nucleus of a helium atom given off during radioactive decay

A positively charged particle, that cannot be distingushed from a helium atom.

Particle emitted in certain types of radioactive decay. It is positively charged and made up of two neutrons and two protons (which is a helium atom nucleus.) It is easily stopped, and cannot penetrate a piece of paper or the skin.

The nuclei of a helium atom (with two neutrons and two protons each) that are discharged by radioactive decay of some heavy elements, including uranium-238, radium-226, and plutonium-239. Alpha, the first letter of the Greek alphabet, is written as .

positively charged particle consisting of two protons and two neutrons

Positively charged matter, consisting of two neutrons and two protons, that is emitted as a form of radioactivity from the nuclei of some radioisotopes. See also beta particle, gamma rays.

Alpha particles, consisting of two protons and two neutrons, are positively charged. They are emitted from naturally occurring elements such as uranium and radium, as well as from man-made elements.

A positively charged particle emitted in the radioactive decay of certain radioactive atoms. An alpha particle is identical to the nucleus of the helium atom.

a positively charged particle ejected from the nucleus of a radioactive atom, being a high-speed ionized atom of helium. A stream of these particles constitutes alpha rays.

4He2 nucleus of the helium atom possessing two protons and two neutrons.

A particle emitted spontaneously from the nuclei of some radioactive elements. It is identical with a helium nucleus, having a mass of four units and an electric charge of two positive units. The alpha particle has a very short range in air and a very low ability to penetrate other materials, but it has a strong ability to ionize materials. Alpha particles are unable to penetrate even the thin layer of dead cells of human skin and consequently are not an external radiation hazard. Alpha-emitting nuclides inside the body as a result of inhalation or ingestion are a considerable internal radiation hazard. See; Alpha Decay, Fission Products, Radioactivity.

A positive particle consisting of 2 protons and 2 neutrons. It is the nucleus of a helium atom.

The nucleus of a Helium-4 atom. This has a double positive charge and is rapidly stopped when interacting with other atoms.

a positively charged particle that is the nucleus of the helium atom; emitted from natural or radioactive isotopes

a double positively charged helium nucleus

a fast moving packet containing two protons and two neutrons (a helium nucleus )

a helium nucleus consisting of two protons and two neutrons all strongly bound together by nuclear forces

a high energy, positively charged particle given off by the nucleus of a radioactive atom

helium nucleus emitted from a heavy radioactive element.

The nucleus of a helium atom, consisting of two protons and two neutrons.

A particle comprising two protons and two neutrons emitted by a radionuclide.

the nucleus of a helium atom, made up of two neutrons and two protons with a charge of +2. Certain radioactive nuclei emit alpha particles. Alpha particles generally carry more energy than gamma or beta particles, and deposit that energy very quickly while passing through tissue. Alpha particles can be stopped by a thin layer of light material, such as a sheet of paper, and cannot penetrate the outer, dead layer of skin. Therefore, they do not damage living tissue when outside the body. When alpha-emitting atoms are inhaled or swallowed, however, they are especially damaging because they transfer relatively large amounts of ionizing energy to living cells. See also beta particle, gamma ray, neutron, x-ray.

A helium nuclei, which contains two protons and two neutrons. Alpha particles are emitted from larger atoms as a result of radioactive decay. An alpha particle will only travel a few centimeters in air, or about 25 microns in silicon, before interacting with the matter it is travelling through.

an electrically charged ( + ) particle emitted from the nucleus of some radioactive chemicals, cf. plutonium. It contains 2 protons and 2 neutrons, and is the largest of the atomic particles emitted by radioactive chemicals. It can cause ionisation.

A charged particle consisting of two neutrons and two protons. It is sometimes emitted from the nucleus of high atomic number elements during radioactive decay. The alpha particle is the nucleus of a Helium-4 atom. Due to the +2 charge, it causes ionizations along its path length. An alpha particle will travel a few centimetres in air and is stopped by a sheet of paper or the skin's layer of dead cells.

A positively charged particle emitted by certain radioactive material consisting of two neutrons and two protons.  A dangerous carcinogen when inhaled or ingested.

A strongly ionizing particle emitted from the nucleus during radioactive decay which is equivalent to a helium nucleus (2 protons and 2 neutrons).

The nuclei of a helium atom (with two neutrons and two protons each) that are discharged by radioactive decay of many heavy elements, such as uranium-238 and plutonium-239.

The nucleus of the helium atom. The alpha particle has a double positive charge.

Charged particles emitted from a radioactive atom. Each charged particle consists of two protons and two neutrons.

A heavy particle emitted from the nucleus of an atom. It consists of two protons and two neutrons, which is identical to the nucleus of a helium atom without orbital electrons. These heavy charged particles lose their energy very rapidly in matter. Thus, they are easily shielded by paper or the surface layer of skin. Alpha particles are only hazardous when they are internally deposited. ALARA Acronym for "As Low As Reasonably Achievable." It means making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical. Be consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations. These means are in relation to utilization of nuclear energy and licensed materials in the public interest.

a helium nucleus consisting of two neutrons and two protons, with a mass of 4 AMU and a charge of +2.

Alpha Particle - A positively charged, sub-atomic particle, a product of radioactive decay, similar to the nucleus of a helium atom, having 2 protons and 2 neutrons.

