Track Etch Rate Research Articles

Impact of infrared radiation on track etching parameters of Lexan track detector to fission fragments from 252Cf source

In this research work, the impact of infrared (IR) radiation on the etching parameters like bulk etch rate VB, track etch rate VT, Sensitivity S, Critical angle of etching θC and track registration efficiency η of Lexan track detector, irradiated to fission fragments from 252Cf source, were investigated. The changes in etching parameters due to infrared radiation for 0, 12 and 24 h at different temperatures (328–348 K) are discussed based on chain scission and cross-linking mechanisms. Bulk and track etch rates increase with infrared radiation in case of post-exposed as compared to un-exposed while sensitivity slightly decreases for 12 h exposure with infrared radiation but slightly increases for 24 h exposure with infrared radiation as compared to un-exposed. On the other hand, bulk and track etch rates decrease with infrared radiation in case of pre-exposed as compared to un-exposed while sensitivity slightly increases. Critical angles increase and track registration efficiency decreases with etching temperatures. Activation energies for bulk and track etching rates have been determined by fitting Arrhenius equation to the experimental data of bulk and track etch rates which show a decrease in bulk activation energies in case of post-exposed but slightly increase in case of pre-exposed as compared to un-exposed Lexan track detectors. Track activation energies show the same trend as for bulk etch rate.

Strong etching investigation on PADC CR-39 as a thick track membrane with deep depth profile study

Shape and size of micro-tubes produced by high energy Au, Ni, Si and Fe ions on thick CR-39 polymer processed in strong etching solution were studied. Deep internal polymer track parameters of sensitivity (V); bulk (Vb) and track etch rates (Vt) were intensively investigated by measuring the track opening as well as the track cone length. Development of track envelope with etching was studied using track profile technique, TPT. Variations in Vb, Vt, and V with deep depth inside the polymer were studied down to ≈100 μm depth or more. CR-39 sensitivity was reduced to 60–70% at the first 25 μm inwards. Microphotographs for the developed track profile for each ion was shown. Fe and Si profiles show new and interesting track profile for the first time where their profiles deviate from the normal cone shape of the track. Ion's track membranes (TMs) for thick CR-39 polymer were produced and their properties were determined.

Fission-track evolution in Macusanite volcanic glass

Macusanite is a natural volcanic glass, which is produced by the rapid cooling of magma during a volcanic eruption. Since it typically contains concentrations of uranium, it can be used for fission-track dating. Understanding the fission-track formation process and its morphology in natural volcanic glass is of major importance in this dating method. Therefore, in this work the latent fission-track structure was investigated using the geometry evolution of etched tracks. This evolution was characterized as a function of the chemical etching time via optical microscopy and atomic force microscopy. In this way, measurements of track diameters and theoretical estimation of track depths of normal incident fission fragments were made in order to determine the bulk and track etch rates. As a result, both rates yield constant values, and therefore the defect density along the fission fragment trajectory can be considered constant.

Effects of UV irradiation on Fission-fragment track parameters in Makrofol-E detector

This study gives information about the effects of UV (here, the wavelength is 160 nm) exposure on the bulk etch rate ([Formula: see text], track etch rate ([Formula: see text], the detector sensitivity ([Formula: see text], critical angle ([Formula: see text] and etching efficiency ([Formula: see text] of Makrofol-E Solid State Nuclear Track Detector. The effect of UV on the activation energy of Makrofol-E was also studied. Nine pieces of Makrofol-E Solid State Nuclear Track Detector were separated into three equal sets as set A, set B and set C. Set A, named as reference set (Fission fragment FF), was irradiated to [Formula: see text]Cf source. Set B, called as post-exposed ([Formula: see text]), was first irradiated to [Formula: see text]Cf and then exposed to UV. The process was reversed for set C named as pre-exposed ([Formula: see text]) at the same conditions. From the results, it is concluded that radiation produces small but significant effect on activation energy [Formula: see text] of bulk etch rate for pre-exposed and post-exposed samples. Also, the activation energies [Formula: see text] of track etch rate for post-exposed and Fission fragment samples are within experimental uncertainty. The energy carried by UV radiation may be responsible for cross networking processes occurring during the exposure which results small change in activation energies for both [Formula: see text] and [Formula: see text]. The [Formula: see text] can be increased by hardening detector material of the pre-exposed detector.

