Hasil untuk "Radioactivity and radioactive substances"

F. D. Amaro, R. Antonietti, E. Baracchini et al.

Dark matter, which is considered to account for approximately the 27% of the Universe's energy-mass content, remains an open issue in modern particle physics along with its composition. The CYGNO Experiment aims to exploit an innovative approach applied to the direct detection search of low energy nuclear recoils possibly induced by cold particle-like dark matter candidates. CYGNO employs a directional detector based on a Time Projection Chamber (TPC) filled with a He:CF$_{4}$ gas mixture and equipped with an optical readout. Currently, the CYGNO Collaboration is constructing the detector demonstrator, CYGNO-04, in Hall F at Laboratori Nazionali del Gran Sasso (LNGS). This 0.4 m$^3$ detector has the goal of proving the scalability of the technology and assessing the physics and radiopurity capabilities. Given the low radioactivity requirements, especially in internal components such as field cage and cathode, the reduction of material while keeping the correct electrical behavior is paramount. In this paper, we present the validation of several internal components, mainly focusing on the field cage material and support structure. The tests included geometrical asymmetries in the electric field response, collection efficiency as well as measurement of known physical quantities. A preferred configuration is found with a structure based on Nylon material which supports a PET or Kapton sheet with copper strips deposited on.

Thamyra Cybelle Vieira dos Santos, Dayana Azeredo da Conceição, José Ubiratan Delgado

The combination therapy approaches are gaining popularity, particularly the radiopharmaceutical therapy with external radiotherapy, immunotherapy or both. Radioembolization using Yttrium-90 Microspheres, SIR-Spheres and TheraSphere, has been used clinically in the treatment of locally advanced and unresectable Hepatic Carcinomas. According to the literature, the standardization of microspheres is not yet well established. In view of the practice of 90Y in therapies in Brazil, it is essential to develop solid standards for its measurement, in order to verify the absorbed radiation dose and its administration to the patient. This paper proposes a study of the existing standardization infrastructure for 90Y microspheres through a literature review and analysis of the measuring instruments available at the National Laboratory for Ionizing Radiation Metrology, a general analysis was made of the spectrometry and calibration methods available in Brazil, specifically at LNMRI, evaluating those suitable for use in the standardization of Yttrium microspheres. The results showed that in the period between 2000 and 2024 90Y was widely cited in treatment by radioembolization with microspheres, qualitative and quantitative evaluation of the activity quantity in PET/CT scans and its metrological characterization involving proficiency tests, study of impurities, standardization by primary and secondary methods

P. S. Druzhinina

In modern clinical practice, multiple computed tomography examinations are increasingly common, which can lead to the accumulation of significant effective doses of patients. The aim of this study was to identify cases of high cumulative effective doses (more than 100 mSv) of adult patients undergoing computed tomography examinations in two departments of the Leningrad Regional Clinical Oncological Dispensary. Materials and Methods. The study is based on the analysis of patient effective dose data obtained from computed tomography examination logbooks for the periods 2020–2021 (Department No. 1) and 2019–2021 (Department No. 2). Effective doses were calculated based on dose-length product values using appropriate conversion coefficients in accordance with methodological guidelines MU 2.6.1.3584-19. Results. The study results showed that in Department No. 1, 1 % of patients (18 individuals) received cumulative doses exceeding 100 mSv, with a maximum value of 239 mSv. In Department No. 2, the corresponding figure was 0.3 % (9 individuals), with a maximum dose of 147 mSv. The dose accumulated over both extended periods (up to a year) and short intervals (less than a month). A comparison of the obtained results with international data showed that cumulative effective doses more than 100 mSv are often observed in non-oncological patients, including patients under the age of 40. In the study sample, most patients were over 40 years old. Justification and optimization of computed tomography examinations are the main tools for managing high cumulative effective doses in patients. It is important to emphasize the need to assess not only effective but also absorbed organ doses during multiple computed tomography examinations, especially when planning radiation therapy. Conclusions. Systematic monitoring of high cumulative effective doses in patients is necessary in the Russian Federation, particularly among younger patients.

Angélica Bueno Barbezan, Ana Carolina de Araújo Bispo, Bruno Melo Mendes et al.

