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[[File:Alpha Decay.svg|thumb|240px|right|Visual representation of alpha decay]]
Throughout history, forms of [[art]] have gone through periodic abrupt changes called '''artistic revolutions'''.  Movements have come to an end to be replaced by a new movement markedly different in striking ways. See also [[cultural movement]]s.
{{Nuclear physics}}
'''Alpha decay''', or α-decay, is a type of [[radioactivity|radioactive decay]] in which an [[atomic nucleus]] emits an [[alpha particle]] and thereby transforms (or 'decays') into an atom with a [[mass number]] 4 less and [[atomic number]] 2 less. For example, [[uranium-238]] decaying through α-particle emission to form [[thorium-234]] can be expressed as:<ref name="suchocki">Suchocki, John. ''Conceptual Chemistry'', 2007. Page 119.</ref>


== Artistic revolution and cultural/political revolutions ==
:<math>\mathrm{~^{238}_{92}U}\rightarrow\mathrm{~^{234}_{90}Th} + {\alpha }</math>


The role of [[fine art]] has been to simultaneously express values of the current culture while also offering criticism, balance, or alternatives to any such values that are proving no longer useful. So as times change, art changes. If changes were abrupt they were deemed revolutions. The best artists have predated society's changes due not to any prescIence, but because sensitive perceptivity is part of their 'talent' of seeing.
Because an [[alpha particle]] is the same as the nucleus of a [[helium-4]] atom - consisting of two [[proton]]s and two [[neutron]]s and thus having [[mass number]] 4 and [[atomic number]] 2 - this can also be written as:


Artists have had to 'see' issues clearly in order to satisfy their current clients, yet not offend potential patrons. For example, paintings glorified aristocracy in the early 17th century when leadership was needed to nationalize small political groupings, but later as leadership became oppressive, satirization increased and subjects were less concerned with leaders and more with more common plights of mankind.
:<math>\mathrm{~^{238}_{92}U}\rightarrow\mathrm{~^{234}_{90}Th} + \mathrm{~^{4}_{2}He}</math>


In its origins and its first golden age, no art owes quite as much to state power as French painting does. It was in the age of absolute monarchy launched by Louix XIV in the 17th century that the likes of Poussin and Le Brun put France in the forefront of European art. Versailles found its stately mirror in the powerful idea of classicism – a painting style, enduring in later artists like Ingres, whose austerity and grandeur express the authority of a world where Jove is very much in his throne.<ref>jonathanjonesblog</ref>
Notice how, on either side of the nuclear equation, both the mass number and the atomic number are conserved: the mass number is 238 on the left side and (234 + 4) on the right side, and the atomic number is 92 on the left side and (90 + 2) on the right side.


Examples of revolutionary art in conjunction with cultural/political movements:
The alpha particle also has a charge +2, but the charge is usually not written in nuclear equations, which describe nuclear reactions without considering the electrons. This convention is not meant to imply that the nuclei necessarily occur in neutral atoms. Alpha decay typically occurs in the heaviest nuclides. In theory it can occur only in nuclei somewhat heavier than nickel (element 28), where overall [[binding energy]] per [[nucleon]] is no longer a minimum, and the nuclides are therefore unstable toward spontaneous fission-type processes. In practice, this mode of decay has only been observed in nuclides considerably heavier than nickel, with the lightest known alpha emitter being the lightest [[isotope]]s (mass numbers 106–110) of [[tellurium]] (element 52).


*[[Trotskyist]] & [[Diego Rivera]]
Alpha  decay is by far the most common form of [[cluster decay]] where the parent [[atom]] ejects a defined [[decay product|daughter]] collection of [[nucleon]]s, leaving another defined product behind (in [[nuclear fission]], a number of different pairs of daughters of approximately equal size are formed). Alpha decay is the most likely cluster decay because of the combined extremely high [[binding energy]] and relatively small mass of the helium-4 product nucleus (the alpha particle). Alpha decay, like other cluster decays, is fundamentally a [[quantum tunneling]] process. Unlike [[beta decay]], alpha decay is governed by the interplay between the [[nuclear force]] and the [[electromagnetic force]].
*[[Black Panther Party]] & [[Emory Douglas]]
*Cuban [[Poster art]]
*[[Social realism]] & [[Ben Shahn]]
*[[Feminist art]] & the [[Guerrilla Girls]]
*[[Industrial Workers of the World]] & [[Woody Guthrie]]
* [http://revolutionarytides.stanford.edu/main.html Revolutionary Tides]


