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New single-cell multi-size detector electrochemical etching system
Journal Pre-proof New single-cell multi-size detector electrochemical etching system Mehdi Sohrabi, Sahel Rabiee PII:
S0969-806X(19)31246-0
DOI:
https://doi.org/10.1016/j.radphyschem.2020.108744
Reference:
RPC 108744
To appear in:
Radiation Physics and Chemistry
Received Date: 25 September 2019 Revised Date:
20 January 2020
Accepted Date: 1 February 2020
Please cite this article as: Sohrabi, M., Rabiee, S., New single-cell multi-size detector electrochemical etching system, Radiation Physics and Chemistry (2020), doi: https://doi.org/10.1016/ j.radphyschem.2020.108744. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd.
New single-cell multi-size detector electrochemical etching system
Mehdi Sohrabi*, Sahel Rabiee Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology Tehran, Islamic Republic of Iran
Abstract: Electrochemical etching (ECE) methods can process lower-LET heavy charged particles such as protons, deuterons, alphas, neutrons-induced recoils, etc. in polymers in particular polycarbonate track detectors (PCTD) to a point observed by the unaided eyes. In this study, a new single-cell multi-size detector ECE system was invented for processing circular PCTDs of different sizes especially with ~7.0, ~10.0, ~16.0, ~19.0 cm effective diameters of 250 µm thick detectors as used. From many physical and chemical parameters controlling the amplification of particle tracks in these detectors, effective etched area and position sensitivity of the detector as well as field strength were investigated on detection responses of alpha particles of fixed fluence ~1.0x104 alphas.cm-2 at 8 distinct energies within ~0.3 to ~4.0 MeV energy range. While no position sensitivity was observed on track detection efficiency and diameter responses of each detector effective etched area, the responses differed slightly from one detector effective area to another due to changes in the dissipated real output power (load) which decreases as detector effective area increases. Accordingly by applying a compensated voltage factor for each effective size, the responses were all matched well demonstrating that the new single-cell multi-size detector ECE system can be
effectively used to a number of relatively large-area circular detectors. Keywords: Single-cell; Electrochemical etching; Multi-size detector; Polycarbonate detector; Effective detector area; Voltage compensation factor
Corresponding Author; dr_msohrabi @yahoo.com
1
1. Introduction Since the development of the electrochemical etching (ECE) method by Tommasino (1970) and by Sohrabi (Sohrabi and Becker, 1971; Sohrabi, 1974), different ECE chambers have been designed and constructed in order to process only one detector (Tommasino, 1970; Sohrabi and Becker, 1971; Somogyi, 1977), simultaneous etching of many equal-size detectors (Sohrabi, 1974; 1975; Sohrabi and Morgan, 1978; Turek, 1992), specific chambers for example for multi-detector/multi-parameter studies (Sohrabi, 1985), triplet ECE (TECE) chamber for etching large number of detectors in parallel rows (Sohrabi, 1993), pressurecontrolled chamber (Sohrabi and Katouzi, 1993), thin film ECE chamber (Tommasino et al. 1991), simultaneous 100 detector processing chamber (Sohrabi and Zainali, 1995), internal dielectric heating studies (Sohrabi, 1986; Sing and Virk, 1987; Turek et al., 1991), dual-cell large ECE chambers (Sohrabi et al., 2016a,b; Sohrabi and Soltani, 2019), thickness dependence verification of ECE polymer detectors (Sohrabi and Rabiee, 2018), and in particular the novel single-cell mega-size ECE systems which can process (e.g. 33 cm x 71 cm PCTD) by being laid down on the laboratory bench in a simple fashion during processing (Sohrabi, 2017; 2018; Soltani et al., 2019). It has been a common practice that the ECE chambers designed and used in some applications can process only small one-size detectors. In particular, polycarbonate detectors due to having many advantages such as being of potential use from applying a very small to very large detector sizes (Sohrabi, 2017; Sohrabi and Soltani, 2019), requires design and construction of versatile multi-size chambers in particular for circular polycarbonate detectors. On the other hand, using detectors with larger effective etched areas impose a reduction in the dissipated real output power (load) which decreases as the detector effective etched areaincreases. Therefore, it is the purpose of this paper to: 1. Design, construct and use a new circular single-cell multi-size detector ECE system in order to process PCTDs of different effective etched areas in only one single-cell chamber system, 2. Study the effects of effective etched area and position sensitivity of the detector as well as field strength on detection responses of alpha particles of a fixed fluence ~1.0x104 alphas.cm-2 at 8 distinct energies within ~0.3 to ~4.0 MeV energy range, and 3. Make attempt to equalize alpha detection efficiency and track diameter responses versus alpha energy as well as alpha detection energy range of different detector effective etched areas by applying relevant applied voltage or field strength compensation factors. 2
2. Materials and Methods
2.1
Design of new circular single-cell ECE chamber
In ECE processing of charged particle tracks in PCTDs, the detector is always sandwiched between two semi-chambers to insulate them from each other when filled with a chemical etchant by using two silicon rubber washers on each side of the PCTD in order to isolate two semi-chamber and prevent any sparking and/or etchant leakage through the detector which stop the ECE process. Recently single-cell mega-size ECE chamber have been invented (Sohrabi, 2017), using one single dry cell electrode and one wet semi-chamber filled with etchant. The basic design of the versatile ECE chamber developed in this study is basically the same as that design with some specifications for processing circular PCTDs of different effective etched areas (Sohrabi, 2017). This chamber has two equal size flat transparent Plexiglas sheets (2 cm thick) as chamber walls; one Plexiglas wall with a flat stainless steel electrode attached on it which serves as a dry cell with no etchant required laying on the laboratory bench and the other Plexiglas wall which lays over a silicon rubber washer holding the circular PCTD between them tight to be processed. In this arrangement, a circular PCTD in a special size is laid on the stainless steel flat electrode. Then one silicone rubber washer with a size smaller than the detector size is laid on the PCTD symmetrically. This rubber washer plays the roles of a wet cell for holding the etchant and an insulator to insulate dry and wet cells from each other. The other Plexiglas wall has a short stainless steel rod electrode at the center with also having two holes on it; one for feeding and discharging the etchant and one for inserting a thermometer to control the temperature. Then, the two Plexiglas walls are tightened together by a number of bolts and wing nuts. This new chamber was studied only for 4 different PCTDs with ~7.0, ~10.0, ~16.0, ~19.0 cm effective etched diameters with effective etched areas ~38, ~78, ~200 and ~283 cm2 using 250 µm thick polycarbonate detectors. However, the chamber can also be applied to PCTDs with other effective etched areas or other thicknesses provided that proper silicon washers for any other effective etched areas can also be used. Fig. 1 shows the schematic design of the new single-cell multi-size detector ECE
system; (a) different components of the system and (b) assembled chamber system.
