ANDOVER, Mass., Oct. 4 -- MKS Instruments Inc. has entered into a definitive merger agreement to acquire Applied Science and Technology Inc., a Wilmington, Mass.-based company that designs, develops, and manufactures precision reactive gas solutions. MKS Instruments will be the surviving corporation. The merger is in keeping with MKS Instruments' strategy of offering a one-stop, broad-based product range for its OEM and end-user customers. ASTeX's product line is based on its core technologies, which include reactive gas generation, power sources, and subsystem integration. The ASTeX merger will add manufacturing capabilities in Massachusetts, Colorado, Germany, and Korea.MKS Instruments is a supplier of gas measurement, control and analysis products used in semiconductor and thin-film manufacturing processes.