Owing to the small amounts of produced einsteinium and the short half-life of its most easily produced isotope, there are currently almost no practical applications for it outside of basic scientific research.

Nevertheless, element 99 ( einsteinium ), namely its < sup > 253 </ sup > Es isotope, could be detected via its characteristic high-energy alpha decay at 6. 6 MeV.

Actinium is found only in traces in uranium ores as the isotope < sup > 227 </ sup > Ac, which decays with a half-life of 21. 772 years, predominantly emitting beta particles.

Several unusual applications, such as a nuclear battery or fuel for space ships with nuclear propulsion, have been proposed for the isotope < sup > 242m </ sup > Am, but they are as yet hindered by the scarcity and high price of this nuclear isomer.

Six astatine isotopes, with mass numbers of 214 to 219, are present in nature as the products of various decay routes of heavier elements, but neither the most stable isotope of astatine ( with mass number 210 ) nor astatine-211 ( which is used in medicine ) is produced naturally.

Each element has at least one isotope with an unstable nucleus that can undergo radioactive decay.

Chemists can use isotope analysis to assist analysts with issues in anthropology, archeology, food chemistry, forensics, geology, and a host of other questions of physical science.

The single primordial beryllium isotope < sup > 9 </ sup > Be also undergoes a ( n, 2n ) neutron reaction with neutron energies over about 1. 9 MeV, to produce < sup > 8 </ sup > Be, which almost immediately breaks into two alpha particles.

The production of the second-important isotope berkelium-247 involves the irradiation of the rare synthetic isotope curium-244 with high-energy alpha particles.

About twenty isotopes and six nuclear isomers ( excited states of an isotope ) of berkelium have been characterized with the atomic numbers ranging from 235 to 254.

Its alpha radiation is rather weak – 1. 45 % with respect to the β-radiation – but is sometimes used to detect this isotope.

The isotope effect was reported by two groups on the 24th of March 1950, who discovered it independently working with different mercury isotopes, although a few days before publication they learned of each other's results at the ONR conference in Atlanta, Georgia.

Of the 80 elements with at least one stable isotope, 26 have only one stable isotope, and the mean number of stable isotopes for the 80 stable elements is 3. 1 stable isotopes per element.

Isotopes are distinguished by the atomic mass number ( total protons and neutrons ) for a particular isotope of an element, with this number combined with the pertinent element's symbol.

In supernova explosions, calcium is formed from the reaction of carbon with various numbers of alpha particles ( helium nuclei ), until the most common calcium isotope ( containing 10 helium nuclei ) has been synthesized.

Chromium isotopic contents are typically combined with manganese isotopic contents and have found application in isotope geology.

One isotope of cadmium, < sup > 113 </ sup > Cd, absorbs neutrons with very high probability if they have an energy below the cadmium cut-off and transmits them otherwise.

Californium-252, with a half-life of about 2. 64 years, is the most common isotope used and is produced at the Oak Ridge National Laboratory in the United States and the Research Institute of Atomic Reactors in Russia.

Self diffusion, exemplified with an isotopic tracer of radioactive isotope < sup > 22 </ sup > Na

Its most common isotope einsteinium-253 ( half life 20. 47 days ) is produced artificially from decay of californium-252 in a few dedicated high-power nuclear reactors with a total yield on the order of one milligram per year.

Einsteinium is the element with the highest atomic number which has been observed in macroscopic quantities in its pure form, and this was the common short-lived isotope einsteinium-253.

Some < sup > 238 </ sup > U atoms, however, could absorb another two neutrons ( for a total of 17 ), resulting in < sup > 255 </ sup > Es, as well as in the < sup > 255 </ sup > Fm isotope of another new element, fermium .< ref >< sup > 254 </ sup > Es, < sup > 254 </ sup > Fm and < sup > 253 </ sup > Fm would not be produced because of lack of beta decay in < sup > 254 </ sup > Cf and < sup > 253 </ sup > Es </ ref > The discovery of the new elements and the associated new data on multiple neutron capture were initially kept secret on the orders of the U. S. military until 1955 due to Cold War tensions and competition with Soviet Union in nuclear technologies.

Therefore, for synthetic elements the total nucleus count ( protons plus neutrons ) of the most stable isotope, i. e. the isotope with the longest half-life — is listed in brackets as the atomic mass.