3
Fig. 1. Schematic design of the new single-cell multi-size detector ECE system; (a) different components of the ECE system and (b) assembled chamber system.
2.2
Alpha exposure and ECE processing of circular PCTDs
The PCTDs used in this study are 4 circular polycarbonate detectors of 250 µm thickness (Bayer Company, Germany) with ~7.0, ~10.0, ~16.0, ~19.0 cm effective diameters (~38, ~78, ~200 and ~283 cm2). They were cut from larger sheets masked on both sides to prevent scratches. The circular PCTDs were exposed on a numbers of rows to alpha particles with a constant fluence of ~1.0 x104 alphas.cm-2 by using a specially designed and constructed brass collimator holding an 241Am source. A collimated
241
Am alpha source was used to expose each position on a row of a PCTD to a
known alpha fluence and energy. The
241
Am alpha source was fixed at the end of a short
brass cylindrical holder which has been inserted inside another brass cylindrical collimator with an opening hole (~0.5 cm2 area) constructed such that the detector to source distance and thus the alpha energy and fluence could be precisely changed by degrading the 4
241
Am alpha
energy in air at room temperature. The alpha fluence and energy for each source to detector distance were calibrated with a surface barrier detector coupled to a multichannel analyzer. Each position on a row of PCTD was exposed to an alpha fluence at a known selected energy of ~0.3, ~0.5, ~0.8, ~1.0, ~1.5, ~2.0, ~3.0, and ~4.0 MeV. Then in order to obtain the fixed fluence of ~1.0 x 104 alpha.cm-2, the exposure was continued for a certain time as calculated for a particular energy to obtain that fluence. Fig. 2 (a,b) shows; (a) a brass collimator holding an
241
Am alpha source to provide a known fluence at a known alpha energy (as
constructed in our laboratory) and (b) a PCTD divided into four rows showing also the brass collimator which is exposing an area on the PCTD with a known fluence and energy.
Fig. 2 (a, b). (a) A brass collimator holding an 241Am alpha source to provide known fluences at known alpha energies and (b) a PCTD divided into four rows showing the brass collimator exposing an area on the PCTD with a known fluence and energy.
Depending on the effective etched area of a circular PCTD, 8 alpha exposures each at a fixed energy were made at 8 specific positions on each of radial circular rows 1, 2, 3, and 4 rows in PCTDs with ~7.0, ~10.0, ~16.0, ~19.0 cm effective diameters respectively. Each row has been divided into 8 circular positions (~0.5 cm2) separated within 45°angle from each other. Each location on each row has been exposed to a fixed alpha fluence at a known energy.
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By using the above stated collimated alpha source, four PCTDs with four different effective etched areas and different rows each with 8 positions to be exposed at a certain alpha energy. Fig. 3 shows four circular PCTDs with four different effective etched areas divided into some rows; each row has 8 exposed positions each with ~0.5 cm2 area where each area has been exposed to one of the 8 known energies selected within ~0.3 to ~4.0 MeV energy range.
Fig. 3. Four circular PCTDs, with four different effective etched areas each divided into rows; each row has 8 positions with ~0.5 cm2 area to be exposed to a known alpha fluence and energy within ~0.3 to ~4.0 MeV energy range for a calculated exposure duration.
The alpha-exposed PCTDs were processed electrochemically using the single-cell circular ECE chamber for 3.0 hours applying a constant voltage 2 kV (electric field strength of 80 kV.cm-1) using a 50 Hz - HV generator. Alpha particle and background track (BGT) densities as well as track diameters were determined under a light microscope. The net alpha track density has been obtained by using alpha track density minus background track density in order to calculate the registration efficiency.
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The ‘‘alpha detection efficiency
ε
(%)” determined at each position on each row of each
PCTD was calculated based on the formula given below:
ε (%) = (Dtd (tracks.cm-2) / Φ (alphas.cm-2)) x 100 ε
is in fact defined as the ‘‘ratio of alpha track density (tracks.cm-2) determined at each
position in a PCTD to alpha particle fluence (alpha.cm-2) impinged on the position times 100, where: Dtd = Alpha Track Density (tracks.cm-2), and Φ = Alpha Fluence (alphas.cm-2). 3.
Results and discussion
In order to consistently apply the new single-cell multi-size detector ECE system to circular PCTDs of different effective etched areas with uniform position sensitivity for different applications, some parametric studies have been performed. Among many parameters affecting alpha detection efficiency and track diameters as well as alpha energy range in ECE-processed PCTDs, the effective etched area of a detector and the electrical field strength play crucial roles, when other parameters are fixed. Therefore, the new ECE system as described in Fig. 1, was used for parametric studies. Fig. 4 (a,b,c,d) represents alpha particle efficiency (%) versus alpha energy in PCTDs of 4 different effective etched areas and positions on each row of a PCTD surface for circular PCTDs with effective etched areas; (a) ~283 cm2 with 4 rows, (b) ~200 cm2 with 3 rows, (c) ~78 cm2 with 2 rows, and (d) ~38 cm2 with 1 row, as processed under 50 Hz - 2 kV field conditions in PEW solution at 26±1 °C for 3 hours. The alpha efficiency responses versus alpha energy in Fig. 4 (a,b,c,d) all confirm having the same Bragg-type response trends peaking around 0.7 - 0.8 MeV in the four detectors with different etched areas studied.
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Fig. 4 (a,b,c,d). Alpha particle efficiency (%) versus alpha energy in PCTDs of 4 different effective etched areas; (a) ~283 cm2 with 4 rows, (b) ~200 cm2 with 3 rows, (c) ~78 cm2 with 2 rows, and (d) ~38 cm2 with 1 row, as processed under 50 Hz - 2 kV field conditions in PEW at 26±1 °C for 3 hours. The mean alpha particle track diameters versus alpha energy are given in Fig. 5 (a,b,c,d) for 4 circular PCTDs with effective etched areas; (a) ~283 cm2 with 4 rows, (b) ~200 cm2 with 3 rows, (c) ~78 cm2 with 2 rows, and (d) ~38 cm2 with 1 row, as processed under 50 Hz - 2 kV field conditions in PEW at 26±1 °C for 3 hours. The mean alpha track diameter responses in Fig. 5 (a,b,c,d) all confirm that the mean track diameter versus alpha energy responses for each detector effective etched area overlap each other independent of being in which row exposed.
