Underground radioactivity measurements of meteorites: Development of methods suitable to determine precise terrestrial age of recent falls.

The L6 chondritic meteorite, HaH-346, fell in Libya. However, neither the exact date of the fall nor the exact size of the original meteoroid or asteroid is known. A specimen of the meteorite, weighing 488 g, was measured using ultra low-background gamma-ray spectrometry in the 225 m deep underground facility HADES. Activation products 22Na, 26Al, 60Co, 57Co, 54Mn and 44Ti were detected. The detection efficiency was determined by 3D scanning the meteorite and introducing this in the computer model of the detector and sample implemented in the MCNP6.2 Monte Carlo code. The activities of 22Na and 26Al support the hypothesis that the fall took place on 26 August 2018. Furthermore, the 60Co and 26Al activities indicate that the original radius of meteoroid was between 50 and 80 cm, which suggests the mass prior to atmospheric entry was between 2400 and 7300 kg.

Evaluation of 137Cs, 133Xe and 3H activity concentrations monitored in the Arctic atmosphere.

This paper provides a brief introduction to the Arctic atmospheric radioactivity monitoring network. A decade of monitoring results have shown the 137Cs background levels in Arctic air range from 0.05 to 1.50 µBq/m3. The monitoring stations have sufficient sensitivity to detect 137Cs brought to the atmosphere due to resuspension in local soil and reemissions from biomass burning in a daily temporal resolution. These observations can be used as tracers for atmospheric processes. The 133Xe measurements obtained at Yellowknife, Resolute and Spitsbergen could support other research into how air pollution problems arise across intercontinental distances. It will help develop and improve models capable of predicting the long-distance transport and deposition of trace gases in the Arctic. Rainwater monitoring data collected in Finnish Lapland since the 1960's indicate that 3H radioactivity concentrations reached natural background levels in early 2000s, typically around 1-2 Bq/L monthly, with an annual seasonal variation cycle consistent with the observed of other cosmogenic radionuclides.

Concentration of 7Be, 210Pb, 40K, 137Cs, 134Cs radionuclides in the ground layer of the atmosphere in the polar (Hornsund, Spitsbergen) and mid-latitudes (Otwock-Swider, Poland) regions.

This paper presents results of measurements of selected gamma-radioactive radionuclide concentrations (7Be, 210Pb, 40K, 137Cs, 134Cs) in atmospheric aerosols registered in 2002-2017 at the Polish Polar Station of the Institute of Geophysics Polish Academy of Science in Hornsund and in the S. Kalinowski's Geophysical Observatory Institute of Geophysics Polish Academy of Science in Swider. The above measurements and tests are used to control and track long-term concentrations of radionuclides depending on the geometeorological conditions prevailing in the vicinity of the station. Collecting radiological data from polar regions and comparing them with data from medium latitudes leads to a better understanding of the mechanisms of creation and propagation of radionuclides in the air. Hornsund station is one of the northernmost measuring site for continuous airborne radionuclide monitoring in the Spitsbergen archipelago. It also allows the analysis of the relationship of radionuclides to the Earth's magnetic field.