Adapted Method of Radiation Response Function Calculation for Development of High-Sensitivity Reference Meters Based on Scintillation Detection Units with NaI(Tl) Crystals for Dosimetry of Low-Intensity and Near-Background Levels

Metrological support of photon radiation fields of low-intensity and near-background levels (0.04–100 μSv/h (μGy/h)) by ambient equivalent dose rate or kerma rate in air using scintillation detectors with NaI(Tl) crystals looks promising and in demand in dosimetry, but nontrivial due to the complex dependence of efficiency registration of gamma quanta from energy. The solution of such problems with the use of these detectors can be based on the use of the radiation response functions, which are functionals of the energy distribution of the radiation field fluence. The paper proposes a method for calculating the radiation response function adapted for solving metrological support problems for creating high-precision dosimetric measuring instruments based on scintillation detection units with NaI(Tl) crystals.

Identification of neutron sources and background levels in the polyethylene room of the China Jinping Underground Laboratory

The neutron backgrounds induced by supplementary experimental materials can result in contaminations in rare event search experiments. To address this, we present the neutron background levels arising from ambient materials in the polyethylene room of the China Jinping Underground Laboratory; particularly, we compare simulated spectra with measured neutron spectra unfolded using a genetic algorithm. The genetic algorithm optimizes the continuity of the energy spectra and obtains a reasonable spectral result. A good agreement between the unfolded and simulated spectra is achieved. Moreover, estimated neutron background levels of representative ambient materials such as polyethylene, aluminum, and lead are obtained using an exposure time of 511.27 days via a 28 liter 0.5%-gadolinium-doped liquid scintillator detector. The identification of rare neutron sources can aid in background reduction in next-generation large-scale rare event experiments.

Assessment of Smoke Pollution Caused by Wildfires in the Baikal Region (Russia)

Climate change has increased the prevalence of wildfires, resulting in longer fire seasons and larger geographic area burned. The aim of this work was to assess the air pollution and health risk to the population caused during exposure to smoke in fire season. The study design included: an analysis of long-term air pollution to determine background levels; an analysis of short-term (<24 h) and subchronic (10–14 days) concentrations during wildfires; and an assessment of the health risk in the industrial center of the Baikal region (Russia). In Irkutsk, at a distance of 2000 km from the fire focal points, the maximum short-term concentrations of pollution were noted during the smoke period, when the average CO level increased 2.4 times, and PM1 increased 1.4 times relative to the background levels in August 2021. In Bratsk, located near the fires, the increases in short-term concentrations were: CO—21.0; SO2—13.0; formaldehyde—12.0; TPM—4.4 times. The hazard indices of respiratory and coronary diseases in the burning period exceeded the acceptable level. Acute reactions to smoke can be expected in 30% of the exposed population near fires and 11% in remote areas (Bratsk). The results obtained from the remote sensing of atmospheric smoke can be used to urgently resolve the issue of organizing medical assistance or evacuating the population groups most sensitive to the effects of smoke in fire season.

The design and sensitivity of JUNO’s scintillator radiopurity pre-detector OSIRIS

The OSIRIS detector is a subsystem of the liquid scintillator filling chain of the JUNO reactor neutrino experiment. Its purpose is to validate the radiopurity of the scintillator to assure that all components of the JUNO scintillator system work to specifications and only neutrino-grade scintillator is filled into the JUNO Central Detector. The aspired sensitivity level of $$10^{-16}\hbox { g/g}$$ 10 - 16 g/g of $$^{238}\hbox {U}$$ 238 U and $$^{232}\hbox {Th}$$ 232 Th requires a large ($$\sim 20\,\hbox {m}^3$$ ∼ 20 m 3 ) detection volume and ultralow background levels. The present paper reports on the design and major components of the OSIRIS detector, the detector simulation as well as the measuring strategies foreseen and the sensitivity levels to U/Th that can be reached in this setup.

Hydrogeochemical Processes and Natural Background Levels of Chromium in an Ultramafic Environment. The Case Study of Vermio Mountain, Western Macedonia, Greece

The hydrogeochemical processes and natural background levels (NBLs) of chromium in the ultramafic environment of Vermio Mountain, Western Macedonia, Greece, were studied. Seventy groundwater samples were collected from 15 natural springs between 2014‒2020, and an extensive set of physical and chemical parameters were determined. The ultramafic-dominated environment of western Vermio Mt. favors elevated groundwater concentrations of dissolved magnesium (Mg2+), silicon (Si), nickel (Ni), and Cr in natural spring waters. Chromium was the principal environmental parameter that exhibited a wide range of concentrations, from 0.5 to 131.5 μg/L, systematically exceeding the permissible limit of 50 μg/L for drinking water. Statistical evaluation of hydrogeological, hydrochemical, and hydrological data highlighted the water-ultramafic rock process as the predominant contributor of Cr in groundwater. The NBL assessment for Cr and Cr(VI) was successfully applied to the typical ultramafic-dominated spring “Potistis” that satisfied all the methodology criteria. The NBLs of Cr and Cr(VI) were defined at 130 μg/L and 100 μg/L, respectively, revealing that a natural ultramafic-dominated environment exhibits the geochemical potential to contribute very high concentrations of geogenic Cr to groundwater. The holistic methodology, proposed herein, could be implemented in any catchment scale to assess geogenic and anthropogenic Cr-sources that degrade groundwater quality.

Natural Background Levels in Groundwater

High levels of inorganic compounds in groundwater represent a significant problem in many parts of the world, with major economic, social and environmental drawbacks [...]