Search

Abstract: The indoor radon concentration was estimated based on the radon flux in soil and groundwater. The indoor radon concentration in Budhakedar area of Garhwal Himalaya, India is estimated to be 3.0–131.4Bq/m3 in summer and 4.6–92.4Bq/m3 in winter. Based on the available data from study area, the calculated value of diffusion coefficient for the soil ranges from 0.1×10−2 to 3.0×10−2 cm2 s−1 in the summer season and 0.1×10−2 to 0.4×10−2 cm2 s−1 in the winter season. The calculated value of diffusion flux in the study area is found to vary from 0.1×10−2 to 16.1×10−2 Bqm−2 s−1 in summer season and 0.1×10−2–12.2×10−2 Bqm−2 s−1 in winter season. The formulation was tested by comparing the results of radon values from two different seasons of a year. [Copyright &y& Elsevier]

Abstract: Commercially purchased CR-39 and PET polymers were irradiated by 100MeV O7+ ions of varying fluences, ranging from 1×1011 to 1×1013 ions/cm2. The effects of swift heavy ions (SHI) on the structural, optical and chemical properties of CR-39 and PET polymers were studied using X-ray diffraction (XRD), UV–visible spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The XRD patterns of CR-39 show that the intensity of the peak decreases with increasing ion fluence, which indicates that the semicrystalline structure of polymer changes to amorphous with increasing fluences. The XRD patterns of PET show a slight increase in the intensity of the peaks, indicating an increase in the crystallinity. The UV–visible spectra show the shift in the absorbance edge towards the higher wavelength, indicating the change in band gap. Band gap in PET and CR-39 found to be decrease from 3.87 to 2.91 and 5.3–3.5eV, respectively. The cluster size also shows a variation in the carbon atoms per cluster that varies from 42 to 96 in CR-39 and from 78 to 139 in PET. The FTIR spectra show an overall reduction in intensity of the typical bands, indicating the degradation of polymers after irradiation. [Copyright &y& Elsevier]

In most of the epidemiological studies contemporary radon measurements have been used as surrogates for radon concentrations in past decades even though changes in radon levels and residence may have occurred. Short-lived radon progeny may deposit on available surfaces in dwellings thus giving rise over time to a build up of long-lived progeny. Airborne radon decay products can be deposited and implanted through alpha recoil into the glass surfaces. On glass surface, activities of 210Po may arise as a result of the decay of recoil implanted activity following the alpha decay of surface deposited 218Po or 214Po. Measurement of 210Po implanted on a household glass is a method that can be employed to retrospectively determine the historic level of radon in dwellings. This method is based on the assumption that levels of recoil implanted 210Po in the glass provide a measure of time integrated radon concentration in the environment in which the glass has been located. The surface deposited activity of the radon progenies, which then become implanted in the glass by alpha recoil, is believed to reflect past exposure to airborne activity. Such retrospective measurements on glass are valuable in estimating the human dose derived from radon during the time of exposure. In this paper an account is given of the principles and some field applications of a retrospective technique, using the alpha track detectors, CR-39 and LR-115, to measure 210Po implanted in glass surfaces (surface traps). By using this CR–LR difference technique, the cumulative radon exposure in a dwelling in past decades may be estimated. This method provides reliable radon exposure data as a support to epidemiological studies concerning the health effects of radon exposure in the living environment. [Copyright &y& Elsevier]

Abstract: Research on earthquake-related radon monitoring has received enormous attention recently. Anomalous behaviour of radon in soil and groundwater can be used as a reliable precursor for an impending earthquake. While earthquake prediction may not yet be possible, earthquake prediction research has greatly increased our understanding of earthquake source mechanisms, the structural complexities of fault zones, and the earthquake recurrence interval, expected at a given location. This paper presents some results of continuous monitoring of radon in soil-gas in Garhwal Himalaya, India. Daily soil-gas radon monitoring with seismic activity and meteorological parameters were performed in the same laboratory system, located at H.N.B. Garhwal University Campus, Tehri Garhwal, India. Radon anomalies along with meteorological parameters were found to be statistically significant for the seismic events within the magnitudes M2.0-M6.0 and epicentral distances of 16–250km from the monitoring station. The frequent positive and negative anomalies with constant environmental perturbation indicate the opening and closing of micro cracks within the volume of dilatancy by strain energy. The spike-like and sharp peak anomalies were recorded before, during and after earthquakes occurred in the area. The variations in radon concentrations in soil-gas are found to be correlated with seismic activities in the Garhwal Himalaya. The correlation between radon level and meteorological parameters is also discussed. [Copyright &y& Elsevier]

