Civil Defense geiger counters

This article is about Geiger counters and Ion chamber instruments, and it uses the term "Geiger counter" as a colloquial name for any hand-held radiation measuring device in Civil defense. However, most Civil Defense devices were ion-chamber radiological survey meters capable of measuring only high levels of radiation that would be present after a major nuclear event.

Most Geiger and ion-chamber survey meters were issued by governmental Civil Defense organizations in several countries from the 1950s in the midst of the Cold War in an effort to help prepare citizens for a nuclear attack.

Many of these same instruments are still in use today by some states, Texas amongst them, under the jurisdiction of the Texas Bureau of Radiation Control. They are regularly maintained, calibrated and deployed to fire depts and other emergency services.

CD Counters came in a variety of different models, each with specific capabilities. Each of these models has an analog meter from 1 to 5, with 1/10 tick marks. Thus, at X10, the meter reads from 1 to 50.

CD meters were produced by a number of different firms under contract. Victoreen, Lionel, Electro Neutronics, Nuclear Measurements, Chatham Electronics, International Pump and Machine Works, Universal Atomics, Anton Electronic Laboratories; Landers, Frary, & Clark; El Tronics, Jordan, and Nuclear Chicago are among the many manufacturers contracted. Regardless of producer, most counters exhibit the same basic physical characteristics, albeit with slight variations between some production runs: a yellow case with black knobs and meter bezels. Most US meters had a "CD" sticker on the side of the case.

These are instruments which use the Geiger principle of detection.

The CD V-700 is a Geiger counter employing a probe equipped with a Geiger–Müller tube manufactured by several companies under contract to US federal civil defense agencies in the 1950s and 1960s. This unit is quite sensitive and can be used to measure low levels of Gamma radiation and detect Beta radiation. In cases of high-radiation fields, the Geiger tube can saturate, causing the meter to read a very low level of radiation (close to 0 R/h) hence the necessity of the companion ion-chamber survey meters.

The CD V-718 is a variation of the US military-issue AN/VDR-2 RADIAC made by Nuclear Research Corporation, located in the US State of New Jersey. The Federal Emergency Management Agency (FEMA) purchased a quantity of CD V-718s in the 1990s as a supplement to and partial replacement for the older meters in the inventory. The CD V-718 differs from the military AN/VDR-2 primarily by being painted bright "civil defense" yellow instead of olive green and being graduated in Röntgens rather than Grays. A much more modern and sophisticated device than earlier CD meters and equipped with a probe containing two Geiger-Mueller tubes of differing sensitivities, the CD V-718 can cover a much wider range of radiation levels than the earlier Geiger counters and ion-chamber survey meters combined (from .001mR/hr to 10,000 R/hr). As a result of its military heritage, the CD-V-718 is far more rugged than earlier CD meters, and can easily be mounted in vehicles.

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Wikipedia