Makrofol Polycarbonate Research Articles

Large scale copper microstructures generation using electro-deposition through nuclear track filters

Microstructure fabrication is not only of immense importance for microelectronics technology but also plays a vital role as a potent tool for carrying out investigations relating to behavior of materials at sub micron scales. In the recent years, it has broadened to encompass more and more areas of multidiscipline. A variety of possible applications include high power microwave generation, ultra fast computer and tetra hertz amplifier devices fabrication, radiation and temperature insensitive electronics. Fields where well-established applications already exist include field emitters; electrochemistry; conductive polymer nanofibers fabrication; transparent metal structures and macroscopic quantum tunneling phenomena. Of the many possible geometrical shapes and growth patterns, the simplest structure is probably an ensemble of wires. A variety of techniques like optical, X-rays, electron and ion beam lithography have been used for fabrication of such ensembles. However, electrochemical methods involving electrodeposition of metals into the etched pores of nuclear track filters (NTFs) of mica and polymers, are a convenient and simple technique [1–6]. The morphological study of such structures produced through electrochemical methods and of replicas of etched tracks in NTFs used as templates, has two-fold purpose. One, it provides the finest and critical details of the geometry and dimensions of microstructural constituent elements and the second, as a by product it enables to study the various aspects of interaction of a nuclear particle with given material leading to formation of tracks in NTF. It is well known that parameters, which control the shapes of tracks in NTFs, include the nature of the material; the ion beam and energy deposition rate; pre, post-irradiation storage and environment and the etching conditions. In the present work nuclear track filters of Makrofol (KG) polycarbonate having pore size ca. 2.6 μm and pore density 1 × 106 cm−2 have been used as templates for synthesis of copper microstructures using the technique of electrodeposition (template synthesis). Because the membranes used contain cylindrical pores of uniform diameter, crops of monodisperse microstructures of the desired material, whose dimensions can be carefully controlled, are obtained. Track etch membranes in the form of nuclear track filters have emerged as a spin-off from solid state nuclear track detectors (SSNTDs)-solid dielectric materials capable of storing tracks of energetic, heavily ionizing ions which can subsequently chemically amplified for optical observations as pores or channels of well defined geometry and pore density [3–6]. The size and dimensions of the pore depend upon various factors, viz. the nature and energy of the incident ions, the target material, etch conditions e.g., temperature, nature of the etchant. The pore size which is controllable, may range from few nm to mm. NTFs have been put to numerous applications besides their use in the synthesis of nano/microstructures. The underlying principle of template synthesis technique is akin to that of producing components through the use of replication e.g., die-casting or mold casting, like making ice candies out of molds. In this technique, materials can be deposited with in the template membranes by either electrochemical or chemical (electroless) reduction of the appropriate metal ion. The generated structures can both be homogeneous or heterogeneous depending on the pore size and geometries, with complete control over the aspect ratio (length and diameter ratio). The simple and well known underlying concept of electrodeposition of metals through electroplating is described as an electrochemical process in which metallic ions in a supporting solution are reduced to the metallic state at the cathode, which is closely covered by an NTF membrane, would lead to formation of growth of plated film as the embodiment of micro or nano structure. The etched pores of the membranes would act as templates [1–10]. Electrodeposition (template synthesis) is a versatile technique combining low processing cost with ambient conditions that can be used to prepare metallic, polymeric and semi conducting microstructures. In the case of microstructures arrays, electro deposition is the cost effective method with which such structures have been successfully fabricated. Samples of polycarbonate of thickness 30 μm were irradiated to 13.64 MeV/n 238U ions (fluence 106 ions/cm2)utilizing the heavy ion accelerator UNILAC facility at GSI, Darmstadt, Germany. Samples were etched in 6N NaOH solution at 70 ◦C for 40 min and pore size of 2.6 μm was obtained. After etching nuclear track filter having pore size 2.6 μm and pore density 106/cm2 is used for synthesis of iron microstructures using the technique of electrodeposition. Because the membranes used contain cylindrical pores of uniform diameter, crops of

Structural characterization of diglycol carbonate and polycarbonate SSNTDs irradiated with infrared laser pulses

Samples of solid-state nuclear track detectors (SSNTDs) CR-39 diglycol carbonate and Makrofol polycarbonate polymers were exposed to infrared laser pulses with different exposure doses ranging from 0.0 to 7.5 J/ cm 2 . The development of the noncrystalline phase in the semicrystalline polymers and the effect of laser pulses on the degree of ordering in these two polymers were investigated through X-ray scattering and infrared region spectra studies. The results indicate that similar changes in short-range order take place in both polymers upon laser irradiation. The noncrystalline phase content in the two detectors increases on increasing the laser dose up to 1.5 J/ cm 2 and then decreases when increasing laser dose up to 7.5 J/ cm 2 . Infrared absorbance measurements show that different deformation in molecular microstructure takes place in the two polymers when exposed to laser irradiation and that Makrofol polycarbonate polymer may be used as a sensor for infrared laser irradiation.