Abstract: This paper presents the results of investigation of radon levels in the soil–gas and groundwater of Uttarkashi, India within the distance of 5km in vertical and horizontal directions from the landslide of Varunawat hill. Radon release from the soil and groundwater was found higher than the normal values. Radon concentration in groundwater over and around the landslide was found to vary from 0.51 to . The soil–gas radon concentration was found to vary from 219 to along the slope of landslide. Radon exhalation rate in collected soil samples was found to vary from to . Radon values were not found correlated with major and trace element contents in the upper soil of the area, which indicate that the migration of radon from deeper part of the earth along with landslide contribute to the surface radon concentration. Recorded values show a close association with local geology and Varunawat eruptions. [Copyright &y& Elsevier]

Abstract: Radon concentrations in groundwater and soil–gas along with the terrestrial gamma radiation dose rate have been measured in the different geological formation of Kumaon Himalaya, India. Radon concentrations were found to vary from 1 to 392Bq/l with a mean of 50Bq/l in water and to with a mean value of 5.867kBq/m3 in soil–gas. The radium content in collected groundwater samples from the study area was found to vary from 0.11 to 0.75Bq/l with a mean value 0.35Bq/l. The terrestrial gamma radiation dose rate and uranium content in soil were found to vary from 21.67 to with a mean value of and 0.8 to 15.3ppm with a mean value 3.4ppm, respectively, in different lithotectonic units. The emanation of radon in groundwater and soil–gas are found to be controlled by the geological formation of the area. It was also found to be controlled by the tectonic structure of the area. Radon level was found higher in the area consisting of granite, quartz porphyry, schist, phyllites slates and lowest in the area having sedimentary rocks, predominantly dominated by quartzite rocks. The terrestrial gamma radiation dose rate in the area was found positively correlated with radon concentrations in groundwater and soil–gas. A strong positive correlation was observed between uranium content in soil and terrestrial gamma radiation dose rate. Soil–gas radon concentration was also found positively correlated with the uranium content in the soil. However, a weak correlation was found between uranium content in soil and radon concentrations in groundwater samples from the study area. No correlation was observed between radon concentrations in groundwater and soil–gas. [Copyright &y& Elsevier]

Monitoring of radon, thoron and their daughter products was carried out in houses of Kumaun Himalaya, India using LR-115 plastic track detectors. The measurements were made in residential houses from June 1999 to May 2000 at a height of 2.5 m from ground level using a twin chamber radon dosimeter. The twin chamber radon dosimeter can record the values of radon, thoron and their decay products separately. Maximum and minimum indoor radon and thoron concentrations were evaluated and activity concentrations of radon and thoron daughters were estimated. The resulting dose rates due to radon, thoron and their decay products varied from 0.04 to 1.89 μSv/h. A detailed analysis of the distribution of radon, thoron and their decay products inside the house is also reported. The observed dose rates inside the houses of Kumaun Himalaya were found to be lower than the ICRP recommended value of 200 Bq/m3 and thus are within safe limits. [Copyright &y& Elsevier]

Radon, 222Rn, is the major contributor to natural radiation in human environment. The exposure of high radon is known as one of the causative factors of lung cancer. Though thoron, 220Rn, has been a matter of study in atmospheric science, but it was often neglected compared to radon. It was considered that the amount of thoron in the environment is less than that of radon. However, recent studies show that thoron and its progeny sometime contribute significantly to the radiation dose in residential buildings. A review of methodologies, measurement protocols and concepts used in various thoron measurement surveys performed in India is presented in this paper. The results of measurements of thoron and its progeny, carried out in the Himalayan region and in the high background radiation area of the south-eastern coast of Odisha, India are also presented. The results obtained using various thoron measurements techniques and the resulting doses to the general public are discussed in details. • Radon, thoron and progeny concentrations were measured in the houses of normal and high background radiation areas of India. • The contribution of thoron concentration to total radon and thoron concentrations is 40% in the houses of Garhwal Himalaya. • The contribution of thoron concentration to total radon and thoron concentrations is more than 70% in the houses of HBRA. • The contributions of doses due to thoron and progeny to total radiation dose are 32% and 73% in normal and HBRA houses. • Thoron and progeny has strong interference in indoor radon concentration both in normal and HBRA. [ABSTRACT FROM AUTHOR]

