Low Background Radiation Research Articles

The Development and Application of Tritium-Labeled Compounds in Biomedical Research.

With low background radiation, tritiate compounds exclusively emit intense beta particles without structural changes. This makes them a useful tool in the drug discovery arsenal. Thanks to the recent rapid progress in tritium chemistry, the preparation and analysis of tritium-labeled compounds are now much easier, simpler, and cheaper. Pharmacokinetics, autoradiography, and protein binding studies have been much more efficient with the employment of tritium-labeled compounds. This review provides a comprehensive overview of tritium-labeled compounds regarding their properties, synthesis strategies, and applications.

Maser Activity of Organic Molecules toward Sgr B2(N)

At centimeter wavelengths, single-dish observations have suggested that the Sagittarius (Sgr) B2 molecular cloud at the Galactic Center hosts weak maser emission from several organic molecules, including CH2NH, HNCNH, and HCOOCH3. However, the lack of spatial distribution information on these new maser species has prevented us from assessing the excitation conditions of the maser emission as well as their pumping mechanisms. Here, we present a mapping study toward Sgr B2 north (N) to locate the region where the complex maser emission originates. We report the first detection of the Class I methanol (CH3OH) maser at 84 GHz and the first interferometric map of the methanimine (CH2NH) maser at 5.29 GHz toward this region. In addition, we present a tool for modeling and fitting the unsaturated molecular maser signals with non-LTE radiative transfer models and Bayesian analysis using the Markov Chain Monte Carlo approach. These enable us to quantitatively assess the observed spectral profiles. The results suggest a two-chain-clump model for explaining the intense CH3OH Class I maser emission toward a region with low continuum background radiation. By comparing the spatial origin and extent of maser emission from several molecular species, we find that the 5.29 GHz CH2NH maser has a close spatial relationship with the 84 GHz CH3OH Class I masers. This relationship serves as observational evidence to suggest a similar collisional pumping mechanism for these maser transitions.

Canfranc biology platform: exploring life in cosmic silence

Deep underground laboratory infrastructures have extensively been used for exploring rare events, such as proton decay, dark matter searches or neutrino interactions, taking advantage of their large muon flux reduction. However, only very few investigations have evaluated the effects of low background radiation environments on living organisms. With this purpose, the Canfranc Underground Laboratory (LSC) launched the Biology Platform in 2021, which provides lab space for approved biology experiments. Two identical laboratories have been built (underground and on surface) to replicate biology experiments under the same conditions, with the main difference being the cosmic radiation background. The access protocol to use the LSC facilities includes two open calls per year and assigned time windows for executing the experimental program, which led to the first eight approved and already running experiments. We describe the scientific program of the Canfranc Biology Platform, which explores extremophiles, viral infection, immune system, multicellularity, development or aging in cosmic silence, and the first experimental results. The Platform also allows to observe the response of life to microgravity in absence of radiation, a key condition to explore life in space.

Performance Comparison of DOI-Encoding PET Detectors Based on 1.1-mm Pitch BGO Arrays With Different Reflectors.

Bismuth germanate (BGO)-based positron emission tomography (PET) detectors are potential candidates for low-dose imaging PET scanners, owing to the high stopping power and low background radiation of BGO. In this paper, we compared the performance of two dual-ended readout PET detectors based on 15 × 15 BGO arrays. Both arrays had the same 1.1 mm pitch but utilized different reflectors - barium sulfate (BaSO4) and enhanced specular reflector film (ESR) - for high-resolution PET applications. The detectors were constructed with Hamamatsu 13361-2050-08 SiPM arrays. Each BGO element had dimensions of 1.02 × 1.02 × 20 mm3. The lateral surfaces of the BGO elements were unpolished (saw-cut), while the two ends were polished. Flood histograms showed that the detector based on the BGO array with BaSO4 reflector had much better crystal identification and depth-of-interaction (DOI) resolution. Specifically, the energy, DOI, and timing resolutions for the detector using the BGO array with BaSO4 reflector were 19.8 ± 1.5%, 4.13 ± 0.48 mm, and 2.80 ± 0.23 ns, respectively. In contrast, the values obtained using the BGO array with ESR reflector were 20.9 ± 2.1%, 7.69 ± 1.92 mm, and 2.93 ± 0.20 ns, respectively.

