H S Virk

Publications (23)19.62 Total impact

• Article: Radon, helium and uranium survey in some thermal springs located in NW Himalayas, India: mobilization by tectonic features or by geochemical barriers?

  V Walia, F Quattrocchi, H S Virk, T F Yang, L Pizzino, B S Bajwa
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  ABSTRACT: Radon, helium and uranium measurements have been carried out in hot water springs in the Parbati and Beas valleys of Himachal Himalaya. Most of these hot springs are known as famous pilgrimage centers. The activity of dissolved radon in the liquid phase is found to vary widely, by an order of magnitude, between 10 and 750 Bq L(-1), whereas, the dissolved helium content in these thermal springs varies between 10 and 100 ppm. The uranium contents are low and vary from <0.01 to 5 microg L(-1). The measured values of radon, helium and uranium are possibly controlled by structural geology, namely the presence of pervious fault systems, and by the lithology of the leached host rocks. Redox-potential geochemical barriers cause the mobilization of uranile ions in solution (UO2+); the most plausible hypothesis is when the conditions are oxidising, confirming the importance of physico-chemical conditions up to the supergenic environment, to control the fluid geochemistry of the U-He-222Rn system. Some evidence is available from both geothermometric considerations and geochemical data which will be reported elsewhere, whereas the present study is focused on U decay series-noble gas geochemistry. The first analysis of collected 3He/4He data is consistent with a crustal signature at the studied thermal springs.
  Journal of Environmental Monitoring 10/2005; 7(9):850-5. · 1.99 Impact Factor
• Article: Estimation of coda wave attenuation for NW Himalaya region using local earthquakes.

  Kumar Naresh, A. Imtiyaz, H. S. Virk
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  ABSTRACT: The attenuation of seismic wave energy in NW Himalayas has been estimated using local earthquakes. Most of the analyzed events are from the vicinity of the Main Boundary Thrust (MBT) and the Main Central Thrust (MCT), which are well-defined tectonic discontinuities in the Himalayas. The time-domain coda-decay method of a single back-scattering model is employed to calculate frequency dependent values of Coda Q (Qc). A total of 36 local earthquakes of magnitude range 2.1–4.8 have been used for Qc estimation at central frequencies 1.5, 3.0, 6.0, 9.0, 12.0 and 18.0 Hz through eight lapse time windows from 25 to 60 s starting at double the time of the primary S-wave from the origin time. The estimated average frequency dependence quality factor gives the relation, Qc = 158f1.05, while the average Qc values vary from 210 at 1.5 Hz to 2861 at 18 Hz central frequencies. The observed coda quality factor is strongly dependent on frequency, which indicates that the region is seismic and tectonically active with high heterogeneities. The variation of the quality factor Qc has been estimated at different lapse times to observe its effect with depth. The estimated average frequency dependent relations of Qc vary from 85f1.16 to 216f0.91 at 25 to 60 s lapse window length respectively. For 25 s lapse time window, the average Qc value of the region varies from 131±36 at 1.5 Hz to 2298±397 at 18 Hz, while for 60 s lapse time window its variation is from 285±95 at 1.5 Hz to 2868±336 at 18 Hz of central frequency. The variation of Qc with frequency and lapse time shows that the upper crustal layers are seismically more active compared to the lower lithosphere. The decreasing value of the frequency parameter with increasing lapse time shows that the lithosphere acquires homogeneity with depth.
  Physic of the Earth Planet Interior. 01/2005; 151:243-258.
• Article: Radon monitoring in groundwater of some areas of Himachal Pradesh and Punjab states, India.

  Vivek Walia, B S Bajwa, H S Virk
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  ABSTRACT: Radon measurements have been carried out in groundwater of Himachal Pradesh and Punjab states, India. Radon concentration values in potable water show a wide range of variation from source to source and from place to place. Generally, radon concentration values in thermal springs groundwater have been found to be higher than the values from other sources.
  Journal of Environmental Monitoring 03/2003; 5(1):122-5. · 1.99 Impact Factor
• Article: Indoor radon/thoron levels and inhalation doses to some populations in Himachal Pradesh, India.

