Nuclear physics

Radioactive decay Nuclear fission Nuclear fusion

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Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (two protons and two neutrons bound together into a particle identical to a helium nucleus) and transforms (or 'decays') into an atom with a mass number 4 less and atomic number 2 less. Nuclear physics is the field of Physics that studies the building blocks and interactions of Atomic nuclei. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a The mass number ( A) also called atomic mass number or nucleon number, is the total number of Protons and Neutrons (together known as See also List of elements by atomic number In Chemistry and Physics, the atomic number (also known as the proton For example:

^[1]

although this is typically written as:

(The second form is preferred because the first form appears electrically unbalanced. Fundamentally, the recoiling nucleus is very quickly stripped of two electrons to neutralize the ionized helium cation. )

An alpha particle is the same as a helium-4 nucleus, and both mass number and atomic number are the same. Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical Alpha decay is a form of nuclear fission where the parent atom splits into two daughter products. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may Alpha decay is fundamentally a quantum tunneling process. In Quantum mechanics, quantum tunnelling is a nanoscopic phenomenon in which a particle violates the principles of Classical mechanics by penetrating a Unlike beta decay, alpha decay is governed by the strong nuclear force. In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and

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. 05c. Because of their relatively large mass, +2 charge and relatively low velocity, they 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 comes from the alpha decay of underground deposits of minerals containing uranium or thorium. Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Thorium (ˈθɔːriəm is a Chemical element with the symbol Th and Atomic number 90 The helium is brought to the surface as a by-product of natural gas production. Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane,

Contents 1 History 2 Uses 3 Toxicity 4 See also 5 References

History

By 1928, George Gamow had solved the theory of the alpha decay via tunneling. Year 1928 ( MCMXXVIII) was a Leap year starting on Sunday (link will display full calendar of the Gregorian calendar. George Gamow (pronounced as ˈgamof ( March 4, 1904 &ndash August 19, 1968), born Georgiy Antonovich Gamov (Георгий Антонович 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. Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons

Uses

Americium-241, an alpha-emitter, is used in smoke detectors. Americium (ˌæməˈrɪsiəm is a Synthetic element that has the symbol Am and Atomic number 95 A smoke detector is a device that detects Smoke and issues an Alarm. The alpha particles ionize air between a small gap. Ionization is the physical process of converting an Atom or Molecule into an Ion by adding or removing charged particles such as Electrons A small current is passed through that ionized air. Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. Smoke particles from fire that enter the air gap reduce the current flow, sounding the alarm.

Alpha decay can provide a safe power source for radioisotope thermoelectric generators used for space probes and artificial heart pacemakers. A radioisotope thermoelectric generator ( RTG, RITEG) is an Electrical generator which obtains its power from Radioactive decay. A space probe is a scientific Space exploration mission in which a Robotic spacecraft leaves the Gravity well of Earth and approaches the For other uses see Pacemaker (disambiguation A pacemaker (or artificial pacemaker, so as not to be confused with the heart's natural pacemaker Alpha decay is much more easily shielded against than other forms of radioactive decay. Plutonium-238, for example, requires only 2. Plutonium 238, is a Radioactive isotope of Plutonium with a half-life of 87 5 mm of lead shielding to protect against unwanted radiation. The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly

Static Eliminators typically use Polonium-210, an alpha emitter, to ionize air, allowing the 'static cling' to more rapdily dissipate. Polonium ( Po) has 33 known isotopes, all of which are radioactive.

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. In Physics the mean free path of a particle is the average distance covered by a particle ( Photon, Atom or Molecule) between subsequent impacts 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. The skin is the outer covering of living tissue of an animal (or plant Even touching an alpha source is usually not harmful, though many alpha sources also are accompanied by beta-emitting radiodaughters, 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 equivalent dose ( H T) is a measure of the Radiation dose to tissue where an attempt has been made to allow for the different relative biological

The Relative Biological Effectiveness (RBE) is a measure of the fact that alpha radiation is more effective at causing certain biological effects, notably either cancer or cell-death, compared to photon or beta radiation, for equivalent radiation exposure. Relative Biological Effectiveness (RBE is a Health physics concept introduced in the 1950s after it was noted that different types of radiation might affect living organisms In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena Beta particles are high-energy high-speed Electrons or Positrons emitted by certain types of Radioactive nuclei such as Potassium -40 This is generally attributable to the high Linear Energy Transfer (LET), which is about one ionization of a chemical bond for every Angstrom of travel by the alpha particle. Linear energy transfer (LET is a measure of the Energy transferred to material as an ionizing particle travels through it An ångström or angstrom (symbol Å) (ˈɔːŋstrəm Swedish: ˈɔ̀ŋstrœm is an internationally recognized non- SI unit of length equal 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 and ionizing photon radiation. This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. BETA is a pure Object-oriented language originating within the "Scandinavian School" in object-orientation where the first object-oriented language Simula

However, another component of alpha radiation is the recoil of the parent nucleus, due to the conservation of momentum requiring the parent nucleus to recoil, much like the 'kick' of a rifle butt when a bullet goes in the opposite direction. In Classical mechanics, momentum ( pl momenta SI unit kg · m/s, or equivalently N · s) is the product This gives a significant amount of energy to the recoil nucleus, which also causes ionizaton damage. The total energy of the recoil nucleus is readily calculable, and is roughly the weight of the alpha (4 amu) divided by the weight of the parent (typically about 200 amu) 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. A chromosome is an organized structure of DNA and Protein that is found in cells. In some studies^[2], 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^[3]. Radon (ˈreɪdɒn is the Chemical element that has the symbol Rn and Atomic number 86 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. ^[4]. The death of Marie Curie at age 66 from leukemia was likely caused by prolonged exposure to high doses of ionizing radiation. Curie worked extensively with Radium, which decays into Radon^[5], along with other radioactive materials that emit beta and gamma rays. In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions

The 2006 assassination of Russian dissident Alexander Litvinenko is thought to have been caused by poisoning with Polonium-210, an alpha emitter. Alexander Valterovich Litvinenko (Алекса́ндр Ва́льтерович Литвине́нко ( 30 August 1962 – 23 November 2006 Radiation poisoning, also called " radiation sickness " or a " creeping dose " is a form of damage to organ tissue due to excessive exposure to Polonium ( Po) has 33 known isotopes, all of which are radioactive.

See also

Beta decay

References

Alpha emitters by increasing energy (Appendix 1)

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