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Topic: Alpha particle

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  Alpha particle - Wikipedia, the free encyclopedia
Alpha particles or alpha rays (named after the first letter in the greek alphabet, α) are a highly ionizing form of particle radiation which have low penetration.
When an alpha particle is emitted, the atomic mass of an element goes down by roughly 4 amu, due to the loss of 4 nucleons.
The physicist Ernest Rutherford famously used alpha particles to infer that Lord Kelvin's "plum pudding" model of the atom was fundamentally flawed.
en.wikipedia.org /wiki/Alpha_particle   (769 words)

 Alpha Decay
In alpha decay, the atomic number changes, so the original (or parent) atoms and the decay-product (or daughter) atoms are different elements and therefore have different chemical properties.
In the alpha decay of a nucleus, the change in binding energy appears as the kinetic energy of the alpha particle and the daughter nucleus.
Because this energy must be shared between these two particles, and because the alpha particle and daughter nucleus must have equal and opposite momenta, the emitted alpha particle and recoiling nucleus will each have a well-defined energy after the decay.
www.lbl.gov /nsd/education/ABC/wallchart/chapters/03/1.html   (268 words)

 Facts about topic: (Alpha particle)   (Site not responding. Last check: 2007-10-22)
Alpha particles or alpha rays are a form of particle radiation (additional info and facts about particle radiation) which are highly ionizing (additional info and facts about ionizing) and have low penetration.
This sometimes leaves the nucleus in an excited state, with the emission of a gamma ray (Electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength) removing the excess energy ((physics) the capacity of a physical system to do work; the units of energy are joules or ergs).
In contrast to beta decay (Radioactive decay of an atomic nucleus that is accompanied by the emission of a beta particle), alpha decay is mediated by the strong nuclear force (additional info and facts about strong nuclear force).
www.absoluteastronomy.com /encyclopedia/a/al/alpha_particle.htm   (475 words)

 Alpha (letter) - Wikipedia, the free encyclopedia
Alpha, both as a symbol and term, is used to refer to or describe a variety of things, including the first or most significant occurrence of something.
The uppercase letter alpha is not generally used as a symbol because it tends to be rendered identically to the uppercase latin A.
The alpha particle and alpha decay in physics.
en.wikipedia.org /wiki/Alpha_(letter)   (270 words)

 EPA - Alpha Particles (EPA's Radiation Protection Program: Understanding Radiation)   (Site not responding. Last check: 2007-10-22)
Alpha particles (symbol a) are a type of ionizing radiation ejected by the nuclei of some unstable atoms.
Alpha particles have a velocity in air of approximately one-twentieth the speed of light, depending upon the individual particle's energy.
For example, alpha particles are given off by uranium-238, radium-226, and other members of the uranium decay series.
www.epa.gov /radiation/understand/alpha.htm   (1179 words)

 AiS Computational Science Textbook - 2.2 EXAMPLE PROJECT
Particle, or high energy, physics is the study of the most fundamental building blocks of all matter, and their interactions with one another.
Alpha particles are one form of radioactivity and are naturally emitted by several radioactive elements.
Alpha particles falling on the fluorescent zinc sulfide screen had to be counted one at a time, using a microscope, by whomever was running the experiment.
www.krellinst.org /AiS/textbook/unit2/projdev2.2.html   (3447 words)

Alpha particle emission is modeled as a barrier penetration process.
The alpha particle is the nucleus of the helium atom and is the nucleus of highest stability.
The energy of emitted alpha particles was a mystery to early investigators because it was evident that they did not have enough energy, according to classical physics, to escape the nucleus.
hyperphysics.phy-astr.gsu.edu /hbase/nuclear/radact.html   (564 words)

 Alpha Particles   (Site not responding. Last check: 2007-10-22)
Alpha particles are fairly heavy, positively charged particles that some radioactive atoms commonly emit.
We now know that an alpha particle is actually the nucleus of a helium atom, with two neutrons and two protons.
One of Rutherford's recent experiments had convinced him that alpha particles and helium were the same thing, but "nucleus," "proton," and "neutron" meant nothing to him...yet.
www.colorado.edu /physics/2000/periodic_table/alpha.html   (61 words)

 What are alpha rays? How are they...
An alpha particle is made up of two protons and two neutrons, all held together by the same strong nuclear force that binds the nucleus of any atom.
In fact, an alpha particle really is a nucleus - it's the same as the nucleus of a common atom of helium - but it doesn't have any electrons around it, and it's traveling very fast.
The alpha particle is the radiation given off during the process of "alpha decay".
education.jlab.org /qa/radbegin_04.html   (720 words)

 alpha particle --  Encyclopædia Britannica
Because alpha particles have two positive charges and a mass of four units, their emission from nuclei produces daughter nuclei having a positive nuclear charge or atomic number two units less than their parents and a mass of four...
Because the destructive effect on tissues of alpha particles is far greater than that of gamma rays, the toxicities of these radioisotopes are contributed mainly by the alpha particles.
In alpha decay, an energetic helium ion (alpha particle) is ejected, leaving a daughter nucleus of atomic number two less than the parent and of atomic mass number four less than the parent.
www.britannica.com /eb/article-9005891?&query=alpha   (841 words)

