Nuclear Track Etch Research Articles

Alpha particle detection by Makrofol® DE1-1 and CR-39 NTDs: A comparative study

In this present study, a color contrast approach was proposed to find a method for quantify uncertainty in alpha particle spectroscopy using nuclear track detectors (NTDs). According to this method, this color contrast approach was applied to NTDs as an alpha particle spectrometer. A comparison between the registration of 4.0 MeV alpha particles by Makrofol®DE1-1 and CR-39 NTDs using a color contrast method was carried out in alpha spectroscopy. The contrast of the alpha tracks of each single color channel whether red, green and blue resulting from split RGB image was determined. The measurements were proved that green color channel produced the highest contrast of the alpha tracks of about 85%, in both Makrofol® DE1-1 and CR-39 NTDs. The results of 4.0 MeV alpha particle etch-pits diameters in Makrofol® DE1-1 didn't show homogenous diameters for short etching time. The standard deviation of 4.0 MeV alpha-track diameters in Makrofol® DE1-1 went up to a maximum value of 2.23 μm at a removal thickness of 12.25 μm. When increasing the etching time, they decreased sharply to about 1.18 ± 0.02 μm at a ratio of change 0.047 that was less than 6%. The standard deviation of 4.0 MeV alpha particle etch-pit diameters in CR-39 detector was linearly correlated with the removal thickness at a ratio of change of 0.02 which was less than 5%. Results revealed that the etch-pit diameter in Makrofol® DE1-1detector, in alpha particle spectrometry was best measured around the end of the alpha particle range. Results of this study are discussed within the frame work of nuclear track formation theories and etching mechanism in nuclear track detectors (NTDs).

High-precision angular measurement of 12C ion interaction using a new imaging method with a CR-39 detector in the energy range below 100 MeV/nucleon

In this study, we show that angular measurement of nuclear tracks produced in heavy ion interactions can be made with high precision using a CR-39 solid-state nuclear track detector. For this purpose, we have increased the position resolution of nuclear track (etch pit) analysis and the precission of thickness measurement of the CR-39 detector. The position resolution of the heavy ion track was verified to be 0.02 μm by the dedicated image analysis software package PitFit. The precision of the thickness measurement of the CR-39 detector was increased to 0.6 μm by our new both sides imaging method of the CR-39 detector using the autofocus system of the microscope. As a consequence, the angular distributions of projectiles and fragments can be realized with a precision of 1.4 × 10−2 degrees (2.5 × 10−4 radian). As a demonstration, we applied the angular measurement technique to the diagnosis of heavy ion beam and the small Coulomb scattering angle measurement of interactions of 12C + Al in energies below 100 MeV/nucleon. By this new imaging technique, event-by-event interaction of the projectiles in the CR-39 detector can be measured rapidly and can be applied to the measurement of the total charge-changing cross section, the decay mode, and the branching ratios of the projectile with higher angular precision.

Summary of a comprehensive data bank for nuclear track research using CR-39 detectors

This data bank is the result of systematic experiments on nuclear track etching, fission fragment track annealing, and radiation detection & measurement. Data highlights from a comprehensive nuclear track data bank, and related physics and chemistry are described here briefly and clearly. Uncertainties in the reported data are also presented. All the data presented were collected using the most sensitive nuclear track detector CR-39, or Poly Allyl Diglycol Carbonate (PADC), over two decades. Closely related data sets from the published literature are also reviewed. Necessary details of the reviewed data and their citations are clearly given in the data bank. Aim here is to present tabulated experimental raw data with essentially needed calculations. All the necessary information related to the data bank is described clearly. Study presented here is useful for research students and scientists who possess the rudimentary knowledge of nuclear track detection. Single tabulation of the data, instead of plots, is aimed at making easy access of the data to users.

Design and Construction of an Electrochemical Chamber and a High-Voltage AC Generator for Electrochemical Etching in CR-39 Polycarbonates Sheets

An original design for an electrochemical chamber and the construction of a high-voltage AC generator for electrochemical etching (ECE) of nuclear tracks in CR-39 polycarbonates sheets are presented. The electrochemical chamber was designed and manufactured in an engineering plastic in a vertical machining center. The high-voltage AC generator was built by using different electronic circuits: a signal oscillator, a preamplifier, a power amplifier, two power supplies and a voltage converter transformer. The experimental tests showed that the design of the electrochemical chamber allowed that ECE be developed efficiently, achieving a dielectric breakdown in the polycarbonate, and the generator supplied the electric current in a stable manner and with an excellent performance throughout the ECE. The conditions of chemical etching and electrochemical etching, as well as the electrical treeing generated in the CR-39 are also presented.