Overview of DISCOVER22 experiment in the framework of INFN-LNGS Cosmic Silence activity: challenges and improvements in underground radiobiology

One of the most intriguing and still pending questions in radiobiology is to understand whether and how natural environmental background radiation has shaped Life over millions of years of evolution on Earth. Deep Underground Laboratories (DULs) represent the ideal below-background exposure facilities where to address such a question. Among the few worldwide DULs, INFN-Laboratorio Nazionale del Gran Sasso (LNGS) is one of the largest in terms of size and infrastructure. Designed and built to host neutrino and dark matter experiments, since the 1990 s the LNGS has been one of the first DULs to systematically host radiobiology experiments. Here we present the DISCOVER22 (DNA Damage and Immune System Cooperation in VEry low Radiation environment 2022) experiment recently started at LNGS. DISCOVER22 aims at investigating how the low radiation background modulates the Immune System (IS) response in in vitro and in vivo models. Underground radiobiology experiments are particularly complex and tricky to design and perform. In these studies, the accurate characterization of exposure scenarios is mandatory, but a challenging aspect is to understand how the very few ionizing tracks in the ultra-Low Radiation Environment (LRE) interact with the living matter in space and time in order to trigger different biological responses. In this Perspective, we describe these challenges and how we address them through a microdosimetric and a radiobiological approaches. We aim at linking physical microdosimetric measurements and the corresponding biological radiation responses by using radiation biophysical models that could shed light on many as yet unresolved questions.

Vacuum large-aperture blackbody model in the temperature range 223.15–423.15 K for radiometric calibration of optoelectronic equipment for Earth observation

The structure of the systems for the radiometric calibration of the remote sensing optoelectronic equipment in the infrared spectral range is presented. The analysis of existing facilities for the radiometric calibration of the remote sensing optoelectronic equipment in conditions of vacuum and low-background radiation was carried out. These facilities are based on using of the blackbody models as radiation sources, including reference sources based on the phase transition of pure metals, for example gallium or indium. The wide-aperture blackbody model LABB-380 with an aperture diameter of 380 mm in the temperature range from 223.15 K up to 423.15 K has been developed for a high-vacuum low-background stand, which is currently being developed at the Sciences Research Institute of Optoelectronic Instrumentation for the radiometric calibration of the remote sensing optoelectronic equipment. The results of calculating the normal effective emissivity of the surface of the LABB-380 in the temperature range from 223.15 K to 423.15 K in the spectral range from 3 to 20 μm are presented. The metrological characteristics of LABB-380 obtained during the transmission of a temperature unit from the zero discharge State Standard using a comparator based on the precision pyrometer HETRONIXS are investigated and presented. The instability of the LABB-380 radiation was 0.005 K according to the calibration results in the temperature range from 300.15 K to 390.15 K, and the extended temperature uncertainty was 0.66 K at the temperature of 300.15 K and 0.88 K at a temperature of 390.15 K.

Investigation on the ultraviolet spectral radiation characteristics of two-phase flow plume based on OH and alumina particles.

Ultraviolet detection has advantages over radar and infrared detection, such as low background radiation and high resolution. The UV spectral radiation characteristics of exhaust plume are of extremely great research significance as the main parameters for aircraft detection. We used the BEM-2 two-phase flow plume as the object of study, calculated the scattering characteristics of alumina particles and the UV absorption coefficient of OH in the plume based on the MIE theory and the line-by-line integration method, established the UV radiation transfer model of aircraft plume under gas-solid coupling, simulated the UV spectral radiation characteristics of the plume, and compared them with experimental results. The results show that due to the drastic changes of temperature and pressure at the Mach and non-Mach disks in the plume, the value of OH absorption coefficient fluctuates up and down along the axial direction with the position of the Mach disk; at 261nm, 282nm, and 306nm, the spectral radiation intensity of alumina particles accounts for approximately 96%, 85%, and 73% of the total spectral radiation intensity of the plume, respectively, which are much higher than the proportion of OH gas spectral radiation intensity, but in the infrared wave band, the influence of particle scattering characteristics on the spectral radiation intensity of the plume is much lower compared to the UV wave band; the overall radial range of the UV spectral radiation intensity of the plume is relatively narrow and its tail exhibits a converging shape, showing a good consistency with the experimental results.

