An Automated Digital Apparatus for Measuring the Basic Parameters of Nuclear Detectors

The measurement of the basic parameters of energy-sensitive nuclear detectors (resolution, stability, noise) is simple and well known in principle, but is tedious work in practice. This fact makes the supervision of serially manufactured nuclear probes (photomultipliers, scintillation crystals, semiconductor detectors) especially difficult. The paper discusses the solution of this problem by means of a digital measuring apparatus. The digital operation is obtained by using the proper circuitry of a multichannel pulse height analyser. The stability measuring process is achieved essentially with a peak-position stabilizer and an added pilot-signal generator. The resolving power measurement - for measuring time reduction - is based on a novel principle: two counters are used and the address pulse train plays an important role. The noise measurement is arranged conventionally. A time multiplexing and control unit is added, making it possible to measure six detectors at the same time. The results are in digital form, and displayed on indicator tubes. Print-out facilities and analog outputs are also included. The apparatus measures automatically the resolving power (5-15%), stability (0.1 - 10%) and noise (1-15 keV) of scintillation probes, using a standard 137Cs source. It is also possible to measure semiconductor detectors, but in that case good-quality charge-sensitive, and window amplifiers are needed. (author)