Search

The risk of lung cancer or pneumoconiosis mortality, increases with radioactive radon gas exposures. This article report health risk for underground workers exposed to radioactive gas and radon daughters carried by airborne dust at the coal mining in the Central Mountainous Region of Colombia. A set of 33 measurement points located in that mine galleries were selected to monitor radon gas concentration activity, by passive LR-115 detectors, during two months. Resulting values provided radon concentrations, absorbed dose, environmental equivalent dose and the effective dose; miners increased risk of contracting lung cancer is included. It is concluded that the mine ventilation system satisfies the conditions required by the current radiological protection of the miners. Our study point out that Colombia can effectively address the potential risks associated with radon exposure and ensure a safer living environment for its citizens. • Health risk for underground workers exposed to radioactive gas and radon daughters. • Imminent risk of contracting lung cancer from long-term exposure to radon. • Importance of ventilation systems in mining facilities contribute to the healt of workers. • Detection systems with LR-115 are efficient for radon measurements over long periods of time. [ABSTRACT FROM AUTHOR]

Abstract Inhaled radon and its progenies induce health concern due to high activity-concentration in selected thermal spas of Boyacá region. Hydrogeothermal water sources in a high risk seismic area, are studied to determine by water bubbling method radon concentration values; their occurrence is between few hundreds and 2000 Bq dm−3. Deposits, existing in this area, reach at the surface soil gas radon concentration up to 210 kBq m−3. Maintenance workers, health tourists and visitor's possible detrimental health effects, are discussed in relation to radon balneotherapy beneficial aspects. Highlights • Inhaled radon risk to the health of the employees. • Radon concentrations in the hot springs. • Radon content reduction in thermal spas consists of diluting the geothermal water concentration with fresh water. • Hot springs negative aspect is not confirmed by experimental result (below 20 mSv a-1). [ABSTRACT FROM AUTHOR]

During electron beam stopping on natW target in a linear accelerator, photonuclear (γ, xn) reactions occur; the tungsten converter provides a non-negligible neutron yield with an energy spectrum that significantly depends on surrounding mass nuclei. Reduction of the neutron radiation field is convenient to limit the side-effects that accompany the tumor or cancer radiotherapy. A close-in irradiation geometry is proposed to improve therapy effectiveness. The convenience of the proposed experimental arrangement is assessed using Monte Carlo simulation and experimental results based on nuclear track-etch methodology. Photoneutron yield for two energy groups (thermal and epithermal) are determined experimentally via boron (98%) converter and cadmium-filter employing a passive detector (poly allyl di-glicol carbonate polimer). Etched track diameter histograms are described by distribution functions to determine the ratio between thermal and higher energy neutrons. New insights are given into therapy beam quality and radiotherapy dose delivery based on bar histograms unfolding. • New irradiation with close-in geometry to provide higher-efficiency of radiotherapy. • Monte Carlo simulation to assess radiation field effectiveness and acceptability. • Distribution function of charged particles in on nuclear track-etch methodology. • Fast neutron yield at the W nat target converter. [ABSTRACT FROM AUTHOR]

Abstract: The microscopic process taking place during chemical etching is described in terms of a dynamic framework governed by capillary condensation. The aim is to obtain physical information on how the cone shaped tracks with curved walls evolve during chemical etching under a close examination of first principles. The results obtained with the proposed theory are compared with published values to establish their range of validity. [Copyright &y& Elsevier]

Abstract: A large set of data on long term performance of n-type HPGe detectors used in GASP, EUROBALL and CLARA γ spectrometers, as well as environmental measurements have been collected over two decades. In this paper a detailed statistical analysis of this data is given and detector long term behaviour is provided to the scientific community. We include failure, failure mode, repair frequency, repair outcome and its influence in the energy efficiency and energy resolution. A remarkable result is that the life span distribution is exponential. A detector''s failure is a memory-less process, where a previous failure does not influence the upcoming one. Repaired spectrometers result in high reliability with deep implications in the management of large scale high-resolution gamma spectrometry related projects. Findings show that on average, detectors initial counting efficiency is slightly lower (∼2%) than that reported by the manufacturers and the repair process (including annealing) does not affect significantly the energy efficiency, even after a long period of use. Repaired detector energy resolution statistics show that the probability, that a repaired detector will be at least as good as it was originally, is more than 3/4. [Copyright &y& Elsevier]