Abstract: In present investigation, newly designed twin cup pin-hole dosimeter with LR-115 track detector has been used for the integrated measurements of radon and thoron in the environmental air of a high background radiation area in coastal Orissa. The twin cup dosimeters were calibrated before installation in the field. The calibration experiment was made in an inter calibration exercise at NIRS, Chiba, Japan. The resulting calibration factors were used to obtain the values of radon and thoron in the study area. Radon and thoron concentrations in the houses of study area were found to vary from 24 Bq/m3 to 98 Bq/m3 and 46 Bq/m3 to 689 Bq/m3, respectively. The indoor and outdoor gamma dose rates in the study area vary from 0.124 μGy/h to 0.257 μGy/h and 0.109 μGy/h to 0.361 μGy/h, respectively. The annual effective dose due to the exposure to indoor radon and progeny was found to vary from 0.70 mSv to 2.84 mSv with an average value of 1.73 mSv. However, the annual effective dose due to the exposure to thoron and progeny was found to vary from 1.16 mSv to 17.36 mSv with an average value of 7.36 mSv. Thoron concentration and gamma dose rate were found relatively higher in the area. [Copyright &y& Elsevier]

Abstract: Levels of radon, thoron, and their progeny were measured in the houses of Garhwal and Kumaun Himalaya using LR-115 plastic track detectors. Radon and thoron concentrations were found to vary from 7 to 191 Bq/m3, and from 1 to 145 Bq/m3, respectively. The equilibrium factor between radon and progeny varies from 0.02 to 0.90, with an average of 0.26 for the region. The resulting dose rate due to radon, thoron, and their decay products varied from 0.04 to 1.89 μSv/h with an average of 0.96 μSv/h. In comparison to the international recommendations, the observed dose rates due to radon, thoron and progeny was found somewhat higher but well below the international recommendations. [Copyright &y& Elsevier]

The self-standing films of non-conducting polymethyl methacrylate (PMMA) were irradiated in vacuum using high energy light ions (HELIs) of 50 MeV Lithium (Li +3 ) and 80 MeV Carbon (C +5 ) at various ion dose to induce the optical changes in the films. Upon HELI irradiation, films exhibit a significant enhancement in optical reflectivity at the highest dose. Interestingly, the photoluminescence (PL) emission band with green light at (514.5 nm) shows a noticeable increase in the intensity with increasing ion dose for both ions. However, the rate of increase in PL intensity is different for both HELI and can be correlated with the linear energy transfer by these ions in the films. Origin of PL is attributed to the formation of carbon cluster and hydrogenated amorphous carbon in the polymer films. HAC clusters act as PL active centres with optical reflectivity. Most of the harmful radiation like UV are absorbed by the material and is becoming opaque after irradiation and this PL active material are useful in fabrication of optoelectronic devices, UV-filter, back-lit components in liquid crystal display systems, micro-components for integrate optical circuits, diffractive elements, advanced materials and are also applicable to the post irradiation laser treatment by means of ion irradiation. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, the concentrations of 226Ra, 232Th and 40K are measured in building material and soil samples collected from different locations of Una, Himachal Pradesh, India. The collected soil samples and building materials are analysed using NaI(Tl) gamma ray spectrometry. The activity concentration of the naturally occurring radionuclides 226Ra, 232Th and 40K in the soil samples varies from 36.4 to 51.9, 9.3 to 26.1 and 1361.0 to 1732.4Bqkg−1, respectively but in building material it varies from 27.8 to 236.0, BDL to 146.1 and 1059.6 to 1582.9Bqkg−1, respectively. The radium equivalent activity, absorbed dose rate, annual effective dose and hazard index are also calculated for the assessment of radiological risk. The concentration of radionuclides depends upon the rock formation and chemical properties within the earth. The average radium equivalent activity from the soil samples and building material is 177.6 and 201.1Bqkg−1. The concentration of 226Ra, 232Th and 40K in the collected samples is higher than the world average concentrations of 35, 30 and 400Bqkg−1, respectively. This study is important to generate a baseline data for radiological mapping of the study area in the future. [Copyright &y& Elsevier]

The radon content in water may serve as a useful tracer for several geohydrological processes. The hydrodynamic factor, presence of radium in host rocks, as well as the soil porosity and permeability control its concentration in groundwater. In order to understand the factors that control the occurrence of radon in groundwater of Doon valley in Outer Himalaya, a total of 34 groundwater samples were collected from handpumps and tubewells covering three hydrogeological units/areas in the eastern part of Doon valley. Radon variation in tubewells and handpumps varies from 25.4±1.8 to 92.5±3.4 Bq/l with an average of 53.5±2.6 Bq/l. A significant positive correlation between radon concentration and depth of the wells was observed in the Doiwala–Dudhli and Jolleygrant areas suggesting that radon concentration increases with drilling depth in areas consisting of sediments of younger Doon gravels, whereas samples of the Ganga catchment show negative correlation. The high radon levels at shallower depths in the Ganga catchment (consisting of fluvial terraces of Ganga basin) indicate uranium-rich sediments at shallower depth. [Copyright &y& Elsevier]

