There are a number of considerations that should be taken into account when purchasing a Geiger counter. Increased public concerns about radiation exposure, especially since Fukushima, have resulted in an explosion of inexpensive hand-held Geiger counters being brought onto the market. There are many manufacturers and models. If you going to buy a Geiger counter, here is a list of things to watch out for.

Radiation: The counter should be able to measure all three types of ionizing radiation including alpha, beta and gamma. It should have some system of shutters that will allow the unit to measure only gamma, gamma and beta or gamma, beta and alpha.

Measurement units: The counter should be able to measure radiation in both metric and English Units. Metric measurements are in micro-Sieverts per hour or μSv/hr. English measurements are in milli-Roentgens per hour or mR/hr.

Sensitivity and range: The measurement sensitivity of the counter should start well below normal ambient background radiation at around .01 micro-Sieverts per hour and go up to level that can cause cancer at around 1 Sievert per hour.

Measurement Display: The counter should be able to indicate radioactivity both digitally and graphically.

Audio: The counter should have an audio system which will click once for each ionizing particle detected. There should be a switch to turn the audio on or off.

Calibration: The counter should be calibrated against a standard radiation source by a certified testing facility.

Control: The counter should be easy to use with simple controls and clear instructions.

Power supply: The counter should be a low power consumption model. Many counters have built in batteries that last for years which is very convenient.

Maintenance: The counter should be self-contained and not require any user maintenance other than changing the batteries.

Size: The counter should be as small and light as possible to make carrying and using easy. Many of the new inexpensive models are around six inches long by three inches wide by one inch thick.

Durability: The counter should be shock resistant, waterproof, able to withstand extremes of heat and humidity, and be made of a strong material that won’t crack if dropped. Most of the inexpensive models are made of plastic.

Data storage: The counter should have a built-in memory that allows it to accumulate readings over a period of time. Memory chips are inexpensive. Some counters can store data for weeks or months.

Connectivity: The counter should have ability to connect to a computer with a standard interface such as a USB port. There should be software provided with the counter to allow analysis of data downloaded to a computer and a cable to provide connection.

FCC-Compliance: The counter should be compliant with FCC-15 standards to ensure it will not interfere with radio transmissions.

            When evaluating Geiger counters it is best to go to a source that sells multiple models from multiple manufacturers. Look for comparison charts so you can check how the different models comply with the recommended features listed above.

 

            Geiger counters have many important uses with respect to the detection and measurement of alpha, beta and gamma radiation. Uranium-238 with traces of  uranium-235 is mined for refinement use as a fuel. Plutoium-239 and thorium-232 are also used as nuclear fuels. The use of commercial radioisotopes is wide-spread. Sources of alpha particles or helium nuclei include polonium-210 and uranium-238. Sources of beta particles or fast electrons include strontium-90, thallium-204, carbon-14 and hydrogen-3 or tritium. Sources of energetic photons of gamma include barium-133, cadmium-109, cobalt-57, cobalt-60, europium-152, manganese-54, sodium-22, zinc-65 and technetium-99. Cesium-137 emits gamma and beta. Americium-241emits gamma and alpha.

Non-nuclear Industrial Uses

            Radiation and Geiger counters are used to measure the strength of welds, the wear and corrosion of metals, and in the analysis of minerals and fuels. Gamma rays from Cobalt-60 are used to kill bacteria in foods and halt cellular processes that would lead to sprouting. This process must be closely monitored.

Nuclear Industry Uses

            Geiger counters are used for detecting leakage of radioactive materials from containers during storage and transportation, detecting radioactive contamination of other objects and materials, detecting leakage of radiation from pipes and containment vessels in nuclear power plants. Geiger counters are used to locate and evaluate deposits of uranium ores.