A higher yield of rare isotope production methods, for example, isotope separation on-line (ISOL), is expected to be developed for the EURISOL facility. In this paper as a part of the ongoing project, high power-target assembly and passive detector inclusion are given. Theoretical calculations of several configurations were done using Monte Carlo code FLUKA aimed to produce 1015 fiss/s on LEU-Cx target. The proposed radioactive ion beam (RIB) production relies on a high-power (4MW) multibody target; a complete target design is given. Additionally we explore the possibility to employ PADC passive detector as a complementary system for RIB characterization, since these already demonstrated their importance in nuclear interactions phenomenology. In fact, information and recording rare and complex reaction product or short-lived isotope detection is obtained in an integral form through latent track formation. Some technical details on track formation and PADC detector etching conditions complete this study. [ABSTRACT FROM AUTHOR]

Abstract: Material recognition is studied by measuring the transmission spectrum of 252Cf fission gamma rays in the energy range E γ=0.1–5.5MeV for 0.1-MeV-wide energy bins through a number of elementary samples. Each transmitted spectrum is compared with a library of reference spectra for different elements providing the possibility of material identification. In case of elemental samples with known thickness, this procedure allows the identification of the sample Z with uncertainty typically lower than 3 Z-units over a wide range of elements. Applications to composite materials are also reported. [Copyright &y& Elsevier]

Abstract: Diffusion of alpha emitter radon progeny inside a cylindrical diffusion chamber was simulated. In the simulation of atomic movements, we took into account the random nature of the diffusion direction and the decay process. The alpha emitter distributions in volume, lateral wall and top cover of a 6.0cm height diffusion chamber for different diameters were determined. Results show non-uniform distribution of radon progeny. As chamber diameter increases, the tendency of radon progeny is to accumulate in central regions of the chamber volume and inner wall ( and ). Depending on chamber diameter and detector size, non-uniform distribution of radon progeny deposited on SSNTs surface can be achieved if the detector is horizontally located at the bottom. The fraction of surface where progeny are deposited diminishes as chamber diameter increases. Due to the relatively short half-life, for diameters larger than the assumed height its subsequent atoms decay in air before their deposition on chamber wall. The form in which radon progeny is distributed in volume and walls of chamber can affect the quantity and distribution of tracks in detector. [Copyright &y& Elsevier]

Gamma-ray induced X-ray emission (GIXE) technique for elemental lead in-vivo tibial measurement using a large volume hyper pure germanium detector is presented with the most convenient source-sample-detector geometry. The system operates advantageously when several parameters are considered for a lower dead time operation. The detection limit (DL) is better that 3.5 μg/g of Ca. Results of in-vivo average tibial lead concentration for some of the monitored groups are: control 7 μg of lead per g of Ca; gasoline filling attendants 6 μg/g of Ca; custom office workers near the DL; industrial workers range from DL up to 84±3 μg/g of Ca, suggesting that lead accumulation in the bone does not represent a major health risk [ABSTRACT FROM AUTHOR]

Environmental monitoring has been one of the major issues worldwide since the Rio Conference 1992. In Venezuela several projects started to assess the industrial activity as a burden on the living environment. In this work we present a quantitative analysis of environmental samples collected in a residential and industrial sector of the Capital using the powerful technique of total reflection X-ray fluorescence. Sample preparation is described and results are shown of lead and other heavy metals. The elements with higher concentration were Fe, Sn and Pb which reported values in the range of 1.9–2.9 wt.%, 0.8–1.4 wt.% and 0.2–0.4 wt.%, respectively. Total heavy element concentration in street dust is in the range of 3–4 wt.% underscoring the need for governmental programs to implement pollution limiting measures by displacing the heavy industries away from Caracas and to implement advanced instrumental techniques to monitor the environment. [Copyright &y& Elsevier]

This paper presents three new materials composed of Ti X V 0,035X Cu X-1,035 (X = 2, 4 and 6%), is proposed as Linear Accelerator target. Its response to electron beam based on photoneutron production, is assessed by MC simulation and nuclear track-etch methodology. The outcome is compared to a tungsten target irradiated by energetic 16 MeV electron beam. Photoneutron yield, of two energy groups (thermal and epithermal) were determined via converter matter 10B (98%) and Cd-filter by PADC-track density comparison. The multi-metal Ti 2 V 0,07 Cu 97.93 target related to therapy beam quality, resulted advantageous in comparison to that provided by W-target, commonly used in the LINAC. • New target is assessed by thermal and fast photo-neutron yield of a medical LINAC. • The MCNP Monte Carlo code provide expected photoneutron dose per target alloy of Cu, Ti, V. • Low cost PADC-detector is convenient to assess target photoneutron production. • Partially amorphous target related therapy beam quality is better in comparison to tungsten. [ABSTRACT FROM AUTHOR]

