Two-Dimensional Pulse-Height Analyzer

Abstract

A two-dimensional analyzer classifies a coincidence event between two detectors according to both pulse amplitudes. The events are sorted into ``channels'' covering a plane instead of the linear array of a conventional analyzer. For coincidence measurements in which the amplitude spectrum from one detector is examined as a function of the pulse height from the other over a wide range, such a device provides maximum efficiency in recording the data. An analyzer is described, in which each coincidence is recorded on a punched paper tape memory as a pair of correlated numbers (the two pulse heights) in binary notation (1–127). In the subsequent read-out these two numbers specify a two-dimensional channel. To examine the information in a particular region of the plane, a circuit controlled by a mechanical tape reader determines those events for which one coordinate lies in a preselected range. The corresponding coordinates are then displayed as a spectrum on a conventional 100-channel analyzer by a digital-to-analog conversion system in such a way that each event appears in the channel whose number is punched on the tape. The maximum recording rate is 8/sec; read-out is at 10/sec. The maximum number of channels is (127)2. In experiments with low coincidence rates the time taken to record and analyze such data is very considerably less than by conventional methods. Examples are given of the application of the analyzer to a (p,p′γ) experiment and to the identification of energetic charged particles by measuring simultaneously their energy and differential energy loss.