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Geiger counter is a colloquial name for any hand-held radiation measuring device in civil defense, but 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 departments 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/h to 10,000 R/h). 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. [1]
These are instruments using the ionisation chamber principle.
If the meter on any of the ion chamber devices is observed to respond at all to a radiation source, evacuation of the area should be considered. No legally exempt source of gamma radiation would be expected to cause any visible deflection of the meter on its most sensitive setting, so it might be assumed that such a radiation field could be dangerous. Such a meter would not be expected to detect the presence of radiation except the very high levels that might be found in the event of a nuclear weapon detonation or a major release of radioactive material as from a nuclear reactor meltdown. The CD V ion chamber units are now all approaching 50 years old at a minimum and that they contain parts that are sensitive to moisture, so relatively frequent calibration and inspection by an accredited and properly equipped facility is required to ensure reliable and accurate function.
The CD V-710 was another high range survey meter, however, unlike the CD V-720, CD V-715, and CD V-717 its scale is only 0-50 R/H (0-0.5, 0–5, and 0-50) making it more of a mid range meter, however it is still far too high to respond to any exempt sources. The CD V-710 was made in 5 different versions from 1955 to at least 1958, the model 1 was produced by El-Tronics, models 2 and 4 were produced by Jorden Electronics, and models 3 and 5 were produced by Victoreen Instruments, models 1-3 were metal, and 4 and 5 were plastic. All versions of the CD V-710 use a combination of D batteries and obsolete 22.5 volt B batteries. By 1959, 170,750 were procured, however the model was ultimately superseded by the CD V-715 and in September 1985 FEMA issued instructions that remaining CD V-710s should be disposed of as obsolete.
By far the most common US civil defense meter on the market today. This is a simple ion chamber radiological survey meter, specifically designed for high-radiation fields for which Geiger counters will give incorrect readings (see above). Survey meters do not read alpha or beta radiation. They work by radiation penetrating the case of the unit and the enclosed ionization chamber to produce a visible reading between 0.1 R/h and 500 R/h (× 0.1, × 1, × 10, and × 100 scales). The CDV-715 ion chamber controls a subminiature type 5886 tube, but no 22.5 volt batteries are necessary for the B circuit of this tube. A transistor oscillator coupled to a step-up transformer furnishes the necessary B current for the tube, with necessary rectifier diodes and filter capacitors. The entire unit is thus powered by a single 1.5 volt D cell.
Similar to the CD V-715, this unit reads from 0.1R/h to 500R/h. It is also a survey meter with an ionization chamber, however this unit's chamber is detachable for hanging outside your shelter or basement. When used, the ionization chamber would be inserted into a yellow anti-contamination bag, tied off, and hung outside a bomb shelter to measure radioactivity levels from a safe distance. An extension coaxial cord, typically stored inside the unit, is then run from the outdoor chamber to the indoor meter. The coaxial spool is used to prop the meter up for reading. This would allow those hiding to wait until outside radiation levels have fallen to a "safe" level before emerging. When using the extension cable, the accuracy of the meter can be slightly reduced to plus or minus 20%.
Similar to the CD V-715, the CD V-720 is a fixed-position ionization chamber survey meter. Unlike any other survey meter, however, this unit has a movable beta shield on the bottom of the unit for detecting high levels of beta radiation. When slid to the open position, beta particles are allowed to directly penetrate the ionization chamber. With the beta shield closed, only gamma rays can penetrate both the shield and ionization chamber. This meter reads from 1 R/h to 500 R/h (×1, ×10 and ×100 scales). The CD V-720 was produced in 4 models (1, 2, 3, and 3A), Chatham made the model 1, Landeds Fray and Clark made the model 3 (along with Victoreen Instruments), and Victoreen Instruments made all other models. All but the Victoreen model 3 and model 3A used a combination of D and 22.5 volt B batteries, while the Victoreen models 3 and 3A just used 2 D batteries. By 1962 113,231 had been procured, but in September 1985 FEMA declared all models except the Victoreen model 3 and model 3A obsolete.
Another meter of note is the Kearny fallout meter. The plans for this meter were published in Appendix C of Nuclear War Survival Skills by Cresson Kearny from research performed at Oak Ridge National Laboratory. [2] It was designed to be able to be constructed from household materials by someone with moderate mechanical ability on the eve of an attack. [3] The plans are presented in a newspaper printable format. [3]
The United States manufactured approximately 500,000 Geiger counters. Britain manufactured about 20,000 of each of its major types, and is second after the U.S. Some instruments were also manufactured by other countries in smaller numbers.