Abstract: Binary glass metal theories of glass formation require boron distribution knowledge; this can be achieved by thermal neutron -radiography employing the reaction and LR-115 detectors. Non-uniform distribution within up to a depth of is observed. [Copyright &y& Elsevier]

Abstract: Scanning Probe Microscope (SPM) images reveal important fingerprint features of latent tracks induced in diamond by fission fragments from a californium source. Collimated fission fragments with a binary distribution of the predominant energies of 79.4 and 103.8MeV, are assumed. Cavities, reticular formations around these cavities, and black spots of graphite were found. A brief discussion on the possible track formation mechanism is given on the basis of the explosion spike theory; an attempt to determine latent track core and halo parameters is included. [Copyright &y& Elsevier]

Abstract: A recently developed add-on card for data acquisition from National Instrument has the possibility of being employed in the field of the gamma ray spectrometry as an industrial and teaching tool. The card''s technical capability, the operating program designed for gamma spectrometry and results of the system''s reliability, dynamic characteristics, limits in data processing and the quality of the obtainable gamma spectra are given. The advantages and deficiencies as well as important features are emphasised when prompt gamma analysis is of interest in industrial applications and educational issues. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Abstract Radioactive related pollution due to suspended particulate matter dispersion is an important workplace and health care issue. Recycling oil production ducts and contaminated production equipment, represent a health hazard to workers and public alike. Radioactive plate-out NORM scales with crystal deposit is analyzed by different techniques; results provide proper information on physico-chemical features and emitted alpha particles. Recommendations for handling and recycling procedures are included in relation to health risk and radiological hazard. Graphical abstract Image 1 Highlights • Crystals related to barite, uranium and silicium are identified. • Hot spot evidenced by electron microscope. • Crystals NORM component. • Inclusion mechanism of 212 Pb and 210Po is suggested. • Non uniform NORM in oil pipe scale. [ABSTRACT FROM AUTHOR]

A compact and modern equipment for implementing the fast neutron and γ-ray transmission technique (FNGT) has been developed in order to estimate the sulphur content of crude oil. FNGT is employed for non- destructive analysis of different kinds of samples. The compact system presented in this work represents an improvement of our previous experimental set-up [1, 2]. It makes use of a Cf source, an EJ-301 liquid scintillator detector (2″ × 2″) with excellent n/γ discrimination capabilities, and modern nuclear electronics based on fast digitizers. The fast neutron and gamma transmission technique was employed to study a system for on-line sulphur concentration measurement in Venezuelan heavy sour oil. The range of sulphur concentrations investigated is between 0.1 and 6.5 wt%. The equipment performances and limitations are compared with those predicted by a Monte Carlo model built in GEANT4 v10.01. The results show the possibility to implement a compact unit for on-line determination of sulphur concentration in crude oil. [ABSTRACT FROM AUTHOR]

A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field. [ABSTRACT FROM AUTHOR]

A commercial boron-loaded liquid scintillator EJ-339 A was studied, using a 252 Cf source with/without polyethylene moderator, to examine the possibility of discriminating slow-neutron induced events in 10 B from fast-neutron events, resulting from proton recoils, and gamma-ray events. Despite the strong light quenching associated with neutron induced events in 10 B, correct classification of these events is shown to be possible with the aid of digital signal processing. [ABSTRACT FROM AUTHOR]

Abstract: The light output response and the neutron and gamma-ray detection efficiency are determined for liquid scintillator EJ-309. The light output function is compared to those of previous studies. Experimental efficiency results are compared to predictions from GEANT4, MCNPX and PENELOPE Monte Carlo simulations. The differences associated with the use of different light output functions are discussed. [Copyright &y& Elsevier]

