Nuclides decay

Transition, Isomeric—The process by which a nuclide decays to an isomeric nuclide (i.e., one of the same mass number and atomic number) of lower quantum energy. Isomeric transitions (often abbreviated I.T.) proceed by gamma ray and/or internal conversion electron emission. 

De-excitation of 99mTc has specific features. This nuclide decays with a half-life of 6 hours, but its half-life varies slightly according to environmental conditions [30] or chemical states [31,32], Moreover, the emission probabilities of characteristic X-rays just after the isomeric transition 99mTc — "Tc are influenced by environmental factors [33] which result in a change of the K/VKoc X-ray intensity ratio [34],... 

Pb from h. The Pb systems are discussed last because of the complexities of the U-Th-Pb system in several aspects. One is that each of the nuclides and h undergoes a long chain of decay to the final stable nuclide decays... 

A sample of 100 mg of a radioactive nuclide decay to 81.85 mg of the same in exactly 7 days. The decay constant for this disintegration and the half life of the nuclide. Calculated ... 

Some nuclides decay by more than one mode. Some nuclei may decay by either (3+ decay or electron capture others by a decay or spontaneous fission still others by... 

Example Problem An important delayed neutron emitter in nuclear fission is 137I. This nuclide decays with a half-life of 25 s and emits neutrons with an average energy of 0.56 MeV and a total probability of approximately 6%. Estimate the energy of an excited state in 137Xe that would emit a 0.56-MeV neutron. 

To adequately treat these many applications and to illustrate the specific ways in which decay data make useful, if not crucial, contributions to them is a task that lies beyond the space and time limitations of this paper. We have thus chosen to limit the scope of this presentation to the discussion of several selected examples, drawn mostly from the area of fission-reactor physics. These include the results of recent significant developments in actinide-nuclide decay data and, in the spirit of this symposium, decay data of fission-product nuclides off the line of p stability and some of the problems and challenges they present to both experimental capabilities and nuclear theory. 

An International Coordinated Program of Actinide-Nuclide Decay-Data Measurement and Evaluation... 

Actinide half-lives, as standards for nuclear data measurements, 95-96 Actinide-nuclide decay data,... 

Consider the two nuclides of mass number 7, 7Li and 7Be. Which of the two is the more stable How does the unstable nuclide decay into the more stable one ... 

Nuclide Decay Products Half-Life Uses... 

Since Individual radionuclides decay exponentially with time, the time Interval from the end of Irradiation to the beginning of counting Is very Important, especially for the measurement of short-lived radionuclides. If the time Interval Is equal to the half-life of the nuclide to be separated (and the nuclide has no parent nuclide, the nuclide decays during that Interval to one-half the quantity which existed at the end of Irradiation If the time Is two half-lives, it decays to one quarter the quantity,. etc. Thus the time of separation must be considered In light of the half-life of the desired radioelement. 

In this case the mother nuclide decays faster than the daughter nuclide, and the ratio between the two changes continuously, until the mother nuclide has disappeared and only the daughter nuclide is left. The situation is plotted in Fig. 4.6. No radioactive equilibrium is attained. 

Nuclides Decay mode Half-life (year)... 

FIGURE 19.6 The radioactive nuclide decays via a series of alpha and beta emissions to the stable nuclide ° Pb. 

The nuclide decays by positron emission to Be. What is the energy released (in MeV) ... 

The nuclide decays by beta emission with a half-life of 87.1 days. 

Examples of reactions proceeding during stellar nucleosynthesis are shown in Table 1. To illustrate the sequence of events, the decay series of uranium-238 is depicted in this table. Radiogenic nuclides decay by the emission of alpha, beta and gamma radiation or by electron capture into so called daughter nuclides at their half-lives. This half-life ranges from parts of seconds to billions of years. 

Parent nuclide Decay mode Ti/2 Daughter nuclide Energy (keV) T 2... 

For nuclides decaying by electron capture (EC), the effective energy per decay (other than gamma rays from isomeric transitions of the daughter) was taken as the energy of the Ka x-ray... 

When a nuclide decays, it forms a nuclide of lower energy, and the excess energy is carried off by the emitted radiation. The three most common types of radioactive emission are ... 

The °Br nuclide decays either by 3 decay or by electron capture, (a) What is the product of each process (b) Which process releases more energy (Masses of atoms °Br = 79.918528 amu °Kr = 79.916380 amu °Se = 79.916520 amu neglect the mass of the electron involved.)... 

---