The American instruments dating from the Kennedy administration era were designed to use low voltage transistor electronics, and the batteries are still available today. However, most British civil defence instruments retained until 1982 or later were manufactured from 1953 to 1957, and required high voltage batteries which became obsolete after portable valve radios were superseded by transistor ones.
All British civil defence instruments were jointly designed by the Home Office and the Ministry of Defence, and were also a military issue.
The first large scale British civil defence issue was the Geiger–Müller counter Meter, Contamination, No. 1 set — stock number "5CG0012", of 1953. [4] It had 0–10 mR/hour range with external probe and headphones. This was designed to use two 150 volt batteries, although later they were fitted with a vibrator power pack which used four 1.35 volt mercury cells or, alternatively, a mains electricity power pack. Many of these units remained in service until the 1980s. There was also a Mk. 2 model which used rubber connectors and cable for the probe unit, compared to the Plessey connectors of the Mk.1.
This used cold-cathode valves and very high impedance circuitry throughout to extend useful battery life as long as possible with the existing technology.
The British "Radiac Survey Meter No. 2" [5] dates from 1953 to 1956, and required now-obsolete 15 and 30 volt high voltage batteries and a 1.5 volt standard cell, the latter used to power the valve heater filaments and meter illumination bulb. There was also a training unit, [6] which measured 0–300 mR/h, and ran on four 30 volt batteries plus one 1.5 V cell for the filaments. This meter used a large Geiger–Müller tube, as opposed to the ionisation chamber of the RSM No. 2.
These meters were favoured, as they had been tested on fallout in Australia after Operation Buffalo nuclear tests, and were retained until 1982 by commissioning a manufacturer to regularly produce special production runs of the obsolete batteries.
The UK's Royal Observer Corps (ROC) initially used the RSM No. 2 as its prime radiation detector until it was replaced by the specially-designed "Fixed Survey Meter", which used the same obsolete high voltage batteries as the RSM. The ROC retained the RSM No. 2 for use during external "post-attack" mobile monitoring surveys.
In 1982 the British PDRM82 was issued for civil defence. This model is lightweight, with an LCD display and a plastic case, and has all the electronics, including miniature Geiger tube (shielded against beta particles), on a single, EMP-hardened, PCB. It was designed by Plessey to use three standard 1.5 volt cells, and is microprocessor controlled with digital readout.
For use by the Royal Observer Corps, the instrument was also provided in the fixed version designated the PDRM82(F). The fixed version had an external coaxial socket mounted on its rear that accepted a cable from the above ground ionisation detector under a polycarbonate dome. For training purposes, timed simulated readings could be fed to the meter from an EPROM.
The 1958–1959 "Quartz Fibre Dosimeter Chargers, No. 1 and 2" were retained until the early 1990s, as they incorporate a simple, handle-driven generator and do not require batteries at all. A later British civil defence dosimeter charger was developed by R. A. Stephen Ltd and manufactured from 1967 to 1988, and uses a single 1.5 volt cell. It is similar to American dosimeter chargers.
A fallout shelter is an enclosed space specially designated to protect occupants from radioactive debris or fallout resulting from a nuclear explosion. Many such shelters were constructed as civil defense measures during the Cold War.
A Geiger counter is an electronic instrument used for detecting and measuring ionizing radiation. It is widely used in applications such as radiation dosimetry, radiological protection, experimental physics and the nuclear industry.
Particle radiation is the radiation of energy by means of fast-moving subatomic particles. Particle radiation is referred to as a particle beam if the particles are all moving in the same direction, similar to a light beam.
A radiation dosimeter is a device that measures dose uptake of external ionizing radiation. It is worn by the person being monitored when used as a personal dosimeter, and is a record of the radiation dose received. Modern electronic personal dosimeters can give a continuous readout of cumulative dose and current dose rate, and can warn the wearer with an audible alarm when a specified dose rate or a cumulative dose is exceeded. Other dosimeters, such as thermoluminescent or film types, require processing after use to reveal the cumulative dose received, and cannot give a current indication of dose while being worn.
The Geiger–Müller tube or G–M tube is the sensing element of the Geiger counter instrument used for the detection of ionizing radiation. It is named after Hans Geiger, who invented the principle in 1908, and Walther Müller, who collaborated with Geiger in developing the technique further in 1928 to produce a practical tube that could detect a number of different radiation types.
In experimental and applied particle physics, nuclear physics, and nuclear engineering, a particle detector, also known as a radiation detector, is a device used to detect, track, and/or identify ionizing particles, such as those produced by nuclear decay, cosmic radiation, or reactions in a particle accelerator. Detectors can measure the particle energy and other attributes such as momentum, spin, charge, particle type, in addition to merely registering the presence of the particle.