A group of 46 archaeological figurines samples ( ad 1300 and 1500) from Venezuelan mainland and northern island were analyzed by k0-instrumental neutron activation analysis (k0-INAA) to obtain their elemental content and give a step ahead to establish the provenance of the island figurines. In total 37 elemental concentrations were measured with uncertainties between 3 and 20 %. To make the study of provenance, a complete statistical analysis was achieved; Fisher linear discriminant, principal component analysis, hierarchical clustering and the Hotelling T test were used to this end. Furthermore, not only the 46 samples analyzed in this work by k0-INAA were used, but also 40 samples analyzed by PGNAA and reported by Sajo-Bohus et al. (JRNC 265(2):247-256, 2005) were included in the statistical analysis. It was done in order to increase the size of the data set, and then to obtain from the statistical techniques more reliable results. It was found that a very good differentiation exits between the figurines from the island and from the mainland supporting the idea that the raw materials of the figurines come from different places. [ABSTRACT FROM AUTHOR]

Abstract: A compact neutron/gamma detector has been developed using a liquid scintillator cell coupled to a Flat Panel PMT; performances have been compared with a second cell coupled to a traditional linearly-focused 12 dynodes PMT. Energy resolution and pulse shape discrimination (PSD) measured by using a fast digitizer are very similar for the two detectors with the time resolution of the Flat Panel PMT slightly worse. The new detector results to be weakly affected by the influence of a moderate magnetic field while the traditional PMT exhibits strong pulse reduction. The compact size and the low power consumption obtained by using the Flat Panel PMT are very useful in portable neutron/gamma spectrometers. [Copyright &y& Elsevier]

Accurate differential cross sections have been measured at specific beam energies and angles to be used in a method proposed previously for the simultaneous quantification of light elements ( ) present in evaporated liquid biological samples. Targets containing 1H, 7Li, 12C, 16O, 19F, 28Si and 197Au have been bombarded with 13MeV 6Li3+ and 20MeV 16O5+ beams. The 16O+ 1H, 16O+ 12C, 16O+ 16O, 16O+ 19F, 16O+ 28Si and 16O+ 197Au cross sections, shown to be consistent with the Rutherford formula predictions at 15° and 20°, have been used to determine cross sections for the 6Li+ 1H, 6Li+ 12C, 6Li+ 16O, 6Li+ 19F, 6Li+ 28Si and 6Li+ 197Au scatterings respectively at 17.5°, 24°, 25°, 26°, 28° and 30°. Although 6Li+ 7Li cross sections have not been obtained from 16O+ 7 Li cross sections, they have been determined from measured 6Li+ 19F cross sections and, in addition, used to obtain 16O+ 7Li cross sections at 15° and 20°. The reliability of the new cross sections determined in this investigation for the 6Li+ 1H, 6Li+ 7Li and 6Li+ 19F scatterings is based on the Rutherford behavior of the measured 6Li+ 197Au scattering data as expected and the consistency observed between the 6Li+ 12C, 6Li+ 16O and 6Li+ 28Si cross sections obtained in this work and previously reported values. This research has important implications in applied physics. [ABSTRACT FROM AUTHOR]

Abstract: Radon and thoron concentrations in soil pores in a gas production region of the Anzoategui State, Venezuela, were determined by active and passive methods. In this region, water wells are contaminated by natural gas and gas leaks exist in the nearby river. Based on soil gas Radon data surface hydrocarbon seeps were identified. Radon and thoron concentration maps show anomalously high values near the river gas leaks decreasing in the direction of water wells where natural gas is also detected. The area where the highest concentrations of 222Rn were detected seems to indicate the surface projection of the aquifer contaminated with natural gas. The Radon/Thoron ratio revealed a micro-localized anomaly, indicating the area where the gas comes from deep layers of the subsoil. The radon map determined by the passive method showed a marked positive anomaly around abandoned gas wells. The high anomalous Radon concentration localized near the trails of ascending gas bubbles at the river indicates the zone trough where natural gases are ascending with greater ease, associated with a deep geological fault, being this the main source of methane penetration into the aquifer. It is suggested that the source of the natural gas may be due to leaks at deep sites along the structure of some of the abandoned wells located at the North-East of the studied area. [Copyright &y& Elsevier]

Abstract: A new laboratory facility for non-destructive analysis (NDA) using a time-tagged 252Cf source is presented. The system is designed to analyze samples having maximum size of about 20×25cm2, the material recognition being obtained by measuring simultaneously total and energy dependent transmission of neutrons and gamma rays. The equipment technical characteristics and performances of the NDA system are presented, exploring also limits due to the sample thickness. Some recent applications in the field of cultural heritage are presented. [Copyright &y& Elsevier]