Progress in biological and medical research in the deep underground: an update.

As the growing population of individuals residing or working in deep underground spaces for prolonged periods, it has become imperative to understand the influence of factors in the deep underground environment (DUGE) on living systems. Heping Xie has conceptualized the concept of deep underground medicine to identify factors in the DUGE that can have either detrimental or beneficial effects on human health. Over the past few years, an increasing number of studies have explored the molecular mechanisms that underlie the biological impacts of factors in the DUGE on model organisms and humans. Here, we present a summary of the present landscape of biological and medical research conducted in deep underground laboratories and propose promising avenues for future investigations in this field. Most research demonstrates that low background radiation can trigger a stress response and affect the growth, organelles, oxidative stress, defense capacity, and metabolism of cells. Studies show that residing and/or working in the DUGE has detrimental effects on human health. Employees working in deep mines suffer from intense discomfort caused by high temperature and humidity, which increase with depth, and experience fatigue and sleep disturbance. The negative impacts of the DUGE on human health may be induced by changes in the metabolism of specific amino acids; however, the cellular pathways remain to be elucidated. Biological and medical research must continue in deep underground laboratories and mines to guarantee the safe probing of uncharted depths as humans utilize the deep underground space.

Oxidative genomic damage in humans exposed to high indoor radon levels in Northeast Brazil.

Radon gas inhalation is the main source of exposure to ionizing radiation by humans. There is still lack in knowledge concerning the chronic and indirect effects of exposure to this carcinogenic factor. Therefore, the aim of this work is to analyze the levels of oxidative genomic damage in inhabitants of a medium-high background radiation area (HBRA) (N=82) in Northeastern Brazil and compare them with people living in a low background radiation area (LBRA) (N=46). 8-hydroxy-2-deoxyguanosine (8-OHdG) was quantified in urine, Ser326Cys polymorphism was determined in the hOGG1 gene and indoor radon was measured. HBRA houses had 6.5 times higher indoor radon levels than those from LBRA (p-value < 0.001). The 8-OHdG mean (95% confidence interval) were significantly different, 8.42 (5.98-11.9) ng/mg creatinine and 29.91 (23.37-38.30) ng/mg creatinine for LBRA and HBRA, respectively. The variables representing lifestyle and environmental and occupational exposures did not have a significant association with oxidized guanosine concentrations. On the other hand, lower 8-OHdG values were observed in subjects that had one mutant allele (326Cys) in the hOGG1 gene than those who had both wild alleles (Ser/Ser (p-value < 0.05). It can be concluded that high radon levels have significantly influenced the genome oxidative metabolism and hOGG1 gene polymorphism would mediate the observed biological response.

Ultrahigh-Sensitivity and Fast-Speed Solar-Blind Ultraviolet Photodetector Based on a Broken-Gap van der Waals Heterodiode.

Broad-bandgap semiconductor-based solar-blind ultraviolet (SBUV) photodetectors have attracted considerable research interest because of their broad applications in missile plume tracking, flame detectors, environmental monitoring, and optical communications due to their solar-blind nature and high sensitivity with low background radiation. Owing to its high light absorption coefficient, abundance, and wide tunable bandgap of 2-2.6 eV, tin disulfide (SnS2) has emerged as one of the most promising compounds for application in UV-visible optoelectronic devices. However, SnS2 UV detectors have some undesirable properties such as slow response speed, high current noise level, and low specific detectivity. This study reports a metal mirror-enhanced Ta0.01W0.99Se2/SnS2 (TWS) van der Waals heterodiode-based SBUV photodetector with an ultrahigh photoresponsivity (R) of ∼1.85 × 104 AW-1 and a fast speed with rising time (τr) of 3.3 μs and decay time (τd) of 3.4 μs. Notably, the TWS heterodiode device exhibits a significantly low noise equivalent power of ∼1.02 × 10-18 W Hz-1/2 and a high specific detectivity of ∼3.65 × 1014 cm Hz1/2 W-1. This study provides an alternative method for designing fast-speed SBUV photodetectors with enormous potential in applications.