A new chemical etchant for the development of alpha tracks in CR-39 solid state nuclear track detector

Chemical etching is an important step for enlargement of latent tracks in solid state nuclear track detectors (SSNTD). In the etching process, bulk and track etch rates are determined by various parameters, which decide the sensitivity and efficiency of the track detector. Thus, determination of the etching parameters is essential in introducing a new chemical etchant. For the enlargement of latent tracks in CR-39, chemical etching is usually carried out at temperatures of 60–70 °C by using 6–6.5 N concentrations of alkali like NaOH or KOH. In the present work, a mixture of 8 g NaOH in 25 mL water and 25 mL ethanolamine as an etchant at 70 °C was found to be very effective in the enlargement of alpha tracks in CR-39 SSNTD. The diameters of alpha tracks resulting from this new etchant are found to be a quadratic function of the etching time, whereas those from the standard etchant are linear with respect to the etching time. This results in the reduction in the etching time by a factor of 4 with an increased etching efficiency.

Control of the size of etchable ion tracks in PVDF – Irradiation in an oxygen atmosphere and with fullerene C60

We pursue the possibility of controlling the size of etchable ion tracks of poly(vinylidene-fluoride) (PVDF) films. At first, 330 MeV 40Ar ions were irradiated to a 25-µm-thick PVDF film in oxygen using the uniform-beam formation/irradiation system at Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) cyclotron of National Institutes for Quantum and Radiological Science and Technology (QST, Japan). Compared with the irradiation in a high vacuum, which is the conventional method, it is clear that more oxygen-containing functional groups are formed on the surface, the size of the pores becomes larger and the track-etching rate is accelerated. The result shows that the irradiation in oxygen effectively induces oxidation of ion tracks and the oxidation widens the size of the etchable ion tracks. Next, we attempted the irradiation with 6-MeV fullerene C60+ ions. Compared with the irradiation with 100-keV C+ monatomic ions of the same velocity, the fullerene-ion irradiation induced large sized etchable tracks on the surface of PVDF. The result could represent the effect of local and simultaneous collisions by the aggregated ions. Both of the irradiations showed widening the size of etchable ion tracks and we were able to control the pore diameter by varying the etching time.

IR radiation-induced changes in the optical and registration properties of a CR-39 nuclear track detector

The UV–Vis (ultraviolet–visible) spectra and etching characteristics have been studied of poly allyl diglycol carbonate (PADC, a form of the CR-39 polymer) detector films after exposure to 250 W IR-radiation lamp for various times ranging from 1 to 40 min. Etching experiments were carried out on the IR-exposed CR-39 detectors after alpha particle irradiation using a241Am source. The bulk and track etch rates were measured using the weight loss and alpha track diameter methods, respectively, as well as the sensitivity, the detection efficiency, and the critical angle, were also determined. The optical band gap for both indirect and direct transitions was calculated based on the absorption edge of the UV spectra of the pristine and variously IR-exposed detectors. UV–Vis spectra of pristine and IR irradiated PADC polymer films exhibit a decreasing trend in the optical band gap, direct and indirect transitions, ranging from 4.64 ± 0.23, 3.85 ± 0.20 to 3.40 ± 0.12 and 3.04 ± 0.11 eV, correspondent to IR exposure time from 0 to 40 min, respectively. This decline in the optical band gap with increasing IR exposure time has been discussed on the basis of IR irradiation-induced defects in PADC. Further etching measurements, of 3 and 9 h etching times, confirmed a decrease in sensitivity from 1.86 ± 0.06 to 1.05 ± 0.03 and from 1.78 ± 0.06 to 1.03 ± 0.03 as well as in detection efficiency from 46.2 ± 1.45 to 4.68 ± 0.12 and from 43.91 ± 1.50 to 2.98 ± 0.09 (%) correspondents to IR exposure time from 0 to 40 min, respectively, in IR irradiated CR-39 polymer detector.