  H S Virk, Navjeet Sharma
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  ABSTRACT: It is well established that some areas of Himachal Pradesh (H.P.) state of India situated in the environs of the Himalayan mountains are relatively rich in uranium-bearing minerals. Some earlier studies by our group have indicated high levels of radon (>200 Bq m(-3)) in the dwellings. It is in this context that an indoor radon/thoron survey has been carried out in selected villages of four districts in the state of H.P. This survey has been conducted as a part of a national, coordinated project using twin chamber dosemeter cups designed by the Environmental Assessment Division (EAD), Department of Atomic Energy, Govt. of India. The track-etch technique is used for calibration of plastic detector LR-115 type-II which are employed for recording alpha tracks due to radon/thoron and their daughters. Year long radon/thoron data have been collected for seasonal correlations of indoor radon/thoron in the dwellings. The indoor radon levels have been found to vary from a minimum value of 17.4 Bq m(-3) to a maximum value of 140.3 Bq m(-3). The indoor thoron levels vary from a minimum value of 5.2 Bq m(-3) to a maximum value of 131.9 Bq m(-3). The year average dose rate for the local population varies from 0.03 microSv h(-1) to 0.83 microSv h(-1). The annual exposure dose to inhabitants in all the dwellings lies below the upper limit of 10 mSv given in ICRP-65.
  Journal of Environmental Monitoring 03/2002; 4(1):162-5. · 1.99 Impact Factor
• Article: Role of ion track filters in environmental surveillance.

  H S Virk, S A Kaur, G S Randhawa
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  ABSTRACT: Ion track filters (ITFs) are produced by physiochemical treatments to thin films of polymers and mica irradiated by heavy ions. These ITFs have many applications in the fields of science and technology. In the present investigation, the developed ITFs from polycarbonate films have been used to filter bacteria of various types in water. It is observed that the electric conduction through these filters depends upon the concentration of contaminants and pore diameter of filters. Filtration experiments were carried out using both single and multipore filters. Other applications related to environment surveillance have also been reported.
  Environment International 12/2001; 27(5):359-62. · 5.30 Impact Factor
• Article: Helium/Radon Precursory anomalies of Chamoli Earthquake, Garhwal Himalaya, India.

  H. S. Virk, V. Walia, Kumar Naresh
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  ABSTRACT: In the Garhwal Himalaya, the Bhagirthi and Alaknanda valleys were rocked respectively by two major earthquakes; the Uttarkashi earthquake of magnitude mb=6.5, Ms= 7.0 on 20 October, 1991 and the Chamoli earthquake of mb =6.8, Ms=6.5 on 29 March 1999, during this decade only. Both these seismic events are associated with ongoing deformation along the main central thrust (MCT) of the Himalayas. The helium and radon anomalies on 24 and 27 March 1999, respectively, were recorded at Palampur which is about 393 km from the Chamoli earthquake epicentre. A helium/radon ratio anomaly was recorded on 20 March, 9 days before the Chamoli earthquake. The precursory nature of radon and helium anomalies is a strong indicator of the physical basis of earthquake prediction and a preliminary test for the proposed conceptual helium/radon ratio model.
  Journal of Geodynamics. 01/2001; 31:201-210.
• Article: Indoor radon/thoron survey report from Hamirpur and Una districts, Himachal Pradesh, India.