 Ion Systems - Products
Ionizers using alpha ionization employ polonium-210, a naturally occurring radioisotope that emits millions of alpha particles per second, each of which produces thousands of ion pairs through collisions with gas molecules in the air.
Alpha sources are only harmful when ingested or when the internal live human tissue is exposed to them.
For alpha particle exposure external to the human body, the dose equivalent is zero.
www.ion.com /products/Alphasafety/Alphasafety.html   (577 words)

 Mars Exploration Rover Mission: The Mission
The APXS determines the elemental chemistry of rocks and soils using alpha particles and X-rays.
Alpha particles are emitted during radioactive decay and X-rays are a type of electromagnetic radiation, like light and microwaves.
The energy distribution of the alphas and X-rays measured by the detectors is analyzed to determine elemental composition.
marsrovers.nasa.gov /mission/spacecraft_instru_apxs.html   (209 words)

 Alpha IICH   (Site not responding. Last check: 2007-10-22)
Alpha Emitters are radioisotopes that emit an alpha particle during decay.
Alpha IICH Inc. was incorporated in 2001 to build a business around the production and marketing of alpha-emitting radionuclides for cancer therapy.
The other founding party of Alpha IICH is iso-Solutions, Inc. (iso-Solutions.com) which brings to the venture 20 years of experience in the nuclear medicine markets of North America and Europe.
www.alphaiich.com   (151 words)

 Experiment #2: Alpha Please Leave Home
particle is a nucleus of a helium-4 atom.
The new nucleus that results from alpha decay will have a mass and charge different from those of the parent nucleus.
Measurements show that the sum of the masses of the daughter nucleus and the alpha particle is less than the mass of the parent isotope.
www.lbl.gov /abc/experiments/Experiment2.html   (365 words)

 Alpha Decay   (Site not responding. Last check: 2007-10-22)
Alpha particles are helium nuclei released from an unstable nucleus.
Alpha particles are emitted from the nucleus atom at 10 percent the speed of light.
During alpha decay, the atomic mass of the element undergoing the change decreases by four and the atomic number by two.
wey238ab.ch.iup.edu /Carl/alphadec.htm   (170 words)

 Alpha Particle Tunneling   (Site not responding. Last check: 2007-10-22)
The half-lives of heavy elements which emit alpha particles varies over 20 orders of magnitude, from about a tenth of a microsecond to 10 billion years.
The illustration represents an attempt to model the alpha decay characteristics of polonium-212, which emits an 8.78 MeV alpha particle with a half-life of 0.3 microseconds.
To evaluate this probability, the alpha particle inside the nucleus is represented by a free-particle wavefunction subject to the nuclear potential.
hyperphysics.phy-astr.gsu.edu /hbase/nuclear/alptun.html   (191 words)

 alpha   (Site not responding. Last check: 2007-10-22)
Alpha decay is a radioactive process in which a particle with two neutrons and two protons is ejected from the nucleus of a radioactive atom.
The particle is identical to the nucleus of a helium atom.
Typical alpha particles will travel no more than a few centimeters in air and are stopped by a sheet of paper.
www.physics.isu.edu /radinf/alpha.htm   (196 words)

 Alpha and Beta Damage
An alpha particle is a "helium nucleus", two protons and two neutrons joined together as a nucleus.
The average alpha particle has less kinetic energy than does the average beta particle, so alpha particles tend to have lower frequencies and longer wavelengths.
Now, for particles with mass traveling at speeds less than about 1/10 the speed of light, the speed and kinetic energy are related by E = (ms^2)/2, where m is the particle's mass.
www.newton.dep.anl.gov /askasci/phy00/phy00386.htm   (555 words)

 Alpha particle studies during JET DT experiments
Alpha particle heating was clearly observed in a series of 10 MW hot ion H modes by scanning the DT mixture from 0% T to 93% T. Maxima in central temperature and energy content were obtained which corresponded with the maximum in fusion yield.
Ion cyclotron emission (ICE) was detected at harmonics of the alpha particle cyclotron frequency at the outer edge of the plasma.
The high energy neutral particle spectra showed features which are ascribed to a mixture of alphas, neutralized by helium-like impurities, and deuterons born from elastic collisions with alpha particles and neutralized by hydrogen-like impurities.
stacks.iop.org /0029-5515/39/1619   (383 words)