In this paper, undoped and 7 %, and 20 % chromium doped titanium dioxide thin films were synthesized on silicon and quartz substrates by utilizing the sol-gel spin coating process. The films were then annealed at 450 °C. The synthesis process and the effects of doping on the structural, optical, and vibrational properties were studied. XRD analysis showed that the undoped thin film had an anatase phase with a crystalline size of about 15.4 nm. However, as the concentration of chromium increased, the crystalline size decreased, and we obtained a mixed phase of rutile and anatase for doped films. The FTIR spectra revealed that undoped films had Ti–O bonding at 435 cm−1 and bond with stretching at 619 cm−1 wavenumbers, which decreased to 379 cm−1 and 377 cm−1 wavenumbers for 7 % and 20 % Cr doping, respectively. The optical measurements showed that the films were homogeneous and had high transmission, reaching 95 % in the visible range for the undoped thin film and 80 % for higher doping levels of chromium. These films have a remarkable level of transparency, and because of that they are highly regarded in the field of thin-film solar cells. Their optical properties make them an excellent choice for use as optical windows in these types of solar cells. As the amount of chromium in the film increases, the optical bandgap decreases from 3.23 eV to 2.26 eV. This suggests that chromium has a significant impact on the optical properties of these films, which might be helpful to researchers and professionals working in the fields of solar energy, optoelectronic devices, photocatalytic systems, gas sensors, and solar cell passivation. • The decrease in crystallinity of TiO 2 thin film was observed with the increase of chromium doping. • Increase in chromium doping leads to the reduction in the bandgap of TiO 2 thin films. • The chemical bond (619 cm−1) stability in TiO 2 thin films increases with increase in chromium doping. [ABSTRACT FROM AUTHOR]

Humans receive a significant portion (˃50%) of the total dose attributed to all the natural radiation sources from indoor radon (222Rn), thoron (220Rn), and their progeny. While progeny contributes an overwhelming part to the dose, in most surveys, only radon gas is measured because of the simplicity of measurement. Progeny concentration is usually estimated by multiplying gas concentration with an assumed factor, called the equilibrium factor, and taken from literature. Recently, results of the measurements of equilibrium factors for 222Rn and 220Rn were reported from various parts of the globe. In India, many such studies have been conducted in the current decade. The studies show a wide variation of equilibrium factors which suggests that they depend on environmental factors and measurement conditions. Therefore, they should be determined site specifically if accurate site-specific dose estimation is targeted. This paper summarizes concepts, definitions, and methods to determine equilibrium factors and reviews literature about reported equilibrium factors worldwide, focusing on data reported from India. • Concepts, definitions and methods to determine 222Rn and 220Rn equilibrium factors. • Review of literature about 222Rn and 220Rn equilibrium factors reported from India. • A significant variation in the equilibrium factors is reported across the country. • Site-specific values of 222Rn equilibrium factors should be used in the dose estimation. • Dose due to 220Rn should be estimated from the directly measured progeny concentrations. [ABSTRACT FROM AUTHOR]

Study reports on the influence of swift heavy ion irradiation (SHII) induced electronic excitations (EEs) on structural, optical and electrical properties of undoped SnO 2 (TO) and antimony doped SnO 2 (ATO) thin films. EEs in the thin films were induced by 70 MeV Si ion irradiation. It is noticed from the structural analysis that the crystallinity of TO and ATO almost remains unchanged upon Si ion beam irradiation. However, morphological studies by atomic force microscopy and scanning electron microscopy show surface modification upon irradiation. Interestingly, transport measurements show that the pristine ATO film possesses high conductivity which further increases upon irradiation for a fluence of 1 × 10 12 ions/cm 2 , followed with drastic decrease in conductivity and carrier concentration at higher fluences of irradiation. Band gap modification in TO and ATO films are also reported with irradiation fluence and found to be in agreement with quantum confinement (QC) model for TO; while with Burstein-Moss shift (BMS) model for ATO films. However, the modifications at higher fluence can be ascribed to the band tail states due to very high disorder in the lattice as revealed by very high value of Urbach energy in corroboration with transmittance investigations, which also exhibits a significant decrease in transmittance in both films at irradiation fluence ≥ 1 × 10 13 ions/cm 2 . [ABSTRACT FROM AUTHOR]

