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Item type:Publication, Theoretical and experimental study of the LR-115 detector response in a non-commercial radon monitor(Elsevier, 2020-06-01)B.trαcks, a simulation program for SSNTD's sensitivity, has been developed to study the response of LR-115 (cellulose nitrate) and CR-39 (poly allyl glycol carbonate) nuclear track detectors. Detectors are located inside detector holders and are used for radon measurements. The program incorporates a variety of special features gathered together to achieve good agreement between theoretical approach and experimental results. The input parameters to study the detector response are radon exposure, geometry and dimensions of a detector holder (it can be cylindrical, conical or semi-spherical), entrance type for radon gas, detector type, and V function (four different functions were selected from literature). The output results are detector response and radon progeny distribution onto internal chamber walls. In this article, the response of the LR-115, which is placed inside a non-commercial-conductive radon monitor based on diffusion chambers called G2, was theoretically and experimentally studied. The common Monte Carlo simulation procedure and an alternative approach that replicates how monitors are exposed to different radon exposures were used as theoretical approaches. Experimental methodology was conducted in a radon test chamber from Italy (MI.AM s.r.l.). Comparison results of both theoretical and experimental methodology are presented and discussed. One of the major results, among others, shows that the monitor material (conductive or non-conductive) does not influence the LR-115 response. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Simple and low cost alternative method for detecting photoneutrons produced in some radiotherapy treatments using SSNTDs(Elsevier, 2020-07-01)A simple and low cost alternative which is able to identify thermal and fast neutrons in a clinical environment of radiotherapy is presented. CR-39 and LR-115 Solid State Nuclear Track Detectors (SSNTDs) were used, estimating their viability. In order to register alpha tracks due to thermal neutrons, natural boric acid tablets were placed in close contact to the detector, whereas in order to detect epithermal neutrons, some were additionally covered in a thin cadmium layer. Different configurations were assembled, changing the position of the converter with respect to the detector and the incident neutron fluence, which was evaluated in different positions of a radiotherapy table. The contribution due to environmental 222Rn and its daughters to the track density registered by the detector during the measurements was found to be negligible. It is concluded that the designed experimental set up constitutes a trustworthy and affordable method to carry out neutron measurements with the recommended configurations provided for the CR-39 detector, and not with LR-115. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Nuclear track detector response to energetic heavy ions: study case(Springer, 2020-05-01)Nuclear track methodology (NTM), is employed to analyze PADC detectors response to different energetic ion beams. Due to the passive device linearity response to heavy ions with LET-value > 30 keV μm−1, they are employed in several fields e.g. nuclear industry, medical, environmental radiation and aircraft dosimetry. To further improve application, PADC-detectors were irradiated by beams of 4He (150 MeV nucleon−1), 12C (390 MeV nucleon−1) and 56Fe (465 MeV nucleon−1), in relatively low-dose range ≤ 1 mGy. Results provided, through etched track analysis, valuable information of interest for NTM when high LET ionizing radiation is involved. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Overlapping correction suitable for an LR-115 detector located inside a diffusion chamber(Elsevier, 2021-07-01)A simulation program based on Monte Carlo methods was developed to study the behaviour of the overlapping effect in the LR-115 nuclear track detectors located inside a diffusion chamber. The relation between the non-overlapped tracks and the radon exposure level that the detector was exposed was adopted. This study focuses on very high radon concentration levels found in soil gas, uranium mines, or underground places. These anomalous levels can influence the radiological risk related to inhalation of indoor radon or the spontaneous increases in thermal neutron background. LR-115 detector exposed to anomalous levels can register a large number of latent tracks on its surface. After an etching treatment, some visible tracks can be placed covering one or more visible tracks altering the LR-115 response. In order to develop this work and be more realistic, visible tracks were simulated taking into account radon exposure level, geometry and dimensions of the diffusion chamber, dimensions of the detector, the V function, the etching process and the reading process. Results show that the overlapping effect in the LR-115 inside a cylindrical diffusion chamber exposed to very high levels can be solved with an uncertainty of 5%. The same methodology can also be applied when considering other detectors and geometry and dimensions of a diffusion chamber. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Concentric rings formation on etched LR-115 in bare mode by unconventional exposition(Elsevier, 2021-06-01)Some laboratories and institutions use bare LR-115 polymer (cellulose nitrate + polyester) as a nuclear track detector for radon measurements. They detect alpha particles from radon and its progeny products in the cellulose nitrate layer, whether emitted from the so-called effective volume located in front of the cellulose nitrate layer. However, concentric rings were recorded on the etched LR-115 detector when the possibility of alpha registration was canceled, and the polyester was exposed to natural radiation in different configurations. Concentric rings were formed, apparently, due to the thermally induced self-defocusing effect. The outdoor causative agent can heat and change the refractive index of polyester, generating latent concentric rings. In this work, different configurations have been studied to find the outdoor causative agents and to clarify the possible physical causes. Furthermore, results show reproducibility and suggest that the ultraviolet radiation can cause concentric rings on the cellulose nitrate layer. