_On-Line Data-Acquisition Systems in Nuclear Physics, 1969_ Ad Hoc Panel on On-Line Computers in Nuclear Research Committee on Nuclear Science National Research Council _NATIONAL ACADEMY OF SCIENCES Washington, D.C. 1970_ This is a report of work under Contract NSF-C310, T.O. 47 between the National Science Foundation and the National Academy of Sciences and under Contract AT(49-1)3236 between the U.S. Atomic Energy Commission and the National Academy of Sciences. _Available from_ Committee on Nuclear Science 2101 Constitution Avenue Washington, D.C. 20418 PREFACE The first digital electronic device employed to collect nuclear data was the binary electronic counter (scaler) of the 1930's. In the next decade single and multichannel pulse-height analyzers appeared, still using vacuum tubes. In the 1950's the development of multichannel analyzers continued vigorously, with vast improvement of the analog-to-digital converter sections and with the introduction of computer-type memories, based first on acoustic delay lines and a short time later on ferrite cores. The replacement of vacuum tubes by transistors beginning in the latter half of the 1950's accelerated the pace of development and application of all types of electronic laboratory instruments. The 1960's was the decade of the computer. Before the 1960's almost no on-line computers were used in nuclear research, but since about 1962 the computer has moved into the nuclear laboratory. It provides the research worker with an immensely flexible, powerful, and accurate tool capable of raising the research output of a laboratory while eliminating the most tedious part of the experimental work. The phenomenal speed of development of computer hardware, software, and methodology contributes to the difficulty experienced by everybody involved in decision-making processes regarding data-acquisition systems. Since the cost of a computer system is often a sizable fraction of the total cost of a new laboratory, there is urgent need for a set of guiding rules or principles for use by a laboratory director planning a system, a reviewer going over a proposal for support, or a potential funding agency considering proposals and reviews. The purpose of this report is to assist in filling this need. The material presented is current through 1969. Although we deal with a field that is developing rapidly, we hope that a substantial portion of the material covered will have long-lasting value. The report was prepared by the Ad Hoc Panel on On-Line Computers in Nuclear Research of the Committee on Nuclear Science, National Research Council. Appointed in March 1968, the Panel first met in Washington, D.C., on April 22, 1968.