Cu-doped Zinc Oxide (Cu ZnO) thin films have been prepared on silicon and quartz substrates by sol-gel spin coating method. These films were further annealed at 700 °C in controlled oxygen environment for improving crystalline quality and stoichiometry. In order to understand the material properties of thin films, X-ray Diffraction, Scanning Electron Microscopy, Atomic Force Microscopy, Raman Spectroscopy and UV–Visible Spectroscopy methods have been used in the present study. Polycrystalline nature of the Cu ZnO thin films is confirmed by structural analysis with increased crystallite size upon increasing the doping concentrations of the thin films. The phonon evolution at different doping concentrations is understood by Raman spectroscopy, thus confirming the wurtzite phase stability of the thin films with increase in crystallite size and presence of mixed phases have also been reported. In addition, widening and narrowing of band gap for the Cu ZnO thin films have been discussed in optical studies. This anomalous behavior in band gap tuning such as widening (+0.5 eV) and narrowing (−0.6 eV) under different doping concentrations and annealing temperature is understood by the influence of induced stress effects due to creation of intrinsic defects with band gap renormalization and secondary phase formation. [ABSTRACT FROM AUTHOR]

A huge band gap tuning and low temperature transport phenomenon in highly transparent antimony doped tin oxide thin film (Sb:SnO 2 ) under the influence of swift heavy ions irradiation (SHII) is reported. Structural analysis shows an enhancement in crystallinity at initial fluence of irradiation followed by amorphization at higher fluences. Films were also well studied for their surface morphology by atomic force microscopy and scanning electron microscopy. Band gap analysis reveals a drastic band gap narrowing around 1.1 eV upon SHI irradiation. Transport measurements show that the high conductivity and the carrier concentration decrease upon increase in the fluence of irradiation. The mechanism of charge carrier transport investigated at low temperature is attributed to nearest neighbor hopping (NNH) and variable range hopping (VRH) in different temperature regimes. Origin of the band gap tuning is understood in framework of Burstein–Moss (BM) shift, Quantum Confinement (QC) effect and band-tailing states in amorphous semiconductors. [ABSTRACT FROM AUTHOR]

The measurements of radon, thoron and their progeny concentrations have been carried out in the dwellings of Uttarkashi and Tehri districts of Garhwal Himalaya, India using LR-115 detector based pin-hole dosimeter and DRPS/DTPS techniques. The equilibrium factors for radon, thoron and their progeny were calculated by using the values measured with these techniques. The average values of equilibrium factor between radon and its progeny have been found to be 0.44, 0.39, 0.39 and 0.28 for rainy, autumn, winter and summer seasons, respectively. For thoron and its progeny, the average values of equilibrium factor have been found to be 0.04, 0.04, 0.04 and 0.03 for rainy, autumn, winter and summer seasons, respectively. The equilibrium factor between radon and its progeny has been found to be dependent on the seasonal changes. However, the equilibrium factor for thoron and progeny has been found to be same for rainy, autumn and winter seasons but slightly different for summer season. The annual average equilibrium factors for radon and thoron have been found to vary from 0.23 to 0.80 with an average of 0.42 and from 0.01 to 0.29 with an average of 0.07, respectively. The detailed discussion of the measurement techniques and the explanation for the results obtained is given in the paper. [ABSTRACT FROM AUTHOR]

High-energy ion beam irradiation of polymer is an effective technique to enhance the optical, structural and mechanical properties. Lexan polycarbonate films were irradiated by oxygen ions (energy 100 MeV, charge state O+8) with fluence varying from 3×1010to 3×1012 ions/cm2. Ion beam-induced optical and structural modifications were studied by ultraviolet–visible (UV–Vis), X-ray diffractometer and Fourier Transform Infrared (FTIR) spectroscopy. It is observed that optical absorption increases with increasing fluencies. The absorption edge was also found to shift from the UV region to the visible region. Value of band gap shows a decreasing trend with increasing ion fluences. The correlation between the optical band gap and number of carbon atoms inside the carbon clusters embedded in the network of Lexan has been discussed. X-ray Diffraction (XRD) analyses show the significant change in crystallinity with fluences. FTIR spectra show that the intensity of the absorption bands of Lexan polymer decreases after ion beam irradiation. [ABSTRACT FROM AUTHOR]

