A bhangmeter is a non-imaging

radiometer A radiometer or roentgenometer is a device for measuring the radiant flux (power) of electromagnetic radiation. Generally, a radiometer is an infrared radiation detector or an ultraviolet detector. Microwave radiometers operate in the micro ...

installed on

reconnaissance In military operations, military reconnaissance () or scouting is the exploration of an area by military forces to obtain information about enemy forces, the terrain, and civil activities in the area of operations. In military jargon, reconnai ...

and

navigation satellite A satellite navigation or satnav system is a system that uses satellites to provide autonomous geopositioning. A satellite navigation system with global coverage is termed global navigation satellite system (GNSS). , four global systems are op ...

s to detect atmospheric nuclear detonations and determine the yield of the nuclear weapon. They are also installed on some

armored fighting vehicles An armoured fighting vehicle (British English) or armored fighting vehicle (American English) (AFV) is an armed combat vehicle protected by armour, generally combining operational mobility with offensive and defensive capabilities. AFVs can b ...

, in particular NBC reconnaissance vehicles, in order to help detect, localise and analyse tactical nuclear detonations. They are often used alongside pressure and sound sensors in this role in addition to standard radiation sensors. Some

nuclear bunkers Nuclear may refer to: Physics Relating to the Atomic nucleus, nucleus of the atom: *Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear ...

and military facilities may also be equipped with such sensors alongside seismic event detectors. The bhangmeter was developed at

Los Alamos National Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development Laboratory, laboratories of the United States Department of Energy National Laboratories, United States Department of Energy ...

by a team led by Hermann Hoerlin.

History

The bhangmeter was invented, and the first proof-of-concept device was built, in 1948 to measure the nuclear test detonations of

Operation Sandstone Operation Sandstone was a series of nuclear weapon tests in 1948. It was the third series of American tests, following Trinity in 1945 and Crossroads in 1946, and preceding Ranger. Like the Crossroads tests, the Sandstone tests were carried o ...

. Prototype and production instruments were later built by

EG&G EG&G, formally known as Edgerton, Germeshausen, and Grier, Inc., was a United States national defense contractor and provider of management and technical services. The company was involved in contracting services to the United States government ...

, and the name "bhangmeter" was coined in 1950 by

Frederick Reines Frederick Reines ( ; March 16, 1918 – August 26, 1998) was an American physicist. He was awarded the 1995 Nobel Prize in Physics for his co-detection of the neutrino with Clyde Cowan in the neutrino experiment. He may be the only scientist in ...

. Bhangmeters became standard instruments used to observe US

nuclear test Nuclear weapons tests are experiments carried out to determine the performance of nuclear weapons and the effects of their explosion. Nuclear testing is a sensitive political issue. Governments have often performed tests to signal strength. Bec ...

s. A bhangmeter was developed to observe the detonations of

Operation Buster-Jangle Operation or Operations may refer to: Arts, entertainment and media * ''Operation'' (game), a battery-operated board game that challenges dexterity * Operation (music), a term used in musical set theory * ''Operations'' (magazine), Multi-Man ...

(1951) and

Operation Tumbler-Snapper Operation or Operations may refer to: Arts, entertainment and media * ''Operation'' (game), a battery-operated board game that challenges dexterity * Operation (music), a term used in musical set theory * ''Operations'' (magazine), Multi-Man ...

(1952). These tests lay the groundwork for a large deployment of nationwide North American bhangmeters with the Bomb Alarm System (1961–1967). US president

John F. Kennedy John Fitzgerald Kennedy (May 29, 1917 – November 22, 1963), also known as JFK, was the 35th president of the United States, serving from 1961 until his assassination in 1963. He was the first Roman Catholic and youngest person elected p ...

and the

First Secretary of the Communist Party of the Soviet Union The General Secretary of the Central Committee of the Communist Party of the Soviet Union. was the leader of the Communist Party of the Soviet Union (CPSU). From 1924 until the country's dissolution in 1991, the officeholder was the recognize ...

Nikita Khrushchev Nikita Sergeyevich Khrushchev (– 11 September 1971) was the General Secretary of the Communist Party of the Soviet Union, First Secretary of the Communist Party of the Soviet Union from 1953 to 1964 and the Premier of the Soviet Union, Chai ...

signed the

Partial Test Ban Treaty The Partial Test Ban Treaty (PTBT), formally known as the 1963 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water, prohibited all nuclear weapons testing, test detonations of nuclear weapons except for those co ...

on August 5, 1963, under the condition that each party could use its own technical means to monitor the ban on nuclear testing in the atmosphere or in outer space. Bhangmeters were first installed, in 1961, aboard a modified US

KC-135A The Boeing KC-135 Stratotanker is an American military aerial refueling tanker aircraft that was developed from the Boeing 367-80 prototype, alongside the Boeing 707 airliner. It has a narrower fuselage and is shorter than the 707. Boeing gave ...

aircraft monitoring the pre-announced Soviet test of

Tsar Bomba The Tsar Bomba (code name: ''Ivan'' or ''Vanya''), also known by the alphanumerical designation "AN602", was a Thermonuclear weapon, thermonuclear aerial bomb, and by far the most powerful nuclear weapon ever created and tested. The Soviet phy ...