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Fig. 5 (a,b,c,d). Alpha particle mean track diameter versus alpha energy in for 4 circular PCTDs with effective etched areas; (a) ~283 cm2 with 4 rows, (b) ~200 cm2 with 3 rows, (c) ~78 cm2 with 2 rows, and (d) ~38 cm2 with 1 row, as processed under 50 Hz - 2 kV field conditions in PEW at 26±1 °C for 3 hours. In order to demonstrate comparatively the appearance of alpha tracks in terms of track density and track diameter, the alpha tracks processed under the ECE conditions applied were photographed under a light microscope. Fig. 6 shows the microphotographs of particle tracks for alpha particles of 8 different energies in row B (Having the same distance from the center of each PCTD) of the 4 PCTDs of different effective etched areas, as shown in Fig. 3. The appearance in terms of the number and diameter of alpha tracks in different effective etched areas are well demonstrated. In particular, at the Bragg-peak with an energy of ~0.7-0.8 MeV, it is well observed that alpha particle tracks appear with the same characteristics in terms of track density and track diameter with an efficiency of near ~100% independent of 9
the detector effective etched area. This is due to the fact that alpha particle stopping power (dE/dX) is the highest at the Bragg peak. Therefore, in order reveal the alpha tracks by the ECE process, it requires a minimum field strength; what is met at each detector effective etched area. This is also a reason why the efficiency at this energy is the highest with the same value in the four detector effective etched areas. On other hand, the dE/dX decreases around the Bragg peak which leads to lower efficiencies depending on the alpha energy.
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Fig. 6. Microphotographs of particle tracks of alpha particles of 8 different energies on row B
of each of the 4 PCTDs with different effective etched areas (100X) for 8 selected alpha energies by applying the ECE conditions of 50 Hz - 2 kV, PEW, 26±1 °C for 3 hours. 11
By analyzing the responses of Fig. 4 (a,b,c,d) and Fig. 5 (a,b,c,d), it can be simply concluded that alpha track detection efficiencies and mean track diameters at different energies overlap each other in the detectors independent of the effective etched areas and location of the area exposed to alpha particles at the stated ECE conditions. The responses highly support that each detector under the ECE processing conditions applied has uniform electric field uniformity independent of the position of the area exposed to alpha particles on the detector. This observation is demonstrated by plotting alpha detection efficiency and mean track diameter responses as functions of distance of the location of the area exposed to alpha particles from the center of the circular detector, as shown in Fig. 7 (a,b), for the largest PCTD with effective etched area of ~283 cm2. Of course the same plots for the other three smaller detector effective etched areas will also confirm the same conclusions. These conclusions can also well be observed in Fig. 8 showing microphotographs of alpha particles tracks of 8 different energies registered in the PCTD with an effective etched area of ~283 cm2 in four rows.
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Fig. 7 (a,b). (a) Alpha registrant efficiency (%) and (b) mean track diameter versus distance of the positions exposed to alpha particles on the largest effective etched area ~283 cm2 for different selected alpha energies by applying the ECE conditions of 50 Hz - 2 kV, PEW, 26±1 °C for 3 hours. 13
Fig. 8. Microphotographs (100 X) of alpha particles of different energies in 4 rows B, C, D, E (as shown in Fig. 3) of the PCTD with an effective etched area of ~283 (cm2) for 8 selected alpha
energies by applying the ECE conditions of 50 Hz - 2 kV, PEW, 26±1 °C for 3 hours. 14
On the other hand, as the detector effective etched area has increased, the field strength has been reduced. This can be simply observed when the similar responses of 4 detectors such as the alpha detection energy and mean alpha track diameters in different effective etched areas are plotted comparatively. Fig. 9 (a,b) shows; (a) alpha particle detection efficiency and (b) mean track diameter versus alpha energy responses of the detectors with 4 different effective etched areas.
Fig. 9 (a,b). (a) Alpha detection efficiency (%) and (b) mean alpha track diameter versus alpha energy in 4 PCTDs with different effective etched areas processed at the same ECE conditions of 50 Hz – 2 kV, PEW, 26±1 °C for 3 hours. 15
Fig. 9 (a,b) well demonstrates that alpha detection efficiency, mean track diameter and alpha detection energy range have decreased as the detector effective etched area has increased. The decrease in the value of the three parameters are due to the fact that as the detector effective etched area increases, the field strength on the detector decreases, as further discussed below. In fact, a polycarbonate detector of a certain thickness being a dielectric material is a capacitive load, when placed in the ECE chamber, like parallel plates of a capacitor. In a purely resistive AC circuit, voltage and current waveforms are in the same phase when having changes in their polarity in each cycle. Therefore, the output power entering the load is completely dissipated and consumed in that load. On the other hand, when a reactive load is present in a circuit as a capacitor or an inductor, the energy storage in the load results in a phase difference between the current and voltage waveforms. During each cycle of the AC voltage, extra energy in addition to any energy consumed in the load is temporarily stored in the load, and then returned to the power grid. In the ECE chamber, polycarbonate detector of a thickness d has a capacitance C = k.εo.A / d where k, εo, and A are respectively the relative dielectric constant, permittivity constant and detector effective etched area respectively. Also the reactive capacitance of the circuit is Xc = 1/(2πfC) where f is the frequency, and C is the capacitance. Such a circuit therefore induces a current I = V/Xc. Considering such basic fundamental relations, one can simply conclude that as the detector effective etched area A(cm2) increases, the capacitance C increases, the reactive capacitance Xc decreases and accordingly the current I in the system increases. Therefore, since the power applied to each of four detectors in the system is constant, the real voltage applied to the system will be reduced as the effective etched area increased. Therefore, in order to keep the power of the system when applied to detectors of different effective etched areas constant, the high voltage V applied to etch larger detector effective areas should be compensated depending on the effective etched area. Having said the above, in order to improve the differences observed in the responses of Fig. 9 (a,b) such that they have the same responses and overlap each other, the compensation coefficients recommended in a previous study were applied (Sohrabi and Soltani, 2019); i.e. the voltages applied to the detector effective etched areas ~38, ~78, ~200 and ~283 cm2 were compensated by voltage compensation factors ~1.0, ~1.1, ~1.25, ~1.45 leading to compensated applied voltages ~2.0, ~2.2, ~2.5 and ~2.9 kV respectively, while other ECE conditions were kept the same. Fig. 10 (a,b) shows alpha detection efficiency and mean alpha track diameter versus alpha energy after the applied voltage were compensated for the 16
PCTDs with 4 different effective etched areas. As the alpha detection efficiency and mean track diameter versus alpha energy of Fig. 10 (a,b) can be seen, the four responses either for the alpha efficiency and also for the mean track diameter as well as the detection energy range well match each other within the standard deviations.
