The impact on alpha emission rates of varying distances between a CR-39 detector and alpha-emitting bone samples
رشا صبيح أحمد
Authors :
Background Changing the distance between a sample and an exposed solid-state nuclear track detector affects the number of alpha tracks recorded by the detector. This concept had been used to distinguish high-energy alpha particles by computing the alpha emission rate at two distances (0 and 2 cm) from animal bone ash. Materials and methods Two Cr-39 detectors were placed in a container with bone ash inside to measure the alpha emission rate when the detectors were in contact with the ash and hung at a distance of 2 cm from the ash. Results The alpha emission rate was found to be 62.7 × 10−4 Bq cm−2 when the detector was in contact with the sample (a small exposure area) and 324.4 × 10−4 Bq cm−2 when the sample was placed 2 cm away (a larger exposure area). A mathematical equalization of the exposure areas was conducted (the area of the detector exposed to the alpha emitter sample at a distance of 2 cm was equalized to the area exposed when in contact with the sample). After equalization, a reduction in the average value of the alpha emission rate from 324.4 × 10−4 to 17.4 × 10−4 Bq cm−2 was observed. Conclusion The increase in distance between the sample and the detector allowed only high-energy alpha particles with a range greater than the traveled distance to reach the detector. Thus, this system can distinguish the type and number of nuclides in the sample by changing the distance between the detector and the sample according to each nucleus range. Additionally, the results show that the alpha emission rates in these bone samples are higher than the local values.

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