond radiation detector

A method of detecting, counting or otherwise measuring nuclear radiation includes the steps of exposing a diamond containing single substitutional paramagnetic nitrogen to the nuclear radiation to cause electrons or holes to be trapped at lattice imperfections within the diamond crystal structure, heating the diamond to cause it to luminesce and utilizing the luminescence as a means for the detection, counting or measurement of the nuclear radiation. The method is characterized by subjecting the diamond to a high dose of neutron or electron irradiation prior to exposing it to the nuclear radiation to be detected. This, it has been found, improves both the sensitivity of the diamond as a thermoluminescent material and linearity of the thermoluminescent response to nuclear radiation dose.

Detection of nuclear radiation

The invention provides a method of preparing a detector which is sensitive to ionizing radiation or atomic emissions. The method includes the steps of forming at least two discrete conductive regions on a counting diamond by ion implantation, at a temperature below 500.degree. C. Subsequently, contacts are applied to the conductive regions to allow charged carriers liberated by the radiation to be detected by an electronic circuit. The invention extends to a detector prepared according to the method. An example of a detector according to the invention comprised a synthetic diamond having a paramagnetic nitrogen impurity concentration of less than 150 parts per million. Two conductive regions were formed on the diamond by bombardment with carbon ions, and contacts were formed on the conductive regions by the applications of silver-loaded epoxy paint.

Forming contacts on diamonds

Diamond having a nitrogen content not exceeding 100 ppm and electrons or holes trapped at lattice imperfections within the crystal structure has been found to be a good thermoluminescent material. The diamond is produced by taking a diamond having a nitrogen content not exceeding 100 ppm and subjecting it to nuclear radiation.

Growing community of inventors

Bez Valley, Johannesburg, Transvaal, South Africa

Tom L Nam