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Nuclear physics
Radioactive decay
Nuclear fission
Nuclear fusion
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In nuclear physics, beta decay is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. 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 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. Beta particles are high-energy high-speed Electrons or Positrons emitted by certain types of Radioactive nuclei such as Potassium -40 The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. In the case of electron emission, it is referred to as "beta minus" (β−), while in the case of a positron emission as "beta plus" (β+). Positron emission is a type of Beta decay, sometimes referred to as " beta plus " (&beta+ Kinetic energy of beta particles has continuous spectrum ranging from 0 to maximal available energy (Q), which depends on parent and daughter nuclear states participating in the decay. The kinetic energy of an object is the extra Energy which it possesses due to its motion For other definitions see Q value In Nuclear physics and chemistry, the Q value for a reaction is the amount Typical Q is of order of 1 MeV, but it can be from few keV to few tens MeV. The most energetic beta particles are ultrarelativistic, with speeds very close to the speed of light.

Contents


β− decay

Beta-minus (β−) decay. The intermediate emission of a W− boson is omitted.
Beta-minus (β−) decay. The intermediate emission of a W− boson is omitted. The W and Z bosons are the Elementary particles that mediate the Weak force.

In β− decay, the weak interaction converts a neutron (n0) into a proton (p+) while emitting an electron (e−) and an antineutrino (νe):

n0 → p+ + e− + νe

At the fundamental level (as depicted in the Feynman diagram below), this is due to the conversion of a down quark to an up quark by emission of a W− boson; the W− boson subsequently decays into an electron and an antineutrino. The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Physics, antineutrinos, the Antiparticles of Neutrinos are neutral particles produced in nuclear Beta decay. This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Physics, antineutrinos, the Antiparticles of Neutrinos are neutral particles produced in nuclear Beta decay. In Particle physics, an elementary particle or fundamental particle is a particle not known to have substructure that is it is not known to be made Motivation and history When calculating Scattering cross sections in Particle physics, the interaction between particles can be described The down quark is a first-generation Quark with a charge of -(1/3 e. The up quark is a particle described by the Standard Model theory of Physics. The W and Z bosons are the Elementary particles that mediate the Weak force. In Physics, antineutrinos, the Antiparticles of Neutrinos are neutral particles produced in nuclear Beta decay.

β+ decay

The Feynman diagram for beta minus decay of a neutron into a proton, electron, and electron antineutrino via an intermediate heavy W− boson
The Feynman diagram for beta minus decay of a neutron into a proton, electron, and electron antineutrino via an intermediate heavy W− boson
See also: Positron emission

In β+ decay, energy is used to convert a proton into a neutron, a positron (e+) and a neutrino (νe):

energy + p+ → n0 + e+ + νe

So, unlike β−, β+ decay cannot occur in isolation, because it requires energy, the mass of the neutron being greater than the mass of the proton. Motivation and history When calculating Scattering cross sections in Particle physics, the interaction between particles can be described This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost The W and Z bosons are the Elementary particles that mediate the Weak force. Positron emission is a type of Beta decay, sometimes referred to as " beta plus " (&beta+ The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object β+ decay can only happen inside nuclei when the absolute value of the binding energy of the mother nucleus is higher than that of the daughter nucleus. Binding energy is the Mechanical energy required to disassemble a whole into separate parts The difference between these energies goes into the reaction of converting a proton into a neutron, a positron and a neutrino and into the kinetic energy of these particles.

Electron capture (k -capture)

In all the cases where β+ decay is allowed energetically (and the proton is a part of a nucleus with electron shells), it is accompanied by the electron capture process, when an atomic electron is captured by a nucleus with the emission of a neutrino:

energy + p+ + e− → n0 + νe

But if the energy difference between initial and final states is low (less than 2mec2), then β+ decay is not energetically possible, and electron capture is the sole decay mode. Electron capture (sometimes called inverse beta decay) is a Decay mode for Isotopes that will occur when there are too many Protons in the The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost Electron capture (sometimes called inverse beta decay) is a Decay mode for Isotopes that will occur when there are too many Protons in the

Nuclear transmutation

If the proton and neutron are part of an atomic nucleus, these decay processes transmute one chemical element into another. The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom Nuclear transmutation is the conversion of one Chemical element or Isotope into another which occurs through Nuclear reactions Natural transmutation occurs For example:

13755Cs   → 13756Ba + e− + νe (beta minus decay)
2211Na   → 2210Ne + e+ + νe (beta plus decay)
2211Na + e− → 2210Ne + νe   (electron capture)