Fig. 10 (a,b). (a) Alpha detection efficiency and (b) mean alpha track diameter versus alpha energy after the voltage applied to each of the 4 detector effective etched areas have been compensated.
4. Conclusions 17
A new single-cell multi-size detector ECE system was designed, constructed, and put into effective operation with a capacity to etch at a time one polycarbonate detector of a size such as ~7.0, ~10.0, ~16.0, ~19.0 cm effective etched diameters respectively with effective etched areas ~38, ~78, ~200, and ~283 cm2. It should be mentioned that these are not the only etched areas to be applied; if necessary, other detector effective etched areas can also be applied depending on the application. The studies on the role of detector effective etched area on the responses conclude that while each group of alpha detection efficiency versus alpha energy responses and mean track diameter versus alpha energy responses overlap each other independent of the effective etched area, they are different from each other from one effective detector etched area to another. The systematic variations have been due to the physical fact that as detector effective etched area A increases, capacitance C increases, reactive capacitance Xc also decreases and accordingly the current I in the system increases based on which the voltage has been compensated in order to keep the effective power for each detector effective etched area constant. By applying a relevant voltage compensation factor to each detector, the detection efficiency and mean effective diameters were all improved and overlapped each other within standards deviations of the measurements. Acknowledgements Research was carried out under the current budget of the Amirkabir University of Technology. References Singh, R. C., Virk, H. S., 1987. Internal heating effect during electrochemical etching of Lexan polycarbonate, Nucl. Instrum. Methods Phys. Res., Sect. B 29, 579-582. Sohrabi, M., 1974. Electrochemical etching amplification of recoil particle tracks in polymers and is applications in fast neutron personnel dosimetry, Health Phys. 27, 598-582. Sohrabi, M., 1975. Electrochemical etching amplification of low-LET recoil particle tracks in polymers for fast neutron dosimetry. Diss. Georgia Institute of Technology. Atlanta, Ga. Sohrabi, M., 1985. A new multi-chamber electrochemical etching system approach for rapid characteristic responses in polymeric dosimeters, Radiat. Prot. Dosim. 12, 55-59. Sohrabi, M., 1986. Discovery of and internal heating effect during electrochemical etching of polymeric dosimeters: A study of polymer characteristics, Int. J. Radiat. Appl. Instrum., Part D. Nucl. Tracks Radiat. Meas. 12, 179-183. 18
Sohrabi, M., 1993. A new triplet electrochemical etching (TECE) method, Radiat. Prot. Dosim. 48.3, 279-283. Sohrabi, M., 2017. Novel single-cell mega-size chambers for electrochemical etching of panorama position-sensitive polycarbonate ion image detectors, Rev. Sci. Instrum. 88 (11), 113305. Sohrabi, M., 2018. Breakthroughs in 4π panorama ionology in plasma focus devices for mechanisms understanding and advanced applications, Radiat. Meas. 119, 192-198. Sohrabi, M., Becker, K., 1971. Some studies on the application of track etching in personnel fast neutron dosimetry. Oak Ridge National Laboratory Rep, ORNL-TM-36051. Sohrabi, M., Morgan. K. Z., 1978. A new polycarbonate fast neutron personnel dosimeter, Am. Ind. Hyg. Assoc. J. 39, 433-447. Sohrabi, M., Katouzi. M., 1993. A new parameter in the electrochemical etching of polymer track detectors. Nucl. Instrum. Methods Phys. Res. B 82, 442-446. Sohrabi, M., Zainali, Gh. 1995, A new multi-detector ECE processing chamber system for large-scale radon and neutron dosimetry applications. Radiat. Meas. 25.1-4, 463-464. Sohrabi, M., Rabiee, S. 2018, Thickness dependence verification of electrochemically-etched polymer track detectors. Meas. 124, 40-46. Sohrabi, M., Soltani, Z., 2019. Uniform position-sensitivity verification of novel electrochemically-etched panorama mega-size polymer ion image detectors. Meas. 135, 806813 Sohrabi, M., Zarinshad, A., Habibi, M., 2016a. Breakthrough in 4ℼ ion emission mechanism understanding in plasma focus devices, Sci. Rep. 6, 38843-38857. Sohrabi, M., Hakimi, A., Mahdavi. S.R., 2016b. A novel position-sensitive mega-size dosimeter for photoneutron in high-energy X-ray medical accelerators, Phys. Med. 32 (6), 778-786. Soltani, Z., Sohrabi, M., Habibi, M., 2019. Analysis of 3D deuterium ion emission angular distribution in plasma focus device using novel panorama polycarbonate detectors, Radiat. Phys. Chem. 165, P.108404. Somogyi, G., 1977. Processing of plastic track detectors, Nucl. Track Detection. 1, 3-18.
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Tommasino, L., 1970. Electrochemical etching of damage track detectors by HV pulse and sinusoidal waveforms, Procs. 7th Int. Coll. Corpuscular Phot. Solid Detectors, Barcelona. Tommasino, L., Torri, G., Notaro, M., 1991. Unique characteristics of thin film electrochemical etching, Nucl. Tracks Rad. Meas, 19 (1-4), 223-224. Turek, K., 1992. Universal multi-detector etching stand for electrochemically etched plastic track detectors. Nucl. Tracks Radiat. Meas. 20, 601-604. Turek, K., Bednar, J., Dajko, G., Spurny, F. 1991, Study of parameters influencing the internal heating effect during electrochemical etching at room temperature rate, Int. J. Radiat. Appl. Instrum., Part D Nucl. Tracks Radiat. Meas. 19, 227-230.
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HIGHLIGHTS • • • • •
New circular single-cell multi-size detector ECE system for 4 detectors presented. Four detector effective etched areas with position sensitivity were studied. 8 energies (0.3-4.0 MeV) at fixed alpha fluence 1.0x104 applied for each detector. Detection efficiency and track diameter and energy range for each detector studied. Efficiency/diameter/energy range responses fixed by voltage compensation factors.
Acknowledgements Research was carried out under the current budget of the Amirkabir University of Technology. There is not conflict of interest.
I am pleased to provide you with a revised version of an original article entitled:
New single-cell multi-size detector electrochemical etching system by Mehdi Sohrabi, Sahel Rabiee for publication in the prestigious “Radiation Physics and Chemistry” Journal. The article has been revised and further edited considering all the comments made by the distinguished reviewer. Responses to the Reviewer’s comments are also attached. I express sincere thanks to the time spent for reviewing and making excellent comments to the paper. I would like to inform you that the article can only be published under normal standard copyright agreement but not as gold open access. Would you need any additional information please advise.