Radioactive source strength effect on gamma radiation monitoring with a NaI (Tl) scintillation detector

The accurate monitoring of gamma radiation doses in the environment has become essential due to its effect on human health. In this study, the temperature dependence of NaI (Tl) scintillation detectors based on the daily/annually measured dose rate in the environment as well as the importance of selecting the appropriate radioactive source strength when calibrating NaI (Tl) detectors for gamma radiation monitoring were investigated. The temperature correction coefficients discovered during the calibration of the BDKG-03 detector by Atomtex were verified, and whether the time duration of the measurement interval has an effect on readings of gamma radiation was also investigated in the city of Tomsk. NaI (Tl) scintillation detectors were used to monitor the gamma background radiation in the environment. The detectors were calibrated with both high and low radioactive sources to obtain a temperature correction coefficient in order to stabilize the influence of temperature change on the detector at different time intervals. This was used to study the correlation between the daily and annual dose rates of low gamma background radiation. The results showed that there was a shift in the spectrum of the daily and annual dose rates calculated using the algorithm obtained when the detector was calibrated with a highly radioactive source to the position of the constant coefficient for low-level dose. However, the ones obtained when the detector was calibrated with a low radioactive source and that of the constant coefficient for a low-level dose overlapped each other. This demonstrated that the type of radioactive source used in detector calibration during manufacture has an effect on the temperature correction coefficient, which in turn has an effect on the accuracy of the ambient dose rate when used to monitor gamma radiation. The duration of the time interval for measurement was found to be very important since it has an effect on dose rate readings.

Thermal optics of a collimator radiatively cooled under vacuum

Infrared optoelectronic equipment with cooled optics operating in a background limited mode is tested in a vacuum and a low radiation background. The latter is ensured by cooling the optical elements of the collimator and preventing direct illumination of the entrance pupil of the equipment by warm elements of the vacuum chamber. Subject of study. The thermal optics of a two-mirror collimator are investigated in this study. The mirrors of this collimator are cooled by heat transfer through infrared emission to the cooled cylindrical shields of the thermostat, which was specifically designed for collimator cooling. Method. The collimator cooling modes are calculated considering both thermophysical material properties and structural features of the elements comprised in the thermostat and collimator. The thermophysical model of thermal equilibrium in an isolated system of solid bodies is used in the calculations. The issue of selecting a particular material for the collimator mirrors is considered provisionally. The thermal stability of the mirror material calculated as a ratio of the coefficient of thermal expansion β to its heat conduction coefficient λ is used as a parameter determining the choice. Sitall, silicon, and silicon carbide were considered in this study as materials for infrared mirrors. Main results. The magnitude of thermal deformations is determined by not only the occurring temperature gradients in a plane mirror but also the variation in the curvature of the mirror surface under general cooling of the nonplanar mirrors. The maximum temperature gradient over the surface is observed for the mirrors composed of sitall. The temperature gradient in the mirror composed of silicon carbide is significantly smaller. This is related to the heat conduction coefficient of silicon carbide being 2 orders of magnitude higher than that of sitall. Consequently, the thermal deformations of the mirror surface are also smaller in the plane mirror composed of silicon carbide. These results correspond to the criterial parameter of thermal stability β/λ for each of the discussed materials. However, in the case of cooling of the nonplanar (spherical or aspherical) mirrors, the calculations show that their thermal deformations result from not only the nonuniformity of heat flow distribution over the mirror surface but also the general reduction in mirror temperature. Practical significance. When cooled infrared mirrors are used in optical systems, the appearance of thermal deformation of their mirror surface should be considered. This thermal deformation is determined by not only the occurring temperature gradients in the volume of the mirror material, but also the change in the curvature of the mirror surface. In this regard, the mirrors composed of sitall are preferable for use under thermal vacuum conditions over mirrors composed of silicon carbide.

