The crystal lattice of solid americium and its compounds contains intrinsic defects, which are induced by self-irradiation with alpha particles and accumulate with time ; this results in a drift of some material properties.

The second longest-lived isotope of astatine, astatine-211, is the only one currently having any commercial application, being employed in medicine to diagnose and treat some diseases via its emission of alpha particles ( helium-4 nuclei ).

In 1909, Hans Geiger and Ernest Marsden, under the direction of physicist Ernest Rutherford, bombarded a sheet of gold foil with alpha rays — by then known to be positively charged helium atoms — and discovered that a small percentage of these particles were deflected through much larger angles than was predicted using Thomson's proposal.

The letter alpha represents various concepts in physics and chemistry, including alpha radiation, angular acceleration, alpha particles, alpha carbon and strength of electromagnetic interaction ( as Fine-structure constant ).

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.

The alpha particles ionize air between a small gap.

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.

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.

If substances emitting alpha particles are ingested, inhaled, injected or introduced through the skin, then it could result in a measurable dose.

These particles continue to decay, emitting alpha particles which can damage cells in the lung tissue.

The single primordial beryllium isotope < sup > 9 </ sup > Be also undergoes a ( n, 2n ) neutron reaction with neutron energies over about 1. 9 MeV, to produce < sup > 8 </ sup > Be, which almost immediately breaks into two alpha particles.

Neutrons are liberated when beryllium nuclei are struck by energetic alpha particles producing the nuclear reaction

The production of the second-important isotope berkelium-247 involves the irradiation of the rare synthetic isotope curium-244 with high-energy alpha particles.

However, it decays with a half-life of 330 days to californium-249, which is a strong and hazardous emitter of alpha particles.

This gradual transformation is an important consideration when studying the properties of elemental berkelium and its chemical compounds, since the formation of californium brings not only chemical contamination, but also self-radiation damage, and self-heating from the emitted alpha particles.

This target was irradiated with 35 MeV alpha particles for 6 hours in the 60-inch cyclotron at the Lawrence Radiation Laboratory, University of California, Berkeley.

This reaction was studied for the first time in 2008 by the team at RIKEN, Japan, in order to study the decay properties of < sup > 266 </ sup > Bh, which is a decay product in their claimed decay chains of ununtrium .< ref > The decay of < sup > 266 </ sup > Bh by the emission of 9. 05-9. 23 MeV alpha particles was further confirmed in 2010.

Beginning with carbon, elements are produced in stars by buildup from alpha particles ( helium nuclei ), resulting in an alternatingly-larger abundance of elements with even atomic numbers ( these are also more stable ).

Iron-56 is particularly common, since it is the most stable element that can easily be made from alpha particles ( being a product of decay of radioactive nickel-56, ultimately made from 14 helium nuclei ).

Calcium-40 is created in extremely large and hot ( over 2. 5 × 10 < sup > 9 </ sup > K ) stars, as part of the silicon-burning process in which alpha particles are added to silicon atoms.

Where there is ambiguity, long and short alpha are sometimes written with a macron and breve today: Ᾱᾱ, Ᾰᾰ.

Uppercase and lowercase Greek alpha are represented in Unicode as U + 0391 ( Α ) and U + 03B1 ( α ) respectively.

They are known as 2 -, alpha -, or α-amino acids ( generic formula H < sub > 2 </ sub > NCHRCOOH in most cases < ref > Proline is an exception to this general formula.

Even touching an alpha source is usually not harmful, though many alpha sources also are accompanied by beta-emitting radio daughters, and alpha emission is also accompanied by gamma photon emission.

However, if this pixel uses premultiplied alpha, all of the RGB values ( 0, 1, 0 ) are multiplied by 0. 5 and then the alpha is appended to the end to yield ( 0, 0. 5, 0, 0. 5 ).

where is the result of the operation, is the color of the pixel in element A, is the color of the pixel in element B, and and are the alpha of the pixels in elements A and B respectively.

If it is assumed that all color values are premultiplied by their alpha values (), we can rewrite the equation for output color as:

Of the 88 modern constellations, there are at least 30 in which " Alpha " is not the brightest star, and four of those lack an alpha star altogether.

New atoms are also naturally produced on Earth as radiogenic daughter isotopes of ongoing radioactive decay processes such as alpha decay, beta decay, spontaneous fission, cluster decay, and other rarer modes of decay.

Centaurus contains several very bright stars because of its position in the Milky Way ; in addition, its alpha and beta stars are used to find the constellation Crux.

Several radioactive substances are considered carcinogens, but their carcinogenic activity is attributed to the radiation, for example gamma rays and alpha particles, which they emit.

These are all considered stable, although < sup > 156 </ sup > Dy decays by alpha decay with a half-life of over 1 × 10 < sup > 18 </ sup > years.

In the subsurface environment, it is also produced through neutron capture by or alpha emission by calcium.

Because an alpha particle is the same as a helium-4 nucleus, which has mass number 4 and atomic number 2, this can also be written as:

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.

If an alpha channel is used in an image, it is common to also multiply the color by the alpha value, to save on additional multiplications during compositing.

This alpha value also corresponds to the ratio of " SRC over DST " in Porter and Duff equations.

The β sheet ( also β-pleated sheet ) is the second form of regular secondary structure in proteins, only somewhat less common than the alpha helix.

In addition to news, rumors and screenshots, unauthorized leaked alpha versions also circulated online.

This decay also produced alpha, beta, and gamma radiation.

In 1913, Soddy also showed that an atom moves lower in atomic number by two places on alpha emission, higher by one place on beta emission.

It is also acrophonically called azbuki from the names of its first two letters in Bulgaria, on the same model as ' alpha ' + ' beta '.

It is also partly responsible for the fact that the alpha particle is by far the most common type of baryonic particle to be ejected from atomic nuclei ; in other words, alpha decay is far more common than cluster decay.

Uses include its application as a vector for the cloning of recombinant DNA ; the use of its site-specific recombinase ( int ) for the shuffling of cloned DNAs by the gateway method ; and the application of its Red operon, including the proteins Red alpha ( also called ' exo '), beta and gamma in the DNA engineering method called recombineering.

By the turn of the century physicists had also discovered three types of radiation emanating from atoms, which they named alpha, beta, and gamma radiation.