S0969-806X(19)31246-0
DOI:
https://doi.org/10.1016/j.radphyschem.2020.108744
Reference:
RPC 108744
To appear in:
Radiation Physics and Chemistry
Received Date: 25 September 2019 Revised Date:
20 January 2020
Accepted Date: 1 February 2020
Please cite this article as: Sohrabi, M., Rabiee, S., New single-cell multi-size detector electrochemical etching system, Radiation Physics and Chemistry (2020), doi: https://doi.org/10.1016/ j.radphyschem.2020.108744. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd.
New single-cell multi-size detector electrochemical etching system
Mehdi Sohrabi*, Sahel Rabiee Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology Tehran, Islamic Republic of Iran
Abstract: Electrochemical etching (ECE) methods can process lower-LET heavy charged particles such as protons, deuterons, alphas, neutrons-induced recoils, etc. in polymers in particular polycarbonate track detectors (PCTD) to a point observed by the unaided eyes. In this study, a new single-cell multi-size detector ECE system was invented for processing circular PCTDs of different sizes especially with ~7.0, ~10.0, ~16.0, ~19.0 cm effective diameters of 250 µm thick detectors as used. From many physical and chemical parameters controlling the amplification of particle tracks in these detectors, effective etched area and position sensitivity of the detector as well as field strength were investigated on detection responses of alpha particles of fixed fluence ~1.0x104 alphas.cm-2 at 8 distinct energies within ~0.3 to ~4.0 MeV energy range. While no position sensitivity was observed on track detection efficiency and diameter responses of each detector effective etched area, the responses differed slightly from one detector effective area to another due to changes in the dissipated real output power (load) which decreases as detector effective area increases. Accordingly by applying a compensated voltage factor for each effective size, the responses were all matched well demonstrating that the new single-cell multi-size detector ECE system can be
effectively used to a number of relatively large-area circular detectors. Keywords: Single-cell; Electrochemical etching; Multi-size detector; Polycarbonate detector; Effective detector area; Voltage compensation factor
Corresponding Author; dr_msohrabi @yahoo.com
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1. Introduction Since the development of the electrochemical etching (ECE) method by Tommasino (1970) and by Sohrabi (Sohrabi and Becker, 1971; Sohrabi, 1974), different ECE chambers have been designed and constructed in order to process only one detector (Tommasino, 1970; Sohrabi and Becker, 1971; Somogyi, 1977), simultaneous etching of many equal-size detectors (Sohrabi, 1974; 1975; Sohrabi and Morgan, 1978; Turek, 1992), specific chambers for example for multi-detector/multi-parameter studies (Sohrabi, 1985), triplet ECE (TECE) chamber for etching large number of detectors in parallel rows (Sohrabi, 1993), pressurecontrolled chamber (Sohrabi and Katouzi, 1993), thin film ECE chamber (Tommasino et al. 1991), simultaneous 100 detector processing chamber (Sohrabi and Zainali, 1995), internal dielectric heating studies (Sohrabi, 1986; Sing and Virk, 1987; Turek et al., 1991), dual-cell large ECE chambers (Sohrabi et al., 2016a,b; Sohrabi and Soltani, 2019), thickness dependence verification of ECE polymer detectors (Sohrabi and Rabiee, 2018), and in particular the novel single-cell mega-size ECE systems which can process (e.g. 33 cm x 71 cm PCTD) by being laid down on the laboratory bench in a simple fashion during processing (Sohrabi, 2017; 2018; Soltani et al., 2019). It has been a common practice that the ECE chambers designed and used in some applications can process only small one-size detectors. In particular, polycarbonate detectors due to having many advantages such as being of potential use from applying a very small to very large detector sizes (Sohrabi, 2017; Sohrabi and Soltani, 2019), requires design and construction of versatile multi-size chambers in particular for circular polycarbonate detectors. On the other hand, using detectors with larger effective etched areas impose a reduction in the dissipated real output power (load) which decreases as the detector effective etched areaincreases. Therefore, it is the purpose of this paper to: 1. Design, construct and use a new circular single-cell multi-size detector ECE system in order to process PCTDs of different effective etched areas in only one single-cell chamber system, 2. Study the effects of effective etched area and position sensitivity of the detector as well as field strength on detection responses of alpha particles of a fixed fluence ~1.0x104 alphas.cm-2 at 8 distinct energies within ~0.3 to ~4.0 MeV energy range, and 3. Make attempt to equalize alpha detection efficiency and track diameter responses versus alpha energy as well as alpha detection energy range of different detector effective etched areas by applying relevant applied voltage or field strength compensation factors. 2
2. Materials and Methods
2.1
Design of new circular single-cell ECE chamber
In ECE processing of charged particle tracks in PCTDs, the detector is always sandwiched between two semi-chambers to insulate them from each other when filled with a chemical etchant by using two silicon rubber washers on each side of the PCTD in order to isolate two semi-chamber and prevent any sparking and/or etchant leakage through the detector which stop the ECE process. Recently single-cell mega-size ECE chamber have been invented (Sohrabi, 2017), using one single dry cell electrode and one wet semi-chamber filled with etchant. The basic design of the versatile ECE chamber developed in this study is basically the same as that design with some specifications for processing circular PCTDs of different effective etched areas (Sohrabi, 2017). This chamber has two equal size flat transparent Plexiglas sheets (2 cm thick) as chamber walls; one Plexiglas wall with a flat stainless steel electrode attached on it which serves as a dry cell with no etchant required laying on the laboratory bench and the other Plexiglas wall which lays over a silicon rubber washer holding the circular PCTD between them tight to be processed. In this arrangement, a circular PCTD in a special size is laid on the stainless steel flat electrode. Then one silicone rubber washer with a size smaller than the detector size is laid on the PCTD symmetrically. This rubber washer plays the roles of a wet cell for holding the etchant and an insulator to insulate dry and wet cells from each other. The other Plexiglas wall has a short stainless steel rod electrode at the center with also having two holes on it; one for feeding and discharging the etchant and one for inserting a thermometer to control the temperature. Then, the two Plexiglas walls are tightened together by a number of bolts and wing nuts. This new chamber was studied only for 4 different PCTDs with ~7.0, ~10.0, ~16.0, ~19.0 cm effective etched diameters with effective etched areas ~38, ~78, ~200 and ~283 cm2 using 250 µm thick polycarbonate detectors. However, the chamber can also be applied to PCTDs with other effective etched areas or other thicknesses provided that proper silicon washers for any other effective etched areas can also be used. Fig. 1 shows the schematic design of the new single-cell multi-size detector ECE
system; (a) different components of the system and (b) assembled chamber system.