Etched ion tracks in amorphous SiO2 characterized by small angle x-ray scattering: influence of ion energy and etching conditions

Small angle x-ray scattering was used to study the morphology of conical structures formed in thin films of amorphous SiO2. Samples were irradiated with 1.1 GeV Au ions at the GSI UNILAC in Darmstadt, Germany, and with 185, 89 and 54 MeV Au ions at the Heavy Ion Accelerator Facility at ANU in Canberra, Australia. The irradiated material was subsequently etched in HF using two different etchant concentrations over a series of etch times to reveal conically shaped etched channels of various sizes. Synchrotron based SAXS measurements were used to characterize both the radial and axial ion track etch rates with unprecedented precision. The results show that the ion energy has a significant effect on the morphology of the etched channels, and that at short etch times resulting in very small cones, the increased etching rate of the damaged region in the radial direction with respect to the ion trajectory is significant.

Search for the “stability island” of superheavy nuclei using natural track detectors

The method of using natural track detectors, i.e., meteorite olivine crystals, is developed and improved applied to the problem of searching for superheavy nuclei in nature, in galactic cosmic rays (GCR). The new technique implements the sequence of etching, grinding, and track identification operations using the automated PAVICOM facility. The data on the track length and etching rate in combination with the results of calibration on heavy nucleus accelerators allowed the development of a technique for determining the GCR nucleus charge with an accuracy of ±2. On this basis, a significant set of experimental data on superheavy nuclei of natural origin was obtained (21743GCRheavy nucleiwithZ >20, including three nucleiwith a charge of 119−6+10). The minimum lifetime Tmin of the last-mentioned is within 50 years< Tmin < 100 years, which exceeds the lifetime of transfermium nuclei synthesized on accelerators by many orders of magnitude. The long-lived superheavy nuclei detected in the GCR spectrum can belong to the “stability island”.

Track revelation and optical properties of pentaerythritol tetrakis (allyl carbonate) plastic for application as nuclear track detector: effects of gamma radiations

ABSTRACTThe etching conditions of an indigenously prepared thin film of pentaerythritol tetrakis(allyl carbonate) (PETAC) were standardised for the use as a nuclear track detector. The optimum etching times in 6 N NaOH at 70°C for the appearance of fission and alpha tracks recorded in this detector from a 252Cf solid source were found to be 30 min and 1.50 h, respectively. The experimentally determined values for the bulk and track-etch rates for this detector in 6 N NaOH at 70°C were found to be 1.7 ± 0.1 and 88.4 ± 10.7 µm/h, respectively. From these results, the important track etching properties such as the critical angle of etching, the sensitivity and the fission track registration efficiency were calculated and compared with the commercially available detectors. The activation energy value for bulk etching calculated by applying Arrhenius equation to the bulk etch rates of the detector determined at different etching temperatures was found to be 0.86 ± 0.02 eV. This compares very well with the value of about 1.0 eV reported for most commonly used track detectors. The effects of gamma irradiation on this new detector in the dose range of 200–1000 kGy have also been studied using bulk etch rate technique. The activation energy values for bulk etching calculated from bulk etch rates measurements at different temperatures were found to decrease with the increase in gamma dose indicating scission of the detector due to gamma irradiation. The optical band gap of this detector was also determined using UV–visible spectrometry and the value was found to be 4.37 ± 0.05 eV.

Generation and application of LET calibration curve for neutron dosimetry using CR-39 detector and microwave induced chemical etching.