The Effect of α-Particle Dose on the Dielectric Properties of Solid State Nuclear Track Detectors

Dielectric constants and dielectric losses of CR-39 diglycol carbonate and Makrofol polycarbonate have been measured in the frequency range from 100 Hz to 100 kHz for the solid state nuclear track detector (SSNTD). The samples from these detectors were irradiated with α-particles of initial energies at levels between 5.1 and 34 MeV. The dielectric constant and dielectric loss of the unirradiated samples are also measured to increase at heating up to 90 °C. The frequency dependence of the dielectric constant is characterized by a primary relaxation process. In addition, the effects of α-particle dose on the frequency dependencies of the dielectric constant and its loss have been measured at room temperature. The α-particle dose gives an advantage for the increasing correlation between the dielectric constant and the physical degradation which is related to the increase in the degree of soft segments.

The effect of alpha particle dose on the thermal degradation of some SSNTDs

Non-isothermal studies were carried out using thermogravimetry (TG) and differential thermogravimetry (DTG) to obtain the activation energy of decomposition for solid state nuclear track detectors namely CR-39 diglycol carbonate and Makrofol polycarbonate detectors before and after exposure to α-particles of initial energies at levels between 5.1 and 34 MeV. Thermal gravitational analysis (TGA) indicated that the Makrofol detector decomposed in one main breakdown stage, while the CR-39 detector decomposed in two main breakdown stages. For CR-39 and Makrofol detectors an increase in activation energies was observed followed by a decrease on increasing the α dose. Also, the variation of the transition temperatures with the α dose has been determined using differential scanning calorimeter (DSC).

Probability of ternary fission of93Nb andnatAg nuclei induced by (0.8÷1.8) GeV photons

The yields of ternary fission of93Nb andnatAg nuclei induced by bremsstrahlung photons of 0.8, 1.0, 1.4 and 1.8 GeV end-point energies have been measured by using the 2π-forward geometry with thick target metal foils in contact with makrofol polycarbonate sheets as fission-track detectors. Absolute mean cross-sections per photon in the range (0.8÷1.8) GeV have been obtained as (0.3±0.3) μb and (0.5±0.4) μb, respectively, for93Nb andnatAg nuclei. These correspond to a probability of ternary fission of ≈10−5 for both nuclei. Results are discussed and compared with previous ternary fission data obtained by us for nuclei ofA≲90.

Cross-section of ternary fission of Al, Ti, Co, and Zr nuclei induced by (0.8÷1.8) GeV photons

A research on ternary fission of Al, Ti, Co and Zr nuclei induced by bremsstrahlung photons of 0.8, 1.0, 1.4 and 1.8 GeV end-point energies has been carried out using makrofol polycarbonate and CR-39 polymer as fission-track detectors. Thick target metal foils were used in contact with the plastic detectors. From the observation and analysis of double divergent, etched fission tracks from a common point inside the target the number of events of ternary fission has been evaluated. Absolute mean cross-sections per photon of ternary fission in the range (0.8÷1.8) GeV have been obtained as (0.3±0.7), (1.7±1.5), (0.5±0.5), and (1±1) μb, respectively, for Al, Ti, Co and Zr nuclei. A probability of ternary fission of ∼10−4 has been deduced. Results are discussed and compared with other ternary fission data.

12C(12C,8Be)16O cross-section measurement at sub-barrier energies.