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Fig. 1. Schematic design of the new single-cell multi-size detector ECE system; (a) different components of the ECE system and (b) assembled chamber system.
2.2
Alpha exposure and ECE processing of circular PCTDs
The PCTDs used in this study are 4 circular polycarbonate detectors of 250 µm thickness (Bayer Company, Germany) with ~7.0, ~10.0, ~16.0, ~19.0 cm effective diameters (~38, ~78, ~200 and ~283 cm2). They were cut from larger sheets masked on both sides to prevent scratches. The circular PCTDs were exposed on a numbers of rows to alpha particles with a constant fluence of ~1.0 x104 alphas.cm-2 by using a specially designed and constructed brass collimator holding an 241Am source. A collimated
241
Am alpha source was used to expose each position on a row of a PCTD to a
known alpha fluence and energy. The
241
Am alpha source was fixed at the end of a short
brass cylindrical holder which has been inserted inside another brass cylindrical collimator with an opening hole (~0.5 cm2 area) constructed such that the detector to source distance and thus the alpha energy and fluence could be precisely changed by degrading the 4
241
Am alpha
energy in air at room temperature. The alpha fluence and energy for each source to detector distance were calibrated with a surface barrier detector coupled to a multichannel analyzer. Each position on a row of PCTD was exposed to an alpha fluence at a known selected energy of ~0.3, ~0.5, ~0.8, ~1.0, ~1.5, ~2.0, ~3.0, and ~4.0 MeV. Then in order to obtain the fixed fluence of ~1.0 x 104 alpha.cm-2, the exposure was continued for a certain time as calculated for a particular energy to obtain that fluence. Fig. 2 (a,b) shows; (a) a brass collimator holding an
241
Am alpha source to provide a known fluence at a known alpha energy (as
constructed in our laboratory) and (b) a PCTD divided into four rows showing also the brass collimator which is exposing an area on the PCTD with a known fluence and energy.
Fig. 2 (a, b). (a) A brass collimator holding an 241Am alpha source to provide known fluences at known alpha energies and (b) a PCTD divided into four rows showing the brass collimator exposing an area on the PCTD with a known fluence and energy.
Depending on the effective etched area of a circular PCTD, 8 alpha exposures each at a fixed energy were made at 8 specific positions on each of radial circular rows 1, 2, 3, and 4 rows in PCTDs with ~7.0, ~10.0, ~16.0, ~19.0 cm effective diameters respectively. Each row has been divided into 8 circular positions (~0.5 cm2) separated within 45°angle from each other. Each location on each row has been exposed to a fixed alpha fluence at a known energy.
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By using the above stated collimated alpha source, four PCTDs with four different effective etched areas and different rows each with 8 positions to be exposed at a certain alpha energy. Fig. 3 shows four circular PCTDs with four different effective etched areas divided into some rows; each row has 8 exposed positions each with ~0.5 cm2 area where each area has been exposed to one of the 8 known energies selected within ~0.3 to ~4.0 MeV energy range.
Fig. 3. Four circular PCTDs, with four different effective etched areas each divided into rows; each row has 8 positions with ~0.5 cm2 area to be exposed to a known alpha fluence and energy within ~0.3 to ~4.0 MeV energy range for a calculated exposure duration.
The alpha-exposed PCTDs were processed electrochemically using the single-cell circular ECE chamber for 3.0 hours applying a constant voltage 2 kV (electric field strength of 80 kV.cm-1) using a 50 Hz - HV generator. Alpha particle and background track (BGT) densities as well as track diameters were determined under a light microscope. The net alpha track density has been obtained by using alpha track density minus background track density in order to calculate the registration efficiency.
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The ‘‘alpha detection efficiency
ε
(%)” determined at each position on each row of each
PCTD was calculated based on the formula given below:
ε (%) = (Dtd (tracks.cm-2) / Φ (alphas.cm-2)) x 100 ε
is in fact defined as the ‘‘ratio of alpha track density (tracks.cm-2) determined at each
position in a PCTD to alpha particle fluence (alpha.cm-2) impinged on the position times 100, where: Dtd = Alpha Track Density (tracks.cm-2), and Φ = Alpha Fluence (alphas.cm-2). 3.
Results and discussion
In order to consistently apply the new single-cell multi-size detector ECE system to circular PCTDs of different effective etched areas with uniform position sensitivity for different applications, some parametric studies have been performed. Among many parameters affecting alpha detection efficiency and track diameters as well as alpha energy range in ECE-processed PCTDs, the effective etched area of a detector and the electrical field strength play crucial roles, when other parameters are fixed. Therefore, the new ECE system as described in Fig. 1, was used for parametric studies. Fig. 4 (a,b,c,d) represents alpha particle efficiency (%) versus alpha energy in PCTDs of 4 different effective etched areas and positions on each row of a PCTD surface for circular PCTDs with effective etched areas; (a) ~283 cm2 with 4 rows, (b) ~200 cm2 with 3 rows, (c) ~78 cm2 with 2 rows, and (d) ~38 cm2 with 1 row, as processed under 50 Hz - 2 kV field conditions in PEW solution at 26±1 °C for 3 hours. The alpha efficiency responses versus alpha energy in Fig. 4 (a,b,c,d) all confirm having the same Bragg-type response trends peaking around 0.7 - 0.8 MeV in the four detectors with different etched areas studied.
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Fig. 4 (a,b,c,d). Alpha particle efficiency (%) versus alpha energy in PCTDs of 4 different effective etched areas; (a) ~283 cm2 with 4 rows, (b) ~200 cm2 with 3 rows, (c) ~78 cm2 with 2 rows, and (d) ~38 cm2 with 1 row, as processed under 50 Hz - 2 kV field conditions in PEW at 26±1 °C for 3 hours. The mean alpha particle track diameters versus alpha energy are given in Fig. 5 (a,b,c,d) for 4 circular PCTDs with effective etched areas; (a) ~283 cm2 with 4 rows, (b) ~200 cm2 with 3 rows, (c) ~78 cm2 with 2 rows, and (d) ~38 cm2 with 1 row, as processed under 50 Hz - 2 kV field conditions in PEW at 26±1 °C for 3 hours. The mean alpha track diameter responses in Fig. 5 (a,b,c,d) all confirm that the mean track diameter versus alpha energy responses for each detector effective etched area overlap each other independent of being in which row exposed.
