Isotopes decay modes

Isotope Atomic mass Half-hfe, Decay mode... 

Isotope PET/SPECT Decay mode (%) Half-life (min) (max/most abundant) (half-value thickness) reactor (R), generator (G)... 

G. W. C. Kaye and T. H. Laby, Tables of Physical and Chemical Constants, Longman 1995, gives a table of properties of the nuclides including isotopic abundance or half-life, decay modes, mass excess, neutron capture cross-section and ground-state spin and parity. This publication, with a prospect of regular updates, is available on the website http //www.kayelaby.npl.co.uk/. 

Sometimes it is difficult to predict if a particular isotope is stable and, if unstable, what type of decay mode it might undergo. All isotopes that contain 84 or more protons are unstable. These unstable isotopes will undergo nuclear decay. For these large massive isotopes, we observe alpha decay most commonly. Alpha decay gets rid of four units of mass and two units of charge, thus helping to relieve the repulsive stress found in the nucleus of these isotopes. For other isotopes of atomic number less than 83, we can best predict stability by the use of the neutron to proton (n/p) ratio. 

A plot of the neutrons (n) versus the protons (p) for the known stable isotopes gives the nuclear belt of stability. (See your textbook for a figure of the belt of stability.) At the low end of this belt of stability (Z < 20), the n/p ratio is 1. At the high end (Z 80), the n/p ratio is about 1.5. We can then use the n/p ratio of the isotope to predict if it will be stable. If it is unstable, then the isotope will utilize a decay mode that will bring it back onto the belt of stability. 

Consider neon-18 or Ne-18. It has lOp and 8n, giving an n/p ratio of 0.8. For a light isotope, like this one, this value is low. A low value indicates that this isotope will probably be unstable. Neutron-poor isotopes, meaning that it has a low n/p ratio do not have enough neutrons (or has too many protons) to be stable. Decay modes that increase the number of neutrons and/or decrease the number of protons are favorable. Both positron emission and electron capture accomplish this by converting a proton into a neutron. As a rule, positron emission occurs with lighter isotopes and electron capture with heavier ones. 

Isotopes that are neutron-rich, that have too many neutrons or not enough protons, lie above the belt of stability and tend to undergo beta emission because that decay mode converts a neutron into a proton. 

ISOTOPES There are a total of 30 isotopes of protactinium. All are radioactive, and none are stable. Their decay modes are either alpha or beta decay or electron capture. Their half-lives range from 53 nanoseconds to 3.276x10+ ears. 

ISOTOPES There are a total of 15 Isotopes for rutherfordlum, ranging from Rf-253 to Rf-264. Their half-lives range from 23 microseconds to 10 minutes. They are all artificially made, radioactive, and unstable. Their decay modes are a combination of alpha decay and spontaneous fission (SF). 

ISOTOPES There are a total of 10 isotopes of unnilseptium (bohrium). Not all their half-lives are known. However, the ones that are known range from 8.0 milliseconds to 9.8 seconds for Bh-272, which is the most stable Isotope of bohrium and which decays Into dubnlum-268 through alpha decay. Only one Isotope, Uns-261, has a decay mode that Involves both alpha decay and spontaneous fission. All the others decay by alpha emission. 

Symbol Bk atomic number 97 atomic weight of most stable isotope 247.07 a transuranium radioactive element synthesized in the laboratory electronic configuration [Rn]5/97s2 oxidation states -i-3 and +4. Isotopes, half-hfe and decay modes are given below ... 

Symbol Ca atomic number 20 atomic weight 40.078 a Group IIA (Group 2) alkaline-earth metaUic element ionic radius 1.06 A (Ca2+) electron configuration [Ar]4s2 valence state +2 standard electrode potential, E° = -2.87V stable isotopes and their abundance Ca-40 (97.00%), Ca-44 (2.06%) Ca-42 (0.64%), Ca-48 (0.18%), Ca-43 (0.145%), and Ca-46 (0.003%) also the element has six unstable isotopes of which Ca-41 has the longest half-life, l.lxlO yr (decay mode electron capture), and Ca-38 has shortest half life 0.66 sec (P-decay). 

Symbol Cm atomic number 96 atomic weight 247 a radioactive transuranium actinide series element electron configuration [Rn]5/ 6di7s2 most stable valence state +3 most stable isotope Cm-247. Curium isotopes, half-hves and decay modes are ... 

The isotopes, their half-lives and decay modes are tabulated below ... 