Microwave induced chemical etching (MICE) has been established as a faster and improved technique compared to other contemporary etching techniques for the development of tracks in a CR-39 detector. However, the methodology could not be applied for LET (linear energy transfer) spectrometry due to lack of a calibration curve using this method. For this purpose, a new LET calibration curve in the range of 12 keV/μm-799 keV/μm was generated considering different ions such as H, Li, C, O, and F on CR-39 having different LETs in water. An empirical relation was established from the obtained calibration curve for determining the value of LET (in water) from the value of V, the ratio of track etch rate to bulk etch rate. For application of this calibration curve in neutron dosimetry, CR-39 detectors were irradiated to neutrons generated from 120 and 142 MeV 16O+27Al systems followed by a similar MICE procedure. The absorbed dose (DLET) and the dose equivalent (HLET) were obtained from the LET spectra and were found to be 13% and 10% higher for 142 MeV 16O+27Al system than those for 120 MeV 16O+27Al system, respectively. The outcome of the study demonstrates the possibility of using the MICE technique for neutron dose estimation by CR-39 via LET spectrometry.

TrackEtching — A Java based code for etched track profile calculations in SSNTDs

A java code incorporating a user friendly GUI has been developed to calculate the parameters of chemically etched track profiles of ion-irradiated solid state nuclear track detectors. Huygen’s construction of wavefronts based on secondary wavelets has been used to numerically calculate the etched track profile as a function of the etching time. Provision for normal incidence and oblique incidence on the detector surface has been incorporated. Results in typical cases are presented and compared with experimental data. Different expressions for the variation of track etch rate as a function of the ion energy have been utilized. The best set of values of the parameters in the expressions can be obtained by comparing with available experimental data. Critical angle for track development can also be calculated using the present code. Program summaryProgram Title: TrackEtchingProgram Files doi:http://dx.doi.org/10.17632/7wb6pvpbgh.1Licensing provisions: CC0 1.0Programming language: JavaNature of problem: Calculation of the etched track profiles in ion irradiated SSNTDs is important for the application in the field of nucleopore filters and for their use as templates for nano wire fabrication.Solution method: A numerical approach, based on Huygen’s method for optical wavefront calculations has been employed. At any etching time, the etching is assumed to proceed along the normal to the etched surface. Several analytical functions are tried for the variation of the track etch velocity along the ion track as a function of the depth inside the surface and the energy/stopping power of the ion in the medium.Additional comments including Restrictions and Unusual features: The program does not generate three-dimensional profile. Provision for double sided etching will be incorporated in a later version of the code.

Access DeniedSingle-track length measurements of step-etched fission tracks in Durango apatite: “Vorsprung durch Technik”

Fossil and induced confined fission-tracks in the Durango apatite do not etch to their full etchable lengths with the current protocols. Their mean lengths continue to increase at a diminished rate past the break in slope in a length vs. etch-time plot. The mean length of the fossil tracks increases from 14.5(1) to 16.2(1) μm and that of the induced tracks from 15.7(1) to 17.9(1) μm between 20 and 60 s etching (5.5 M HNO 3 ; 21 °C); both are projected to converge toward ~18 μm after ~180 s. This increase is due to track etching, not bulk etching. The irregular length increments of individual tracks reveal a discontinuous track structure in the investigated length intervals. The mean lengths of the fossil and induced tracks for the standard etch time (20 s) for the (5.5 M HNO 3 ; 21 °C) etch are thus not the result of a shortening of the latent fission tracks but instead of a lowering of the effective track-etch rate v T . The rate of length increase of individual fossil confined tracks correlates with their length: older tracks are shorter because they etch slower. Step etching thus makes it possible to some extent to distinguish between older and younger fossil fission tracks. Along-track v T measurements could reveal further useful paleo-temperature information. Because the etched length of a track at standard etch conditions is not its full etchable length, geometrical statistics based on continuous line segments of fixed length are less secure than hitherto held.

