Abstract: 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.

Abstract: A semi-permanent peripheral grinding wheel comprising ultrahard abrasives such as diamond or cubic boron nitride is provided which overcomes the serious problems caused by "chatter". The wheel comprises a hub mounting the ultrahard abrasive, the abrasive being resiliently depressible radially inwardly of the wheel. The wheel preferably has a radial static stiffness of no more than 1.5.times.10.sup.6 N/m per mm. of wheel width and a first radial natural frequency of at least 500 Hertz. The resiliency may be provided by rubber pads between the abrasive and the hub, or by mounting the abrasive on a hub made of resiliently deformable metal such as "RETIMET" (Registered Trade Mark) sponge-like metal.