Environmental Uses

            Geiger counters are used to monitor radiation levels in the atmosphere, ground water, lakes, rivers and oceans. Radiation is monitored in landfills and dumps, nuclear waste repositories, warehouses and transport areas. Radioisotopes can help monitor pollutants and to measure the movement of surface waters as well as the runoff of rain water. Geiger counters are used by first responders to check for radiation at a disaster site or the site of a terrorist attack.

Home Uses

            Radon gas is a significant danger in homes and should be monitored. Smoke detectors contain radioactive materials that may be released if the detectors are damaged. Radioactive particles and gases may invade the home from nuclear accidents and can be tested for with Geiger counters.

Medical Uses

            A number of different isotopes are utilized in modern medicine that must be carefully handled and should be monitored by Geiger counters. Some medical equipment emits radiation such as X-rays. Radioisotopes injected into patients are taken up by specific tissues and used for imaging or for treatment of cancers.

Laboratory Uses

            Geiger counters are useful in modern science for monitoring of radioisotopes in such applications as dating the age of rocks, and biological materials and artifacts, the analyzing the structures of materials such as proteins, tracing biological processes in plants and animals,

            There are a variety of different types of Geiger counters utilized for these different purposes. There are other types of radiation detection technologies but Geiger counters are the most common.

 

            Ionizing radiation is measured by a device called a Geiger counter. The Geiger counter is named after its inventor Hans Geiger who created the Geiger counter in 1908. Walther Müller collaborated on improving the counter in 1928 and the counters are also called Geiger-Müeller counters.  A Geiger counter consists of a Geiger-Müeller tube which detects radiation by emitting a pulse of electrical energy when penetrated by ionizing radiation and supporting hardware.

            Geiger-Mueller tubes come in a range of sizes, shapes and sensitivities. One end is open to allow the entry of ionizing radiation. Some Geiger counters allow thin shields which block alpha particles and thick shields which block beta particles to be shifted into position over the open end of the tube. The tube may be included inside a handheld device or it may be on a cable attached to a box containing the support hardware. Inexpensive Geiger counters for wide spread use have evolved over the years.

            The US federal civil defense agencies had a Geiger counter design called a CD V-700 manufactured by 15 different contractors beginning around 1950.. The early models used special high voltage batteries which were replaced by standard D cells in the later models. CD V-700 design included  bulky metal box about twelve inches long by eight inches high by six inches wide and weighting about 5 pounds. The box has a long handle running the length of the top. The Geiger-Müeller tube is about nine inches long and three inches in diameter on a thirty six inch cable. The CD V-700 is used to detect gamma and beta radiation. Some were modified to be able to detect alpha radiation by making the window in the end of the tube larger to provide more area. Tens of thousands of these models were distributed to build state and local civil defense agencies in the 1950s and 1960s These Geiger counters are what people usual think of when Geiger counters are mentioned. They have been featured in many movies and television shows and many are still in use today.

            A newer design was manufactured for the U.S. government in the 1980s by the Victoreen company, one of the contractors for the original CD V-700. The model 496 was build in the same box as the CD V-700 but featured some improvements such as BNC connectors for external probes, a built in speaker that clicks to indicate radiation, a batter test circuit and a meter graduated in clicks per minute.

            A new generation of handheld Geiger counters has evolved since the CD V-700 and 496. These new models are very light and portable. The Geiger-Müeller tubes are inside the cases which are about six inches by three inches by one inch. The whole units weight around six ounces. These new designs feature digital displays, moveable shields for blocking alpha and beta radiation, internal memories, switchable units for measuring radiation, audio output, interfaces for connecting to computer and software for manipulating data on radiation measurements.

            Further advancements in radiation measurements include Geiger-Müeller tubes with USB connectors to directly connect to computers and cell phones with radiation detectors built in. There has been an explosion of design, manufacture and sales recently driving by fears of wide spread radiation contamination related to the Fukushima disaster.

 

            Ionizing radiation is measured by a device called a Geiger counter. The Geiger counter is named after its inventor Hans Geiger who created the Geiger counter in 1908. Walther Müller collaborated on improving the counter in 1928 and the counters are also called Geiger-Mueller counters.