Laser Effect on the Activation Energies, Bulk Etch Rate and Track Etch Rate of CR-39 Polymeric Detector

The aim of this paper is to find the effect of Nd: YAG laser of wavelength (532 nm), laser power 150 MW on the CR-39 polymer. Twenty three detectors were divided in to three sets. The first set (ten detectors) (post-exposed) was first exposed to alpha radiation from 241Am source at 3MeV and then treated in air with laser at different exposure time started from 10 minutes to 100 minutes with ten minutes differ between them (alpha + laser). For the second set (ten detectors) (pre-exposed), the process was reversed (laser +alpha) under the same conditions, for the last set (three detectors) (un-exposed to laser), used as a control set, was irradiated with an alpha source (241Am). Alpha track diameters, bulk etching velocity (VB), track etching velocity (VT), etching efficiency (η), etching ratio (V) were determined. The activation energies of bulk etch (EB) and track etch (ET) for unexposed, post- exposed and pre-exposed are found to be equal to 1.10, 0.92, 0.82 eV and 1.07, 0.86, 0.79 eV respectively.

Studying Different Etching Methods Using CR-39 Nuclear Track Detector

In this research we try to investigate the optimum etching time for the tracks originate in (CR-39) solid state nuclear track detector after irradiated with alpha source (241Am) using three different etching techniques: the traditional method (water bath), microwaves and ultrasound devices. The track etching parameters: bulk etch rate (VB), track etch rate (VT), track etch rate ratio evaluates (V), critical angle (θC), and etching efficiency (η) were calculated in this research. It’s seen that the optimum etching time was ranging with (60 - 150 min), (20 - 30 min) and (60 - 120 min) when etching with water bath, microwave and ultrasound respectively. Also we observed that the critical angle was (24.29) when etching CR-39 detector with microwave. This value is lower than the critical angles values for the detector etched with water bath or ultrasound; thus it can be the optimum magnitude because its decrease leads to increasing the number of the tracks appeared in the detector and the etching efficiency.

Standardless fission-track dating of the Durango apatite age standard

Five dating strategies were used for determining the standardless fission-track age of the Durango apatite. These use the same fossil-track densities but differ in the manner in which the induced-track densities are determined. A conventional age calculation, without correction for experimental factors, gives inconsistent ages with method-related differences >15%. Correcting for these factors brings the ages in line with each other and with the reference age but leaves no room for a partial-annealing correction based on the confined-track lengths. Three further reasons suggest that a length correction is not appropriate. (1) The evidence for length-based corrections is inconclusive. (2) The plateau age of the Durango apatite is consistent with its apparent fission-track age to within 1%. (3) The calculated effective etchable length of the fossil tracks agrees within error with that of the induced tracks; both are further consistent with the measured mean length of confined induced tracks. The circumstance that the (U,Th)/He ages of the accepted and proposed apatite age standards are consistent with their reference ages leaves no margin for a lowered fission-track age resulting from partial annealing, although the case of the Durango apatite itself is inconclusive because of its exceptional crystal size. It is conjectured that the shortening of the fossil tacks in the Durango apatite is due to a lowering of the track etch rate over time. In this case, annealing equations fitted to induced-track data underestimate the extent of confined-track-length reduction in geological samples.

Ultraviolet radiation-induced modifications of the optical and registration properties of a CR-39 nuclear track detector

The UV–VIS (ultraviolet–visible) spectra and etching characteristics of poly allyl diglycol carbonate (PADC, a form of the CR-39 polymer) detector films after exposure to UV radiation for various times have been studied. Etching experiments were carried out on the UV-exposed CR-39 detectors after alpha particle and fission-fragment irradiation using a 252Cf source. The bulk and track etch rates were measured using the alpha and fission-fragment track diameters, and the sensitivity and the detection efficiency were also determined. The optical band gap for both indirect and direct transitions was calculated based on the absorption edge of the UV spectra of the pristine and variously UV-exposed detectors. The optical band gap evidently indicates a gradual change in the optical properties of the CR-39 detector that is induced by the UV radiation. This study shows that the UV-exposed CR-39 detectors were demonstrated to be highly sensitive to alpha particles, but proved to be somewhat less sensitive to the fission fragments.

