RADIAC CP-95A/PD DT-60 Reader (ca. 1960s)

CP-95A/PD Reader for DT-60

The CP-95A/PD was used by the U.S. Navy to read its DT-60/PD glass dosimeters. It determined the integrated dose to the dosimeter, the dosimeter is never "zeroed." In other words, the dosimeter (DT-60/PD) reading has to be determined before and after deployment.

Quoting the NAVSHIPS Directory of Radiac Equipment (ca. 1960):

Functional Description

Radiac Computer-Indicator CP-95A/PD is designed as a portable radiac computer-indicator, for computing & indicating the total amount of X and gamma radiation to which Radiac Detector DT-60()/PD has been exposed (and thus revealing the X and gamma radiation to which the wearer of the DT-60()/PD had been exposed). The CP-95A/PD operates in conjunction with Radiac Detector DT-60()/PD (not supplied) which contains a specially compounded silver-actuated phosphor glass. When the total radiation dosage of a DT-60()/PD is to be measured, the DT-60()/D is placed in Radiac Computer-Indicator C-95A/PD and exposed to a source of ultraviolet light. The ultraviolet light causes the silver-activated glass to emit an orange luminescence, the intensity of which is proportional to the total amount of radiation the glass has received. The intensity of the orange luminescence is measured by a photomultiplier tube which is fitted with a filter to prohibit the passage of blue and green light. The photomultiplier tube employs the principle of secondary emission to amplify the initial electron emission caused by the filtered orange illumination of the light-sensitive cathode. The output of the photomultiplier tube is applied to an indicating circuit to indicate the total amount of radiation to which the wearer of the DT60()/PD has been exposed.

CP-95A/PD Reader for DT-60

This is a close-up of the loading mechanism. The opened dosimeter is placed in the opening and the lever to the right is pulled upwards so that the dosimeter is rotated into the unit and positioned in front of the photomultiplier tube.

RADIAC DT60/PD Personnel Dosimeter

This photo shows the DT-60/PD glass dosimeter that is read by the CP-95A/PD.

Relation to Similar Equipment

Radiac Computer-Indicator CP-95A/PD is an improved version of, and a direct replacement of Radiac Computer-Indicator CP-95/PD. The manufacturer’s nomenclature for the CP-95A/PD is Dosimeter Reader Model 95A.

Sensing element: Photomultiplier tube 

Size: ca. 9" x 9" x 17"

Weight: 22 pounds.

Dose ranges: 0-200 R, 0-600R

Price: ca. $400 in 1975; $2,500 in 1987


  • Department of the Navy Directory of Radiac Equipment NAVSHIPS 94200.5, page date August 1961.
  • Naval Electronic Systems Command List of Radiacs in the Navy Program P-9670-1, February 1975.
  • Defense Nuclear Agency List of Military and Civil Defense Radiac Devices HQDNA(AR)-124 3M, August 1987.