Landsverk Pocket Dosimeters, Models L-49, L-50, L-51, L-53

The following photograph shows, from the top down, the Models L-49, L-50 and L-51 pocket dosimeters manufactured by the Landsverk Electrometer Company of Glendale California. The models L-49 and L-51 date from the 1960s while the Model L-50 dates from the 1950s.

The Model L-49 (4" long and 0.5" in diameter) has an anodized aluminum barrel and responds to both thermal neutrons and gammas in the 0-200 mrem range. The claimed accuracy is +/- 10% for gammas and +/- 20% for neutrons. The Military designation for this model (not indicated) is the IM-112/PD.

The Model L-50 (4" long and 0.5" in diameter) responds to gamma rays in the 0-200 mR range. The Military designation for this model (not indicated) is the IM-9 series/PD. For some odd reason (most likely it was a mistake), Landsverk also used the Model L-50 designation for a ring dosimeter that employed an indirect reading chamber.

The Model L-51 (4.5" long and 0.5" in diameter) has an anodized aluminum barrel and responds to gamma rays in the 0-5 R range.

The Model L-53 (4.5" long and 0.5" in diameter) has an anodized aluminum barrel and responds to gamma rays in the 0-20 R range. The L-53 is identical to the Landsverk version of the civil defense dosimeter, the CD V-730.

Charging Voltage: 160 volts

Energy Dependence: 15% for 80 to 2,000 keV

Leakage: 2% in 24 hours

The Model L-53 was kindly donated by Amelia Engelmann.

References

• Landsverk Instrument Catalog, G-14 (enclosed price list dated June 1, 1968).
• Advertisement, Nucleonics, May 1958, page 33.