Tracerlab Model PS-1 Portable Spectrometer (ca. 1963-1970)


The Model PS-1 is a NaI gamma scintillator that is capable of both measuring the count rate and performing an integrated count over a selected count time. When operated in the integrating mode, the count time is selected with a timer, much like a kitchen timer, on the end of the instrument case. At the end of the counting interval, the count is indicated by the position of the needle on the meter. The integration is accomplished by accumulating the incoming pulses on a capacitor. At the end of the count, the count is “read” by measuring the voltage on the capacitor. 

The unit is described as a “Spectrometer” because it incorporates a single channel analyzer (SCA). When operated in the “Spec” mode rather than the “Scint” mode, the SCA is operative and the detector can be “tuned” to a particular isotope.  To set the SCA window, the nuclide of interest (e.g.,Cs-137) is counted and the “Tune” control knob is adjusted so that the count rate is maximized. This sets the window about the selected gamma peak (e.g., the Cs-137 662 keV gamma ray).


Detector:   NaI crystal, 1.5” diameter, 1” thick

Range:   0 – 2,000 cpm and 0 – 10,000 cpm in the ratemeter mode and 0 – 500 counts in the integrating mode.

Timer:   0 – 15 minutes

Audio:   no speaker but has jack for headphones

Batteries:  Two 1.5 volt D cells.

Size:   8” x 5” x 5”

Weight:  4 pounds

Tracerlab Operating Instructions for Model PS-1 Portable Radiological Spectrometer. Blueprints dated June 1962 and November 1963.

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Last updated: 05/10/11
Copyright 1999, Oak Ridge Associated Universities