Health physics, also referred to as the science of radiation protection, is the profession devoted to protecting people and their environment from potential radiation hazards, while making it possible to enjoy the beneficial uses of radiation. Health physicists normally require a four-year bachelor’s degree and qualifying experience that demonstrates a professional knowledge of the theory and application of radiation protection principles and closely related sciences. Health physicists principally work at facilities where radionuclides or other sources of ionizing radiation are used or produced; these include research, industry, education, medical facilities, nuclear power, military, environmental protection, enforcement of government regulations, and decontamination and decommissioning—the combination of education and experience for health physicists depends on the specific field in which the health physicist is engaged.
The measurement of ionizing radiation is sometimes expressed as being a rate of counts per unit time as registered by a radiation monitoring instrument, for which counts per minute (cpm) and counts per second (cps) are commonly used quantities.
The ionization chamber is the simplest type of gaseous ionisation detector, and is widely used for the detection and measurement of many types of ionizing radiation, including X-rays, gamma rays, alpha particles and beta particles. Conventionally, the term "ionization chamber" refers exclusively to those detectors which collect all the charges created by direct ionization within the gas through the application of an electric field. It uses the discrete charges created by each interaction between the incident radiation and the gas to produce an output in the form of a small direct current. This means individual ionising events cannot be measured, so the energy of different types of radiation cannot be differentiated, but it gives a very good measurement of overall ionising effect.
Gaseous ionization detectors are radiation detection instruments used in particle physics to detect the presence of ionizing particles, and in radiation protection applications to measure ionizing radiation.
The United Kingdom Warning and Monitoring Organisation (UKWMO) was a British civilian organisation operating to provide UK military and civilian authorities with data on nuclear explosions and forecasts of fallout across the country in the event of nuclear war.
The Kearny fallout meter, or KFM, is an expedient radiation meter. It is designed such that someone with a normal mechanical ability would be able to construct it before or during a nuclear attack, using common household items.
Nuclear MASINT is one of the six major subdisciplines generally accepted to make up Measurement and Signature Intelligence (MASINT), which covers measurement and characterization of information derived from nuclear radiation and other physical phenomena associated with nuclear weapons, reactors, processes, materials, devices, and facilities. Nuclear monitoring can be done remotely or during onsite inspections of nuclear facilities. Data exploitation results in characterization of nuclear weapons, reactors, and materials. A number of systems detect and monitor the world for nuclear explosions, as well as nuclear materials production.
Survey meters in radiation protection are hand-held ionising radiation measurement instruments used to check such as personnel, equipment and the environment for radioactive contamination and ambient radiation. The hand-held survey meter is probably the most familiar radiation measuring device owing to its wide and visible use.
The Fixed Survey Meter was a specialist detection instrument used by the Royal Observer Corps during the Cold War between 1958 and 1982 to detect ionising radiation from nuclear fallout generated by a ground burst.
A quartz fiber dosimeter, sometimes called a self indicating pocket dosimeter (SIPD) or self reading pocket dosimeter (SRPD) or quartz fibre electrometer (QFE), is a type of radiation dosimeter, a pen-like device that measures the cumulative dose of ionizing radiation received by the device, usually over one work period. It is clipped to a person's clothing, normally a breast pocket for whole body exposure, to measure the user's exposure to radiation.
The Royal Observer Corps (ROC) was a civil defence organisation operating in the United Kingdom between October 1925 and 31 December 1995, when the Corps' civilian volunteers were stood down.. Composed mainly of civilian spare-time volunteers, ROC personnel wore a Royal Air Force (RAF) style uniform and latterly came under the administrative control of RAF Strike Command and the operational control of the Home Office. Civilian volunteers were trained and administered by a small cadre of professional full-time officers under the command of the Commandant Royal Observer Corps; a serving RAF Air Commodore.
The CD V-700 is a Geiger counter employing a probe equipped with a Geiger–Müller tube, manufactured by several companies under contract to United States federal civil defense agencies in the 1950s and 1960s. While all models adhere to a similar size, shape, coloring and form-factor, there were substantial differences between various models and manufacturers over the years the CD V-700 was in production. Many of the earlier units required the use of now-obsolete high-voltage batteries, and were declared obsolete by the end of the 1970s.
Operation Peppermint was the codename given during World War II to preparations by the Manhattan Project and the European Theater of Operations United States Army (ETOUSA) to counter the danger that the Germans might disrupt the June 1944 Normandy landings with radioactive poisons.
John Austin Victoreen was a self-taught physicist, engineer, inventor and otologist. He founded the Victoreen Instrument Company and was the author of two books, various technical papers on radiation and sound waves, and holder of over 30 patents.