A charged particle, composed of two protons and two neutrons, emitted from the nucleus of an atom. Alpha particles can be stopped by thin layers of light materials, such as a sheet of paper, and pose no direct or external radiation threat; however, they can pose a serious health threat if ingested.

a strongly ionizing particle emitted from the nucleus during radioactive decay having a mass and charge equal in magnitude to a helium nucleus, consisting of 2 protons and 2 neutrons with a double positive charge.

(42He) A particle that is commonly ejected from radioactive nuclei, consisting of two protons and two neutrons. Alpha particles are helium nuclei. Alpha particles have a mass of 6.644 655 98 ¡¿ 10-27 kg or 4.001 506 1747 atomic mass units. [1998 CODATA values

A particle consisting of two protons and two neutrons, given off by the decay of many elements, including uranium, plutonium, and radon. Alpha particles cannot penetrate a sheet of paper. However, alpha emitting isotopes in the body can be very damaging.

Helium atom stripped of its two electrons, that is, helium atom with only two protons and two neutrons and has positive charge. When alpha particles are ejected from radioactive material, they interact with all matter in their path and produce large number of ions before gaining two electrons and becoming neutral helium. Alpha particles are unable to penetrate outer layer of human skin, but if taken internally they can cause massive damage of the surrounding tissue. For this reason alpha emitters are never used in nuclear medicine.

Alpha particles are composed of two protons and two neutrons. Alpha particles do not travel very far from their radioactive source. They cannot pass through a piece of paper, clothes or even the layer of dead cells which normally protects the skin. 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. The risk from indoor radon is due to inhaled alpha particle sources which irradiate lung tissue.

A helium-4 nucleus emitted during the course of alpha decay. It is radioactive and can disrupt organic matter.

A positively charged particle made up of two neutrons and two protons emitted by certain radioactive nuclei. Alpha particles can be stopped by thin layers of light materials, such as a sheet of paper, and pose no direct or external radiation threat; however, they can pose a serious health threat if ingested or inhaled.

A positively charged particle emitted by certain radioactive material. It is made up of two neutrons and two protons; hence it is identical with the nucleus of a helium atom.

A positively charged particle emitted by radioactive material. It consists of two neutrons and two protons bound together; hence, it is identical with the nucleus of a helium atom. It is the least penetrating of the three common types of radiation -- alpha, beta, and gamma -- and it is stopped by a sheet of paper. It is not dangerous to plants, animals, or humans unless the alpha-emitting substance has entered the organisms. Alpha particles are ejected from a nucleus during the decay of some radioactive elements; for example, an alpha particle is emitted when either of the radon progeny polonium-218 or polonium-214 decays.

A positively charged particle containing two protons and two neutrons which is emitted by certain radioisotopes.

A positively charged particle (a Helium-4 nucleus) made up of two neutrons and two protons. It is the least penetrating of the three common forms of radiation, being stopped by a sheet of paper. It is not dangerous to living things unless the alpha-emitting substance is inhaled or ingested or comes into contact with the lens of the eye.

A specific particle ejected from a radioactive atom. It has low penetrating power and short range. Alpha particles will generally fail to penetrate the skin. Alpha-emitting atoms can cause health effects if introduced into the lungs or wounds.

A type of particle that is ejected from radioactive nuclei. Alpha particles consist of two protons and two neutrons and thus are equivalent to helium nuclei.

A type of fast ion emitted by many heavy radioactive nuclei, such as uranium. Actually, the nucleus (atom stripped of all electrons) of the gas helium.

A charged particle emitted from the nucleus of an atom having a mass and charge equal in magnitude to a helium nucleus; i.e., two protons and two neutrons with a +2 charge.

Two neutrons and two protons bound as a single particle that is emitted from the nucleus of certain radioactive isotopes in the process of decay.

A positively charged particle, consisting of two neutrons and two protons, emitted by certain radioactive materials. Alpha particles can travel only a few inches in the air and lose their energy almost as soon as they collide with anything. They are easily shielded by a sheet of paper or the outer layer of a person's skin. Contact-handled transuranic (CH-TRU) waste primarily emits alpha particles.

A heavy particle produced by the radio-active decay process and consisting of two protons and two neutrons, thus carrying an elementary charge of +2. It is identical to the nucleus of a helium atom.

A small electrically charged particle of very high velocity thrown off by many radioactive materials, including uranium and radium. It is made up of two neutrons and two protons. Its electric charge is positive.

A densely ionizing particle emitted from the nucleus during radioactive decay, having a mass and charge equal in magnitude to a helium nucleus (two protons and two neutrons).

A positively-charged particle from the nucleus of an atom, emitted during radioactive decay. Alpha particles are helium nuclei, with 2 protons and 2 neutrons.

A particle consisting of two protons plus two neutrons. Emitted by a radionuclide.

A particle, , which consists of two protons and two neutrons. It is identical to the nucleus of a helium atom and is ejected by heavy particles undergoing alpha decay.

Alpha particles (named after the first letter in the Greek alphabet, α) are a highly ionizing form of particle radiation that have low penetration. They consist of two protons and two neutrons bound together into a particle identical to a helium nucleus; hence, it can be written as He2+. The alpha particle mass is 6.644656×10-27 kg, which is equivalent to the energy of 3.72738 GeV.