The Vela satellites were the first space-based observation devices jointly developed by the

U.S. Air Force The United States Air Force (USAF) is the air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its origins to 1 ...

and the

Atomic Energy Commission Many countries have or have had an Atomic Energy Commission. These include: * National Atomic Energy Commission, Argentina (1950–present) * Australian Atomic Energy Commission (1952–1987) * Bangladesh Atomic Energy Commission (1973–present) * ...

. The first generation of Vela satellites were not equipped with bhangmeters but with

X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

sensors to detect the intense single pulse of X-rays produced by a nuclear explosion. The first satellites which incorporated bhangmeters were the Advanced Vela satellites. Since 1980, bhangmeters have been included on US

GPS The Global Positioning System (GPS) is a satellite-based hyperbolic navigation system owned by the United States Space Force and operated by Mission Delta 31. It is one of the global navigation satellite systems (GNSS) that provide geol ...

navigation satellites.

Description

The

silicon Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...

photodiode A photodiode is a semiconductor diode sensitive to photon radiation, such as visible light, infrared or ultraviolet radiation, X-rays and gamma rays. It produces an electrical current when it absorbs photons. This can be used for detection and me ...

sensors are designed to detect the distinctive bright double pulse of visible light that is emitted from

atmospheric nuclear weapons explosion A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, th ...

s. This signature consists of a short and intense flash lasting around 1 millisecond, followed by a second much more prolonged and less intense emission of light taking a fraction of a second to several seconds to build up. This signature, with a double intensity maximum, is characteristic of atmospheric nuclear explosions and is the result of the Earth's atmosphere becoming opaque to visible light and transparent again as the explosion's shock wave travels through it. The effect occurs because the surface of the early fireball is quickly overtaken by the expanding "case shock", the atmospheric shock wave composed of the ionised plasma of what was once the casing and other matter of the device. Although it emits a considerable amount of light itself, it is opaque and prevents the far brighter fireball from shining through. The net result recorded is a decrease of the light visible from outer space as the shock wave expands, producing the first peak recorded by the bhangmeter. As it expands, the shock wave cools off and becomes less opaque to the visible light produced by the inner fireball. The bhangmeter starts eventually to record an increase in visible light intensity. The expansion of the fireball leads to an increase of its surface area and consequently an increase of the amount of visible light radiated off to space. The fireball continues to cool down so the amount of light eventually starts to decrease, causing the second peak observed by the bhangmeter. The time between the first and second peaks can be used to determine its

nuclear yield The explosive yield of a nuclear weapon is the amount of energy released such as blast, thermal, and nuclear radiation, when that particular nuclear weapon Effects of nuclear explosions, is detonated. It is usually expressed as a ''TNT equivalent ...

. The effect is unambiguous for explosions below about altitude, but above this height a more ambiguous single pulse is produced.

Origin of the name

The name of the detector is a

pun A pun, also known as a paronomasia in the context of linguistics, is a form of word play that exploits multiple meanings of a term, or of similar-sounding words, for an intended humorous or rhetorical effect. These ambiguities can arise from t ...

which was bestowed upon it by

Fred Reines Frederick Reines ( ; March 16, 1918 – August 26, 1998) was an American physicist. He was awarded the 1995 Nobel Prize in Physics for his co-detection of the neutrino with Clyde Cowan in the neutrino experiment. He may be the only scientist in ...

, one of the scientists working on the project. The name is derived from the Hindi word "

bhang Bhang (International Alphabet of Sanskrit Transliteration, IAST: ''Bhāṅg'') is an Cannabis edible, edible preparation made from the leaves of the Cannabis (drug), cannabis plant originating from the Indian subcontinent. ''Cannabis sativa'' ...

", a locally grown variety of

cannabis ''Cannabis'' () is a genus of flowering plants in the family Cannabaceae that is widely accepted as being indigenous to and originating from the continent of Asia. However, the number of species is disputed, with as many as three species be ...

which is smoked or drunk to induce intoxicating effects, the joke being that one would have to be on drugs to believe the bhangmeter detectors would work properly. This is in contrast to a "bangmeter" one might associate with detection of nuclear explosions.

History

Description

Origin of the name

See also

References

Further reading