This study investigates the potential mutagenic and genotoxic effects of 2-Alkylcyclobutanones (2-ACBs), by-products formed in irradiated foods. 2-ACBs are compounds derived from the irradiation of fat-containing foods, with recognized genotoxic potential. The research focused on the compounds 2-dodecylcyclobutanone (2-dDCB) and 2-tetradecylcyclobutanone (2-tDCB), evaluating their mutagenicity through the micronucleus assay in hepatic cell lines (HepG2, BRL3A, and HTC) and genotoxicity through the Ames test using five bacterial strains (TA-98, TA-100, TA-1535, TA-1537, and WP2uvrA). Results from the Ames test indicated that 2-dDCB and 2-tDCB did not significantly increase mutagenic reversion rates, while the micronucleus assays showed no genotoxic damage in the tested cell lines. It is concluded that, at the evaluated concentrations, the compounds 2-dDCB and 2-tDCB do not exhibit mutagenic or genotoxic potential, supporting the safety of irradiated foods. However, further research is recommended to assess long-term effects and different irradiation conditions.

Fan NING, Shu-ping TAN, Li-fei ZHAO et al.

The dust and soil contaminated during the decommissioning process of nuclear facilities need to be sorted into radioactive waste and sent to the disposal site for disposal. According to the document requirements of “Radioactive Waste Classification”, technetium(Tc), as one of the important radionuclides in nuclear waste management, needs to accurately measure its radioactive activity concentration. The analysis process of 99Tc in dust and soil mainly includes four processes: sample pretreatment, chemical separation and purification, source preparation and measurement. At present, technetium is extracted from the sample matrix by leaching method, total dissolution method or alkali fusion method, and then one or more methods are combined by co-precipitation method, solvent extraction, ion exchange, extraction chromatography and other separation methods for purification, removal of interfering components, and finally determination by liquid scintillation counting or mass spectrometry. The whole pre-processing process is tedious and takes several hours to several days, which takes a long time. Due to the high temperature volatilization of technetium oxide(Tc2O7), the high temperature volatilization method can be used to extract technetium from dust and soil samples, effectively remove the matrix and non-volatile interference substances, and obtain a simpler solution composition, making the subsequent purification steps simpler. In terms of measurement, the beta counting method uses the radioactivity of 99Tc(T1/2=2.1×105 a). Although the source is simple and easy to use, due to the long half-life of 99Tc, it is necessary to measure large samples for a long time to meet the detection requirements when analyzing low-level samples. Inductively coupled plasma mass spectrometry(ICP-MS) is widely used in the analysis of long-lived radionuclides because of its fast analysis speed, high sensitivity and low detection limit. Rhenium(Re) and technetium(Tc) are members of the ⅦB group and have similarities in electron layer structure, atomic radius, solubility, thermal stability and volatility. A high temperature oxidation inductively coupled plasma mass spectrometry(ICP-MS) method was developed for the determination of rhenium in soil by replacing technetium with rhenium. The results show that when the high temperature oxidation temperature is 1100 ℃, the flow rate of argon and oxygen is 200 mL/min, the high temperature oxidation time is 15 min, the simulated soil sample is treated with 10 mL 1.0 mol/L Na2CO3 solution as the absorption solution, and the ICP-MS measurement is carried out. The recovery of rhenium in soil is 89%-99%, and the relative standard deviation of the method is 4.5%(n=6)(rhenium mass concentration is 10 μg/g). It provides a method basis and separation scheme for the determination of 99Tc in the dust of decommissioning facilities.

T. Stetz, H. Mayr, V. Werner et al.

The $M1$ transition strengths between excited $2^+$ states of the neutron-rich, radioactive nuclide $^{132}$Te have been studied through direct lifetime measurements using the Doppler-shift attenuation method in a two-neutron transfer reaction on a $^{130}$Te target. An unambiguous identification of the lowest-lying mixed-symmetry $2^+$ state has been achieved on the basis of the large $B(M1;2^+_2\rightarrow2^+_1$)=0.18(2) $μ_\mathrm{N}^2$ transition strength, in agreement with shell-model calculations. Results are compared to the shell model, and the analysis of both, data and calculations, unambiguously identifies the second-excited $2^+$ state of $^{132}$Te as the one-quadrupole phonon mixed-symmetry state of this isotope. A lowering of the energy and $B(M1;2^+_\mathrm{ms}\rightarrow 2^+_1)$ strength within the $N$=80 isotones toward the $Z$=50 shell closure is observed, which goes alongside with the lowering of the $E2$ collectivity approaching the magic proton shell.

