Daughter activity

Transient Equilibrium—If the half-life of the parent is short enough so the quantity present decreases appreciably during the period under consideration, but is still longer than that of successive members of the series, a stage of equilibrium will be reached after which all members of the series decrease in activity exponentially with the period of the parent. At this time, the ratio of the parent activity to the daughter activity is constant. 

For the determination of the free fraction the attached and the total radon daughter activity concentration were measured. The separation of the free radon daughters from the total daughter concentration was carried out by means of a high-volume diffusion screen battery (Reineking and Porstendorfer, 1986) with a 50 % penetration efficiency for 4 nm particles and for a flowrate of 2.4 m h-1. ... 

All our measurements i/ere carried out in rooms with i < 1 hr1 and the radon concentration outdoors (c 5 Bq nr 3) i/as always much smaller than indoors (cj > 100 Bq m 3). Assuming a constant radon emanation, a homogeneous activity distribution and 100 % prefiltering of the free fractions of the incoming air, the radon, the free and attached radon daughter activity concentrations indoors (cj cjf cja) and outdoors (eg c f c a) under steady conditions are ... 

The plateout rates of the free radon decay products on room surfaces are about 200 times higher than the values of the aerosol radon daughters and have a great influence on the radon daughter activity concentrations indoors. 

Reineking, A. and J. Porstendorfer, High-volume Screen Diffusion Batteries and the Alpha Spectroscopy for Measurements of the Radon Daughter Activity Size Distributions in the Environment, J. of Aerosol Science 17 (1986) (accepted for publication). 

The half-life of isotopes provides scientists with a nuclear clock that can be used to date objects. The concept is based on knowing the fraction of original material that is present in a sample. For instance, if half of the original isotope is present in the sample, then the sample s age is equivalent to the isotope s half-life. If one-fourth of the original material is present, then the sample s age is 2 half-lives. Because the use of radio-metric dating involves making accurate measurements of parent and daughter activities in the sample, it is assumed that parent... 

The potential yield of a Rb-82 generator is dictated by the nature of secular equilibrium. Thus, the activities of parent (Sr-82) and daughter (Rb-82) are nearly equivalent at equilibrium (Rb-82/Sr-82 1.00004). After separation of the Rb-82 by generator elution, equilibrium is re-established quickly. The fractional regeneration of daughter activity is given by (Eq. 1) ... 

Table I illustrates that the theoretical maximum amount of the daughter activity that is continuously available from a 10 mCi generator is a function of the half-life of the daughter nuclide. It is clear that continuous elution is particularly...

The direct measurement methods to determine the daughter activity proposed here involve the measurement of a sample of the eluted daughter activity (SEA) and the determination from these data the value of the (TEA). This involves solution of relationship (7) for the experimental conditions used. Two... 

If four half-lives (Tly ) occur between two successive bolus elutions, the growth of daughter activity will correspond to 94% of the maximum possible per bolus and the total waiting time will be defined by equation (17). 

These two equations, (3.21) and (3.22), are the general expressions for the number of daughter nuclei and the daughter activity as a function of time, respectively. 

Thus, there must be a time when the daughter activity is the maximum. We can calculate this time by noting the condition for a maximum in the activity of 2 is... 

If however the short-lived radionuclide has a long-lived parent nuclide from which the former activity is produced genetically, the parent activity can be purified by standard radiochemical techniques. Then, after the establishment of transient radioactive equilibrium, the daughter activity Is separated from the parent by rapid radiochemical techniques In which the time to separate the nuclide from the parent must be considered. 

Recoiling daughter activities were collected along the rim of the disc and the a-particles from these activities were counted through the slit window of the a particle counting chamber. 

The Na2 m daughter activities were then collected on a negative electrode and measured, after removal of the neon gas... 

For some samples, the gas was allowed to decay for two half-lives, the residual gas removed by purging with a hot air stream, and the remaining short-lived daughter activities observed. The time required for handling, separation and transport to the counter for regular gas samples was 20-30 seconds. ... 

Polarographlc method. Application of the polarographlc technique to the detection of short-lived daughter activity... 

This method is specific for rare earths and Y. Separation of the La daughter activity is effected by pptn. of the fluoride from the Ce44 soln. containing Ce134. 

At the desired time for the milking of Fb daughter activity, the soln. Is diluted to 43 ml and heated In a water bath for a few minutes. 

Whereas in secular radioactive equilibrium the activities of the mother and the daughter nuclide are the same, in transient radioactive equilibrium the daughter activity is always higher ... 

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