Differential cross sections for the /sup 12/C(/sup 12/C, /sup 8/Be..-->..2..cap alpha..)/sup 16/O reaction have been measured at eight incident energies in the 2.43less than or equal toE/sub c.m./less than or equal to5.24-MeV range, detecting ..cap alpha.. particles in 200-..mu..m thick Makrofol polycarbonate foils, which were subsequently carefully etched and scanned under microscope for the /sup 8/Be..-->..2..cap alpha.. group and the ..cap alpha.. groups from the /sup 12/C(/sup 12/C, ..cap alpha..)/sup 20/Ne reaction. The /sup 8/Be channel cross section, ranging between 4 x 10/sup -4/ ..mu..b and 280 ..mu..b, is smaller for E/sub c.m./greater than or equal to3.91 MeV, but larger for E/sub c.m./less than or equal to3.13 MeV than the ..cap alpha../sub 0/+/sup 20/Ne/sub g.s./ channel cross section. The /sup 12/C(/sup 12/C, /sup 8/Be)/sup 16/O cross section is well reproduced by the distorted-wave Born approximation calculation of a direct ..cap alpha..-transfer reaction down to E/sub c.m./ = 3.91 MeV. In the 3.13greater than or equal toE/sub c.m./ greater than or equal to2.43-MeV range, however, the measurements exceed the distorted-wave Born approximation prediction by one to three orders of magnitude. It is suggested that the formation of /sup 12/C-/sup 12/C dinuclear states, favoring an ..cap alpha.. transfer, becomes a predominant processmore » at incident energies E/sub c.m./less than or equal to3.13 MeV.« less

Optical transparency of makrofol nuclear track filters

Abstract Makrofol polycarbonate—one of the widely used materials for making nuclear track filters, has been studied for its transparency to light (Λ = 350 nm to 950 nm). Also the optical transmission and IR-spectroscopy results on the Makrofol foils, forming nuclear track filters by irradiating with 14 MeV/n 238U ions, with and without post-irradiation UV and γ-exposures, are presented. Studies have been extended to these filters to investigate the variation of percentage transmission with etch-time, pore diameter, at different values of Λ.

Experiences with track etch detectors for radon measurements

Closed Makrofol polycarbonate detectors have been used for radon surveys in dwellings. Three types of plastic detector cups were tested; of these the one painted inside with conductive paint proved to have the smallest standard deviation. Radon measurements with high track densities require a linearity correction.

Track etch rate characteristics of makrofol polycarbonate plastic detector exposed to xenon ions

Abstract Track etch rate characteristics of makrofol polycarbonate plastic detector exposed to 54 Xe 129 heavy ions of 7.5 MeV/n energy at GSI, Darmstadt have been investigated. It is observed that the bulk etching rate, V b , as well as track etching rate, V t , by keeping the concentration of the etchant (6.25N NaOH) constant, increase with the increase of etching temperature. Complete etching times have been found to be 32, 15, 9 minutes at etching temperatures of 50°C, 60°C and 65°C, respectively. The activation energies for bulk etching and track etching are determined to be 0.9 eV and 1.38 eV, respectively. The etching efficiency (η) has been found to be independent of the etching temperature. The threshold value of energy loss rate of makrofol polycarbonate has been determined from a semi-empirical relation between V t , V b and REL, and has been found to be 4.29 MeV mg -1 cm -2 . The suitability of single sheet charged particle identification method has been examined. Using this method, makrofol detector has been found to quite suitable for identifying low energy Xe ions.

Calibration of Makrofol Polycarbonate plastic track detector using heavy ions

Abstract In this paper the measurements of the dependence of track etch rate on the specific energy loss, (dE/dx) of different charged particles are presented. In the method, 6C12, 8O16, 10Ne22-ions of energy 5.5 MeV/N and 18Ar40-ions of energy 7.5 MeV/N are used as energetic heavy ions for track formation in Makrofol Polycarbonate track detector. The maximum etched track lengths of these ions are compared with the theoretically computed ranges. The bulk etch rate and track etch rate are determined for different temperatures ranging from 50°C to 90°C. The experimental results show that the track registration sensitivity of Makrofol plastic detector exposed to heavy ions remains constant between 50° and 90°C. The normalized track etch rate, V=Vt/Vb depends only on dE/dx and not on the etching temperature. The variation of normalized track etch rate along the particle trajectory is also shown for different temperatures. Moreover, the experimental data are presented for the influence of different annealing c...

Response of Makrofol polycarbonate plastic track detector to 1.1 MeV/N 54 132 Xe-ion

Makrofol polycarbonate plastic track detectors have been exposed to 54 132 Xe -ions of energy 1.1 MeV/N from the cyclotron beam. The bulk etch rate and track etch rate are measured for different temperatures and the activation energies are calculated. The maximum etched track length is compared with the theoretically computed range. The critical energy loss is (dE/dx) c =5 MeV cm2 mg−1 for this detector material.