Brígida Gomes de Almeida Schirmer, Isabela Conceição Duarte Dornelas, Letícia de Avelar Ferreira et al.

Positron emission tomography (PET) is one of the most sensitive and effective imaging techniques for detecting very low concentrations of specific radiotracers. It is suitable for analyzing biochemical, metabolic, physiological and functional information at the molecular level in vivo and non-invasively. PET using 2-deoxy-2[18F]-fluoro-D-glucose ([18F]FDG) can be used to identify sites of inflammation and other pathologies and to monitor the efficacy of treatment. This technique can be used to study the effect of rosmarinic acid (RA) in various preclinical models. RA is a natural compound with promising antioxidant and anti-inflammatory effects. Therefore, the aim of this study is to investigate the anti-inflammatory potential of RA and the efficacy of PET/[18F]FDG in localizing inflammation and assessing response to treatment. A sponge implant model in mice was used for this purpose. All experiments were performed with male BALB/c mice aged 6 to 9 weeks and weighing 18 to 22 g, with 5 animals per group (10 animals in total throughout the study). Methods: The mice were implanted with sponge-like polyurethane discs to induce local inflammation. The animals were divided into two experimental groups: those treated with a vehicle and those treated with RA. PET scans with [18F]FDG were performed to evaluate the inflammatory process. Results: The results obtained with [18F]FDG showed a decrease in inflammatory cell infiltrates in the sponge after treatment with RA. Conclusion: The use of [18F]FDG demonstrated its efficacy in quantitatively evaluating the inflammatory process in the mouse subcutaneous sponge model as well as the anti-inflammatory effect of RA.

M. R. Gual, M. C. Maturana, Hugo da Costa Romberg Júnior et al.

The growing demand for electricity, increasing rising fossil fuel prices and global warming in Brazil, together with the lack of access to electricity on the part of the population in certain locations in the Northern Region, such as, for example, Rondônia, Pará and Amazonas, is currently seeking for solutions. The objective of the present study is to carry out a Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis of the inclusion of a project of a floating nuclear power plants (FNPP) in Brazil with a view to solving the lack of electricity in homes and in industries located in remote regions of Brazil. Study results identified several socioeconomic and environmental impacts on this regions. The study concludes that in addition to contributing to the solution of the lack of energy in remote regions, the implementation of this proposal could represent in the future a source of inflow of financial resources in the country and of international collaboration. This SWOT study will encourage investors, researchers, engineers and decision makers to open the debate about the benefit of using a FNPP in Brazil, which in addition to providing economic energy rates for the population, would be a profitable business and an international collaboration.

Adriana de Souza Medeiros Batista, Marlon Santos Silva, Priscila do Carmo Santana

Os exames de imagem considerados de alto custo vantagens diagnósticas apresentam que os tornam relevantes no contexto da saúde pública. Tomografia Emissão de Pósitron exemplos associados à Tomografia Computadorizada realizada com fluorodesoxiglicose ( 18 F-PET-CT) é um exame de alto custo, mas estratégico para o diagnóstico e acompanhamento de doenças que podem ser por meio do metabolismo da glicose nenhum organismo. O presente trabalho deste exame proposta uma discussão sobre a disponibilização do Sistema Único de Saúde (SUS), do Sistema Único de Saúde (SUS), demonstra os seus valores diagnósticos e a inclusão progressiva no rol de exames reembols. exames.Para tanto, foram utilizados dados de exames realizados no Centro de Tecnologia Molecular - Faculdade de Medicina/UFMG (CTMM-FM/UFMG), pagos de forma particular ao longo dos anos de 2012-2019. Os resultados associados indicam uma busca contínua pelo exame para casos ao diagnóstico, estadiamento e acompanhamento do tratamento oncológico, principalmente Linfomas.

G. Lotay, S. A. Gillespie, M. Williams et al.

We have performed the first direct measurement of the 83Rb(p,g) radiative capture reaction cross section in inverse kinematics using a radioactive beam of 83Rb at incident energies of 2.4 and 2.7 A MeV. The measured cross section at an effective relative kinetic energy of Ecm = 2.393 MeV, which lies within the relevant energy window for core collapse supernovae, is smaller than the prediction of statistical model calculations. This leads to the abundance of 84Sr produced in the astrophysical p process being higher than previously calculated. Moreover, the discrepancy of the present data with theoretical predictions indicates that further experimental investigation of p-process reactions involving unstable projectiles is clearly warranted.