== Artistic revolution of style ==
[[Alpha particle]]s have a typical kinetic energy of 5&nbsp;MeV (that is, ≈&nbsp;0.13% of their total energy, i.e. 110&nbsp;TJ/kg) and a speed of 15,000&nbsp;km/s. This corresponds to a speed of around 0.05&nbsp;''[[Speed of light|c]]''. There is surprisingly small variation around this energy, due to the heavy dependence of the half-life of this process on the energy produced (see equations in the [[Geiger–Nuttall law]]). Because of their relatively large mass, +2 [[electric charge]] and relatively low velocity, alpha particles are very likely to interact with other atoms and lose their energy, so their forward motion is effectively stopped within a few centimeters of [[air]]. Most of the [[helium]] produced on [[Earth]] (approximately 99% of it) is the result of the alpha decay of underground deposits of [[mineral]]s containing [[uranium]] or [[thorium]]. The helium is brought to the surface as a byproduct of [[natural gas]] production.


[http://www.art-head-start.com/3d/squid/revolution300.jpg Here] is an example of an Artistic Revolution Piece
==History==
[[Image:Alphaspektroskopie.JPG|thumb|right|Alpha source beneath a radiation detector]]
Alpha particles were first described in the investigations of radioactivity by [[Ernest Rutherford]] in 1899, and by 1907 they were identified as He<sup>2+</sup> ions. For more details of this early work, see [[Alpha particle#History of discovery and use]].


But not all artistic revolutions were political. Revolutions of style have also abruptly changed the art of a culture. For example, when the careful, even tedious, art techniques of French neo-classicism became oppressive to artists living in more exuberant times, a stylistic revolution known as "[[Impressionism]]" vitalized brush strokes and color. [[Edgar Degas]], [[Claude Monet]], [[Pierre-Auguste Renoir]] burst onto the French culture, effecting a revolution with a style that has become commonplace today.
By 1928, [[George Gamow]] had solved the theory of the alpha decay via tunneling. The alpha particle is trapped in a [[potential well]] by the nucleus. Classically, it is forbidden to escape, but according to the (then) newly discovered principles of [[quantum mechanics]], it has a tiny (but non-zero) probability of "[[quantum tunnelling|tunneling]]" through the [[potential barrier|barrier]] and appearing on the other side to escape the nucleus. Gamow solved a model potential for the nucleus and derived, from first principles, a relationship between the [[half-life]] of the decay, and the energy of the emission, which had been previously discovered empirically, and was known as the [[Geiger–Nuttall law]].<ref>[http://www.phy.uct.ac.za/courses/phy300w/np/ch1/node38.html For Gamow's derivation of this law, see]</ref>


An artistic revolution can be begun by a single artist, but unless that artist gains some understanding, he becomes an iconoclast. The first [[Abstract Expressionists]] were considered madmen to give up their brushes and rely on the sheer force of energy to leave an image, but then the import of atomic bombs, all atomic energy, became realized, and art found no better way of expressing its power. [[Jackson Pollock]] is the artist best known for starting that revolution.
==Uses==
[[Americium-241]], an [[alpha emitter]], is used in [[smoke detector]]s. The alpha particles [[Ionization|ionize]] air in an open [[ion chamber]] and a small [[Electric current|current]] flows through the ionized air. Smoke particles from fire that enter the chamber reduce the current, triggering the smoke detector's alarm. ''See [[Smoke_detector#Ionization|Smoke_Detector-Ionization]] for details''.


== Artistic Movements ==
Alpha decay can provide a safe power source for [[radioisotope thermoelectric generator]]s used for [[space probe]]s<ref>{{cite web |url=http://solarsystem.nasa.gov/rps/rtg.cfm |title=Radioisotope Thermoelectric Generator |work=Solar System Exploration |publisher=[[NASA]] |accessdate=25 March 2013}}</ref> and [[Artificial pacemaker|artificial heart pacemakers]].<ref>{{cite web |url=http://osrp.lanl.gov/pacemakers.shtml |title=Nuclear-Powered Cardiac Pacemakers |work=Off-Site Source Recovery Project |publisher=[[Los Alamos National Laboratory|LANL]] |accessdate=25 March 2013}}</ref> Alpha decay is much more easily shielded against than other forms of radioactive decay. [[Plutonium-238]], for example, requires only 2.5 millimetres of [[lead]] shielding to protect against unwanted radiation.{{cn|date=March 2014}}