A search for annihilating dark matter in 47 Tucanae and Omega Centauri

Abstract A plausible formation scenario for the Galactic globular clusters 47 Tucanae (47 Tuc) and Omega Centauri $(\omega$ Cen) is that they are tidally stripped remnants of dwarf galaxies, in which case they are likely to have retained a fraction of their dark matter cores. In this study, we have used the ultra-wide band receiver on the Parkes telescope (Murriyang) to place upper limits on the annihilation rate of exotic Light Dark Matter particles $(\chi)$ via the $\chi\chi\rightarrow e^+e^-$ channel using measurements of the recombination rate of positronium (Ps). This is an extension of a technique previously used to search for Ps in the Galactic Centre. However, by stacking of spectral data at multiple line frequencies, we have been able to improve sensitivity. Our measurements have resulted in $3-\sigma$ flux density (recombination rate) upper limits of 1.7 mJy $\left(1.4\times 10^{43}\, \mathrm{s}^{-1}\right)$ and 0.8 mJy $\left(1.1 \times 10^{43} \mathrm{s}^{-1}\right)$ for 47 Tuc and $\omega$ Cen, respectively. Within the Parkes beam at the cluster distances, which varies from 10–23 pc depending on the frequency of the recombination line, and for an assumed annihilation cross-section $\langle\sigma v\rangle = 3\times 10^{-29} \mathrm{cm}^3\, \mathrm{s}^{-1}$ , we calculate upper limits to the dark matter mass and rms dark matter density of ${\lesssim} 1.2-1.3\times 10^5 f_n^{-0.5}$ $\left(m_\chi/\mathrm{MeV\, c}^{-2}\right)$ $\mathrm{M}_{\odot}$ and ${\lesssim} 48-54 f_n^{-0.5}$ $\left(m_\chi/\mathrm{MeV\, c}^{-2}\right)$ $\mathrm{M}_{\odot} \mathrm{pc}^{-3}$ for the clusters, where $f_n=R_n/R_p$ is the ratio of Ps recombination transitions to annihilations, estimated to be ${\sim}0.01$ . The radio limits for $\omega$ Cen suggest that, for a fiducial dark/luminous mass ratio of ${\sim}0.05$ , any contribution from Light Dark Matter is small unless $\langle\sigma v\rangle &lt; 7.9\times 10^{-28}\ \left(m_\chi/\mathrm{MeV\, c}^{-2}\right)^2 \mathrm{cm}^3 \mathrm{s}^{-1}$ . Owing to the compactness and proximity of the clusters, archival 511-keV measurements suggest even tighter limits than permitted by CMB anisotropies, $\langle\sigma v\rangle &lt; 8.6\times 10^{-31}\ (m_\chi/\mathrm{MeV\, c}^{-2})^2 \mathrm{cm}^3 \mathrm{s}^{-1}$ . Due to the very low synchrotron radiation background, our recombination rate limits substantially improve on previous radio limits for the Milky Way.

Whole Transcriptome Analysis Revealed a Stress Response to Deep Underground Environment Conditions in Chinese Hamster V79 Lung Fibroblast Cells.