Thermodynamics of nuclear track chemical etching

This is a brief paper with new and useful scientific information on nuclear track chemical etching. Nuclear track etching is described here by using basic concepts of thermodynamics. Enthalpy, entropy and free energy parameters are considered for the nuclear track etching. The free energy of etching is determined using etching experiments of fission fragment tracks in CR-39. Relationship between the free energy and the etching temperature is explored and is found to be approximately linear. The above relationship is discussed. A simple enthalpy–entropy model of chemical etching is presented. Experimental and computational results presented here are of fundamental interest in nuclear track detection methodology.

Indoor radon measurements in Turkey dwellings.

In this work, indoor radon radioactivity concentration levels have been measured in dwellings of Turkey within the frame of the National Radon Monitoring Programme. The (222)Rn concentrations were measured with time-integrating passive nuclear etched track detectors in 7293 dwellings in 153 residential units of 81 provinces, and the radon map of Turkey was prepared. Indoor radon concentrations were distributed in the range of 1-1400 Bq m(-3). The arithmetic mean of the radon gas concentration was found to be 81 Bq m(-3); the geometric mean was 57 Bq m(-3) with a geometric standard deviation of 2.3.

Application of Ag+-doped phosphate glasses as nuclear track etch detectors

The Ag+-doped phosphate glass which is commonly employed as the radiophotoluminscence (RPL) dosimeter has been applied as a nuclear track etch detector. The glass is etchable in the NaOH solutions and forms clear nuclear etch pit. The etching performances and track parameters vary as a function of the concentration of NaOH solution. The most sensitive normality was confirmed to be 7 N. The track response is controllable with NaOH concentration at the range of Z∗/β ≥ 80 (Z∗: effective charge, β: velocity). The charge spectroscopic resolution for Xe (Z∗/β = 107) was found to be 0.23 cu (charge unit), which would allow to identify individual nuclear charge of ultra heavy nuclei around Actinides in the cosmic rays. The Ag+-doped phosphate glass would be a promising detector for high Z spectroscopy for cosmic ray and nuclear physics fields and has the potential to operate not only RPL dosimeter but also nuclear track etch detector.

Coupled chemical reactions in dynamic nanometric confinement: V. The influence of Li+ and F− ions on etching of nuclear tracks in polymers

Etching of continuous nuclear tracks in thin polymer foils from both sides is known to lead to the formation of double-conical nanopores. In this work and related ones we try to find out how this etching kinetics is modified when materials are added which react with each other upon their contact towards some new product that influences the etching. For that purpose we have chosen here Li+ and F− ions as the additions, which react with each other to form LiF precipitations. The coupled etching and precipitation kinetics is recorded by measuring the electrical current that is transmitted through the foils upon application of a low-frequency alternating sinusoidal voltage. Depending on the etchant concentrations, the etching temperature and the time of Li+ and F− addition, different effects are found that range from (a) no alteration of the transmitted current at all, via (b) the emergence of an alternating current with a temperature-dependent amplitude, and (c) the complete vanishing of any transmitted current at all, towards (d) chaotic transmitted current histories with phases with strong current spike emission and (e) rather quiet phases, alternating with each other in a rather unsystematic way. The observed effects are ascribed to (a) the enhanced penetration efficiency of both the Li+ and F− ions through the polymeric bulk and/or latent ion tracks after the removal of the polymer's protective surface layer by the etchant, (b) the high mobility of preferentially the F− ions within the polymer, (c) the LiF precipitation within the polymer or on its surface upon encounter of Li+ and F− ions, (d) the nanofluidic properties of narrow etched tracks covered with Li+ ions on the wall surfaces and F− ions beyond, and/or (e) the formation of LiF membranes within the etched tracks.

Measurements of nuclear track etch induction time in Markrofol for alpha particles from a 252-Cf source

Makrofol DE1-4C detectors were exposed to fission fragments and alpha particles (of energy 0.5–3 MeV) from a 252Cf source in a vacuum chamber. The exposed detectors were etched in 6-N NaOH solution at 70 °C to measure etch induction times. An optical microscope was used to investigate various charged particle tracks and diameters in Makrofol detectors. The etch induction times for alpha-particle and fission-fragment tracks were obtained from the intersections of extrapolations of a graph of track diameters with time. The obtained results will be very useful in nuclear track studies, as well as nanotechnology fields.

Mechanisms and kinetics of nuclear track etching and annealing: Free energy analysis of damage in fission fragment tracks

Mechanisms and kinetics of etching and annealing of fission fragment tracks in CR-39 have been investigated. Kinetics of bulk etching and that of fission fragment track etching in CR-39 are described in a systematic manner. Activation energies of etching and annealing were determined from the experimental results through Arrhenius type, t=toexp(Ea/kBT), empirical relationships and models. The increase of free energy in fission fragment track formation in CR-39 is also determined from the measurements of track parameters. Activation barriers of bulk etching, track etching and track annealing in CR-39 are compared and discussed. This paper presents an anatomy of fission fragment tracks. Analyses of experimental results and comparison of above mentioned energies have yielded the important physics information usable in nuclear track methodologies, including nuclear geophysics and geochemistry, and radiation damage in solids.