The Makrofol-KG polycarbonate (M-KG PC) films were irradiated with 45 MeV Li+3and 150 MeV Au+9ion beams at various fluences ranging from 1010to 1012 ions/cm2. Structural, chemical, and optical and surface properties were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV–visible, and atomic force microscopy (AFM), respectviely, as a function of ion fluences. UV–visible spectra exhibit a shift toward the higher wavelength regime after irradiation. This shift clearly reflects decrease in the optical band gap after irradiation. The FTIR spectra show a decrease in intensity of the typical bands. The XRD pattern of M-KG PC shows the decreasing intensity of peak with increase in ions fluence, which reflects loss of crystallinity of the films due to ion beam irradiation. AFM shows that the surface becomes rougher after irridation. The magnitude of the effect of irradiation is larger in the case of 150 MeV Au+9rather than 45 MeV Li+3ions due to high electronic energy loss of the Au ions in M-KG PC. The results can be discussed on the basis of linear energy transfer of the irradiated ions. [ABSTRACT FROM AUTHOR]

Semi-crystalline films (100 μ m) of the non-conducting polymer polyethylene terephthalate (PET) were exposed to swift heavy ions of 45 MeV Li3+ (Se=7.29E+00 eV/Å) and 120 MeV Au9+ (Se=1.157E+03 eV/Å) at ion fluence ranging from 1010 to 1012 ions/cm2. The chemical and structural properties were investigated using Fourier transform infra-red (FTIR) spectroscopy and X-ray diffraction techniques. The optical studies were carried out by UV-visible spectroscopy. It was noticed that the value of the band gap decreases with increasing fluence and depends on energy loss during interaction. A significant loss of crystallinity and change in the size of the particle are observed in irradiated PET. FTIR studies of the samples show the chemical changes after irradiation. The atomic force microscopy observation revealed that the surface morphology changes after irradiation. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, CR-39 polymer of thickness 100μm is irradiated with swift heavy ions of Li+3 (45MeV), Ni+9 (120MeV) and Au+9 (120MeV) with ion fluence ranging from 1010 ion/cm2 to 1012 ion/cm2. The effects of swift heavy ions on the structural, optical and surface properties of CR-39 are determined. The structural and surface properties are investigated using X-Ray diffraction (XRD) and Scanning Electron Microscopy (SEM), whereas the optical studies are carried out employing UV–vis spectroscopy. UV–vis spectroscopy shows that the band gap of the polymer decreases with ion fluence. The decrease in band gap is more significant in the case of Au beam as compared to Li beam. The FTIR spectrum shows reduction in intensity of typical modes, indicating the degradation of polymer after irradiation. The X-ray diffraction patterns show the amorphous nature of CR-39 polymer. The SEM studies show a systematic change in the surface morphology of the polymers with ion fluence. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of nanostructured polypyrrole (Ppy) films by electrochemical process and their modifications by electronic excitations induced by swift heavy ion irradiations is reported in this paper. The electrical property of ion beam irradiated polypyrrole was investigated at low temperature by resistivity measurements. The structural and optical properties were also studied using X-ray diffraction (XRD), UV–vis spectroscopy and scanning electron microscopy (SEM). At low temperature, the polypyrrole films show the metallic behaviour after ion beam irradiation. UV–vis spectroscopy shows a red shift in the absorbance edge and thus reduction in band gap with increasing ion fluence. The structural studies show that the percentage crystallinity improves with increase in ion fluence. The SEM study corroborates the results of structural analysis and shows the formation of rod type structures along with the evolution of amorphous phase with increasing ion fluence. [Copyright &y& Elsevier]

Abstract: The assessment of radiological risk related to inhalation of radon and radon progeny is based mainly on the integrated measurement of radon in both indoor and outdoor environments. The exhalation of radon from the earth crust and building materials forms the main source of radon in indoor environment. In this comparative study, the indoor radon level was measured using twin cup dosimeter in different dwellings of Garhwal Himalayas. Soil samples were collected simultaneously from different geological formations of the same area for laboratory measurement of radon exhalations rate. The radon exhalation rate was measured in the laboratory using LR-115 type II plastic track detectors. The indoor radon concentrations in this study area were found to vary from 13±3Bq/m3 to 178±8Bq/m3 with an average of 61±5Bq/m3 while thoron concentration was found to vary 9±2Bq/m3 to 94±6Bq/m3 with an average of 33±3Bq/m3. The radon exhalation rate was found to vary from (0.43±0.05)×10−5 Bqkg−1 h−1 to (20.10±0.11)×10−5 Bqkg−1 h−1 with an average of (1.95±0.10)×10−5 Bqkg−1 h−1. The detail significance of this study is discussed in radiation protection point of view. [Copyright &y& Elsevier]

