Counting efficiency, improving

Measurement of specific activity. The half-life of a nuclide can be readily calculated if both the number of atoms and their rate of decay can be measured, i.e., if the activity A and the number of atoms of P can be measured, then X is known from A = XP. As instrumentation for both atom counting and decay counting has improved in recent decades, this approach has become the dominant method of assessing half-lives. Potential problems with this technique include the accurate and precise calibration of decay-counter efficiency and ensuring sufficient purity of the nuclide of interest. This technique provides the presently used half-lives for many nuclides, including those for the parents of the three decay chains, U, U (Jaffey et al. 1971), and Th. 

Therefore, for the measurement of the concentrations of radionuclides in environmental samples, and especially for low concentration levels, it is essential to reduce the background rate as well as improving the counting efficiency. 

The crystal itself is usually a circular cyHiider machined from a single crystal of sodium iodide that was carefully grown to ensure optical clarity for efficient light collection. A small amount of thallium is added to the mother liquor to improve performance. The high atomic number of iodine and the density of sodium iodide (3.7g/cm ) favor the absorption of y-radiation. For this reason, a well counter is often referred to as a y-counter. For a typical well detector, the counting efficiency for expressed as the percentage of decays that produces counts, approximates 70%. 

CE also has the ability of providing improved resolutions for similar structures, such as peptides, which may be difficult or impossible to separate by any and all HPLC methods (39). Because it moves analytes and the buffer by electroosmotic flow (EOF) rather than by pressurized flow delivery as in HPLC, individual peaks tend to be much narrower, sharper, symmetrical, and of higher plate counts (efficiency, N (number of theoretical plates or plate count for peak)). This also leads to improved resolutions of nearly identical compounds, assuming that they have some differences in mass-to-charge ratios or can interact with buffer components differently, as with their ligands or receptors. 

One of the main hypotheses in this research is that the preparation times and the time dedicated to the supplements aren t adequate, this, due to the nature of the activities developed in this type of industry. The information obtained from this research will shed light above the construction and maintenance projects administration as well as the cost associated with it, in order to make a more efficient and effective use of the resources with which the company counts, thereby improving productivity and quality of the offered services by the company Aguila Mantenimiento Industrial. 

In the examination of the effect of various combinations of ethanol and water on the toluene-Triton X-100 counting mixtures the toluene-Triton X-100 ratio 1 1 yielded the widest range of compositions with improved Na2C03 capacity. However this capacity was not greatly increased and the counting efficiency was reduced considerably by the large water content required. Possibly these mixtures could be useful for some applications but they were of no immediate interest in the present study. 

In addition to the high scintillation yield required from the scintillation liquid, counting efficiency variations will result from the use of different types of counting vials. Calf and Polach (1974) introduced the use of Teflon vials they improved slightly on carbon-14 detection efficiency compared with low glass vials, and also decreased the background counting rate. 

Improved Cerenkov Radiation Counting Efficiency of Phosphorus P. N. P. CHOW... 

In conclusion, our results showed that counting labeled nucleotides directly on dried DEAE disks produces erroneous results. The failure to recognize this is responsible for the variable and low thymidine kinase activities in the cerebellum reported in previous studies (Weichsel, 1974, Weichsel and Dawson, 1976). The elution of the labeled nucleotides with 1 ml of 1 M HCl containing 0.5 M NaCl in the counting vial in improved counting efficiency and reproducibility. Furthermore, it is not necessary to dry the disks, thus the overall method became less time-consuming. 

Reactions in which radioactivity has been incorporated into a precipitable macromolecule [135]. This technique involves collecting the precipitate on filter paper discs, although glass fibre discs are claimed to be an improvement [136—137] since they can hold more liquid than cellulose, do not curl on drying, and give much improved counting efficiencies for tritium. 

Quite clearly, if our MDA is calculated as a number of Becquerels, the limit in terms of Bq per unit mass (or volume) will be improved (i.e. lowered) by increasing the sample size. Bear in mind that the improvement will not be linear as sample size increases, the average distance of sample from the detector will increase and the overall counting efficiency will decrease. Figure 13.11 shows the... 

---