Three-Parameter Multichannel Recorder-Analyzer System

Abstract

A system is described in which nuclear events characterized by three parameters are recorded in digital form on magnetic tape by the record station. The completed tape is then analyzed off-line by the search station. Events of a typical experiment may consist of two pulse heights and a neutron time-of-flight, two pulse heights and an angle, or three coincident pulse heights. Each parameter is encoded by eight binary characters (bits) or 256 channels; thus, the number of different combinations is (256)3 or approximately 17×106. Each event is recorded as three eight-bit numbers across a 24-track, 1¼-in. magnetic tape. The tape is advanced in steps of 0.01 in. per event at low counting rates in order to conserve tape, and is moved continuously at high counting rates in order to achieve a recording rate of 170 events per second. During search of the recorded tape, restrictions are imposed on two parameters. If both are satisfied, the third variable of the corresponding event is tallied in one quadrant of a 1024-word core memory. There are four such restriction gates, one for each memory quadrant. In a neutron experiment, for example, a single pass of a 2500-ft tape with 3×106 events lasts only 3⅓ min and produces four time-of-flight spectra, each with uniquely selected energy ranges of two coincident gamma rays as parameters. The four spectra may be viewed on a cathode-ray tube or read out simultaneously by a typewriter, punched paper tape, and X-Y recorder at a rate of 5 min per spectrum of 256 channels. For experiments with low coincident counting rates, this system provides an efficient method for accumulating and analyzing data. The entire system is made with solid-state components, including 2100 transistors and 3300 diodes.

Excited-State Spin Assignments Based on (n, γγ) Angular-Correlation Measurements on Medium-Weight Nuclei

“…The coincident pairs of pulse heights were recorded on magnetic tape of the Argonne 3-parameter analyzer. 6 The analyzer was triggered by a pulse formed by a coincidence between either 4-X4-in. crystal and the 6-X8-in.…”