 Alpha - Wikipedia, the free encyclopedia
Alpha (letter), a letter in the Greek alphabet.
Alpha male and "Alpha female", in sociobiology the highest ranking individuals in a community
Alpha channel, a transparency information layer to supplement the three RGB color layers to make the RGBA color space.
en.wikipedia.org /wiki/Alpha   (280 words)

 [No title]
Because an alpha particle has no electrons to balance the positive charge of the two protons, it has a charge of +2 and can be represented as He If a particle has a charge, whether negative or positive, it can be shown as a superscript.
When ejected from a decaying nucleus, alpha particles interact with all matter in their path, whether it be photographic film, lead shielding, or body tissue, stripping electrons from other atoms as they go.
Beta particles are far less massive than alpha particles and carry a charge with only half the magnitude of that of the alpha particle.
genchem.chem.wisc.edu /sstutorial/Text4/Tx45/tx45.html   (1006 words)

 THE ONCOGENIC POTENTIAL OF A SINGLE ALPHA PARTICLE   (Site not responding. Last check: 2007-10-22)
In parallel with these microbeam studies, we conducted "broad beam" alpha particle exposures using different fluences of alpha particles such that cell nuclei were traversed by mean numbers of 0, 1, 2, 4, 6 and 8 particles.
Parallel data are also shown where graded doses of alpha particles were used, calculated to yield the same mean number of alpha-particle traversals, but with a nucleus-to-nucleus Poisson distribution in the actual number of alpha-particle traversals.
For larger numbers of alpha particles the data from the two sets of experiments coincide, indicating that the dosimetry is compatible.
www.crr-cu.org /reports1998/cm11.htm   (593 words)

 Alpha Decay | Atomic Physics | Science | atomicarchive.com
In alpha decay, a positively charged particle, identical to the nucleus of helium 4, is emitted spontaneously.
Alpha decay usually occurs in heavy nuclei such as uranium or plutonium, and therefore is a major part of the radioactive fallout from a nuclear explosion.
Since an alpha particle is relatively more massive than other forms of radioactive decay, it can be stopped by a sheet of paper and cannot penetrate human skin.
www.atomicarchive.com /Physics/Physics6.shtml   (193 words)

 [No title]
Alpha Decay An alpha particle is a He4 nucleus, that is, it consists of 2 protons and 2 neutrons.
If one makes a graph of the potential that the alpha particle experiences in terms of the distance from the center of the nucleus, we have the following function: Figure: Potential of alpha particle as a function of distance from the center of nucleus For short distances, the attractive strong force is the most important.
Gamma Decay: A gamma particle is a photon.
www.csupomona.edu /~pbsiegel/www/bio431/Chapter3.doc   (3626 words)

 ChemTeam: Rutherford Experiment
R is the source, S is the thin metal foil which scatters the particles, Z is the zinc sulfide screen that flashed when struck (it was called the scintillation method), and M is a microscope to view the flashes with.
The alpha emitter was placed at A on top of a lead plate which prevented direct access of the particles to the counter located at S. With nothing placed at position R the counter did not record any hits.
In other words, the alpha particle encounters one gold atom after another and each encounter deflects the alpha a bit more, so that the sum of all the deflections is to make the alpha particle come flying out 90° or more from the direction it went in.
dbhs.wvusd.k12.ca.us /webdocs/AtomicStructure/Rutherford-Exp-History.html   (1994 words)

 ChemTeam: Discovery of Alpha Scattering
She said that this showed that the alpha particles were not scattered, that is, able to be bent from their path.
It seemed that the radius of curvature of the alpha particles path through the slit Y increased as b increased, thereby moving the two images closer together.
The importance of the slowing down of the alpha particle meant that R (the radius of the curvature in a magnetic field) should have gone down, not increased.
dbhs.wvusd.k12.ca.us /webdocs/Radioactivity/Disc-of-Alpha-Scatter.html   (1086 words)

 Theory: Radioactive Decay
An alpha particle is a Helium 4 nucleus (two protons and two neutrons).
Alpha decay is also a type of fission, common because the alpha particle is a particularly low energy arrangement of two protons and two neutrons.
The mass of a nucleus is determined by the sum of the energies of all its constituents.
www2.slac.stanford.edu /vvc/theory/nuclearstability.html   (694 words)

 Alpha particle definition - Medical Dictionary definitions of popular medical terms
Alpha particle: A tiny mass of material composed of two protons and two neutrons.
Because alpha particles cannot penetrate human skin they are not considered an "external exposure hazard." This means that if the alpha particles stay outside the human body they cannot harm it.
However, alpha particle sources located within the body may pose an "internal" health hazard if they are present in great enough quantities.
www.medterms.com /script/main/art.asp?articlekey=9642   (243 words)

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