RADON IN THE WATER

Man and his environment are constantly exposed to the effects of ionizing radiation. Most of this radiation comes from natural and artificial radionuclides and the biggest radioecological problem is the 222Rn radioactive gas. Natural radioactivity comes from unstable radioisotopes that were present during the formation of the Earth, and are present today. According to the research by UNSCEAR(United Nations Scientific Committee on the Effects of Atomic Radiation) it is estimated that the radiation dose, which comes from natural radionuclides and to which man is exposed, is 2.4 mSv per year. Natural sources of radioactivity are cosmic radiation and Earth’s crust that contains primordial radioactive elements including those that are sources of radon (uranium). Radon is a natural inert radioactive gas without smell and taste. It is soluble in water and can easily diffuse with the gaseous and aqueous phase and in this way forms significant concentrations. The techniques and methods most commonly used to detect and determine the activities of radon in water are alpha spectrometry, gamma spectrometry and measurement techniques on a liquid scintillation detector. Throughout epidemiological studies, the World Health Organization has provided convincing evidence of the correlation of exposure to indoor radon and the development of lung cancer. Radon and its decomposition products are considered to be the second cause of lung cancer after consuming tobacco.

Atmospheric charged $$K/\pi $$ ratio and measurement of muon annual modulation with a liquid scintillation detector at Soudan

We report a measurement of muon annual modulation in a 12-l liquid scintillation detector with a live-time of more than 4 years at the Soudan Underground Laboratory. Muon minimum ionization in the detector is identified by its observed pulse shape and large energy deposition. The measured muon rate in the detector is $$28.69\pm 2.09$$28.69±2.09 muons per day with a modulation amplitude of ($$2.64\pm 0.07$$2.64±0.07)% and a phase at Jul $$22 \pm 36.2$$22±36.2 days. This annual modulation is correlated with the variation of the effective atmospheric temperature in the stratosphere. The correlation coefficient, $$\alpha _{T}$$αT, is determined to be $$0.898 \pm 0.025$$0.898±0.025. This can be interpreted as a measurement of the atmospheric charged kaon to pion ($$K/\pi $$K/π) ratio of $$0.094^{+0.044}_{-0.061}$$0.094-0.061+0.044 for $$E_{p} > 7$$Ep>7 TeV, consistent with the measurement from the MINOS far detector. To further constrain the value of $$K/\pi $$K/π ratio, a Geant4 simulation of the primary cosmic-ray protons with energy up to 100 TeV is implemented to study the correlation of $$K/\pi $$K/π ratio and the muon annual modulation for muon energy greater than 0.5 TeV. We find out that a charged $$K/\pi $$K/π ratio of 0.1598, greater than the upper bound (0.138) from this work at the production point 30 km above the Earth surface in the stratosphere cannot induce muon annual modulation at the depth of Soudan.