Abstract: The radon content in groundwater sources depends on the radium concentration in the rock of the aquifer. Radon was measured in water in many parts of the world, mostly for the risk assessment due to consumption of drinking water. The exposure to radon through drinking water is largely by inhalation and ingestion. Airborne radon can be released during normal household activities and can pose a greater potential health risk than radon ingested with water. Transport of radon through soil and bedrock by water depends mainly on the percolation of water through the pores and along fractured planes of bedrock. In this study, radon concentration in springs and hand pumps of Kumaun and Garhwal Himalaya, India was measured using radon emanometry technique. The study shows that radon concentration in springs and hand pumps is controlled by geohydrological characteristics, which in turn is also governed by tectonic processes. [Copyright &y& Elsevier]

Commonly used building construction materials, radiation shielding bricks, hematite aggregate and other materials have been analyzed for the activity concentration of the natural radionuclides, namely 238U, 232Th and 40K, besides the radon exhalation rates. The activity concentration for 238U, 232Th and 40K varies from 29±1 to 98±4Bqkg−1, 20±2 to 112±2.8Bqkg−1, and 200±8 to 1908±15.6Bqkg−1, respectively, in various materials studied in the present work. Radon activity in the various samples varies from 190±11 to 313±14Bqm−3, the mass exhalation rate for radon varies from 1.05±0.07 to 1.92±0.09mBqkg−1 h−1 and surface exhalation rate varies from 9.0±0.30 to 19.8±22mBqm−2 h−1 for materials under investigation. The activity concentrations of uranium, thorium and potassium and radon exhalation rates vary from material to material. Thorium and potassium activity in the granite materials is higher, followed by radiation shielding material compared to other common construction materials. Uranium activity concentration is higher in cement as compared to radiation shielding material and other common construction materials. The absorbed dose varies from 23 to 185nGyh−1 and the indoor annual effective dose varies from 0.11 to 0.91mSv. The outdoor annual effective dose varies from 0.03 to 0.23mSv. The absorbed dose and the effective dose equivalent are found to be higher in the granite, followed by radiation shielding material and other common construction materials. In all the samples, the activity concentration of 238U, 232Th and 40K is found below the permissible levels. A strong correlation coefficient has been observed between radon activity and surface exhalation rate (correlation coefficient=0.899). [Copyright &y& Elsevier]

Abstract: The first radon soil gas survey in Serbia, using passive detectors (SSNTD, CR-39), was carried out in June 2005 at field sites in Niška Banja town. The aim of the survey was to identify risk zones characterised by high levels of this radioactive gas. Radon measurements were made at the depth of 50cm, in the ground according to a systematic grid pattern. Furthermore, at all 48 measurement points, the surface gamma dose rates in the air was also measured at the same locations and soil samples were collected for gamma spectrometric analysis for the radionuclides 226Ra, 228Th and 40K. Radon concentrations were found to range from 1270 to with an average of and a median value of . The geometrical mean value and geometrical standard deviation were calculated as and , respectively. Gamma dose rate varies from 92 to , with an average of . The radium content in collected soil samples ranges from 24 to with an average of . High correlations () between soil gas radon concentration, gamma dose rate and 226Ra content in soil were found for each pair. The distribution of radon concentrations in soil gas shows bimodal shape. [Copyright &y& Elsevier]