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Fig. 5 (a,b,c,d). Alpha particle mean track diameter versus alpha energy in for 4 circular PCTDs with effective etched areas; (a) ~283 cm2 with 4 rows, (b) ~200 cm2 with 3 rows, (c) ~78 cm2 with 2 rows, and (d) ~38 cm2 with 1 row, as processed under 50 Hz - 2 kV field conditions in PEW at 26±1 °C for 3 hours. In order to demonstrate comparatively the appearance of alpha tracks in terms of track density and track diameter, the alpha tracks processed under the ECE conditions applied were photographed under a light microscope. Fig. 6 shows the microphotographs of particle tracks for alpha particles of 8 different energies in row B (Having the same distance from the center of each PCTD) of the 4 PCTDs of different effective etched areas, as shown in Fig. 3. The appearance in terms of the number and diameter of alpha tracks in different effective etched areas are well demonstrated. In particular, at the Bragg-peak with an energy of ~0.7-0.8 MeV, it is well observed that alpha particle tracks appear with the same characteristics in terms of track density and track diameter with an efficiency of near ~100% independent of 9
the detector effective etched area. This is due to the fact that alpha particle stopping power (dE/dX) is the highest at the Bragg peak. Therefore, in order reveal the alpha tracks by the ECE process, it requires a minimum field strength; what is met at each detector effective etched area. This is also a reason why the efficiency at this energy is the highest with the same value in the four detector effective etched areas. On other hand, the dE/dX decreases around the Bragg peak which leads to lower efficiencies depending on the alpha energy.
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Fig. 6. Microphotographs of particle tracks of alpha particles of 8 different energies on row B
of each of the 4 PCTDs with different effective etched areas (100X) for 8 selected alpha energies by applying the ECE conditions of 50 Hz - 2 kV, PEW, 26±1 °C for 3 hours. 11
By analyzing the responses of Fig. 4 (a,b,c,d) and Fig. 5 (a,b,c,d), it can be simply concluded that alpha track detection efficiencies and mean track diameters at different energies overlap each other in the detectors independent of the effective etched areas and location of the area exposed to alpha particles at the stated ECE conditions. The responses highly support that each detector under the ECE processing conditions applied has uniform electric field uniformity independent of the position of the area exposed to alpha particles on the detector. This observation is demonstrated by plotting alpha detection efficiency and mean track diameter responses as functions of distance of the location of the area exposed to alpha particles from the center of the circular detector, as shown in Fig. 7 (a,b), for the largest PCTD with effective etched area of ~283 cm2. Of course the same plots for the other three smaller detector effective etched areas will also confirm the same conclusions. These conclusions can also well be observed in Fig. 8 showing microphotographs of alpha particles tracks of 8 different energies registered in the PCTD with an effective etched area of ~283 cm2 in four rows.
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Fig. 7 (a,b). (a) Alpha registrant efficiency (%) and (b) mean track diameter versus distance of the positions exposed to alpha particles on the largest effective etched area ~283 cm2 for different selected alpha energies by applying the ECE conditions of 50 Hz - 2 kV, PEW, 26±1 °C for 3 hours. 13
Fig. 8. Microphotographs (100 X) of alpha particles of different energies in 4 rows B, C, D, E (as shown in Fig. 3) of the PCTD with an effective etched area of ~283 (cm2) for 8 selected alpha
energies by applying the ECE conditions of 50 Hz - 2 kV, PEW, 26±1 °C for 3 hours. 14
On the other hand, as the detector effective etched area has increased, the field strength has been reduced. This can be simply observed when the similar responses of 4 detectors such as the alpha detection energy and mean alpha track diameters in different effective etched areas are plotted comparatively. Fig. 9 (a,b) shows; (a) alpha particle detection efficiency and (b) mean track diameter versus alpha energy responses of the detectors with 4 different effective etched areas.
Fig. 9 (a,b). (a) Alpha detection efficiency (%) and (b) mean alpha track diameter versus alpha energy in 4 PCTDs with different effective etched areas processed at the same ECE conditions of 50 Hz – 2 kV, PEW, 26±1 °C for 3 hours. 15
Fig. 9 (a,b) well demonstrates that alpha detection efficiency, mean track diameter and alpha detection energy range have decreased as the detector effective etched area has increased. The decrease in the value of the three parameters are due to the fact that as the detector effective etched area increases, the field strength on the detector decreases, as further discussed below. In fact, a polycarbonate detector of a certain thickness being a dielectric material is a capacitive load, when placed in the ECE chamber, like parallel plates of a capacitor. In a purely resistive AC circuit, voltage and current waveforms are in the same phase when having changes in their polarity in each cycle. Therefore, the output power entering the load is completely dissipated and consumed in that load. On the other hand, when a reactive load is present in a circuit as a capacitor or an inductor, the energy storage in the load results in a phase difference between the current and voltage waveforms. During each cycle of the AC voltage, extra energy in addition to any energy consumed in the load is temporarily stored in the load, and then returned to the power grid. In the ECE chamber, polycarbonate detector of a thickness d has a capacitance C = k.εo.A / d where k, εo, and A are respectively the relative dielectric constant, permittivity constant and detector effective etched area respectively. Also the reactive capacitance of the circuit is Xc = 1/(2πfC) where f is the frequency, and C is the capacitance. Such a circuit therefore induces a current I = V/Xc. Considering such basic fundamental relations, one can simply conclude that as the detector effective etched area A(cm2) increases, the capacitance C increases, the reactive capacitance Xc decreases and accordingly the current I in the system increases. Therefore, since the power applied to each of four detectors in the system is constant, the real voltage applied to the system will be reduced as the effective etched area increased. Therefore, in order to keep the power of the system when applied to detectors of different effective etched areas constant, the high voltage V applied to etch larger detector effective areas should be compensated depending on the effective etched area. Having said the above, in order to improve the differences observed in the responses of Fig. 9 (a,b) such that they have the same responses and overlap each other, the compensation coefficients recommended in a previous study were applied (Sohrabi and Soltani, 2019); i.e. the voltages applied to the detector effective etched areas ~38, ~78, ~200 and ~283 cm2 were compensated by voltage compensation factors ~1.0, ~1.1, ~1.25, ~1.45 leading to compensated applied voltages ~2.0, ~2.2, ~2.5 and ~2.9 kV respectively, while other ECE conditions were kept the same. Fig. 10 (a,b) shows alpha detection efficiency and mean alpha track diameter versus alpha energy after the applied voltage were compensated for the 16
PCTDs with 4 different effective etched areas. As the alpha detection efficiency and mean track diameter versus alpha energy of Fig. 10 (a,b) can be seen, the four responses either for the alpha efficiency and also for the mean track diameter as well as the detection energy range well match each other within the standard deviations.
