A key consideration in a variety of manufacturing processes is controlling either the position or shape of an interface defined as the boundary between liquid and solid materials of dissimilar composition or density to within certain allowable tolerances. Automating these processes requires the ability to monitor and maintain the critical growth interface parameters throughout an entire lengthy batch process using an appropriate process feedback control algorithm. A method will be developed to monitor and subsequently control an interface boundary using an appropriate gamma ray emitting radioisotope and a rugged semiconductor detector. Initial results obtained during the Phase I program indicated that this technique is effective. Further research on this method should lead to a commercially viable control system.