Background: Prior studies have shown that the proliferation of V79 lung fibroblast cells could be inhibited by low background radiation (LBR) in deep underground laboratory (DUGL). In the current study, we revealed further molecular changes by performing whole transcriptome analysis on the expression profiles of long non-coding RNA (lncRNA), messenger RNA (mRNA), circular RNA (circRNA) and microRNA (miRNA) in V79 cells cultured for two days in a DUGL.Methods: Whole transcriptome analysis including lncRNA, mRNAs, circ RNA and miRNA was performed in V79 cells cultured for two days in DUGL and above ground laboratory (AGL), respectively. The differentially expressed (DE) lncRNA, mRNA, circRNA, and miRNA in V79 cells were identified by the comparison between DUGL and AGL groups. Quantitative real-time polymerase chain reaction(qRT-PCR)was conducted to verify the selected RNA sequencings. Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway was analyzed for the DE mRNAs which enabled to predict target genes of lncRNA and host genes of circRNA.Results: With |log2(Fold-change)| ≥ 1.0 and p < 0.05, a total of 1257 mRNAs (353 mRNAs up-regulated, 904 mRNAs down-regulated), 866 lncRNAs (145 lncRNAs up-regulated, 721 lncRNAs down-regulated), and 474 circRNAs (247 circRNAs up-regulated, 227 circRNAs down-regulated) were significantly altered between the two groups. There was no significant difference in miRNA between the two groups. The altered RNA profiles were mainly discovered in lncRNAs, mRNAs and circRNAs. DE RNAs were involved in many pathways including ECM-RI, PI3K-Akt signaling, RNA transport and the cell cycle under the LBR stress of the deep underground environment.Conclusion: Taken together, these results suggest that the LBR in the DUGL could induce transcriptional repression, thus reducing metabolic process and reprogramming the overall gene expression profile in V79 cells.

On the Achievable Rate and Capacity for a Sample-Based Practical Photon-Counting Receiver

We investigate the achievable rate and capacity of a non-perfect photon-counting receiver. For the case of long symbol duration, the achievable rate under on-off keying modulation is investigated based on Kullback-Leibler (KL) divergence and Chernoff $\alpha$-divergence. We prove the tightness of the derived bounds for large peak power with zero background radiation with exponential convergence rate, and for low peak power of order two convergence rate. For large peak power with fixed background radiation and low background radiation with fixed peak power, the proposed bound gap is a small positive value for low background radiation and large peak power, respectively. Moreover, we propose an approximation on the achievable rate in the low background radiation and long symbol duration regime, which is more accurate compared with the derived upper and lower bounds in the medium signal to noise ratio (SNR) regime. For the symbol duration that can be sufficiently small, the capacity and the optimal duty cycle are is investigated. We show that the capacity approaches that of continuous Poisson capacity as $T_s=\tau\to0$. The asymptotic capacity is analyzed for low and large peak power. Compared with the continuous Poisson capacity, the capacity of a non-perfect receiver is almost lossless and loss with attenuation for low peak power given zero background radiation and nonzero background radiation, respectively. For large peak power, the capacity with a non-perfect receiver converges, while that of continuous Poisson capacity channel linearly increases. The above theoretical results are extensively validated by numerical results.

First transcriptome profiling of D. melanogaster after development in a deep underground low radiation background laboratory.

Natural background radiation is a permanent multicomponent factor. It has an influence on biological organisms, but effects of its deprivation still remain unclear. The aim of our work was to study for the first time responses of D. melanogaster to conditions of the Deep Underground Low-Background Laboratory DULB-4900 (BNO, INR, RAS, Russia) at the transcriptome level by RNA-seq profiling. Overall 77 transcripts demonstrated differential abundance between flies exposed to low and natural background radiation. Enriched biological process functional categories were established for all genes with differential expression. The results showed down-regulation of primary metabolic processes and up-regulation of both the immune system process and the response to stimuli. The comparative analysis of our data and publicly available transcriptome data on D. melanogaster exposed to low and high doses of ionizing radiation did not reveal common DEGs in them. We hypothesize that the observed changes in gene expression can be explained by the influence of the underground conditions in DULB-4900, in particular, by the lack of stimuli. Thus, our study challenges the validity of the LNT model for the region of background radiation doses below a certain level (~16.4 nGy h-1) and the presence of a dose threshold for D. melanogaster.

Background radiation impacts human longevity and cancer mortality: reconsidering the linear no-threshold paradigm.