A Droplet Measurement Technology (DMT) Cloud Condensation Nuclei Counter (CCNC) was deployed to measure cloud condensation nuclei (CCN) for the first time in the pristine Himalayan region at Himalayan Clouds Observatory (HCO), Swami Ram Tirtha (SRT) Campus (30°34′ N, 78°41′ E, 1706 m AMSL), Hemvati Nandan Bahuguna (HNB) Garhwal University, Badshahithaul, Tehri Garhwal, Uttarakhand, India. The CCN concentration (N CCN) was observed at four supersaturation levels (SS: 0.2, 0.5, 0.8, and 1.0%). In this study, we reported CCN concentration at 0.5% SS in different weather conditions from Aug 01, 2018 to Jun 30, 2019. During this observation period, the monthly averaged value of CCN concentration ranged between 1098.3 ± 448.9 cm−3 (mean ± SD) and 3842.9 ± 2512.9 cm−3. It covers a significantly wide range of daily averaged concentrations from the minimum concentration of 43.84 cm−3 (during heavy wet scavenging due to snowfall) to maximum concentration of 17000 cm−3 (during the events of a forest fire) at the observation site. The highest CCN concentration is observed at the time of sunrise (~07:00 a.m.) and after the sunset (~07:00 p.m.) for the diurnal variation of monsoon, post-monsoon, and winter season. Pre-monsoon season shows peak values at 10:00 a.m. and at 07:00 p.m. with higher concentrations at night hours. The possible reasons for maximum concentration in morning and evening time could be upliftment and settlement of CCN because of the convection process, anthropogenic emission, vehicular emission, and biomass burning in the residential area and valley region adjacent to HCO, Badshahithaul. The highest CCN concentration (3842.9 ± 2513 cm−3) values of the whole observation period were observed in May 2019. It was significantly affected by the heavy fire activities over the Uttarakhand and nearby IGP regions. Diurnal variation of CCN concentration during the HFAD shows higher values in the night time differing from the diurnal pattern of CCN for other months of the observation period. The long-range transport of air mass could also contribute to the high CCN concentration values, as found through the five-day air mass backward trajectory analysis. The lowest value of CCN concentration corresponds to the heavy rains and snowfall days, possibly caused by extensive wet scavenging. Cluster analysis of the air mass trajectories used for the allocation and classification of the possible sources of pollutants reaching the observation site. The highest fraction of CCN concentration (more than 2000 cm−3) corresponds to the air mass from the arid and semi-arid regions of Asian countries. Large air mass fraction (~40–60%) with moderate CCN concentration was received from northwestern IGP region and foothills of central Himalaya. • Time series of CCN at four different levels of supersaturation (Superssaturation: 0.2, 0.5, 0.8, and 1.0%), and its role in the macroscopic cloud formation mechanism over the high-altitude region. • Study of seasonal, diurnal, and temporal variation of CCN over the Himalayan regions and comparisons with different altitude sites, geographic and climatic conditions of India. • Observations provided the average CCN concentration 1411.3 ± 1110.1 cm−3, 1645.7 ± 690.62 cm−3, 1712.3 ± 862.8 cm−3, and 2514.7 ± 2166.4 cm−3 for Monsoon, Post- Monsoon, Winter and Pre-monsoon Seasons respectively. • Analysis of local meteorological conditions impact on the formation of high-altitude cloud, and complexity of local weather phenomenon. • Use of transport models to analyze and characterize the possible sources of the pollutant for rural areas with relatively low urbanization and industrialization activities and role transported pollutants from the urban (highly polluted and populated) regions on the modification of local meteorology of the Garhwal Himalayan regions. [ABSTRACT FROM AUTHOR]

Abstract: Ionizing radiation exposure experienced by the general population is mainly due to the indoor radon. Major part of radon comes from the top layer of the earth. The radon emanation is associated with radon in soil and sleepy back radium in the soil. Both field and laboratory measurements were carried out for the instantaneous and integrated radon concentration in soil-gas. The radon exhalation rate from collected soil samples was measured using LR-115 Type II plastic track detector. The soil-gas radon concentration was measured with the help of radon Emanometry method. The effective radium content of the soil samples was also calculated. The correlation coefficient between radium contents in collected soil samples and soil-gas radon from the same locations was calculated as 0.1, while it is 0.2 between radon exhalation rate and soil-gas radon concentration. The results show weak positive correlation due to the geological disturbance in the equilibrium conditions and high mobility of radon in the same geological medium. [Copyright &y& Elsevier]

Abstract: Environmental radiation exists as a consequence of cosmic, terrestrial and man made sources. Terrestrial radiation are emitted from natural radionuclide present in varying amounts in all types of soils, rocks, air, water and other environmental materials; radon is emitted from the soil surface, although secondary contributors include the oceans, natural gas, geothermal fluids, volcanic gases, ventilation from caves and mines, and combustion of coal. Radon and thoron levels were measured in soil-gas, ground water and indoor air in Budhakedar area of Tehri Garhwal, India. Radon concentrations in soil and groundwater of the Budhakedar area were found to vary from to with an average value and to with mean value , respectively. Measurement of indoor radon, thoron and their daughter products were also measured in the houses of the same area for four different seasons (autumn, winter, summer and rainy) using LR–115 plastic track detectors. The detector is fixed in a twin chamber radon dosimeter, which can record the values of radon, thoron and their decay products separately. The film fixed in bare mode holder gives the concentrations of radon, thoron and their progeny while the films fixed inside the cup with filter and membrane modes give the concentrations of radon/thoron gases and of pure radon gas, respectively. Detailed analysis of the effects of seasonal variation on radon, thoron and their decay products inside the houses are reported in this paper. [Copyright &y& Elsevier]