=== [[Art in ancient Greece|Ancient & Classical Art]] ===
[[Static eliminator]]s typically use [[polonium-210]], an alpha emitter, to ionize air, allowing the 'static cling' to more rapidly dissipate.
Key dates: 15000 BC / 400 BC-200AD / 350 AD-450AD<br />
Ancient - There are few remaining examples with early art often favouring drawing over colour. Work has been found recently in tombs, Egyptian frescoes, pottery and metalwork.<br />
Classical - Relating to or from ancient Roman or Greek architecture and art. Mainly concerned with geometry and symmetry rather than individual expression.<br />
Byzantine - A religious art characterised by large domes, rounded arches and mosaics from the eastern Roman Empire in the 4th Century.<ref name=artmovements>http://www.artmovements.co.uk</ref>


===[[Gothic architecture|Medieval & Gothic]]===
==Toxicity==
Key dates: 400AD<br />
Being relatively heavy and positively charged, alpha particles tend to have a very short [[mean free path]], and quickly lose kinetic energy within a short distance of their source. This results in several [[MeV]] being deposited in a relatively small volume of material. This increases the chance of cellular damage in cases of internal contamination. In general, external alpha radiation is not harmful since alpha particles are effectively shielded by a few centimeters of air, a piece of paper, or the thin layer of dead skin cells that make up the [[epidermis (skin)|epidermis]]. Even touching an alpha source is typically not harmful, though many alpha sources also are accompanied by [[beta decay|beta-emitting]] radio daughters, and alpha emission is also accompanied by gamma photon emission. If substances emitting alpha particles are ingested, inhaled, injected or introduced through the skin, then it could result in a measurable [[Equivalent dose|dose]].
Medieval - A highly religious art beginning in the 5th Century in Western Europe. It was characterised by iconographic paintings illustrating scenes from the bible.<br />
Gothic - This style prevailed between the 12th century and the 16th century in Europe. Mainly an architectural movement, Gothic was characterised by its detailed ornamentation most noticeably the pointed archways and elaborate rib vaulting.<br />
First developed in France, Gothic was intended as a solution to the inadequacies of Romanesque architecture. It allowed for cathedrals to be built with thinner walls and it became possible to introduce stained glass windows instead of traditional mosaic decorations. Some of the finest examples of the style include the cathedrals of Chartres, Reims and Amiens. The term was also used to describe sculpture and painting that demonstrated a greater degree of naturalism.<ref name=artmovements/>


===[[Renaissance]]===
The [[relative biological effectiveness]] (RBE) of alpha radiation is higher than that of beta or gamma radiation. RBE quantifies the ability of radiation to cause certain biological effects, notably either [[cancer]] or [[necrosis|cell-death]], for equivalent radiation exposure. The higher value for alpha radiation is generally attributable to the high [[linear energy transfer]] (LET) coefficient, which is about one ionization of a chemical bond for every [[angstrom]] of travel by the alpha particle. The RBE has been set at the value of 20 for alpha radiation by various government regulations. The RBE is set at 10 for [[neutron]] irradiation, and at 1 for [[Beta decay|beta radiation]] and ionizing photons.
Key dates: 1300s<br />
This movement began in Italy in the 14th century and the term, literally meaning rebirth, describes the revival of interest in the artistic achievements of the Classical world. Initially in a literary revival Renaissance was determined to move away from the religion-dominated Middle Ages and to turn its attention to the plight of the individual man in society. It was a time when individual expression and worldly experience became two of the main themes of Renaissance art. The movement owed a lot to the increasing sophistication of society, characterised by political stability, economic growth and cosmopolitanism. Education blossomed at this time, with libraries and academies allowing more thorough research to be conducted into the culture of the antique world. In addition, the arts benefited from the patronage of such influential groups as the Medici family of Florence, the Sforza family of Milan and Popes Julius II and Leo X. The works of Petrarch first displayed the new interest in the intellectual values of the Classical world in the early 14th century and the romance of this era as rediscovered in the Renaissance period can be seen expressed by Boccaccio. Leonardo da Vinci was the archetypal Renaissance man representing the humanistic values of the period in his art, science and writing. Michelangelo and Raphael were also vital figures in this movement, producing works regarded for centuries as embodying the classical notion of perfection. Renaissance architects included Alberti, Brunelleschi and Bramante. Many of these artists came from Florence and it remained an important centre for the Renaissance into the 16th century eventually to be overtaken by Rome and Venice. Some of the ideas of the Italian Renaissance did spread to other parts of Europe, for example to the German artist Albrecht Dürer of the 'Northern Renaissance'. But by the 1500s Mannerism had overtaken the Renaissance and it was this style that caught on in Europe. <br />
Representative artists:<br />
Leonardo da Vinci, Sandro Botticelli, Filippo Brunelleschi, Raphael da Urbino, Titian, Michelangelo Buonarroti, and Donatello Bardi.<ref name=artmovements/>


