Sears Tower Model 6160 Gamma Scintillator (ca. 1955-1960)

Notice anything wrong with the above picture? Answer at the bottom of the page.

This sodium iodide gamma scintillator was manufactured for the Sears Roebuck Company by El-Tronics Inc. of Philadelphia. A very similar instrument was also sold under the El-Tronics name as the Model PR-30 (the schematic inside the case is labeled as that of the PR-30). The latter was described in the Atomic Energy Commission Instrument Catalog as follows: "Compact and reliable low cost portable scintillation gamma survey meter incorporating sealed sodium iodide (Tl) crystal and photomultiplier with a counting rate meter circuit." I have found no references to the Sears Model 6160.

Detector: NaI crystal (1" x 1" x 1")

Range: 0-0.02, 0-0.06, 0-0.2, 0-0.6, 0-2.0, 0-6.0 mR/hr

Size: ca. 5 1/8" x 8 1/4" x 6 1/4"

Weight: ca. 9 lbs.

Output: No speaker, but it has a phone jack and a small light that flashes according to the count rate

Batteries: One 1 1/2 volt and two 67 1/2 volt

Reference

Atomic Energy Commission. (El-Tronics PR-30), AEC Radiation Measuring Instruments, RIB-8 (supplement 2) July 1, 1954, page SBX-32A.

Problem in the photograph at the top of the page: The orange/red circle on the end of the case is intended to indicate the location of the scintillator crystal. The latter is at the front, not the back, end of the case. When the instrument was last opened up, the bottom of the case was turned around and then reattached backwards.