  H S Virk, N Sharma
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  ABSTRACT: A survey of indoor radon and thoron levels has been carried out in a number of villages in the vicinity of uranium bearing sites in the Hamirpur and Una districts of Himachal Pradesh (H.P.), India. Levels were analysed with reference to the nature of building material, soil type and different seasons of the year. The one year average for radon concentration was found to vary from a minimum of 19.7 to a maximum of 146.3 Bq/m3 while the minimum and maximum thoron concentrations were 9.1 and 70.7 Bq/m3, respectively. The dose rate varied from 0.1 to 8.67 microSv/h. These are discussed in the light of ICRP recommendations.
  Applied Radiation and Isotopes 02/2000; 52(1):137-41. · 1.17 Impact Factor
• Article: 12C5+ radiation effects in SR-86 track recording polymer

  H S Virk, G S Randhawa, R Thangaraj, D K Avasthi, K Asokan
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  ABSTRACT: The samples of SR-86 polymer were irradiated with12C5+ ions of energy 5·0 MeV/u using fluences of 1011−1014 ions/cm2 at NSC Pelletron in a high vacuum scattering chamber. The optical studies show an increase in absorption of UV or IR in the shorter wavelength region (250–500 nm). The study also reveals that the increase in radiation dose extends the optical absorption region to longer wavelengths. It is observed that the bulk etch rate of this polymer is enhanced after heavy ion irradiation.
  Bulletin of Materials Science 04/1999; 22(4):791-795. · 0.88 Impact Factor
• Article: Study of etching and annealing characteristics of ion tracks in Trifol-TN polycarbonate

  R K Jain, G S Randhawa, S K Bose, H S Virk
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  ABSTRACT: The etching and annealing characteristics of heavy ion irradiated Trifol-TN polycarbonate plastic were studied. The values of various etching parameters, namely bulk etch rate , track etch rate , critical angle , sensitivity (S), etching efficiency and activation energies for bulk and track etching are reported. The isochronal annealing was performed on (17.17 and ) ion-irradiated Trifol-TN plastic. The annealing kinetics of heavy ion damaged Trifol-TN is described by using various empirical formulations. Finally, the experimental range of ions in Trifol-TN has been compared with the calculated values from different formulations.
  Journal of Physics D Applied Physics 12/1998; 31(3):328. · 2.54 Impact Factor
• Article: Effects on insulators of swift-heavy-ion irradiation: ion-track technology

  H S Virk, S Amrita Kaur, G S Randhawa
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  ABSTRACT: Polymers (CR-39, SR-86 and Makrofol-KG) and glasses (soda lime and barium phosphate) were irradiated using ions from the 15UD Pelletron at the NSC, New Delhi. The beam energy was fixed at 60 MeV and the fluence was varied in the range -. Irradiation effects were studied using UV-visible and IR spectroscopic techniques. For all the polymer targets there was an increase in absorption due to irradiation mainly in the shorter wavelength region. The change in chemical behaviour of bulk samples is studied by the etching technique. Annealing effects are observed in Makrofol-KG after 75 min heating at C. There is no appreciable change in the optical properties of glasses studied with ion doses in the range -. The morphology of heavy-ion latent tracks in insulators is revealed by atomic force microscopy. The applications of ion-track filters produced by swift heavy ions in thin polymer films are also discussed.
  Journal of Physics D Applied Physics 12/1998; 31(21):3139. · 2.54 Impact Factor
• Article: Alpha-Guard radon survey in soil gas and dwellings of some uranium-rich areas of Himachal Pradesh, India.

  H.S. Virk, Kumar Naresh, N. Sharma, B. S. Bajwa
  Current science. 01/1998; 75:430-431.
• Article: Radon/Helium survey of thermal springs of Parbati, Beas and Sutluj valleys in Himachal, Himalaya.

  H.S. Virk, Kumar Naresh, A. K. Sharma
  Journal of Geological Society of India. 01/1998; 52:523-528.
• Article: Study of charged particle tracks in barium phosphate (BP-1) glass

