Optimal Operation of Cryogenic Calorimeters Through Deep Reinforcement Learning.

Cryogenic phonon detectors with transition-edge sensors achieve the best sensitivity to sub-GeV/c dark matter interactions with nuclei in current direct detection experiments. In such devices, the temperature of the thermometer and the bias current in its readout circuit need careful optimization to achieve optimal detector performance. This task is not trivial and is typically done manually by an expert.

Contributions of fossil and non-fossil fractions to total carbon in urban aerosols in Bratislava (Slovakia).

Radiocarbon measurements of total carbon (TC) fraction of aerosol samples collected at the campus of the Comenius University in Bratislava (Slovakia) during 2022-2023 were carried out. Based on radiocarbon activity of these samples and a source apportionment model we have determined the relative proportion of fossil and non-fossil carbon in collected atmospheric aerosols. The carbon from non-fossil sources (biomass burning and biogenic emissions) was dominant in this time period, on average it formed 72% of carbon present in the aerosols from the atmosphere of Bratislava.

Assessment of environmental impacts from authorized discharges of tritiated water from the Fukushima site to coastal and offshore regions.

In August 2023, the long-planned discharging of radioactive wastewater from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) started after the confirmation of its feasibility and safety. As this water contains elevated amounts of tritium even after being diluted, a lot of resources have been invested in the monitoring of the Fukushima coastal region where the discharge outlet is located. We compare the first H surface activity concentrations from these measurements (up to the end of November 2023) with the available background values to evaluate a possible impact of the long-term discharging on humans and environmental levels of the radionuclide of interest in the same or nearby area.

A new certified reference material IAEA-465 for radionuclides in Baltic Sea sediment.

Certified reference material (CRM) for natural (K,Pb,Po,Ra,Ra,Th,Th,Th,U,U, andU) and anthropogenic (Cs,Pu, andAm) radionuclides in marine sediment from the Baltic Sea (IAEA-465) has been developed. Information values are given for Pu,Pu andPu. Altogether 27 laboratories participated in this exercise.

Long-term radiocarbon variation studies in the air and tree rings of Slovakia.

Fifty-five years of radiocarbon variation studies are reviewed with an emphasis on a better understanding of the impacts of the Bohunice nuclear power plant and fossil fuel CO on the atmosphere and biosphere of Slovakia. The maximum ΔC levels in the air up to about 1200‰ were observed during the 1970s at the Žlkovce monitoring station, which after 2005 decreased to <30‰. A relative decrease in the atmospheric ΔC levels due to increasing levels of fossil CO in the atmosphere has also been significant, for example, in Bratislava down to about -330‰, but after 2005 they were only <50‰ below the Jungfraujoch European clean-air level.

Temporal changes of Cs concentrations in the Far Eastern Seas: partitioning of Cs between overlying waters and sediments.

Deep-ocean sediments, similarly to seawater, are important reservoirs of Cs, an anthropogenic radionuclide with a relatively long half-live found in the Earth system. To better understand the geochemical behaviour of Cs in the ocean, we examined the temporal changes of Cs activity concentrations in the overlying waters and in sediments from the Far Eastern Seas (Sea of Japan, SOJ, and Okhotsk Sea, OS) during the period of 1998-2021. The Cs activity levels showed exponential changes during the observed period.

Impact of the Fukushima Accident on H and C Environmental Levels: A Review of Ten Years of Investigation.

The investigation of the impact of the Fukushima accident is still going on although more than ten years have passed since the disaster. The main goal of this paper was to summarize the results of tritium and radiocarbon determinations in different environmental samples, possibly connected with the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. A document containing compiled data may serve as a solid basis for further research in the selected fields.

Towards an automated data cleaning with deep learning in CRESST.

The CRESST experiment employs cryogenic calorimeters for the sensitive measurement of nuclear recoils induced by dark matter particles. The recorded signals need to undergo a careful cleaning process to avoid wrongly reconstructed recoil energies caused by pile-up and read-out artefacts. We frame this process as a time series classification task and propose to automate it with neural networks.

Secular equilibrium assessment in a CaWO target crystal from the dark matter experiment CRESST using Bayesian likelihood normalisation.