G. Saxena, M. Kumawat, R. Sharma et al.

The exotic phenomenon of two-neutron halos and 2n-radioactivity are explored in the neutron-rich $^{40,42,44}$Mg by employing various variants of the relativistic mean-field approach. The extended tail of spatial density distributions including the enhanced neutron radii and skin thickness, pairing correlations, single-particle spectrum and wave functions predict $^{40,42,44}$Mg to be strong candidates for deformed neutron halos. Weakening of magicity at N$=$28 plays a significant role in the existence of a weakly bound halo in $^{40}$Mg which is currently the heaviest isotope of Mg accessible experimentally. Large deformation, mixing of f-p shell Nilsson orbitals and the valence neutron occupancy of p-states leads to a reduced centrifugal barrier and broader spatial density distributions that favour 2n-radioactivity in $^{42,44}$Mg.

Reginaldo Anderson Silva, Ademar de Oliveira Ferreira

The present study aims to optimize the passive methodology with Solid state Nuclear Track Detector (SSNTD) called the sealed can technique in the physics laboratory of the Federal Institute of Paraná - Telêmaco Borba Campus. The work used a polycarbonate polymer as detector because it is a polycarbonate of national manufacture and of low cost. A factorial design was carried out with three variables, one with two levels, one with three levels and one with four levels, totaling 24 experiments. The factors evaluated were the volume of the sealed can (1000 ml, 300 ml and 200 ml), chemical attack time (1 h, 2 h, 3 h and 4 h) and the chemical attack solution (solution A, PEW-40 and solution B, KOH- 70). In all 24 experiments the can was sealed with aliquots of the same geological sample for 38 days before chemical revelation and counting of the tracks. The results showed that solution B can be discarded due to the low concentration of tracks obtained in all 12 experiments performed with it. The results for solution A showed that the highest concentration of tracks is obtained for the chemical revelation time of 3 h, regardless of volume, and that the volume of 300 ml is the best result. Thus the conclusion of the study is that solution A in the volume of 300 ml and with chemical revelation time of 3 h is the optimal procedure for the development of the tracks.

Thais Braga Teixeira, Clédola Cássia Oliveira de Tello

Brazilian National Nuclear Energy Commission – CNEN – is responsible to build a repository for the low and intermediate--level radioactive wastes generated in Brazil. In accordance of Brazilian legislation it will be a near surface one. In the repository, treated waste will be stored, which will be surrounded by engineering and natural barriers, in order to prevent the release of radionuclides, during the required time to their decay to the limit levels. The focus of this study is to characterize the expanded vermiculite, which can be used as a natural barriers, over and under the engineering barriers and also as a backfill. They have the function of limiting water infiltration and stabilizing the disposal system, filling the empty spaces, controlling the gases and delaying the release of radionuclides. In this paper is presented the characterization of an expanded vermiculite. The tests to determine its physical chemical properties were based on a clay characterization Protocol. The granulometric analysis was performed using a sieving method. The moisture content was established by the gravimetric method of weight loss, and the specific surface area by the BET method. The helium ultrapicnometer method was used to determine the density. The microstructure was analyzed by X-ray diffraction and scanning electron microscopy. The results indicate that the studied vermiculite would be efficient as a natural barrier of the Brazilian surface repository, as the it presented a stable structure.

A. Aguilar-Arevalo, D. Amidei, D. Baxter et al.

We present measurements of bulk radiocontaminants in the high-resistivity silicon CCDs from the DAMIC at SNOLAB experiment. We utilize the exquisite spatial resolution of CCDs to discriminate between $α$ and $β$ decays, and to search with high efficiency for the spatially-correlated decays of various radioisotope sequences. Using spatially-correlated $β$ decays, we measure a bulk radioactive contamination of $^{32}$Si in the CCDs of $140 \pm 30$ $μ$Bq/kg, and place an upper limit on bulk $^{210}$Pb of $< 160~μ$Bq/kg. Using similar analyses of spatially-correlated bulk $α$ decays, we set limits of $< 11$ $μ$Bq/kg (0.9 ppt) on $^{238}$U and of $< 7.3$ $μ$Bq/kg (1.8 ppt) on $^{232}$Th. The ability of DAMIC CCDs to identify and reject spatially-coincident backgrounds, particularly from $^{32}$Si, has significant implications for the next generation of silicon-based dark matter experiments, where $β$'s from $^{32}$Si decay will likely be a dominant background. This capability demonstrates the readiness of the CCD technology to achieve kg-scale dark matter sensitivity.