Fission of U, Th, Bi, Pb, and Au induced by 200 and 300 GeV protons

The cross sections for the binary and ternary fission of U, Th, Bi, Pb, and Au induced by 300 GeV protons have been measured with Makrofol polycarbonate detectors. We deduce that the ternary events and most of the binary events with a projected angle ..cap alpha../sub 12/<170/sup 0/ in the plane perpendicular to the beam direction proceed by the same mechanism which characterizes fission induced by very high energy protons.

Track radiography of heavy-ion induced sputtering

To study heavy-ion induced sputter phenomena, several glasses of different chemical composition were irradiated with 56Fe +-ions in the energy of 70.5–100 keV at the GSI-UNILAC, Darmstadt. A sensitive particle track technique was employed to measure differential sputter yields and the angular distribution of sputtered atoms in 2π-geometry. This techniques utilizes U, Th, Li and B contained in the target matrix as tracer elements. The sputtered target atoms are collected on a cone-shaped catcher (Makrofol polycarbonate or Teflon foil) and the target atoms are recorded via ( n, f) and ( n, ƒ) reactions as particle-track radiographs of the catcher on mica or CA 80-15 cellulose nitrate detectors. The cone shape of the catcher foils allows one to scan the sputtering process in 2π-geometry in a single irradiation experiment. The detection sensitivity for sputtered atoms is estimated to be <5×10 11 target atoms cm −2 in the case phosphate glass containing 0.06% 235U and <10 13 target atoms cm -2 in the case Li 2B 4O 7 glass. Angular distributions for U-phosphate and Li 2B 4O 7 glass sputtered by 100 keV 56Fe +-ions are presented.

On the electrochemical etching of neutron-induced tracks in plastics and its application to personnel neutron dosimetry

The recently developed electrochemical etching method seems to be a promising technique to reveal neutron-induced recoil tracks in plastics. However, very little work has been done and the data presented are preliminary. The purpose of the work presented here was to investigate in some detail the most important parameters affecting the electrochemical etching kinetics of recoil tracks in Makrofol polycarbonate (∼500μm) and to find the optimum conditions for applying this technique to personnel neutron dosimetry. The electric track diameter and the neutron sensitivity were studied as a function of frequency, applied voltage, etching condition, neutron dose, neutron spectrum, and the directional dependence. Special cells were designed in such a way that only one surface of the plastic foils was etched electrochemically while the other surface was made conductive and then connected with the earth terminal of a high voltage function generator. With this technique the electric tracks appear as dark stars on a quite clear background, which permits a more reliable evaluation of the track density, using any automatic or semi-automatic scanning equipment.

Application of solid state nuclear track detectors for personnel monitoring around high energy accelerators

In the framework of the design of a better system for personnel neutron monitoring, an extensive systematic study has been carried out to evaluate the feasibility of different nuclear track detector-radiator combinations. This paper is concentrated on the use of LR115 cellulose nitrate and Makrofol polycarbonate foil with different etching and counting techniques. For LR115, classical etching was applied and automatic track counting and analysis were performed with a Quantimet. For the Makrofol, in addition to the standard spark counting method, electrochemical etching was used. Because of the wide neutron energy spectrum to be covered it was necessary to use a selection of radiators. It appears that an empirical formula for the neutron dose can be derived from the readings of the track density under the chosen radiators consisting of plastic, boron-loaded material, and bismuth. A comparison of the results obtained with this method and the dose recorded by standard radiation survey instrumentation has been performed.

On the use of solid state nuclear track detectors in reactor physics experiments

Abstract Solid state nuclear track detectors of silver-activated phosphate glass and polycarbonate plastic have provided intracell fission density and fast neutron flux distributions in the zero-power critical facility NORA (Institutt for Atomenergi, Kjeller, Norway). The fission density distributions were measured in a clean lattice and within fuel elements in the vicinity of grey absorber control elements. The measured intracell fast neutron flux distributions were used for the evaluation of the so-called ‘fast advantage factors’ (fuel-to-moderator neutron flux ratios at fission energies). Integral measurements of the fast advantage factors were performed by foil activation. As far as the experimental results presented here could be compared with theoretical calculations a good agreement was found. For the measurement of the track density distributions along the detector surface a method was developed which replaces the counting procedure of tracks under a microscope. This method is based upon the relation between track density and intensity of transmitted light through irradiated and etched detectors, whereby a microdensitometer is used for the measurement of the light transmission. Some remarks about the fast neutron sensitivity of Makrofol polycarbonate plastic will be made.