===[[Mannerism]]===
However, another component of alpha radiation is the [[recoil]] of the parent nucleus, termed alpha recoil. Due to the [[conservation of momentum]] requiring the parent nucleus to recoil, the effect acts much like the 'kick' of a rifle butt when a bullet goes in the opposite direction. This gives a significant amount of energy to the recoiling nucleus, which also causes ionization damage (see [[ionizing radiation]]). The total energy of the recoil nucleus is readily calculable, and is roughly the weight of the alpha (4&nbsp;[[Atomic mass unit|u]]) divided by the weight of the parent (typically about 200&nbsp;u) times the total energy of the alpha. By some estimates, this might account for most of the internal radiation damage, as the recoil nuclei are typically [[heavy metal (chemistry)|heavy metals]] which preferentially collect on the [[chromosome]]s. In some studies,<ref>
Key dates: 1520-1600<br />
{{cite journal
Artists of the Early Renaissance and the High Renaissance developed their characteristic styles from the observation of nature and the formulation of a pictorial science. When Mannerism matured after 1520(The year Raphael died), all the representational problems had been solved. A body of knowledge was there to be learned. Instead of nature as their teacher, Mannerist artists took art. While Renaissance artists sought nature to find their style, the Mannerists looked first for a style and found a manner. In Mannerist paintings, compositions can have no focal point, space can be ambiguous, figures can be characterized by an athletic bending and twisting with distortions, exaggerations, an elastic elongation of the limbs, bizarre posturing on one hand, graceful posturing on the other hand, and a rendering of the heads as uniformly small and oval. The composition is jammed by clashing colors, which is unlike what we've seen in the balanced, natural, and dramatic colors of the High Renaissance. Mannerist artwork seeks instability and restlessness. There is also a fondness for allegories that have lascivious undertones. <br />
|author=Winters TH, Franza JR
Representative artists:<br />
|year=1982
Andrea del Sarto, Jacopo da Pontormo, Correggio<ref name=artmovements/>
|title=Radioactivity in Cigarette Smoke
|journal=[[New England Journal of Medicine]]
|volume=306 |issue=6 |pages=364–365
|doi=10.1056/NEJM198202113060613
}}</ref> this has resulted in a RBE approaching 1,000 instead of the value used in governmental regulations.


===[[Baroque]]===
The largest natural contributor to public radiation dose is [[radon]], a naturally occurring, radioactive gas found in soil and rock.<ref>[http://www.ans.org/pi/resources/dosechart/ ANS : Public Information : Resources : Radiation Dose Chart<!-- Bot generated title -->]</ref> If the gas is inhaled, some of the radon particles may attach to the inner lining of the lung. These particles continue to decay, emitting alpha particles which can damage cells in the lung tissue.<ref>EPA Radiation Information: Radon. October 6, 2006, [http://www.epa.gov/radiation/radionuclides/radon.htm], Accessed December 6, 2006</ref> The death of [[Marie Curie]] at age 66 from [[leukemia]] was probably caused by prolonged exposure to high doses of ionizing radiation, but it is not clear if this was due to alpha radiation or X-rays. Curie worked extensively with radium, which decays into radon,<ref>Health Physics Society, "Did Marie Curie die of a radiation overexposure?" [http://www.hps.org/publicinformation/ate/q535.html]</ref> along with other radioactive materials that emit [[beta decay|beta]] and [[gamma ray]]s. However, Curie also worked with unshielded X-ray tubes during World War I, and analysis of her skeleton during a reburial showed a relatively low level of radioisotope burden.
Key dates: 1600s<br />
Baroque Art emerged in Europe around 1600, as a reaction against the intricate and formulaic Mannerist style which dominated the Late Renaissance. Baroque Art is less complex, more realistic and more emotionally affecting than Mannerism.<br />
This movement was encouraged by the Catholic Church, the most important patron of the arts at that time, as a return to tradition and spirituality.<br />
One of the great periods of art history, Baroque Art was developed by Caravaggio, Annibale Carracci, and Gianlorenzo Bernini, among others. This was also the age of Rubens, Rembrandt, Velázquez, and Vermeer.<br />
In the 18th century, Baroque Art was replaced by the more elegant and elaborate Rococo style.<br />
Representative artists:<br />
Caravaggio, Annibale Carracci, Gianlorenzo Bernini, Rubens, Rembrandt, Nicolas Poussin<ref name=artmovements/>