D. T. Yordanov, D. Atanasov, M. L. Bissell et al.

Collinear laser spectroscopy is one of the essential tools for nuclear-structure studies. It allows nuclear electromagnetic properties of ground and isomeric states to be extracted with high experimental precision. Radioactive-beam facilities worldwide strive to introduce such capabilities or to improve existing ones. Here we present the implementation of collinear laser spectroscopy at the ALTO research laboratory, along with data from successful off-line commissioning using sodium beam. The instrumental constituents are discussed with emphasis on simple technical solutions and maximized use of standard equipment. Potential future applications are outlined.

P. A. Butler, L. P. Gaffney, P. Spagnoletti et al.

There is sparse direct experimental evidence that atomic nuclei can exhibit stable pear shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in radium isotopes, electric octupole ($E3$) matrix elements have been determined for transitions in $^{222,228}$Ra nuclei using the method of sub-barrier, multi-step Coulomb excitation. Beams of the radioactive radium isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of $E$3 matrix elements for different nuclear transitions is explained by describing $^{222}$Ra as pear-shaped with stable octupole deformation, while $^{228}$Ra behaves like an octupole vibrator.

Tadelech Sisay, Tilahun Tesfaye

In this study, the activity concentration of natural ( 238 U, 232 Th, 40 K) and artificial radionuclides (137 Cs) were measurements in six different brands of tea have been collected from local market in Ethiopia (Addis Ababa city). have been analyzed by a detection system consisting of High Purity Germanium (HPGe) detector and multichannel analyzer. The average activity concentrations were nuclide M D A report 238U, 232Th and 40 K respectively. The mean values were found 3.66$ \pm$0.47, 18.28$\pm $2.4 and 582.59$ \pm $29.64 Bq/kg respectively. The activity concentration of 40K is increasing faster than the other NORM for Tea. In order to evaluate the radiological hazard of the natural radioactivity, radium equivalent (Raeq ), the external hazard index (Hex), internal hazrd index (Hin) , the total absorbed dose rate (D), the annual effective dose equivalent (AEDE) have been calculated and compared with the international acceptable value.

Julien Guillot, Brigitte Roussière, Sandrine Tusseau-Nenez et al.

Producing intense radioactive beams, in particular those consisting of short-lived isotopes requires the control of the release efficiency. The released fractions of 11 elements were measured on 14 samples that were characterized by various physicochemical analyses in a correlated paper (Part 1). A multivariate statistical approach, using the principal component analysis, was performed to highlight the impact of the microstructure on the release properties. Samples that best release fission products consist of grains and aggregates with small size and display a high porosity distributed on small diameter pores. They were obtained applying a mixing of ground uranium dioxide and carbon nanotubes powders leading to homogeneous uranium carbide samples with a porous nanostructure. A modelling under on-line ALTO conditions was carried out using the FLUKA code to compare the yields released by an optimized and a conventional target.

Raquel Maia Mingote, Regina Apolinária Nogueira, Heliana Ferreira Da Costa

Detection of gross alpha and beta radioactivity is important for a quick surveying of both natural and anthropogenic radioactivity in water. Furthermore, gross alpha and gross beta parameters are included in Brazilian legislation on quality of drinking water. In this work, a low background liquid scintillation spectrometer was used to simultaneously determine gross alpha and gross beta in samples of the public water supplies in the state of Goiás, Brazil, during 2010-2015. Sample preparation involved evaporation to concentrate the sample ten-fold. The results indicate that the water meets the radioactivity standards required by the regulations MS 2914/2011 of the Brazilian Department of Health. Concerning the high level of censored observations, a statistical treatment of data was conducted by using analysis methods of censored data to provide a reference value of the gross alpha and beta radioactivity in drinking water from the state of Goiás. The estimated typical activities are very low, 0.030 Bq.L-1 and 0.058 Bq.L-1, for gross alpha and gross beta, respectively.