  G.S. Randhawa, H.S. Virk
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  ABSTRACT: Samples of barium phosphate (BP-1) glass detector were irradiated by 238U (11.4 MeV/u) ions from the UNILAC accelerator, at GSI, Darmstadt, Germany. Etching characteristics were studied using HF (48 vol%), NaOH (6.25N) and KOH (6.5N) at different temperatures. The sensitivity, () of BP-1 glass is found to vary between 63 and 33 between temperature range 40–70°C. The experimental range of 238U (11.4 MeV/u) ion in BP-1 has been determined and compared with the theoretical range values from different formulations. For study of annealing characteristics, both isothermal and isochronal experiments were performed on BP-1 glass irradiated with 238U (11.4 MeV/u) and fission fragments from 252Cf source. The annealing kinetics of heavy ion damaged BP-1 glass is explained by using different empirical formulations. The activation energy of annealing for heavy ion damaged BP-1 glass is found to be 0.405 ± 0.005 eV.
  Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 132(4):653-659. · 1.21 Impact Factor
• Article: F/α track-etch method for U, Th and isotropic disequilibrium study of geological samples

  N.P. Singh, Surinder Singh, H.S. Virk
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  ABSTRACT: The relation connecting concentration of uranium (U) and thorium (Th) atoms in geological samples with alpha track production rate in plastic track detector, LR-115 type 2, is used for analysis of some rock and fossil bone samples. The alpha track measurements from the samples under secular equilibrium define the total U and Th contents, while fission track measurements yield U concentration alone, thus by combining the results of both these measurements, U, Th and Isotropic disequilibrium is determined. Uranium concentration determined by fission track analysis in radioactive fossil bones is found to vary from 93.8 to 418.0 ppm. The results of U concentration as determined by alpha autoradiography are pronouncedly lower than those determined by fission track analysis indicating the presence of radioactive disequilibrium. However, the quartzite and phosphorite samples analysed using this technique show the presence of radioactive equilibrium.
  International Journal of Radiation Applications and Instrumentation Part D Nuclear Tracks and Radiation Measurements 15:693-697.
• Article: Thermal annealing of heavy ion latent tracks in soda and BP-1 phosphate glasses

  G.S. Randhawa, H.S. Virk
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  ABSTRACT: Annealing behaviour of latent tracks in soda glass has been studied in the temperature range 100–300°C for different time intervals. These latent tracks are created by irradiating these samples with heavy ions viz., 238U (11.4 MeV/u) and 132Xe (11.4 and 5.9 MeV/u) from GSI Darmstadt and 56Fe (4.0 MeV/u) and 48Ti (4.0 MeV/u) from JINR, Dubna. A similar study has been made on Barium Phosphate glass (BP-1) irradiated with 238U (11.4 MeV/u) and fission fragments of 252Cf. The ‘Single Activation Energy’ model proposed by Modgil and Virk (1985) is used as an empirical approach for explaining the thermal fading of these latent tracks. This model always yields a unique value of activation energy of annealing and which is independent of the nature of the ion beam and the degree of annealing. In comparison to this model, Mark et al. (1973) and Green et al. (1985) approach on annealing phenomena has also been used to determine the activation energy. The value of activation energy for annealing of these heavy ion latent tracks is found to be 0.16 and 0.41 eV in soda and BP-1 phosphate glass, respectively. The results of ‘Single Activation Energy’ model are compared with those obtained by using models proposed by Mark et al. (1973) and Green et al. (1985).
  Applied Radiation and Isotopes. 48(4):447-451.
• Article: Radon survey for uranium prospection using alpha detectors

  Manwinder Singh, N.P. Singh, Surinder Singh, H.S. Virk
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  ABSTRACT: The results of radon survey for uranium prospection using alpha track detector and radon emanometer in some geological area are reported. The Rn-Tn discriminator with plastic track detectors in which air column acts as diffusion barrier is employed for separating Rn from Th.
  International Journal of Radiation Applications and Instrumentation Part D Nuclear Tracks and Radiation Measurements 12:879-882.
• Article: Stopping power and range of heavy ions in solids: A comparative study