===[[Rococo]]===
Russian dissident [[Alexander Litvinenko]]'s 2006 murder by [[radiation poisoning]] is thought to have been carried out with [[polonium-210]], an alpha emitter.
Key dates: 1700s<br />
Throughout the 18th century in France, a new wealthy and influential middle-class was beginning to rise, even though the royalty and nobility continued to be patrons of the arts. Upon the death of Louis XIV and the abandonment of Versailles, the Paris high society became the purveyors of style. This style, primarily used in interior decoration, came to be called Rococo. The term Rococo was derived from the French word "rocaille", which means pebbles and refers to the stones and shells used to decorate the interiors of caves. Therefore, shell forms became the principal motif in Rococo. The society women competed for the best and most elaborate decorations for their houses. Hence the Rococo style was highly dominated by the feminine taste and influence.<br />
François Boucher was the 18th century painter and engraver whose works are regarded as the perfect expression of French taste in the Rococo period. Trained by his father who was a lace designer, Boucher won fame with his sensuous and light-hearted mythological paintings and landscapes. He executed important works for both the Queen of France and Mme. de Pompadour, Louis XV's mistress, who was considered the most powerful woman in France at the time. Boucher was Mme. de Pompadour's favorite artist and was commissioned by her for numerous paintings and decorations. Boucher also became the principal designer for the royal porcelain factory and the director of the Gobelins tapestry factory. The Vulcan Presenting Venus with Arms for Aeneas is a template for a tapestry made by this factory. <br />
Characterized by elegant and refined yet playful subject matters, Boucher's style became the epitome of the court of Louis XV. His style consisted of delicate colors and gentle forms painted within a frivolous subject matter. His works typically utilized delightful and decorative designs to illustrate graceful stories with Arcadian shepherds, goddesses and cupids playing against a pink and blue sky. These works mirrored the frolicsome, artificial and ornamented decadence of the French aristocracy of the time.<br />
The Rococo is sometimes considered a final phase of the Baroque period.<br />
Representative artists:<br />
François Boucher, William Hogarth, Giovanni Battista Tiepolo, Angelica Kauffman, Giovanni Antonio Canaletto, Velázquez Vermeer<ref name=artmovements/>


===[[Neoclassicism|Neo-classical]]===
== See also ==
Key dates: 1750-1880<br />
*[[Alpha particle]]
A nineteenth-century French art style and movement that originated as a reaction to the Baroque. It sought to revive the ideals of ancient Greek and Roman art. Neoclassic artists used classical forms to express their ideas about courage, sacrifice, and love of country. David and Canova are examples of neo-classicists.<br />
*[[Beta decay]]
Representative artists:<br />
Jacques-Louis David, Sir Henry Raeburn, Sir Joshua Reynolds, Jean-Auguste-Dominique Ingres, Thomas Gainsborough, Antonio Canova, Arnold Bocklin<ref name=artmovements/>


===[[Romanticism]]===
==References==
Key dates: 1800-1880<br />
{{reflist}}
Romanticism was basically a reaction against Neoclassicism, it is a deeply felt style which is individualistic, beautiful, exotic, and emotionally wrought.<br />
*[http://www.ct.infn.it/~rivel/Didat/SilDet.pdf Alpha emitters by increasing energy (Appendix 1)]
Although Romanticism and Neoclassicism were philosophically opposed, they were the dominant European styles for generations, and many artists were affected to a greater or lesser degree by both. Artists might work in both styles at different times or even mix the styles, creating an intellectually Romantic work using a Neoclassical visual style, for example.<br />
Great artists closely associated with Romanticism include J.M.W. Turner, Caspar David Friedrich, John Constable, and William Blake.<br />
In the United States, the leading Romantic movement was the Hudson River School of dramatic landscape painting.<br />
Obvious successors of Romanticism include the Pre-Raphaelite movement and the Symbolists. But Impressionism, and through it almost all of 20th-century art, is also firmly rooted in the Romantic tradition. <br />
Representative artists:<br />
George Stubbs, William Blake, John Martin, Francisco Goya, Sir Thomas Lawrence, John Constable, Eugène Delacroix, Sir Edwin landseer, Caspar David Friedrich, JMW Turner<ref name=artmovements/>