The effect of ArF laser irradiation (193 nm) on the photodegradation and etching properties of alpha-irradiated CR-39 detectors

The effects of ArF laser irradiation (λ=193nm) at various fluences (energy dose or energy density) on the etching properties of pre-exposed (laser+alpha) CR-39 detectors were studied. First, UV–Vis and Fourier transform infrared (FTIR) spectra were acquired for non-laser-irradiated and laser-irradiated samples to detect the influence of the ArF laser on the chemical modification of the CR-39. Changes observed in the spectra indicated that the predominant process that occurred upon ArF laser irradiation was a bond-scission process. Thereafter, the mean track and bulk etching parameters were experimentally measured in ArF-laser-irradiated CR-39 detectors exposed to an alpha source (241Am, E=5.49MeV). Inhomogeneous regions in the laser-irradiated side of the CR-39 demonstrated a variable etching rate on only the front side of the CR-39 detector. New equations are also presented for the average bulk etching rate for these inhomogeneous regions (front side). The mean bulk and track etching rates and the mean track dimensions increased in a fluence range of 0–37.03mJ/cm2 because of photodegradation and the scission of chemical bonds, which are the predominant processes in this range. When the fluence was increased from 37.03 to 123.45mJ/cm2, the bulk and track etching rates and the track dimensions slowly decreased because of the formation of cross-linked structures on the CR-39 surface. The behavior of the bulk and track etching rates and the track dimensions appears to be proportional to the dose absorbed on the detector surface. It was observed that as the etching time was increased, the bulk and track etching rates and the track dimensions of the laser-irradiated samples decreased because of the shallow penetration depth of the 193nm laser and the reduction in the oxygen penetration depth.

Controlled development of pores in polyethylene terepthalate sheet by room temperature chemical etching method

In the present work, a room temperature chemical etching (RTCE) method has been explored for controlled development of pores in the chlorine ions (115MeV) bombarded polyethylene terepthalate (PET) (25μm) sheets. In this pore development method, a mixture of ethanolamine and NaOH is employed. The pore-size distributions in thus formed PET track-etched membranes have been obtained by the capillary flow porometry, and compared with the results of PET track-etched membranes subjected to widely used chemical etching (CE) at elevated temperature. Multiple pore size distributions have been observed with the CE method. However, with RTCE, pores with single narrow pore size distribution have been observed. To further improve the RTCE method, the chlorine ions bombarded PET sheets have been sensitized with UV radiation (254nm) for 1h, and subjected to RTCE. The average pore-size has been found to increase with UV-sensitization without affecting the nature of pore-size distribution, indicating the possibility of formation of the track-etch membranes with different pore sizes. Track etching studies show that both bulk-etch and track-etch rates increase in RTCE with respect to the conventional chemical etching. The ratio of the track-etch rate to bulk-etch rate governs the shape of the pores. The conical shaped pores with small cone angles are observed when track-etch rate is significantly higher than the bulk-etch rate. However, in the present case, VT is observed to be not very much greater than VB (VT/VB<100), showing the formation of double bowl pores or conical pores with large cone angles. This has been confirmed by the FEG-SEM observations.

Etching characteristic studies for the detection of alpha particles in DAM–ADC nuclear track detector

This study reports the characteristic studies for the detection of alpha particles in DAM–ADC nuclear track detector. Several important parameters that control the track formation such as, the bulk etch rate (VB), track etching rate (VT), dependence of VB and VT on etching concentration and temperature have been extensively studied. The activation energy (Eb) of the bulk etching rate for the DAM–ADC sheets has been calculated, the dependence of etching efficiency and sensitivity upon etchant concentrations and temperature has been investigated, registration efficiency of DAM–ADC detector etched at the optimum etching condition has been examined. The detailed studied results presented in this study provide various useful information about the mechanism of track formation in polymers.