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, An approach to the measurement of radon permeability and transmission factor using Cr-39 detectors inside a diffusion chambers exposed in a new-build radon chamber(RELX Group (Netherlands), 2022-01-01)Many CR-39 (poly allyl glycol carbonate) detectors inside two different diffusion chambers were used to study the radon permeability and the radon transmission factor. This factor represents the percentage of radon concentration that truly enters a diffusion chamber, since there is a loss of radon concentration inside the chamber compared to the outside radon concentration, due to the radioactive nature of radon gas. Here, a theoretical discussion is presented, followed by an experimental study that was carried out in a new-build radon chamber. These initial results are presented in order to check the reliability of the radon chamber. The most remarkable observation is that research consistently shows that the obtained value of radon permeability constant for a commercial membrane is 4.404×10 − 8±0.012×10 − 8cm2/s, which is in a good agreement with literature data. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Comprehensive study of natural radioactivity in building materials: A case study in Ica, Peru(Multidisciplinary Digital Publishing Institute (MDPI), 2024-03-01)This study evaluates radon exhalation rates and assesses the potential radiological risks of external exposure to primordial radionuclides in building materials employed in the Ica region of Peru, particularly those with high uranium content. The radon exhalation rates are currently measured using a combination of a closed chamber and an active monitor. We proposed a novel method that effectively ensured a hermetic seal for the closed chamber and guaranteed that the efficient maintenance of secular equilibrium. The obtained results ranged from below the detection limit (BDL) to a maximum of 52.3 mBq · kg−1h−1. Gamma spectrometry was employed to measure the concentrations of radionuclides by utilizing a 3′ × 3′ NaI detector. The analysis of cement samples revealed a strong positive correlation between the activity concentration of radium and the radon exhalation rate. The activity concentrations for radionuclides varied, with values ranging from BDL to 60.6 mBq · kg−1h−1 for 226Ra, BDL to 22.3 mBq · kg−1h−1 for 232Th, and BDL to 1074 mBq · kg−1h−1 for 40K. These findings contribute valuable insight to decision-making processes in the Peruvian construction industry, particularly regarding material safety and radiological risk management. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Preliminary Applications Carried Out in a New-Build Radon Chamber Using CR-39 Detectors Inside Non-Commercial Diffusion Chambers(Elsevier Ltd, 2023-06-01)Many CR-39 (poly allyl glycol carbonate) detectors inside two different non-commercial diffusion chambers were used to study the radon permeability and the radon transmission factor. This factor represents the percentage of radon concentration that truly enters a diffusion chamber, since there is a loss of radon concentration inside the chamber compared to the outside radon concentration, due to the radioactive nature of radon gas. Here, a theoretical discussion is presented, followed by an experimental study that was carried out in a new-build radon chamber. These initial results are presented in order to show a preliminary performance evaluation of the radon chamber as well as introducing some preliminary applications. The most remarkable observation is that research consistently shows that the obtained value of radon permeability constant for a commercial membrane is 4.404×10−8±0.012×10−8cm2/s, which is in a good agreement with literature data. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Estimation of Indoor 222Rn Concentration in Lima, Peru Using LR-115 Nuclear Track Detectors Exposed in Different Modes(Multidisciplinary Digital Publishing Institute (MDPI), 2023-06-01)Radon is the main source of natural radioactivity, and its measurement is considered extremely important in radioprotection, given its relationship with the occurrence of lung cancer. In the last two years, measurements of this radioactive gas were carried out in Lima considering a grid of 5 km (Formula presented.) and the population density to determine the number of measurements to be carried out. Cellulose nitrate nuclear track detectors exposed in bare mode and diffusion chamber mode were used to estimate (Formula presented.) Rn concentrations. In diffusion chamber mode, non-commercial monitors and commercial monitors were used. The monitoring results are presented for 43 districts of the Lima Province whose population is approximately ten million inhabitants occupying a total area of 2655.15 km (Formula presented.). Measurements were made obtaining an average concentration of 49 Bq·m (Formula presented.) using bare detectors and 66 Bq·m (Formula presented.) using non-commercial diffusion chambers. Average concentrations obtained by both detector exposure modes were below the maximum concentration recommended by the WHO. A radon ((Formula presented.) Rn) map was also obtained as a visual representation of the (Formula presented.) Rn levels in the Lima province using inverse distance weighting (IDW) interpolation. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Environmental Alpha Radiation from the Soil at a Prehispanic Ancient Sacred Site in Lima, Perú(Polskie Towarzystwo Inzynierii Ekologicznej (PTIE), 2023-01-01)In the present work, we investigate the concentration of radon and its alpha-emitting progeny at the archaeological site of Huaca 20 in Lima, Peru. The site holds significant cultural and historical importance as an ancient pre-Inca ruin, providing valuable insights into the lives and rituals of its former inhabitants. We quantified the radon levels accurately with passive CR-39™ detectors deployed within specially designed chambers at the site for 28 days. In a controlled laboratory environment, we processed the detectors afterward, examining and analyzing the resulting tracks using advanced microscopy and the ImageJ analysis software. The ground-level concentration of radon and its alpha-emitting progeny was determined, revealing elevated levels ranging from 2.4 ± 0.6 to 8.9 ± 0.9 (kBq/m3). These findings underscore the unique presence of radon at Huaca 20 and highlight the potential impact on microorganisms at ground level. Likewise, these results can contribute to studies on the radiological risks faced by visitors, excavators and archaeologists. Finally, we show the spatial distribution of radon concentrations within the site by creating an iso-concentra-tion map. The iso-concentration map reveals a relation between areas with elevated radon levels and the good preservation of funerary contexts.