Alpha particle Americium

Most chemical iavestigations with plutonium to date have been performed with Pu, but the isotopes Pu and Pu (produced by iatensive neutron irradiation of plutonium) are more suitable for such work because of their longer half-Hves and consequendy lower specific activities. Much work on the chemical properties of americium has been carried out with Am, which is also difficult to handle because of its relatively high specific alpha radioactivity, about 7 x 10 alpha particles/(mg-min). The isotope Am has a specific alpha activity about twenty times less than Am and is thus a more attractive isotope for chemical iavestigations. Much of the earher work with curium used the isotopes and Cm, but the heavier isotopes... 

Alpha carbon atoms, 348 Alpha decay, 417, 443 Alpha particle, 417 scattering, 245 Aluminum boiling point, 365 compounds, 102 heat of vaporization, 365 hydration energy, 368 hydroxide, 371 ionization energies, 269, 374 metallic solid, 365 occurrence, 373 properties, 101 preparation, 238. 373 reducing agent, 367 Alums, 403 Americium... 

The radiation from exposure to americium is the primary cause of adverse health effects from absorbed americium. Upon entering the body by any route of exposure, americium moves relatively rapidly through the body and is concentrated in bones where it remains for a long time. While in the bone, americium atoms decay, releasing alpha particles and gamma-rays. Alpha... 

Americium toxicity results primarily from the damage done by the alpha particle emitted during radioactive decay. This alpha particle has very limited penetration in tissue, and hence, the cellular damage (including damage to genomic material) occurs only in the immediate vicinity of the sequestered americium. 

Glenn Theodore Seaborg (1912-1999), together with Stanley Gerald Thompson (1912-1967) and Albert Ghiorso ( 1915). The bombardment of americium-241 with alpha particles led to element 97 with atomic mass number 243. The enrichment involved chemical methods, as the properties of the element were assumed to be analogous to those of the lanthanides. 

The pure metal of berkelium does not exist in nature and has never been directly artificially produced, although the first isotope of berkelium produced was berkelium-243. It was artificially formed by bombarding americium-241 with the nuclei of helium (alpha particles), as follows " Am+lalpha particle = 2 protons + 2 neutron)—> Bk. (Note Two protons as well as two neutrons are found in the nucleus of helium, and thus the two protons changed the atomic number of americium [ jAm] to berkelium [j Bk].) Today a different process is used to produce berkelium in small amounts, as follows Cm+(5n = neutrons X = gamma rays) —> (becomes) —> Bk + P- = (beta-minus decay). 

American chemist Glenn T. Seaborg Artificially made and radioactive the alpha particles emitted by its isotope americium-24 1 enable the air to conduct electricity, making it useful in smoke detectors. 

All isotopes of the element are synthesized in the nuclear reactor. The first isotope synthesized had the mass 241, produced by irradiation of milligram quantities of americium-241 with alpha particles of 35 MeV in a cyclotron ... 

While the lighter isotopes are prepared by alpha particle bombardment, the heavier ones by neutron irradiation of large quantities of americium, curium or plutonium ... 

Transuranic wastes are so called because they contain isotopes of elements heavier than uranium, primarily plutonium, americium, and neptunium. Since these isotopes emit alpha particles. 

Another isotope. Lr. hall-life about 45 seconds, was reported by the Soviet Union in 1965. It was produced by impact of oxygen atoms (l

alpha-particle emission and electron capture to form Fm See also Chemical Elements. 

Radioactive substances also have life-saving uses. A radioactive form of cobalt is extensively used in radiation therapy for cancer patients. The treatment was first developed by Harold Johns (1915—) in Canada, where he pioneered cobalt therapy units at the University of Saskatchewan. One of the artificially made elements, Americium (atomic number 95, i.e., with 95 protons in its atomic nucleus), is another life-saving radioactive element. As it decays, it emits alpha particles, which strip electrons from surrounding gas molecules ionized air conducts electricity much better than air containing smoke particles, and the reduction in conductivity produced by smoke is what triggers the alarm in smoke detectors. 

An analyst is measuring the concentration of americium-241 (alpha emitter) in a soil sample. Most of the components in the soil will act as interferents as they physically block the alpha particles reaching the detector. The measured concentration of americium-241 in soil will be low due to the interference caused by the solid material in the sample. Therefore, the sample will require pre-treatment to remove the interferents before the americium-241 concentration can be measured. 

Americium-241 is widely used in smoke detectors. The radiation released by this element ionizes particles that are then detected by a charged-particle collector. The half-life of 24IAm is 432.2 years, and it decays by emitting alpha particles. How many alpha particles are emitted each second by a 5.00-g sample of 241Am ... 

One of the simplest and cheapest safety devices found in homes and other buildings is a battery-operated smoke detector. And americium is an important part of it. A small piece of americium oxide made with the americium-241 isotope is sealed inside the smoke detector. The americium-241 gives off alpha particles. The alpha particles strike air molecules, causing them to break apart. The pieces formed in this process—ions—are electrically charged. 

The UCB researchers fired alpha particles—helium atoms without their electrons—at americium atoms in their particle accelerator. The result was a new element—number 97. 

Smoke detectors depend on nuclear reactions to sound an alarm when a fire starts. Many smoke detectors contain a small amount of americium-241, which decays to form neptunium-237 and alpha particles. 

Explain why nuclei that emit alpha particles, such as americium-241, are safe to use in smoke detectors. 

There are many other uses for radioactive nuclides. For example, some smoke detectors Objective 30 contain the alpha emitter americium-241. The alpha particles it releases ionize the air in the detector s interior, allowing an electric current to pass through. When particles of smoke enter the detector, they block the alpha particles, thus decreasing the number of ions in the air, reducing the electric current, and triggering the alarm. 

Density and Moisture Tester (MC-l). A 50 mCi mixture of Americium-241 and Beryllium is located within the base of the MC-l (about 200 times more than is used in the M43A1 Chemical Agent Detector). Neutron emission occurs when an alpha particle emitter such as Americium-241 is mixed with Beryllium (Be) powder in a tightly compressed pellet. The MC-l also has a 10 mCi Cesium-137 source located in a probe tip used to determine the density of the soil at a construction site. This source is classified as a special form source and is double-encapsulated in stainless steel. TACOM is the NRC license holder for the MC-l and is responsible for item management. 

The long-lived isotopes of americium are Am (458 years), " Am (152 years), and Am (7400 years). All are formed by multiple neutron interactions with uranium and plutonium. Of particular interest is " Am because it identifies the erstwhile presence of its Pu parent. " Am emits alpha particles but can also be measured by its 0.059-MeV (36%) gamma ray. " Am has several isomers that mostly emit beta particles, and " Am emits alpha particles. 

The main radionuclides that are measured in this system are isotopes of thorium, uranium, and plutonium. Others are the longer-lived isotopes of heavy elements such as radium, protactinium, neptunium, americium, and curium. Conventionally, an isotopic tracer of known activity that emits alpha particles is added at the beginning of the radiochemical procedure (see Section 6.3.2). The solution from which the sample for counting will be deposited is thoroughly purified by the radiochemical procedure to remove interfering radionuclides and solids. 



---