==References==
== External links ==
{{Reflist}}
* [[Image:Ndslivechart.png]] '''[http://www-nds.iaea.org/livechart The LIVEChart of Nuclides - IAEA ]''' with filter on alpha decay
* [http://nagysandor.eu/AsimovTeka/AlphaExamples/index_en.html Alpha decay with 3 animated examples] showing the recoil of daughter
 
{{Nuclear processes}}


{{DEFAULTSORT:Artistic Revolution}}
{{DEFAULTSORT:Alpha Decay}}
[[Category:Art history]]
[[Category:Nuclear physics]]
[[Category:Articles lacking sources from June 2009]]
[[Category:Radioactivity]]
[[Category:All articles lacking sources]]
[[Category:Revolutions by type]]

Revision as of 06:21, 19 August 2014

Visual representation of alpha decay

Template:Nuclear physics Alpha decay, or α-decay, is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms (or 'decays') into an atom with a mass number 4 less and atomic number 2 less. For example, uranium-238 decaying through α-particle emission to form thorium-234 can be expressed as:[1]

Because an alpha particle is the same as the nucleus of a helium-4 atom - consisting of two protons and two neutrons and thus having mass number 4 and atomic number 2 - this can also be written as:

Notice how, on either side of the nuclear equation, both the mass number and the atomic number are conserved: the mass number is 238 on the left side and (234 + 4) on the right side, and the atomic number is 92 on the left side and (90 + 2) on the right side.

The alpha particle also has a charge +2, but the charge is usually not written in nuclear equations, which describe nuclear reactions without considering the electrons. This convention is not meant to imply that the nuclei necessarily occur in neutral atoms. Alpha decay typically occurs in the heaviest nuclides. In theory it can occur only in nuclei somewhat heavier than nickel (element 28), where overall binding energy per nucleon is no longer a minimum, and the nuclides are therefore unstable toward spontaneous fission-type processes. In practice, this mode of decay has only been observed in nuclides considerably heavier than nickel, with the lightest known alpha emitter being the lightest isotopes (mass numbers 106–110) of tellurium (element 52).

Alpha decay is by far the most common form of cluster decay where the parent atom ejects a defined daughter collection of nucleons, leaving another defined product behind (in nuclear fission, a number of different pairs of daughters of approximately equal size are formed). Alpha decay is the most likely cluster decay because of the combined extremely high binding energy and relatively small mass of the helium-4 product nucleus (the alpha particle). Alpha decay, like other cluster decays, is fundamentally a quantum tunneling process. Unlike beta decay, alpha decay is governed by the interplay between the nuclear force and the electromagnetic force.

Alpha particles have a typical kinetic energy of 5 MeV (that is, ≈ 0.13% of their total energy, i.e. 110 TJ/kg) and a speed of 15,000 km/s. This corresponds to a speed of around 0.05 c. There is surprisingly small variation around this energy, due to the heavy dependence of the half-life of this process on the energy produced (see equations in the Geiger–Nuttall law). Because of their relatively large mass, +2 electric charge and relatively low velocity, alpha particles are very likely to interact with other atoms and lose their energy, so their forward motion is effectively stopped within a few centimeters of air. Most of the helium produced on Earth (approximately 99% of it) is the result of the alpha decay of underground deposits of minerals containing uranium or thorium. The helium is brought to the surface as a byproduct of natural gas production.

History

Alpha source beneath a radiation detector

Alpha particles were first described in the investigations of radioactivity by Ernest Rutherford in 1899, and by 1907 they were identified as He2+ ions. For more details of this early work, see Alpha particle#History of discovery and use.