Development of an energy discriminate CR-39 ® nuclear track etch dosimeter for Radon-220 gas measurements

An energy discriminate CR-39 ® nuclear track etch dosimeter for use in a 220Rn and 222Rn gas monitor has been developed and experimentally assessed. It utilises a thin film of Mylar ® C to attenuate the alpha particle energies to allow only the damage tracks created by the 8.785 MeV alpha particles emitted from 212Po of the 232Th decay chain to be registered in the CR-39 ® plaque, allowing for the direct measurement of 220Rn gas concentrations. The dosimeter was developed through a combination of experimental investigations and theoretical simulations using the Monte Carlo ion transport modelling program Stopping and Range of Ions in Materials (SRIM 2008). A film thickness of 54 μm has been shown to attenuate all alpha energies less then 7.7 MeV.

SHI induced nano track polymer filters and characterization

Swift heavy ion irradiation produces damage in polymers in the form of latent tracks. Latent tracks can be enlarged by etching it in a suitable etchant and thus nuclear track etch membrane can be formed for gas permeation / purification in particular for hydrogen where the molecular size is very small. By applying suitable and controlled etching conditions well defined tracks can be formed for specific applications of the membranes. After etching gas permeation method is used for characterizing the tracks. In the present work polycarbonate (PC) of various thickness were irradiated with energetic ion beam at Inter University Accelerator Centre (IUAC), New Delhi. Nuclear tracks were modified by etching the PC in 6N NaOH at 60 (±1) °C from both sides for different times to produce track etch membranes. At critical etch time the etched pits from both the sides meet a rapid increase in gas permeation was observed. Permeability of hydrogen and carbon dioxide has been measured in samples etched for different times. The latent tracks produced by SHI irradiation in the track etch membranes show enhancement of free volume of the polymer. Nano filters are separation devices for the mixture of gases, different ions in the solution and isotopes and isobars separations. The polymer thin films with controlled porosity finding it self as best choice. However, the permeability and selectivity of these polymer based membrane filters are very important at the nano scale separation. The Swift Heavy Ion (SHI) induced nuclear track etched polymeric films with controlled etching have been attempted and characterized as nano scale filters.

INVESTIGATION OF RADON CONCENTRATIONS COMING FROM NATURAL GAS IN SOME BUILDINGS IN BURSA REGION

In this study, the contributions coming from natural gas in indoor environments of Bursa Distinct were investigated. Using the solid state nuclear track etching LR-115 film detectors, the radon concentrations of the closed buildings (houses) where natural gas is used and not used were determined. The obtained mean values were compared to each other. It was found that the mean radon concentrations in closed atmospheres using natural gas varied from 111.51 Bq m-3 to 236.98 Bq m-3. In the buildings where natural gas is not used the mean radon concentrations were found between 67.63 Bq m-3, 69.68 Bq m-3. It is clearly seen that the radon values of the houses where natural gas is used is higher than the houses not using natural gas.

The study of radon levels and absorbed dose in the staff and visitors of Alisadr Cave

CR-39 passive integrating Solid State Nuclear Track etch Detectors (SSNTDs) were used to measure atmospheric radon concentrations in the Alisadr show cave in Hamedan province, Iran. This was done in order to assess the risk from natural environmental radiation to tourists and cave guides. The study was carried out in 12 locations in the winter and spring periods. The mean radon concentration during the winter period was 1504.6 Bq m−3 and the highest value was 2280.4 Bq m−3 during spring. The average absorbed dose for visitors and guides was estimated as 0.02 mSv per visit, and 4.32 mSv per season, respectively. The annual average absorbed dose is rather more significant for staff, being in the order of 16.50 mSv.

On the long standing question of nuclear track etch induction time: Surface-cap model

Using a systematic set of experiments, nuclear track etch induction time measurements in a widely used CR-39 detector were completed for accessible track-forming particles (fission fragments, 5.2MeV alpha particles and 5.9MeV antiprotons). Results of the present work are compared with appropriately selected published results. The possibility of the use of etch induction time for charged particle identification is evaluated. Analysis of experimental results along with the use of well-established theoretical concepts yielded a model about delay in the start of chemical etching of nuclear tracks. The suggested model proposes the formation of a surface-cap (top segment) in each nuclear track consisting of chemically modified material with almost same or even higher resistance to chemical etching compared with bulk material of the track detector. Existing track formation models are reviewed very briefly, which provide one of the two bases of the proposed model. The other basis of the model is the general behavior of hot or energised material having a connection with an environment containing a number of species like ordinary air. Another reason for the delay in the start of etching is suggested as the absence of localization of etching atoms/molecules, which is present during etching at depth along the latent track.

