Retrospective radon measurements based on implanted 210Po in glass objects using polycarbonate detectors

In the present investigation, a surface-deposited polonium was measured in 37 houses in Rasht and Ramsar cities of Iran with the aim of evaluating the retrospective radon concentration. The CR-LR technique is widely used in this regard, but for the first time, Lexan polycarbonate detectors were used to measure the activity of 210Po planted in glassy objects. These detectors were placed on glassy surfaces for 153 to 365 days. A passive cylindrical diffusion chamber was used for the contemporary radon concentration measurements. The diffusion chamber consists of the Lexan polycarbonate films as a solid state nuclear track detectors and filter. The surface-deposited 210Po activity concentration was found to vary from 0.26 to 11.96 mBqcm-2 with average of 2.62 mBqcm-2. The sensitivity of 210Po to polycarbonate was determined to be 0.06456 track per cm2 per mBqhcm-2. Thus, the radon concentration was found to vary from 122 to 4840 Bqm-3 with an average value 1243 Bqm-3 and the contemporary radon concentration in the area was found to vary from 15 to 2420 Bqm-3 with an average 513 Bqm-3. The results indicate that there is a significant correlation between the concentration of the retrospective radon and the concentration of the contemporary radon gas in the indicated areas with a coefficient of 0.80672.

Advective balance in pipe-formed vortex rings

Vorticity distributions in axisymmetric vortex rings produced by a piston–pipe apparatus are numerically studied over a range of Reynolds numbers, $Re$, and stroke-to-diameter ratios, $L/D$. It is found that a state of advective balance, such that $\unicode[STIX]{x1D701}\equiv \unicode[STIX]{x1D714}_{\unicode[STIX]{x1D719}}/r\approx F(\unicode[STIX]{x1D713},t)$, is achieved within the region (called the vortex ring bubble) enclosed by the dividing streamline. Here $\unicode[STIX]{x1D701}\equiv \unicode[STIX]{x1D714}_{\unicode[STIX]{x1D719}}/r$ is the ratio of azimuthal vorticity to cylindrical radius, and $\unicode[STIX]{x1D713}$ is the Stokes streamfunction in the frame of the ring. Some, but not all, of the $Re$ dependence in the time evolution of $F(\unicode[STIX]{x1D713},t)$ can be captured by introducing a scaled time $\unicode[STIX]{x1D70F}=\unicode[STIX]{x1D708}t$, where $\unicode[STIX]{x1D708}$ is the kinematic viscosity. When $\unicode[STIX]{x1D708}t/D^{2}\gtrsim 0.02$, the shape of $F(\unicode[STIX]{x1D713})$ is dominated by the linear-in-$\unicode[STIX]{x1D713}$ component, the coefficient of the quadratic term being an order of magnitude smaller. An important feature is that, as the dividing streamline ($\unicode[STIX]{x1D713}=0$) is approached, $F(\unicode[STIX]{x1D713})$ tends to a non-zero intercept which exhibits an extra $Re$ dependence. This and other features are explained by a simple toy model consisting of the one-dimensional cylindrical diffusion equation. The key ingredient in the model responsible for the extra $Re$ dependence is a Robin-type boundary condition, similar to Newton’s law of cooling, that accounts for the edge layer at the dividing streamline.

Find the concentration of radon gas emitted naturally from the bones and skin of some kinds of birds and local and imported chicken available in the City of Baghdad

In the present research we the study the deposition of radioactive elements naturally and particularly radioactive radon gas in parts of the body of organisms which are of direct relevance to human life in the city of Baghdad as the samples which were collected from the bones and skin of some kinds of birds and chicken based on the principle that radioactive elements are concentrated always on the bones. We use of this as the exercise detector impact nuclear (CR-39), using the technology Cylindrical diffusion , the results indicated that the largest concentration of radon found in the bone bird Seagull tapered as it was (625 ± 37) Bq.cm-3, and less concentration of radon gas in the chicken bones of Al-kafeel as it was (105 ± 10) Bq.cm-3 as well as in chicken bones of Al-muriad to be reached (110±10)Bq.cm-3 either in the skin reached the highest concentration in the skin of seagulls tapered(610 ± 20) Bq.cm-3 and the lowest value in the skin local chicken as it was (90 ± 9) Bq.cm-3 .