By 1928, George Gamow had solved the theory of the alpha decay via tunneling. The alpha particle is trapped in a potential well by the nucleus. Classically, it is forbidden to escape, but according to the (then) newly discovered principles of quantum mechanics, it has a tiny (but non-zero) probability of "tunneling" through the barrier and appearing on the other side to escape the nucleus. Gamow solved a model potential for the nucleus and derived, from first principles, a relationship between the half-life of the decay, and the energy of the emission, which had been previously discovered empirically, and was known as the Geiger–Nuttall law.[2]

Uses

Americium-241, an alpha emitter, is used in smoke detectors. The alpha particles ionize air in an open ion chamber and a small current flows through the ionized air. Smoke particles from fire that enter the chamber reduce the current, triggering the smoke detector's alarm. See Smoke_Detector-Ionization for details.

Alpha decay can provide a safe power source for radioisotope thermoelectric generators used for space probes[3] and artificial heart pacemakers.[4] Alpha decay is much more easily shielded against than other forms of radioactive decay. Plutonium-238, for example, requires only 2.5 millimetres of lead shielding to protect against unwanted radiation.Template:Cn

Static eliminators typically use polonium-210, an alpha emitter, to ionize air, allowing the 'static cling' to more rapidly dissipate.

Toxicity

Being relatively heavy and positively charged, alpha particles tend to have a very short mean free path, and quickly lose kinetic energy within a short distance of their source. This results in several MeV being deposited in a relatively small volume of material. This increases the chance of cellular damage in cases of internal contamination. In general, external alpha radiation is not harmful since alpha particles are effectively shielded by a few centimeters of air, a piece of paper, or the thin layer of dead skin cells that make up the epidermis. Even touching an alpha source is typically not harmful, though many alpha sources also are accompanied by beta-emitting radio daughters, and alpha emission is also accompanied by gamma photon emission. If substances emitting alpha particles are ingested, inhaled, injected or introduced through the skin, then it could result in a measurable dose.

The relative biological effectiveness (RBE) of alpha radiation is higher than that of beta or gamma radiation. RBE quantifies the ability of radiation to cause certain biological effects, notably either cancer or cell-death, for equivalent radiation exposure. The higher value for alpha radiation is generally attributable to the high linear energy transfer (LET) coefficient, which is about one ionization of a chemical bond for every angstrom of travel by the alpha particle. The RBE has been set at the value of 20 for alpha radiation by various government regulations. The RBE is set at 10 for neutron irradiation, and at 1 for beta radiation and ionizing photons.

However, another component of alpha radiation is the recoil of the parent nucleus, termed alpha recoil. Due to the conservation of momentum requiring the parent nucleus to recoil, the effect acts much like the 'kick' of a rifle butt when a bullet goes in the opposite direction. This gives a significant amount of energy to the recoiling nucleus, which also causes ionization damage (see ionizing radiation). The total energy of the recoil nucleus is readily calculable, and is roughly the weight of the alpha (4 u) divided by the weight of the parent (typically about 200 u) times the total energy of the alpha. By some estimates, this might account for most of the internal radiation damage, as the recoil nuclei are typically heavy metals which preferentially collect on the chromosomes. In some studies,[5] this has resulted in a RBE approaching 1,000 instead of the value used in governmental regulations.

The largest natural contributor to public radiation dose is radon, a naturally occurring, radioactive gas found in soil and rock.[6] If the gas is inhaled, some of the radon particles may attach to the inner lining of the lung. These particles continue to decay, emitting alpha particles which can damage cells in the lung tissue.[7] The death of Marie Curie at age 66 from leukemia was probably caused by prolonged exposure to high doses of ionizing radiation, but it is not clear if this was due to alpha radiation or X-rays. Curie worked extensively with radium, which decays into radon,[8] along with other radioactive materials that emit beta and gamma rays. However, Curie also worked with unshielded X-ray tubes during World War I, and analysis of her skeleton during a reburial showed a relatively low level of radioisotope burden.

Russian dissident Alexander Litvinenko's 2006 murder by radiation poisoning is thought to have been carried out with polonium-210, an alpha emitter.

See also

References

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External links

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  1. ↑ Suchocki, John. Conceptual Chemistry, 2007. Page 119.
  2. ↑ For Gamow's derivation of this law, see
  3. ↑ Template:Cite web
  4. ↑ Template:Cite web
  5. ↑ One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
  6. ↑ ANS : Public Information : Resources : Radiation Dose Chart
  7. ↑ EPA Radiation Information: Radon. October 6, 2006, [1], Accessed December 6, 2006
  8. ↑ Health Physics Society, "Did Marie Curie die of a radiation overexposure?" [2]
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