            The heart of a Geiger counter is the Geiger-Müller (GM) tube. The GM tube is filled with a gas (usually neon) at a low pressure of about one tenth of normal atmospheric pressure at sea level. The tube is either made of a conductive metal or is coated with a conductive substance. There is a conductive wire in the center of the tube separated by insulators from the conductive shell. A potential of several hundred volts is maintained between the positively charged conductive wire or anode and the negatively charged conductive shell or cathode.

            When the tube is subjected to ionizing radiation, some of the gas is ionized creating pairs of electrons and positively charged ions. The positive ions are attracted to the cathode and the electrons are attracted to the anode. The strong electrical charge between the anode and the cathode causes the ions and electrons to accelerate and collide with more gas atoms which results in a cascade of electrons and ions. The ultimate result is a brief strong pulse of current flow from the cathode to the anode. This pulse is counted as an indicator of ionizing radiation, hence the name counter for this instrument. Some Geiger counters also have an audio amplifier which lets the instrument emit an audible pulse or click when it encounters radiation.

            The exact behavior of the GM tube is governed by a complex relationship between the level of voltage and the effected triggered by the radiation. There is an optimal voltage range for a given GM tube. Below that voltage range, the incoming radiation will not trigger a reaction and above that range, the cascade reaction will saturate and all the gas in the tube will be ionized. It is necessary to have a well regulated and stable voltage source for a GM tube to give reliable readings.

            One end of the GM tube is sealed and opaque to some radiation. The other end contains the end-window. A glass end GM tube cannot detect alpha radiation because it is blocked by the glass. Mica end GM tubes can detect alpha, beta, X-ray and Gamma radiation although the common types of GM tubes are inefficient at detecting Gamma.  GM tubes do not normally detect neutrons because they are neutral and do not react with the gas in the tube. Special GM tubes coated with boron or containing tritium gas are able to detect neutrons.

            In order to insure that the GM tube accurately registers just one pulse per ionizing particle, it is necessary to quench any secondary activity triggered by the entering particle. However, this quenching temporarily renders the GM tube unable to detect additional particles arriving at the tube. The time required to regain sensitivity is known as the dead time. Quenching can be accomplished by external electronics, by adding organic vapors of butane or ethanol to the gas in the tube. Currently, most GM tubes employ a design that was invented by Stanly Liebson in 1947 to take advantage of a halogen gas effect that allows a lower voltage to be utilized in the tubes.

 

            Scientists have discovered four fundamental forces of nature. These are gravitational, electromagnetic, weak and strong forces. All of these are connected to radiation in some way.

Gravitation

            Gravitation is the least important for our discussion. Gravitation is a force that causes attraction between material objects. Although gravitation influences radiation on a cosmic scale, it is by far the weakest force of nature and is of little importance in our discussion of radiation and its dangers on a human scale.

Electromagnetism

            The next force in terms of strength is the electromagnetic force. Early research on electricity found that there were two types that attracted and cancelled each other which we call positive and negative. Because of a mistake that Ben Franklin made, electrons are said to be positive and protons are said to be negative in charge. It would make a lot more sense to say that electrons had a positive charge but tradition dictates otherwise.

            Electricity and magnetism were thought of as two separate forces but then it was discovered that magnetic fields are a manifestation of moving electrical charges. When electrons in orbit around atomic nuclei change energy levels, they either absorb or emit a packet of electromagnetic energy known as a photon. Photons have a frequency and a wavelength that are inversely related. As the frequency increases, the wavelength decreases. The amount of energy carried by a photon is directly related to the frequency of the photon and increases as the frequency increases. The electromagnetic spectrum extends from a frequency of a million cycles per second with a wavelength of a kilometer up to a frequency of ten followed by eighteen zeros per second and a wavelength of one ten billionths of a meter. Photons travel at one hundred and eighty six thousand miles per second in a vacuum but will move slower when passing though gases, liquids and solids.