Novel Al2O3:C,Mg fluorescent nuclear track detectors for passive neutron dosimetry

The latest advances in the development of a fluorescent nuclear track detector (FNTD) for neutron and heavy charged particle dosimetry are described and compared with CR-39 plastic nuclear etched track detectors (PNTDs). The technique combines a new luminescent aluminium oxide single crystal detector (Al(2)O(3):C,Mg) with an imaging technique based on laser scanning and confocal fluorescence detection. Detection efficiency was obtained after irradiations with monoenergetic neutron and proton beams. Dose dependences were measured for different configurations of the detectors exposed in fast- and thermal-neutron fields. A specially developed image processing technique allows for fast fluorescent track identification and counting. The readout method is non-destructive, and detectors can be reused after thermal annealing.

Population dose in the vicinity of closed Hungarian uranium mine

In order to determine the exposure to natural sources of radiation for people in the vicinity of remediated Hungarian uranium mine regional surveys were carried out. The surveys evaluated indoor radon concentrations and outdoor and indoor external gamma dose rates. Radon concentration has been measured with nuclear etched track detectors for 4 months in 129 houses in Kovágószolos and in 23 houses in Cserkút. In some houses measurements have been carried out for a year and the measurement results of the 4 months were corrected according to these. The corrected radon concentrations altered between 15 and 2314 Bq m(-3). An average of 257 Bq m(-3) in Kovágószolos and 125 Bq m(-3) in Cserkút was measured. The average was 434 Bq m(-3) for the 48 houses within 100 m of the passage of the former mine that is under the village of Kovágószolos. The higher values of Kovágószolos are likely to be the result of the influence of mining. The terrestrial gamma-ray dose rate was measured outdoors and indoors at these houses. Values of 139 (62-233) nGy h(-1) and 133 (93-275) nGy h(-1) were measured in Kovágószolos and Cserkút, respectively. The average annual effective doses for the two villages studied were 3 and 5 mSv y(-1), but the maximum value was 40 mSv y(-1).

Radon concentration measurements in the AMASRA coal mine, Turkey

In this study, the results of atmospheric radon measurements that were performed for the Amasra underground coal mine in Zonguldak bituminous coal basin (Turkey) are presented. The radon measurements were performed for 40 days between November 2004 and December 2004 using passive nuclear etched track detectors. The radon concentrations vary from a minimum value 49 Bq m(-3) in a site located at +40 m to a maximum value 223 Bq m(-3) in a site located at -100 m. Mean concentration is 117 (Bq m(-3)). This value is well below the action level of 500-1,500 Bq m(-3) recommended by the International Commission on Radiological Protection (ICRP) (1993). The mean effective dose value for workers of this mine of 3.4 microSv per day was obtained. This result shows that protection against radiological hazards would not be necessary for workers of this mine((2)).

On the Feasibility of Detecting Quantized Conductance in Neutral Matter

When an electrochemical potential difference (i.e., a voltage) is applied across a metal wire whose transverse dimensions are on the order of the electron’s Fermi wavelength, the conductance G≡ I/ΔV becomes quantized in units of 2e2/h. We present calculations that show that when a chemical potential difference Δμ3 is applied across an array of small apertures whose sizes are comparable to the Fermi wavelength of 3 He in a 3 He:4 He mixture, the mass conductance $$G \equiv \left(\frac{I_3}{\Delta \mu_3/m_{3}^{\ast}}\right)$$ will be quantized in units of 2m 3 * /h where m 3 * is the 3He effective mass. We show that the mass conductance will be quantized for a 0.1% mixture passing through 10 nm diameter pores at temperatures below 25 mK. The phenomenon should be observable in a filter material made by nuclear track etching.

Radon concentration measurements in bituminous coal mines

Radon measurements were carried out in Kozlu, Karadon and Uzülmez underground coal mines of Zonguldak bituminous coal basin in Turkey. Passive-time integrating method, which is the most widely used technique for the measurement of radon concentration in air, was applied by using nuclear etched track detectors (CR-39) in the study area. The radon concentration measurements were performed on a total of 42 points in those three mines. The annual exposure, the annual effective dose and lifetime fatality risk, which are the important parameters for the health of workers, were estimated based on chronic occupational exposure to the radon gas, which is calculated using UNCEAR-2000 and ICRP-65 models. The radon concentrations at several coal production faces are higher than the action level of 1000 Bq m(-3). It is suggested that the ventilation rates should be rearranged to reduce the radon concentration.