Fig. 10 (a,b). (a) Alpha detection efficiency and (b) mean alpha track diameter versus alpha energy after the voltage applied to each of the 4 detector effective etched areas have been compensated.
4. Conclusions 17
A new single-cell multi-size detector ECE system was designed, constructed, and put into effective operation with a capacity to etch at a time one polycarbonate detector of a size such as ~7.0, ~10.0, ~16.0, ~19.0 cm effective etched diameters respectively with effective etched areas ~38, ~78, ~200, and ~283 cm2. It should be mentioned that these are not the only etched areas to be applied; if necessary, other detector effective etched areas can also be applied depending on the application. The studies on the role of detector effective etched area on the responses conclude that while each group of alpha detection efficiency versus alpha energy responses and mean track diameter versus alpha energy responses overlap each other independent of the effective etched area, they are different from each other from one effective detector etched area to another. The systematic variations have been due to the physical fact that as detector effective etched area A increases, capacitance C increases, reactive capacitance Xc also decreases and accordingly the current I in the system increases based on which the voltage has been compensated in order to keep the effective power for each detector effective etched area constant. By applying a relevant voltage compensation factor to each detector, the detection efficiency and mean effective diameters were all improved and overlapped each other within standards deviations of the measurements. Acknowledgements Research was carried out under the current budget of the Amirkabir University of Technology. References Singh, R. C., Virk, H. S., 1987. Internal heating effect during electrochemical etching of Lexan polycarbonate, Nucl. Instrum. Methods Phys. Res., Sect. B 29, 579-582. Sohrabi, M., 1974. Electrochemical etching amplification of recoil particle tracks in polymers and is applications in fast neutron personnel dosimetry, Health Phys. 27, 598-582. Sohrabi, M., 1975. Electrochemical etching amplification of low-LET recoil particle tracks in polymers for fast neutron dosimetry. Diss. Georgia Institute of Technology. Atlanta, Ga. Sohrabi, M., 1985. A new multi-chamber electrochemical etching system approach for rapid characteristic responses in polymeric dosimeters, Radiat. Prot. Dosim. 12, 55-59. Sohrabi, M., 1986. Discovery of and internal heating effect during electrochemical etching of polymeric dosimeters: A study of polymer characteristics, Int. J. Radiat. Appl. Instrum., Part D. Nucl. Tracks Radiat. Meas. 12, 179-183. 18
Sohrabi, M., 1993. A new triplet electrochemical etching (TECE) method, Radiat. Prot. Dosim. 48.3, 279-283. Sohrabi, M., 2017. Novel single-cell mega-size chambers for electrochemical etching of panorama position-sensitive polycarbonate ion image detectors, Rev. Sci. Instrum. 88 (11), 113305. Sohrabi, M., 2018. Breakthroughs in 4π panorama ionology in plasma focus devices for mechanisms understanding and advanced applications, Radiat. Meas. 119, 192-198. Sohrabi, M., Becker, K., 1971. Some studies on the application of track etching in personnel fast neutron dosimetry. Oak Ridge National Laboratory Rep, ORNL-TM-36051. Sohrabi, M., Morgan. K. Z., 1978. A new polycarbonate fast neutron personnel dosimeter, Am. Ind. Hyg. Assoc. J. 39, 433-447. Sohrabi, M., Katouzi. M., 1993. A new parameter in the electrochemical etching of polymer track detectors. Nucl. Instrum. Methods Phys. Res. B 82, 442-446. Sohrabi, M., Zainali, Gh. 1995, A new multi-detector ECE processing chamber system for large-scale radon and neutron dosimetry applications. Radiat. Meas. 25.1-4, 463-464. Sohrabi, M., Rabiee, S. 2018, Thickness dependence verification of electrochemically-etched polymer track detectors. Meas. 124, 40-46. Sohrabi, M., Soltani, Z., 2019. Uniform position-sensitivity verification of novel electrochemically-etched panorama mega-size polymer ion image detectors. Meas. 135, 806813 Sohrabi, M., Zarinshad, A., Habibi, M., 2016a. Breakthrough in 4ℼ ion emission mechanism understanding in plasma focus devices, Sci. Rep. 6, 38843-38857. Sohrabi, M., Hakimi, A., Mahdavi. S.R., 2016b. A novel position-sensitive mega-size dosimeter for photoneutron in high-energy X-ray medical accelerators, Phys. Med. 32 (6), 778-786. Soltani, Z., Sohrabi, M., Habibi, M., 2019. Analysis of 3D deuterium ion emission angular distribution in plasma focus device using novel panorama polycarbonate detectors, Radiat. Phys. Chem. 165, P.108404. Somogyi, G., 1977. Processing of plastic track detectors, Nucl. Track Detection. 1, 3-18.
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Tommasino, L., 1970. Electrochemical etching of damage track detectors by HV pulse and sinusoidal waveforms, Procs. 7th Int. Coll. Corpuscular Phot. Solid Detectors, Barcelona. Tommasino, L., Torri, G., Notaro, M., 1991. Unique characteristics of thin film electrochemical etching, Nucl. Tracks Rad. Meas, 19 (1-4), 223-224. Turek, K., 1992. Universal multi-detector etching stand for electrochemically etched plastic track detectors. Nucl. Tracks Radiat. Meas. 20, 601-604. Turek, K., Bednar, J., Dajko, G., Spurny, F. 1991, Study of parameters influencing the internal heating effect during electrochemical etching at room temperature rate, Int. J. Radiat. Appl. Instrum., Part D Nucl. Tracks Radiat. Meas. 19, 227-230.
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HIGHLIGHTS • • • • •
New circular single-cell multi-size detector ECE system for 4 detectors presented. Four detector effective etched areas with position sensitivity were studied. 8 energies (0.3-4.0 MeV) at fixed alpha fluence 1.0x104 applied for each detector. Detection efficiency and track diameter and energy range for each detector studied. Efficiency/diameter/energy range responses fixed by voltage compensation factors.
Acknowledgements Research was carried out under the current budget of the Amirkabir University of Technology. There is not conflict of interest.
I am pleased to provide you with a revised version of an original article entitled:
New single-cell multi-size detector electrochemical etching system by Mehdi Sohrabi, Sahel Rabiee for publication in the prestigious “Radiation Physics and Chemistry” Journal. The article has been revised and further edited considering all the comments made by the distinguished reviewer. Responses to the Reviewer’s comments are also attached. I express sincere thanks to the time spent for reviewing and making excellent comments to the paper. I would like to inform you that the article can only be published under normal standard copyright agreement but not as gold open access. Would you need any additional information please advise.