            Electromagnetic energy is present in many ways in our lives both naturally and artificially. Natural types of EM radiation include heat, visible light, ultraviolet light and highly energetic gamma rays. Artificial EM radiation includes all sorts of radio communication from AM radio to microwaves, lasers that utilize visible light for many things, ultraviolet light for many uses and X-rays to probe the interior of things. Many of the frequencies of EM radiation have biological effects, some benign and some harmful. Gamma rays are highly energetic photons that are released by radioactive decay and also generated by astrophysical processes which bombard the earth with these packets of energy. This type of EM radiation is harmful to living things.

Weak Force

            The weak force is much weaker than both the electromagnetic and the strong force. This force holds an electron and a proton together to create a neutron. Electric charges come in two polar opposite types referred to a positive and a negative charge. When the weak force holds an electron and a proton together, the resulting particle is called a neutron because the two charge types cancel each other and the neutron is electrically neutral. When a neutron is expelled from a radioactive nucleus in what is called beta decay, it spontaneously splits into an electron and a proton in about 15 minutes. The weak force is also involved in thermonuclear fusion which takes place stars and results in the creation of all the elements in the periodic table from hydrogen atoms.

Strong Force

            Like electrical charges repel each other. The protons in the nucleus of an atom carry a positive charge and so they are pushed apart by their charge. However, the strong force overcomes the repulsive EM force and holds the nucleus together. The strong force is about one hundred times stronger than the EM force at atomic distances. The strong force also binds together the particles called quarks to create protons and neutrons. The nuclear binding energy is a measure of the energy that is holding the nucleus together. Depending on the mass of the nucleus and the number of neutrons, the splitting of some nuclei in nuclear fission results in the release of nuclear binding energy which is the source of the heat used to generate power in a nuclear reactor or destructive force in a nuclear explosion.

 

            In 1958, the European Nuclear Energy Agency (ENEA) was formed as a special agency within the Organization for Economic Co-operation and Development with the United States as an associate member. With the entry of Japan in 1972, the name was changed to the Nuclear Energy Agency.

            The mission of the NEA is to “assist its Member countries in maintaining and further developing, through international co-operation, the scientific, technological and legal bases required for the safe, environmentally friendly and economical use of nuclear energy for peaceful purposes.“

            There are thirty member counties including Australia, Austria, Belgium, Canada, the Czech  Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Luxembourg, Mexico, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, South Korea, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States.

            The NEA deals with nuclear safety and regulation, nuclear energy development, radioactive waste management, radiation protection and public health, nuclear law and liability, nuclear science, nuclear information and communication. NEA members host about eighty five percent of the nuclear generating capacity of the world. Almost a fourth of the electricity produced in the member nations is generated by nuclear reactors.

            The NEA utilizes a relatively small staff to coordinate technical committees charged with carrying out the seven primary functions of the Agency. The committees are composed of technical experts from the member nations. The committees foster discussions, technical exchanges, cooperative research programs, consensus building and cost reduction in nuclear research. The NEA has made major contributions to nuclear waste disposal and reactor technology development during the past 30 years.

            The NEA just released its strategic plan for 2011-2016. The three main topics or concern are supplying the increasing world demand for energy, insuring the security of the energy supply and minimizing impacts on the environment.  The document emphasizes that the current trends in energy supply and use are unsustainable with increasing demands, reliance on fossil fuels, competition for natural gas and oil deposits, increasing CO₂ levels and severe environmental impacts. The plan calls for increased use of nuclear power because of it releases no CO₂ or other pollutants and it is currently cost competitive with coal, oil and natural gas. The challenge for greater acceptance of nuclear power lie in finding solutions to the long term management of spent nuclear fuel, the safe and permanent disposal of radioactive waste, the security of nuclear materials and facilities and the insurance of non-proliferation of nuclear weapons.