Beta decay does not change the number of nucleons A in the nucleus but changes only its charge Z. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Physics, antineutrinos, the Antiparticles of Neutrinos are neutral particles produced in nuclear Beta decay. The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost In Physics a nucleon is a collective name for two Baryons the Neutron and the Proton. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. Thus the set of all nuclides with the same A can be introduced; these isobaric nuclides may turn into each other via beta decay. A nuclide (from lat nucleus is a species of Atom characterized by the constitution of its nucleus and hence by the number of Protons, the number of Among them, several nuclides (at least one) are beta stable, because they present local minima of the mass excess: if such a nucleus has (A, Z) numbers, the neighbour nuclei (A, Z−1) and (A, Z+1) have higher mass excess and can beta decay into (A, Z), but not vice versa. The mass excess of a Nuclide is the difference between its actual mass and its Mass number. It should be noted, that a beta-stable nucleus may undergo other kinds of radioactive decay (alpha decay, for example). 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 In nature, most isotopes are beta stable, but a few exceptions exist with half-lives so long that they have not had enough time to decay since the moment of their nucleosynthesis. Half-Life (computer-game page here It's already listed in the disambiguation page Nucleosynthesis is the process of creating new atomic nuclei from preexisting Nucleons (protons and neutrons One example is 4019K, which undergoes all three types of beta decay (β−, β+ and electron capture) with a half life of 1. 277×109 years.

Double beta decay

Main article: Double beta decay

Some nuclei can undergo double beta decay (ββ decay) where the charge of the nucleus changes by two units. In the process of Beta decay, unstable nuclei decay by converting a Neutron in the nucleus to a Proton and emitting an Electron and an electron In most practically interesting cases, single beta decay is energetically forbidden for such nuclei, because when β and ββ decays are both allowed, the probability of β decay is (usually) much higher, preventing investigations of very rare ββ decays. Thus, ββ decay is usually studied only for beta stable nuclei. Like single beta decay, double beta decay does not change A; thus, at least one of the nuclides with some given A has to be stable with regard to both single and double beta decay.

Beta decay can be considered as a perturbation as described in quantum mechanics, and thus follows Fermi's Golden Rule. In Quantum physics, Fermi's golden rule is a way to calculate the transition rate (probability of transition per unit time from one energy Eigenstate of a quantum

Kurie plot

A Kurie plot (also known as a Fermi-Kurie plot) is a graph used in studying beta decay, in which the square root of the number of beta particles whose momenta (or energy) lie within a certain narrow range, divided by a function worked out by Fermi, is plotted against beta-particle energy; it is a straight line for allowed transitions and some forbidden transitions, in accord with the Fermi beta-decay theory.

History

Historically, the study of beta decay provided the first physical evidence of the neutrino. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost In 1911 Lise Meitner and Otto Hahn performed an experiment that showed that the energies of electrons emitted by beta decay had a continuous rather than discrete spectrum. Lise Meitner (7 or 17 November 1878 &ndash 27 October 1968 was an Austrian born later Swedish physicist who studied Radioactivity and Otto Hahn (8 March 1879 &ndash 28 July 1968 was a German Chemist who received the 1944 Nobel Prize in Chemistry for discovering Nuclear fission This was in apparent contradiction to the law of conservation of energy, as it appeared that energy was lost in the beta decay process. In Physics, the law of conservation of energy states that the total amount of Energy in an isolated system remains constant and cannot be created although it may A second problem was that the spin of the Nitrogen-14 atom was 1, in contradiction to the Rutherford prediction of ½. Ernest Rutherford 1st Baron Rutherford of Nelson, OM, PC, FRS (30 August 1871 – 19 October 1937 was a New Zealand Physicist

In 1920-1927, Charles Drummond Ellis (along with James Chadwick and colleagues) established clearly that the beta decay spectrum is really continuous, ending all controversies. Sir Charles Drummond Ellis (b Hampstead, 11 August 1895; died Cookham 10 January 1980) was a Physicist and scientific Sir James Chadwick, CH (20 October 1891 &ndash 24 July 1974 was an English Physicist and Nobel laureate in physics awarded for his discovery of the

In a famous letter written in 1930 Wolfgang Pauli suggested that in addition to electrons and protons atoms also contained an extremely light neutral particle which he called the neutron. He suggested that this "neutron" was also emitted during beta decay and had simply not yet been observed. In 1931 Enrico Fermi renamed Pauli's "neutron" to neutrino, and in 1934 Fermi published a very successful model of beta decay in which neutrinos were produced. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost In Physics, Fermi's interaction is an old explanation of the Weak force, proposed by Enrico Fermi.

Making it simple to understand the concept of beta decay is generally represented in the following way:

AZXN   →    AZ+1YN-1 + e− + νe (beta minus decay)
AZXN   →    AZ-1YN+1 + e+ + νe (beta plus decay)
AZXN + e− →    AZ-1YN+1 + νe   (electron capture)

Where X and Y represent the parent and daughter nuclei respectively, (A= mass number, Z= atomic number, N= number of neutrons). The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Physics, antineutrinos, the Antiparticles of Neutrinos are neutral particles produced in nuclear Beta decay. The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost

See also

References

Dictionary

beta decay

-noun

  1. (physics) A nuclear reaction in which a beta particle (electron or positron) is emitted
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