Abstract: The light output of neutron detectors based on the plastic scintillator EJ228 is studied as a function of neutron energy using a time tagged 252Cf source. Calibration of the light output scale is performed by fitting the experimental distribution of Compton scattering events of photons from a 22Na source with a response function obtained by Gaussian smearing of the predicted line-shape. The light output curve as well as the pulse height resolution for the EJ228 scintillators is very close (within 5%) to those recently reported for NE213 type organic liquid scintillators. [ABSTRACT FROM AUTHOR]

Abstract: A new method, based on Digital Holographic Microscopy (DHM), to visualize and to analyze etched tracks in SSNTD has been developed. The proposed method is based on the possibility of the digital holography to perform whole reconstruction of the recorded wave front, so that phase and intensity distribution at a plane located between the object and recording plane and along the reconstructed image of the object can be determined. In a DHM system, the back focal plane of the lens can be reconstructed so that complex amplitudes of the Fraunhofer diffraction of light distribution across the object can be known. With the knowledge and manipulation of the components of this plane is possible to design different methods of image analysis. In this paper, the DHM method was applied to determine the track parameters in CR-39 detectors, showing that most of studies carried out with Confocal Microscopy and Atomic Force Microscopy could be also done, with the sufficient exactitude and precision, but in a simpler and more economic way. The developed microholographic method provides a new alternative procedure that overcomes the current techniques at least in technological simplicity. [ABSTRACT FROM AUTHOR]

Abstract: Evaporated amniotic fluid (AF) targets have been bombarded with a 13MeV 6Li3+ beam. Forward angle data have served to identify the 1H(6Li,1H)6Li reaction as an alternative for hydrogen characterization of such organic samples. Detected 6Li ions elastically scattered from C, N, O, Na and Cl can also be used to determine the concentrations of these elements in AF. The analyzed AF samples have been diluted with distilled water. The effect of sample dilution on the improvement of spectrum energy resolution has been observed, confirming previous reports. The hydrogen concentration determined in the studied AF targets is shown to vary linearly with sample dilution. Two detector arrangements have been used to find out which detection scheme is the most convenient. The combination of a counter telescope and a single detector, set up at the same polar angle on the opposite side of the beam, seems to be the best choice to have a reliable particle identification and an adequate energy resolution simultaneously. [Copyright &y& Elsevier]

Abstract: Exposure to indoor radon and suspended particulate matter (SPM) is considered a high risk in lung cancer aetiology. In this paper indoor radon and SPM concentration measurements and their correlations, associated with lung cancer cases are given. Mexico City suffers high concentration of SPM as well as other photochemical pollutants such as ozone. During the last decade in Mexico City, radon and SPM have been monitored. The indoor radon measurements were done using the Nuclear Track Methodology, basically the close-end-cup device with polyallyldiglycol carbonate as detector material, followed of an established chemical etching protocol, and automatic digital image analyzer system for counting. SPM size and concentration were obtained from monitoring stations located along the city. The results show that the central–north part of Mexico City has a large concentration of SPM and the vulnerable population (older than 65 years and younger than 14 years) is located essentially in the same region. In this area, a large number of lung cancer cases were found, even if indoor radon levels were below the recommended limits. [Copyright &y& Elsevier]

Abstract: Passive nuclear track detectors in the study of multi fragmentation and compound nucleus fission in the fusion reaction 54Cr+ 208Pb, leading to composite systems with Z =106 is given. Results indicate that mostly nuclear tracks are related to fragments with low atomic number and less than 11% to beam like particles in opposition to the expected distribution. [Copyright &y& Elsevier]

Abstract: Material recognition by measuring simultaneously the transmission of neutron and gamma ray produced by a 252Cf source has been studied, determining the average atomic number resolving power. In addition, it is demonstrated the possibility to derive direct signatures able to identify light elements (C, N, O) using the measured transmission versus neutron time-of-flight. This allows one to determine the relevant elemental ratios (C/O and C/N) normally used to identify threat organic materials such as explosives and drugs. [Copyright &y& Elsevier]

Abstract: The validity of the concentrations of carbon and oxygen reported in formvar previously and the underlying assumption that these elements are uniformly distributed in our formvar films have been checked. New elastically scattered 13MeV 6Li+12C and 13MeV 6Li+16O cross-sections have been measured at 17.5°, 25° and 28°. By use of these cross-sections, carbon and oxygen concentrations, a factor of 10 higher than previously reported values, have been determined for the first time in our formvar backings with a dispersion per backing not greater than 7%. [Copyright &y& Elsevier]