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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: 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]

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 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 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]

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]

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]

Soil radon gas movement depends on soil geology, environmental thermodynamic parameters and, micro-seismic telluric activity. Mapping radon time dependent concentration at the relaxation depth in a selected area, provide transport direction in a seismically high-risk region. Nuclear track methodology is employed to determine main gradient vector for radon transport. Applying the gradient definition, a "radon rose" graph is constructed from which prone area can be promptly identified. Results show that short time interval, Rn-transport direction may change unpredictably, however, the length of each "spoke" around the circle provides information on the soil Rn-gas probable shifts towards or from a direction per time interval. The new graph is a novelty and provide improved approach for environmental protection and radon dosimetry. • Rn-Rose is presented, this allows discriminate preferential direction of gas radon. • This information combined with soil or climate properties discriminate the influence of these factors. • Results shows that at the porous mediums scale, temperature affects the radon diffusion rate. • Soils with high porosity and moisture seem to be preferential orientation of radon accumulation. • Discriminate preferential radon directions is key for remedial actions in rural households. [ABSTRACT FROM AUTHOR]

In this work, the seasonal variation of the concentration of radon in soil and its contribution to concentrations inside of a bunker used for the storage and operation of radioactive material was studied. The measurements obtained inside and outside of the installation allowed establish a method for the calculation of the diffusion coefficient for the concrete, variable that directly influences the concentration of radon gas inside of the bunker. With the obtained results of the gamma dose rate and the concentration of radon inside the bunker, the S-index was calculated in order to determine whether the bunker would require some remediation process. The high radon gas concentration rates to which workers are exposed led to study the relative risk of contracting lung cancer (RRLC). • Concentration of radon in soil and its contribution inside of a bunker used for the storage of radioactive material. • The calculation of the diffusion coefficient for the concrete directly influences the concentration of radon gas. • The S-index was calculated in order to determine whether the bunker would require some sort of remediation process. • The relative risk to contract lung cancer (RRLC) due to exposure to Rn inside of the bunker was also studied. [ABSTRACT FROM AUTHOR]

Paraffin, water and water-extended polyester (WEP) were used as main moderator to design a mobile shielding for a 666 GBq 241Am–Be source used in oil industry. The shielding performance was estimated using Monte Carlo methods where the γ-rays induced by the neutron interaction with the shielding materials were also included. The spectra of neutrons and γ-rays around the shielding were estimated, as well as the total neutron and g-ray total fluences per history. The neutron source strength was used to calculate ambient dose equivalent rates, aiming to satisfy the international recommendation (2 mSv/h at the shielding surface). Moderators modify the neutron spectrum of the source reducing the amount of fast neutrons (0.5–11 MeV) and producing epithermal and thermal neutrons. During neutron transport in the moderator neutron capture and inelastic scattering produce gamma-rays. Paraffin has the best shielding performance however it is not suitable because can be affected by extreme temperatures. WEP and water have similar shielding performance, however water do not satisfy the international recommendations because at one site the neutron and γ-ray doses rates are larger than 2 mSv/h. WEP is the best option because fulfill the international recommendations, it is stable and temperatures where paraffin fails. The WEP-based shielding weights 66 kg. • Using Monte Carlo methods, a mobile shielding for a241Am–Be source was calculated. • The geometric parameters and type of materials were established. • With the H*(10) calculations it is possible to establish the most adequate shields. • A geometry with dimensions for the construction of the container is presented. [ABSTRACT FROM AUTHOR]

Abstract: The results of radon concentration measurements inside of the Gabriel caves of Mexico, during three consecutive two-month periods covering almost three seasons, are reported in the present work. The radio-ecological importance of this site is related to the radon and its concentration-dynamic behavior in the cave. Further interest in radiation safety motivated this initiative since routine biological field work is done, with people spending long periods of time there. CR-39 passive nuclear track detector was chosen for this survey. Radon concentration levels decrease during the rainy season and show different values depending on the ventilation and geometeorological structure. Measured values range between 956 and , an indication that radon doses may exceed the allowed values for workers. This project is part of a larger study of indoor radon alpha emitters in Mexican caves. [Copyright &y& Elsevier]