The current linearno-threshold paradigm assumes that any exposure to ionizing radiation carries some risk, thus every effort should be made to maintain the exposures as low as possible. We examined whether background radiation impacts human longevity and cancer mortality. Our data covered the entire US population of the 3139 US counties, encompassing over 320million people. This is the first large-scale study which takes into account the two major sources of background radiation (terrestrial radiation and cosmic radiation), covering the entire US population. Here, we show that life expectancy, the most integrative index of population health, was approximately 2.5years longer in people living in areas with a relatively high vs. low background radiation. (≥ 180 mrem/year and ≤ 100 mrem/year, respectively; p < 0.005; 95% confidence interval [CI]). This radiation-induced lifespan extension could to a great extent be associated with the decrease in cancer mortality rate observed for several common cancers (lung, pancreas and colon cancers for both genders, and brain and bladder cancers for males only; p < 0.05; 95% CI). Exposure to a high background radiation displays clear beneficial health effects in humans. These hormetic effects provide clear indications for re-considering the linear no-threshold paradigm, at least within the natural range of low-dose radiation.

Biological Effects of Low Background Radiation: Prospects for Future Research in the Low-Background Laboratory DULB-4900 of Baksan Neutrino Observatory INR RAS

Study of the effects of low background radiation on biological systems is a new field in radiation biology. Due to the availability of new experimental methods, studies of the problem of adaptation to low background radiation conditions entered an even more dynamic stage in 2015–2019. Genomic stability/variability during prolonged exposure to low background radiation conditions and the positive/negative effects of the absence of natural background radiation on living organisms are the most debated issues. The data obtained by different scientific teams do not allow obtaining a universal model explaining the observed events. This report discusses currently accumulated experimental data, requirements for work under conditions of low background radiation, and prospects of cooperation work between JINR and BNO INR RAS in carrying out biological experiments under unique conditions of the low-background laboratory DULB-4900.

SPECTROMETRIC AND RADIOMETRIC TECHNIQUES OF NUCLEAR RADIATIONS IN THE ASSESSMENT OF ENVIRONMENTAL RADIOACTIVITY

The paper contains a synthesis of research results in the study of the level of environmental radioactivity obtained by using spectrometric technique, of high precision and high sensitivity, of atomic and nuclear radiations. Spectrometric technique were used to measure gamma nuclear radiation in determining the radioactivity of ash samples taken from the dumps of the ROMAG TERMO Drobeta Turnu Severin thermal power plant, Mehedinți county. By gamma spectrometry with high energy resolution semiconductor detector, high efficiency and protection for the cosmic radiation background (low radiation background) was determined the radioactivity of ash samples, taken from two coal dumps from ROMAG TERMO Drobeta Turnu Severin power plants, Romania. The results showed that the activities of the main radionuclides in the environmental samples including, 228Ac (7.5 ÷ 18.7 Bq/kg), 226Ra (6.2 ÷ 21.3 Bq/kg), 137Cs (0.3 ÷ 1, 53(Bq/kg) and 40K (169 ÷ 362 Bq/kg) are among the lowest values found compared to the maximum allowed limits.

Estimation of Concentration of Naturally Occurring Radioactivity and Radiation Hazards, in Iron Ore Deposit Soil from Wag-Himra Zone, Ethiopia

The current study looked at the concentration of naturally occurring radioactivity and radiation hazards in iron ore deposited in soil. The aim of this study was to identify the dose of radiation which is emitted from rocks, soil and some building materials, the radiation dose and the effect in the area. In this work, analyses of the sample soils were performed with a computer-based gamma-spectrometry system with software of G-2000 for qualitative and quantitative determination of gamma-emitting radionuclide of natural occurrence of radioactive materials. The quantitative investigation of natural radioactive materials of ²³⁸U, ²³²Th and ⁴⁰K were 11.688±0.42Bq/kg, 23.505±0.925Bq/kg and 141.48±4.403Bq/kg respectively. In addition to this, the results of absorbed dose rate, annual effective dose equivalent, radium equivalent activity and representative gamma index of the sample were much less as compared to recommended international values by UNSCEAR-2000. At low activity concentrations of the radionuclides produce low background radiation to the environment. The value obtained from the experiment reveals that the radiation hazards emitted by natural radionuclides in the soil cause insignificant harm to the public from the Wag-himra iron ore deposit soil. The concentration of natural radioactive elements in this area's soil could be used for construction purposes without causing any significant radiological hazards to humans for the time being.