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Ionization smoke detectors use a small amount of radioactive material, americium-241, to detect smoke. On this page: About Americium in Ionization Smoke Detectors.
What form of radioactive decay do smoke detectors use?
The isotope of americium used in smoke detectors is americium-241, which decays by α emission to neptunium-237 with a half-life of 432.2 years.
Do smoke detectors still use americium?
Most smoke detectors use americium-241 as their source. Some early models used radium-226, and commercial smoke detectors and some residential units used nickel-63. The types of radiation from these sources cannot make anything else radioactive.
Do smoke alarms contain radioactive material?
Ionisation smoke alarms contain a tiny amount of a radioactive isotope. This emits alpha particles causing the ‘ionisation’ in the air within a smoke detector.
How is radioactivity used in smoke alarms?
An isotope of americium which emits alpha particles is used in smoke alarms. Alpha radiation ionises the air and this allows a small current to flow between two electrodes. Alpha is weakly penetrating so smoke stops it, the current drops and the alarm goes off.
How smoke detectors use radioactive isotopes?
The Am-241 emits alpha particles which ionise the air and allow a current between two electrodes. If smoke enters the detector it absorbs the alpha particles and interrupts the current, setting off the alarm.
What happens if you touch americium?
Exposure to extremely high levels of americium, as has been reported in some animal studies, has resulted in damage to organs such as the lungs, liver, kidneys, and thyroid. It is rare, however, that a person would be exposed to amounts of americium large enough to cause harmful effects in these organs.
Why is americium 242 not used in smoke detectors?
The radioactive source emits alpha particles. The alpha particles ionise the air inside the sensor which causes a small electric current. The change in current sets the alarm off. (i) The smoke detector would not work if a radioactive source that emitted only gamma rays was used.
Can you buy radioactive material?
By regulation, the general public is allowed to order these materials without possessing a radioactive materials license, so vendors will sell these compounds directly to any customer. However, educational institutions are not allowed to possess more than 3.3 pounds of uranium or thorium at any one time.
Can radon set off smoke detectors?
So, to answer the question of whether or not carbon monoxide detectors also detect radon, the answer is no. CO detectors are made to do just what the name implies: detect carbon monoxide gas. Radon gas can only be detected by a radon test kit, which is a one-time use kit.
Which type of radiation is not a particle?
Gamma radiation, unlike alpha or beta, does not consist of any particles, instead consisting of a photon of energy being emitted from an unstable nucleus.
What is the energy of alpha particle?
Alpha particles have a net spin of zero. Due to the mechanism of their production in standard alpha radioactive decay, alpha particles generally have a kinetic energy of about 5 MeV, and a velocity in the vicinity of 4% of the speed of light.
Are all isotopes radioactive?
All artificial (lab-made) isotopes are unstable and therefore radioactive; scientists call them radioisotopes. Some elements can only exist in an unstable form (for example, uranium).
Why is gamma radiation not used in smoke detectors?
The main reason that alpha particles are used is that they are strongly ionizing, because they are helium nuclei without any orbiting electrons; they will rip electrons off of any particles that they encounter, whereas gamma rays and beta particles will not.
Are gamma rays radioactive?
The penetrating power of gamma rays has many applications. However, while gamma rays penetrate many materials, this does not make them radioactive. The three radionuclides that are by far the most useful are cobalt-60, caesium-137, technetium-99m and americium-241.
Which type of radiation is made up of high energy electrons?
Beta radiation consists of high energy electrons emitted from the nucleus.
What are the uses of alpha radiation?
Uses of alpha radiation Ionisation is useful for smoke detectors. Radioactive americium releases alpha radiation, which ionises the air inside the detector. Smoke from a fire absorbs alpha radiation, altering the ionisation and triggering the alarm.
Why is americium-241 in smoke detectors?
Ionization smoke detectors use americium as a source of alpha particles. Alpha particles from the americium source ionize air molecules. This makes some particles positively charged and some negatively charged. Because of this shielding, the smoke detector poses no radiation health risk when they are properly handled.
Where is americium found?
Americium occurs naturally in uranium minerals, but only in trace amounts. The main source of the element is the neutron bombardment of plutonium in nuclear reactors. A few grams are produced in this way each year. It is also formed when nuclear weapons are detonated.
Can you own americium?
Americium is the only man-made element which is legal to posses, and the amazing part is that you can buy it for less than $10 at any hardware store.
Are bananas radioactive?
Bananas have naturally high-levels of potassium and a small fraction of all potassium is radioactive. Each banana can emit . 01 millirem (0.1 microsieverts) of radiation.
What does americium look like?
Americium, a silvery-white, synthetic element, is created during nuclear reactions of heavy elements. The element and its isotopes have very few but important uses including smoke detectors found in nearly all buildings and the potential to power future space missions.
