[en] In this paper a thermic method for electret production is described. Electrets were used for radon daughters collection. The factor of electrostatic al collection of positively charged daughters was determined experimentally. ²¹⁴ Bi is collected more efficiency than ²¹⁸ Po, for one order of magnitude. The reason for so large collection efficiency is short half life of ²¹⁸ Po in comparing with ²¹⁴ Bi. (author)

[en] The teaching of radioactivity in the high school is often difficult to implement, especially from an experimental point of view. In this paper an activity based on a laboratory experiment on radioactivity is presented. The activity was proposed to high school students in their fourth year of studies attending the summer internship organized by the University of Pavia at the Department of Physics. The experiment concerns the radon decay chain, and in particular the measurement of the activity of ²¹⁴Bi, both in absence and in presence of its progenitor ²²²Rn. This way it is possible to observe two different decay curves: the first provides a ²¹⁴Bi decay constant in agreement with the theoretical one, whereas the trend of the second one can be understood only through the hypothesis of secular equilibrium with ²²²Rn. Using an engaging and interesting game with dice, a model of radioactive decay was developed and performed with students divided in small groups.

[en] The results of the experimental investigations on quantitative evaluation of the ²¹⁸Po and ²¹⁴Bi washout efficiency by fog in an aerosol chamber are presented. The radioactivity has been measured by means of α-spectrometric method. Comparison of eXperimental and calculated data is made. The ²¹⁸Po and ²¹⁴Bi washout efficiency ratio is found to be dependent mainly on the aerosol concentration. The change of ²¹⁸Po concentration imitates the process of coagulation of free atoms of light ions, and that of ²¹⁴Bi - of aerosol particles by fog droplets

[en] The ratios of ²¹⁴Bi to ²¹⁴Pb in the surface atmosphere at Bombay on the west coast of India have been measured. In all, about 500 measurements were carried out at the ground surface and on top of a building 20 m high. The analysis techniques consisted in the least squares resolution of the alpha decay curves of high volume air filter samples counted by using large ZnS scintillation detectors. The collection and counting periods were optimized for minimizing the errors. The sample collection procedure consisted in taking a morning and an afternoon sample everyday. The measured ratios varied from 0.3 to 1.0, the average values being in the range 0.6-0.9. The afternoon ratios were generally higher than were the morning values. The data also showed that during late winter and spring the ratios reached the minimum values observed during the year. The possible reasons for the variations in the measured ratios are discussed

[en] The hypothesis of possible production, with probability 10%, in the decay of ²¹⁴Bi, of a new (e⁺ e^- e^-) particle, with mass approx-gt 1.5 MeV/c² and lifetime ∼ 10^-10 sec, decaying into an electron and a γray, has been tested experimentally. An upper limit on the probability of production of such a particle in the decay of ²¹⁴Bi was found (with confidence level 90%) to be 10^-3 by measuring (in coincidence with γrays) the spectrum of electrons from the possible decay of these particles in flight. 13 refs., 3 figs., 1 tab

[en] When a two-dimensional map contains points that appear to be scattered somewhat at random, a question that often arises is whether groups of points that appear to cluster are merely exhibiting ordinary behavior, which one can expect with any random distribution of points, or whether the clusters are too pronounced to be attributable to chance alone. A method for detecting clusters along a straight line is applied to the two-dimensional map of ²¹⁴Bi anomalies observed as part of the National Uranium Resource Evaluation Program in the Lubbock, Texas, region. Some exact probabilities associated with this method are computed and compared with two approximate methods. The two methods for approximating probabilities work well in the cases examined and can be used when it is not feasible to obtain the exact probabilities

[en] Recent in situ ²²²Rn/²¹⁴Bi soil profile measurements on hermetically sealed and weighed samples have been made using a new, experimental field method based on sequential measurements of the prompt decay of the ²¹⁴Bi counting rate. At least two ²¹⁴Bi count rate measurements are made in the first 11/2 - 2 h after sample collection and sealing, T₀. Two subsequent ²¹⁴Bi count rate measurements are made: the first within 4 - 12 h, and the second approximately 900 h after T₀. These measurements yield the following information for each sample: (1) the extrapolated, T₀²¹⁴Bi count rate and, indirectly, the T₀ in situ ²²²Rn activity; (2) a minimum ²¹⁴Bi count rate if ²²²Rn was lost in the sampling process; and (3) a final, constant and usually a maximum ²¹⁴Bi count rate reflecting the establishment of secular radioactive equilibrium between the ²²⁶Ra, ²²²Rn and ²¹⁴Bi in the sealed sample. This information provides the basis for; (1) assessing the state of ²²⁶Ra/²²²Rn radioactive equilibrium in the soil sample for the 2-3 h period immediately preceding sample collection; (2) characterising the potential loss of ²²²Rn from a soil profile; (3) identifying factors contributing to the mobility and transport of ²²²Rn; and (4) modelling the ²²²Rn surface flux values that might be expected under different soil moisture and atmospheric conditions. (author)

[en] Present study examines the utility of gamma rays of energies 1.12 MeV and 1.76 MeV of uranium in estimation of uranium in airborne gamma ray spectrometric survey (AGRS) in comparison to the conventional 1.76 MeV alone used world wide. As a case study, the AGRS data of northern part of Cuddapah Basin is considered. Multi-channel processing is applied on this dataset to reduce the spectral noise and use of combined 1.12 MeV and 1.76 MeV has reduced the Poisson's related statistical error. Uranium is estimated using above two energies individually and in combination, using multi-channel processing followed by standard corrections procedure. Result indicates that a combination of both energies has given best estimation due to a reduction in overall noise which helped in demarcating geological entities and litho-contacts. This indicates the efficacy of this technique which improved the radio-geochemistry of study area in understanding the radio-elemental variation. (author)

No abstract available

[en] The main reason for lung cancer of non-smokers is regarded to be environmental pollution or natural exposure to radon. Radon decay products (progenies) like ²¹⁴Bi which emits beta rays can also play a role. In this paper the behavior of radon progenies in the air is studied experimentally. A sample is set under scintillating fibers after it was exposed to windless room air. A Cherenkov detector using silica aerogel was set over the scintillating fibers. This result suggests that ²¹⁴Bi attaches on our surroundings and the concentration becomes to be saturated just after the radon decay in the air. Furthermore, it also suggests the radon progenies (²¹⁸Po, ²¹⁴Pb, ²¹⁴Bi, ²¹⁴Po, etc.) do not fall down to ground, and stay in the air. Therefore, the inhaling of radon progenies should be taken into account for assessing the natural exposure dose. (authors)