This makes < sup > 128 </ sup > Te the isotope with the longest half life among all radionuclides, which is approximately 160 trillion ( 10 < sup > 12 </ sup >) times the age of known universe.

< sup > 69m </ sup > Zn has the longest half-life, 13. 76 h. The superscript m indicates a metastable isotope.

The longest lived, and most common, isotope of radium is < sup > 226 </ sup > Ra with a half-life of 1600 years.

14 radioisotopes have been discovered, with mass numbers from 6 to 21, all with short half-lives, the longest being that of < sup > 8 </ sup > B, with a half-life of only 770 milliseconds ( ms ) and < sup > 12 </ sup > B with a half-life of 20. 2 ms. All other isotopes have half-lives shorter than 17. 35 ms, with the least stable isotope being < sup > 7 </ sup > B, with a half-life of 150 yoctoseconds ( ys ).

This isotope of radioactive iodine used for ablative treatment is more potent than diagnostic radioiodine ( usually iodine-123 or a very low amount of iodine-131 ), which has a biological half life from 8 – 13 hours.

This isotope is described as decaying to element H with a half life of.

The team repeated the experiment several times over the next few years, and in 1971, they revised the spontaneous fission half time for the isotope at 4. 5 seconds.

Critics of the latter idea point out that the half-life of Pu-240 is 6, 560 years and Pu-239 is 24, 110 years, and thus the relative enrichment of one isotope to the other with time occurs with a half-life of 9, 000 years ( that is, it takes 9000 years for the fraction of Pu-240 in a sample of mixed plutonium isotopes, to spontaneously decrease by half — a typical enrichment needed to turn reactor-grade into weapons-grade Pu ).

Because of this exponential nature, one of the properties of an isotope is its half-life, the time by which half of an initial number of identical parent radioisotopes have decayed to their daughters.

However, this isotope has a day half life of 59 years, and thus in the supernova grains derived from such explosians, is soon converted entirely to calcium-44.

In this process the neutron half of an energetic deuteron ( a stable isotope of hydrogen with one proton and one neutron ) fuses with a target nucleus, transmuting the target to a heavier isotope while ejecting a proton.

Due to its volatility, short half life, and high abundance in fission products, < sup > 131 </ sup > I, ( along with the short-lived iodine isotope < sup > 132 </ sup > I from the longer-lived < sup > 132 </ sup > Te with a half life of 3 days ) is responsible for the largest part of radioactive contamination during the first week after accidental environmental contamination from the radioactive waste from a nuclear power plant.

They consider as one of the options a life support system generating drinking water with low content of Deuterium ( a stable isotope of hydrogen ) to be consumed by the crew members.

For example geochemical signatures from rocks may help to discover when life first arose on Earth, and analyses of carbon isotope ratios may help to identify climate changes and even to explain major transitions such as the Permian – Triassic extinction event .< ref name =" Twitchett "> A relatively recent discipline, molecular phylogenetics, often helps by using comparisons of different modern organisms ' DNA and RNA to re-construct evolutionary " family trees "; it has also been used to estimate the dates of important evolutionary developments, although this approach is controversial because of doubts about the reliability of the " molecular clock ".

The last three also occur as fission products, along with < sup > 79 </ sup > Se, which has a half-life of 327, 000 years .< ref name = life > The final naturally occurring isotope, < sup > 82 </ sup > Se, has a very long half-life (~ 10 < sup > 20 </ sup > yr, decaying via double beta decay to < sup > 82 </ sup > Kr ), which, for practical purposes, can be considered to be stable.

In September 1944, he arrived at Los Alamos, shortly after breathing life into the first Hanford reactor, which had been poisoned by a xenon isotope.

The molybdenum isotope has a half-life of approximately 66 hours ( 2. 75 days ), so the generator has a useful life of about two weeks.

A biosignature is any substance-such as an element, isotope, molecule, or phenomenon-that provides scientific evidence of past or present life.

Because bone is a dynamic tissue that is remodeled over time, and because different parts of the skeleton are laid down at particular times over the course of a human life, stable isotope analysis can be used to investigate population movements in the past and indicate where people lived at various points of their lives.