CRESST is a leading direct detection sub-GeVc dark matter experiment. During its second phase, cryogenic bolometers were used to detect nuclear recoils off the CaWO target crystal nuclei. The previously established electromagnetic background model relies on Secular Equilibrium (SE) assumptions.

[Diagnostic value of 18F-FDG PET/CT in fever of unknown origin].

Fever of unknown origin is a common differential diagnostic problem in medicine. More than 60 years have passed since the first established definition of the disease, and despite constant development and improvement of diagnostic procedures, the differential diagnosis and choosing adequate therapy still remains a challenge in this patient population. The medical literature lists at least 200 diseases that may manifest with fever of unknown origin, and it encompasses a wide clinical spectrum.

The Winchcombe meteorite, a unique and pristine witness from the outer solar system.

Direct links between carbonaceous chondrites and their parent bodies in the solar system are rare. The Winchcombe meteorite is the most accurately recorded carbonaceous chondrite fall. Its pre-atmospheric orbit and cosmic-ray exposure age confirm that it arrived on Earth shortly after ejection from a primitive asteroid.

PIXE analysis of iron in rabbit cerebellum after exposure to radiofrequency electromagnetic fields.

Purpose: We investigated iron accumulation and the possible mechanisms in the rabbit cerebellum after the exposure to the real GSM and generated radiofrequency electromagnetic fields (RF EMF) using inductively coupled plasma mass spectrometry (ICP MS) and particles induced X-ray emission (PIXE).

Materials And Methods: Four groups of rabbits were exposed to the real EMF, generated EMF, combination of both the real and generated signals and the control group with no exposition. For determination of iron concentration in the four groups of cerebellum samples ICP MS was used.

Tritium and radiocarbon in the water column of the Red Sea.

Despite being the busiest transient sea in the world due to the Suez Canal, radionuclide distribution studies in seawater and sediment of the Red Sea remain rare. A sampling expedition in the Red Sea was conducted from June 9 to July 6, 2021, visiting a transect of several deep sampling stations located along the central axis of the basin from the Gulf of Aqaba to the southern Red Sea (near Farasan Island, Saudi Arabia). The collected seawater profile samples were analyzed for tritium, radiocarbon and oxygen-18.

RADIOCARBON DATING OF CHARCOALS FROM HISTORICAL MORTARS FROM TÝŘOV AND PYŠOLEC CASTLES.

Organic inclusions in lime binders provide useful samples for radiocarbon dating of historical objects. Two Czech castles Týřov and Pyšolec from Late Middle Ages were explored, and tens of charcoals were found in their walls. The radiocarbon content of the charcoals was measured with accelerator mass spectrometry.

Sequential scavenging and measurement of seawater radiocesium concentrations and plutonium isotopic ratios offshore Fukushima.

The scientific interest in radiocesium and plutonium found in the oceans and seas has increased enormously in the past years as a consequence of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident and is expected to be ongoing due to many unresolved questions. Hence, continuous development of new and verification of old analytical methods should be at the top of the list of the community, working on the topic. In this study, we processed and analyzed several seawater samples, collected in different time frames (2011-2015) from the North Pacific Ocean offshore Fukushima, to determine their radiocesium activities, Cs/Cs activity ratios and Pu/Pu isotopic ratios using the sequential scavenging method, gamma spectrometry and accelerator mass spectrometry (AMS).

Ten years of investigations of Fukushima radionuclides in the environment: A review on process studies in environmental compartments.

In March 2011, severe nuclear accident happened at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) after the gigantic earthquake and following huge tsunami wave. A lot of investigations to assess environmental and radiological impacts of released radionuclides have been conducted by domestic and international organizations. Environmental radioactivity research related to the FDNPP accident has spread widely over different scientific fields due to specific features of the accident, and specifically its impact on the marine environment.

Distribution of Am and Pu isotopes in the Curonian Lagoon and the south-eastern Baltic Sea seawater, suspended particles, sediments and biota.