Symbol Fr atomic number 87 atomic weight 223 heaviest adtah metal element of Group lA (Group 1) a radioactive element electron configuration [Rn]7sk oxidation state -i-l the most electropositive element the most stable isotope, Fr-223 (ti/2 21 minutes), also is the only natural isotope. Isotopes, half-lives and their decay modes are shown below ... 

Many radioisotopes exist, but not all radioisotopes are created equal. Radioisotopes break down through three separate decay processes (or decay modes) alpha decay, beta decay, and gamma decay. The following sections show you equations detailing each type of decay. Note The symbols showing the isotope notation for each radioactive isotope cire as follows or 2 Y, where... 

Detailed view of a portion of the Chart of the Nuclides. Stable isotopes are shaded. For stable nuclides, isotopic abundances are given below the element symbol and isotopic masses are given at the bottom of the square. Half-lives of the unstable nuclides are given, along with their decay modes. 

Isotope Abundance Decay mode Half-life Decay constant... 

Exotic Nuclei and Their Decay. As reported by J.C. Hardy (Chalk River Nuclear Laboratories. Atomic Energy of Canada, Ltd.), recent advances in nuclear accelerators and experimental techniques have led to an increasing ability to synthesize new isotopes. As isotopes are produced with more and more extreme combinations of neutrons and protons in their nuclei, new phenomena are observed, and the versatility of the nucleus is increased as a laboratory for studying fundamental forces. Hardy reports that, among the newly discovered decay modes are (1) proton radioactivity, (2) triton, two-proton, two-neutron, and three-neutron decays that are beta-delayed, and (3) 14C emission m radioactive decay, Precise tests of the properties of the weak force have also been achieved. 

Table 2.1 Isotopes of arsenic (Audi et al., 2003 Holden, 2007 Lindstrom, Blaauw and Fleming, 2003).15As is the only stable arsenic isotope. The possible decay modes include electron capture (EC), electron emission (P ), positron emission (P+), proton decay (p), internal transition (IT), and neutron emission (ne). Superscripts on some of the arsenic isotope mass numbers designate excited-state isomers. The first (lowest energy) excited state is designated with an m and a second excited state is designated with an n. ...

Isotope Decay Mode Decay Energy (MeV13) Half-life... 

A continuing effort among experimentalists who study nuclei far from beta stability is the measurement of the atomic mass surface As a manifestation of the nuclear force and the nuclear many body system, atomic masses signal important features of nuclear structure on both a macroscopic and microscopic scale It has thus been a challenge to nuclear theorists to devise models which can reproduce the measured mass surface and to predict successfully the masses of new isotopes Both the measured mass surface and that beyond it which can be predicted by these models serve as important input to a variety of fundamental and applied problems, e g, nucleosynthesis calculations, predictions of decay modes of exotic nuclei far from stability, nuclear de-excitation by particle evaporation, decay heat simulations, etc ... 

Nuclear reactions producing exotic nuclei at the limits of stability are usually very non-specific. For the fast and efficient removal of typically several tens of interfering elements with several hundreds of isotopes from the nuclides selected for study mainly mass separation [Han 79, Rav 79] and rapid chemical procedures [Her 82] are applied. The use of conventional mass separators is limited to elements for which suitable ion sources are available. There exists a number of elements, such as niobium, the noble metals etc., which create problems in mass separation due to restrictions in the diffusion-, evaporation- or ionization process. Such limitations do not exist for chemical methods. Although rapid off-line chemical methods are still valuable for some applications, continuously operated chemical procedures have been advanced recently since they deliver a steady source of activity needed for measurements with low counting efficiencies and for studies of rare decay modes. The present paper presents several examples for such techniques and reports briefly actual applications of these methods for the study of exotic nuclei. 

Isotope Tm(h) Methods of production Decay mode (keV) Reference... 

Table 14.3 Half-lives and decay modes for the isotopes of elements 104—116 and 118...

All six elements are found in Nature. Radium has no stable isotopes see Isotopes Isotope Labeling), however, Rahas a half-hfe of 1600years. Its decay mode is by a (4.780 MeV) and y emission. As a consequence of this radioactive nature (see Radioactive Decay), its chemistry remains relatively unexplored. In several arenas, rather comprehensive studies have examined various properties of all of the lighter group 2 elements. Efforts have been made to extend all given comparisons to radium however, in some instances this has proven rather difficult. 

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