  G.S. Randhawa, H.S. Virk
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  ABSTRACT: A comparative study of various stopping power and range formulations has been made by comparing the calculated stopping power and range values with corresponding experimental values for different projectiles, viz. H, He, Li, N, O, Al, Si, Xe, Au, Pb, Bi, U, etc. in different targets, e.g. Be, C, Al, Au, Pb, CR-39, Lexan, Mylar, LR-115, CH, (CH)n, TRIFOL-TN, etc. at various low and high energies. A detailed study has been made taking into consideration different target and projectile combinations, e.g. heavy ion-light target, light ion-heavy target and light ion-light target. Overall the Ziegler et al. (The Stopping Power and Range of Ions in Solids, Vol. 1. Pergamon Press, New York, 1985) formulation (TRIM 95) provides the best agreement with the experimental results for all projectile and target combinations except the heavy ion-light target combination where it underestimates the stopping power data in the limited range of energy of the projectile. Mukherjee and Nayak (Nucl. Instrum. Meth.159, 421, 1979) formulation totally fails at relativistic and low energies of the projectile, irrespective of the projectile-target combination. Northcliffe and Schilling (Atom. Data Nucl. Data TablesA7, 233, 1970) formulation does not show any particular trend. Benton and Henke (Nucl. Instrum. Meth.67, 87, 1969) formulation gives good agreement between experimental and theoretical data within the range of experimental error. The present study has been undertaken in order to determine the best stopping power and range formulation for calibration of solid state nuclear track detectors.
  Radiation Measurements.
• Article: Response of different plastic track detectors to α-particles

  G.S. Randhawa, Shyam Kumar, H.S. Virk
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  ABSTRACT: Samples of various plastic track detectors, namely CR-39, CR-39 (DOP) and SR-86, were exposed to α-particles from radioactive sources, 241Am and 252Cf. The exposed samples were etched in 6.25 N NaOH solution at a constant temperature of 70°C. In the present study, a comparison of the sensitivity of these detectors to α-particles has been made. Finally, an attempt has been made to determine the optimum conditions for the etching of SR-86 plastic track detector.
  Radiation Measurements.
• Article: A comparative study of indoor radon level measurements in the dwellings of Punjab and Himachal Pradesh, India

  B.S. Bajwa, H.S. Virk, Surinder Singh
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  ABSTRACT: The LR-115 type-II plastic track detector has been used for measuring the indoor radon levels in the dwellings of some villages of Punjab and Himachal Pradesh. In Punjab, the villages surveyed are Rampura Phul, Lehra Mahabat and Pitho (villages in Bathinda district), and Amritsar city. The average indoor radon levels in these areas are found to vary from 64 to , which are quite within the safe limits recommended by International Commission on Radiological Protection (Ann. ICRP 23(2)). The indoor radon levels have also been measured in the dwellings of Hamirpur district of Himachal Pradesh. The villages surveyed in this area are Nukhel, Badarn, Galore-Khas, Har-Upper, Tikker Brahamana and Awah-Lower where radon concentration has been found to vary from 261 to . These values are higher than the recommended limit.
  Radiation Measurements.
• Article: Range study of heavy ions in plastic track detectors

  G.S. Randhawa, A.K. Garg, H.S. Virk
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  ABSTRACT: The maximum etchable ranges of heavy ions such as 128U (16.53 MeV/u),208Pb (13.6 MeV/u), 197Au (11.4 MeV/u), 132Xe (14.5 MeV/u, 13.02 MeV/u and 5.6 MeV/u) and 93Nb (18.0 MeV/u) in CR-39 and 238U (16.53 MeV/u, 15.0 MeV/u and 5.6 MeV/u), 198Au (13.42 MeV/u) and 132Xe (14.5 MeV/u and 5.6 MeV/u) in Lexan have been determined experimentally. The ranges of these heavy ions in these detectors have also been computed theoretically using the Mukherjee and Nayak stopping power equations. A reasonably good agreement has been observed between the experimental and theoretically computed values. Finally, a theoretical study of the relation R(range) = aEb (energy) has been made using the Mukherjee and Nayak stopping power equations for different heavy ions in CR-39 and Lexan polycarbonate.
  Radiation Measurements.