            Despite the positive view that the NEA promotes for the greater use of nuclear power, the challenges they list are not just a matter of better government regulation, greater competence and integrity of the private nuclear industry, and greater education of the public.  There are very serious questions about the release of massive amounts of CO₂ during nuclear plant construction, supplies of water for cooling, concerns over available sites and technologies for waste disposal, possibilities of nuclear accidents, cost of recovery from nuclear accidents, increasing cost of uranium, and many other problems that must be solved to make nuclear power safe, efficient and cost effective.

 

 

Radiation Protection advice and tips from the United States EPA

Contains daily radiation readings from Seattle, Washington.

Links that deal with current news about dangerous radiation

Japan Nuclear Cycle Development Institute

            The JNC was established in 1956 as the Atomic Fuel Corporation (AFC). The AFC became the Power Reactor and Nuclear Fuel Development Cooperation (PNC) in 1967. The PNC became the JNC in 1998. The mission of the incarnations of the JNC was involved with researching, developing and monitoring the nuclear fuel cycle in Japan.

Japan Atomic Energy Research Institute

            The JAERI was established in 1956. It’s job was to encourage and oversee research on application of nuclear materials and nuclear energy for Japan.

Japan Atomic Energy Agency

            The Japan Atomic Energy Agency (JAEA) was formed in 2005 by the Japan Atomic Energy Agency Act of 2005. It was created by the merger of two existing agencies, the Japan Nuclear Cycle Development Institute (JNC) and the Japan Atomic Energy Research Institute (JAERI).

            The scope of the JAEA mission includes basic and application nuclear research, technical evolution of the nuclear fuel cycle, facility sharing, human resource development for the nuclear industry, collection and dissemination of nuclear information, safety regulation, nuclear disaster prevention and response, environmental monitoring, international non-proliferation, and decommissioning and disposal of nuclear waste.  There are four major divisions of the JAEA including a Management Sector, R&D directorates, R&D Institutes/centers and a Project Promotion Sector.

            The JAEA came under intense scrutiny and criticism for its response (or lack of response) to the Fukushima nuclear disaster. Part of the problem was the clumsy, biased and incompetent job the JAEA did in communicating with the Japanese public during and after the disaster.

Japanese Atomic Energy Commission

            The Japanese Atomic Energy Commission (JAEC) was created in 1956. It is the primary nuclear regulatory agency for nuclear energy and materials in Japan. Its mission is to plan, consider and decide on policies for the promotion of research, development and utilization of nuclear energy. The JAEC also advises the government on the organization and budgeting of nuclear agencies in Japan.

Japanese Nuclear Safety Commission

            The Japanese Nuclear Safety Commission (NSC) was spun off from the Japanese Atomic Energy Commission in 1978. It is included in the Cabinet of the Japanese Prime Minister and is charged with advising the Prime Minister on matters of nuclear safety.

Japanese Nuclear and Industrial Safety Agency

            The Japanese Nuclear and Industrial Safety Agency (NISA) was created in 2001 by the 2001 Central Government Reform. It was established to serve as a Japanese regulatory and oversight branch of the Agency for Natural Resources and Energy under the Ministry of Economy, Trade and Industry. As with the US AEC, the NISA has been criticized for being too cozy with the industry that they are supposed to be regulating. There have been charges that the NISA tried to influence public symposia on the use of nuclear energy in Japan.

New nuclear regulatory agency

            As of the end of May, 2012, a new nuclear regulatory agency was in the process of being created by separating the Japanese Nuclear and Industrial Safety Agency (NISA) from the Ministry of Economy, Trade and Industry and merging it with the Nuclear Safety Commission to create an agency with less close connection to the Japanese nuclear agency.

            Given the grave consequences of the Fukushima disaster and ongoing dangers of the damaged reactors, we can hope that the reorganization of the Japanese governmental bodies that are charged with nuclear oversight and disaster response in Japan are able to improve their competence and integrity.