Distribution trends and temporal variations of Am and Pu isotopes in the south-eastern Baltic Sea during the study period of 1999-2001 and 2011-2015 were investigated with the aim to study temporal changes of radionuclide levels in seawater, suspended particles and sediment, to estimate Am and Pu levels in marine biota and to assess the radiation doses received by the biota. The activities of Am and Pu were measured by alpha spectrometry after radiochemical purification. Pu was determined radiometrically via the ingrown daughter Am after 10-12 years of storage, while the Pu/Pu atom ratio of was measured by accelerator mass spectrometry.

Temporal variability of plutonium in surface waters of the Sea of Japan.

Long-term temporal variations of plutonium in Sea of Japan (SOJ) surface waters have been examined with the aim to better understand its behavior during several decades. The first observation is that Pu activity concentrations in surface waters of the SOJ during 1977-2019 were 6.5 ± 4.

Hemispheric infiltrative grade II gliomas in adults: association of residual tumour volume and extent of tumour resection with malignant transformation.

Objectives: Evaluation of the impact of surgical treatment on malignant transformation (MT) of adult supratentorial infiltrative grade II gliomas (G2G) in a series of chemotherapy and radiotherapy-naïve patients.

Background: Despite G2G are slow-growing tumours, they typically undergo MT with a subsequent fatal disease course. An extensive resection alone likely changes their biological behaviour and defers MT; however, this impact is not unequivocally confirmed.

Europe-Wide Atmospheric Radionuclide Dispersion by Unprecedented Wildfires in the Chernobyl Exclusion Zone, April 2020.

From early April 2020, wildfires raged in the highly contaminated areas around the Chernobyl nuclear power plant (CNPP), Ukraine. For about 4 weeks, the fires spread around and into the Chernobyl exclusion zone (CEZ) and came within a few kilometers of both the CNPP and radioactive waste storage facilities. Wildfires occurred on several occasions throughout the month of April.

Determination of ultra-trace levels of uranium and thorium in electrolytic copper using radiochemical neutron activation analysis.

Uranium and thorium as natural radioactive elements are present everywhere in the environment. Their trace levels are also present in various materials, such as copper, used as a shielding material in gamma-ray spectrometry, usually located very close to the detector. Ultra-low levels of uranium and thorium in electrolytic copper were determined in this study using radiochemical neutron activation analysis (RNAA) via their induced nuclides U-239/Np-239 and Pa-233, respectively.

The neutron component of background of an HPGe detector operating in a surface laboratory.

Investigation of neutron-induced background was carried out by studying interactions of cosmic-ray neutrons with an HPGe detector inside its shield placed on a ground floor of a 3-storey building. The study was conducted experimentally and by Monte Carlo simulations using GEANT4 simulation tool. Detailed analysis of measured background γ-ray spectra showed that many γ-lines visible in the spectra were induced by neutrons.

Radiocarbon analysis of carbonaceous aerosols in Bratislava, Slovakia.

Aerosols dispersed in the atmosphere represent important factors influencing not only the environment, but also human health. Carbonaceous aerosols are one of the main components of total atmospheric aerosols, and their sources are of great interest. Radiocarbon analysis provides an excellent way to determine the fraction of fossil and non-fossil aerosols in the atmosphere.

Temporal changes in tritium and radiocarbon concentrations in the western North Pacific Ocean (1993-2012).

The western North Pacific is one of the most studied oceanic basins due to its diverse structure and important role in connection with the adjacent reservoirs. Tritium (H) and radiocarbon (C) have been frequently exploited as oceanographic tracers due to their suitable properties; several extensive observation projects, such as GEOSECS, WOCE and WOMARS, used these two radionuclides to investigate different oceanographic processes, pathways, ocean currents and time scales of deep and bottom water formation. Here we evaluate temporal changes in H and C levels in seawater of the western North Pacific Ocean from 1993 to 2012.

Radiocarbon in tree rings from a clean air region in Slovakia.

In order to study radiocarbon levels at a clean air location in Slovakia with no significant local anthropogenic effects, we took tree ring samples from a tree in the vicinity of Jasná recreational area in the Low Tatras region in the central part of Slovakia. There are no significant local fossil fuel emission sources, so these samples represent a regional clean air background important for C studies in Slovakia and Central Europe. The growth rings from the sampled tree (European spruce, Picea abies) cover the period from 1911 to 2016.