Dosimeter Properties of Electret Ionization Chambers

Pretzsch, G.; Darschel, B.; Schanmuth, T.

doi:10.1109/tei.1986.349089

Cited by 6 publications

(7 citation statements)

References 9 publications

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“…The charging temperature, needle bias voltages and its scanning duration were selected to be $ 220 ○ C, AE4 kV (for negative or positive charging) and 4 min, respectively. 5,24,26,27 The needle-to-PTFE disc distances were 13, 21 or 29 mm for positive and 5, 13 or 21 mm for negative corona charging modes, as are usually applied by us in our previous studies. 4 Immediately after charging each PTFE disc, it was rapidly cooled down to $ 16 ○ C using a Peltier cooling device to avoid any probable PTFE surface potential decay due to TSD phenomenon.…”

Section: Effects Of Ptfe Thickness Charge Polarity and Needle-to-ptfmentioning

confidence: 91%

“…4,5,9,12,22 One side of each PTFE disc is covered with a 1-mm-thick aluminum disc as applied in other related dosimetry studies. 4,5,[23][24][25] The surface of the PTFE discs was carefully cleaned by acetone and monitored with an optical microscope to detect dust, other external residues and surface defects which all can result in a probable charge de-trapping. 4,24 All PTFE discs were charged by using the modified corona rotating system (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…4 Immediately after charging each PTFE disc, it was rapidly cooled down to $ 16 ○ C using a Peltier cooling device to avoid any probable PTFE surface potential decay due to TSD phenomenon. 4,24,27,28 It is noteworthy that all electret dosimeters have a defined work limitation and therefore electret with voltages less and more than 100 V and 2.5 kV, respectively, are not allowed to be used in radiation dosimetry due to this matter that more and les electret voltages than the mentioned rang bring about a nonlinearity in the electret dosimeter responses which is not applicable for radiation dosimetry. 4,5,12 Based on our previous studies, 4 kV has to be selected as the optimized corona needle voltage and by applying voltages more than 4 kV to corona needle the electret voltage exceed the allowed maximum electret potential (2.5 kV) and such an electret is not applicable to be used for radiation dosimetry purposes.…”

Section: Effects Of Ptfe Thickness Charge Polarity and Needle-to-ptfmentioning

confidence: 99%

“…32,38 In radiation dosimetry, thick PTFE electret discs (e.g., millimeter) are commonly used due to their better good mechanical stability during charging, handling and also their electrostatic potential measurement. 4,23,24 According to our previous studies, production of a large-area positively charged PTFE electret disc (0.5-mm thickness, 6-cm diameter) by using the modified corona rotating system was unsuccessful (i.e., 41.9% decay of charge over 77 days) based on the pre-or post-charge annealing heat treatment protocol. 5 Such an electret is extremely unacceptable for different applications especially radiation dosimetry.…”

Section: Effects Of Ptfe Thickness Charge Polarity and Needle-to-ptfmentioning

confidence: 99%

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Surface potential uniformity and sensitivity of large-area PTFE electret discs of different thicknesses produced by a modified corona poling rotating system for dosimetry applications

2019

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In this study, large-area (6-cm diameter) Teflon polytetrafluoroethylene (PTFE) discs of different thicknesses (0.2-, 0.5- and 1 -mm) were negatively and positively charged by using the “modified single point-to-plane corona poling rotating system”. The effects of some crucial parameters of the PTFE disc as well as the modified corona poling rotating system on the PTFE surface potential uniformity such as: (a) PTFE disc thickness, (b) PTFE disc polarity and (c) needle-to-PTFE disc distance were successfully reported. Accordingly, closer needle-to-PTFE disc distance, positive charging mode and thinner PTFE disc provided a better PTFE surface potential uniformity. However, the effects of PTFE charge polarity and needle distance on the electrostatic charge potential uniformity were much more remarkable in comparison with the effects of PTFE thickness. Additionally, the surface potential distribution profiles of charged PTFE discs were totally flat and independent of the PTFE thickness at 5- and 13-[Formula: see text]mm needle distances for the negative and positive charging modes, respectively. At the optimized charging conditions, large-area PTFE electret disc (0.5-mm-thick) with positive uniform surface charge potential especially at the edges up to [Formula: see text] 1.8[Formula: see text]kV with stability up to 77 days studied was produced by applying a new multiple heat treatment protocol to the PTFE disc for radon dosimetry. As also observed in this study, the sensitivity of PTFE electret dosimeters to a defined radon gas concentration increases as the PTFE thickness increases. Meanwhile, 0.5-mm-thick PTFE electret disc produced was selected to be used as a high quality electret dosimeter with acceptable and superior parameters for different applications in particular medium-term radiation dosimetry in both low and high dose rate ionizing radiation fields.

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Section: Effects Of Ptfe Thickness Charge Polarity and Needle-to-ptfmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Effects Of Ptfe Thickness Charge Polarity and Needle-to-ptfmentioning

confidence: 99%

Section: Effects Of Ptfe Thickness Charge Polarity and Needle-to-ptfmentioning

confidence: 99%

See 2 more Smart Citations

Surface potential uniformity and sensitivity of large-area PTFE electret discs of different thicknesses produced by a modified corona poling rotating system for dosimetry applications

2019

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“…In radiation dosimetry, usually negatively or positively charged thick Teflon electret discs (e.g. millimeter) are used due to its better good mechanical stability during handling, charging and its voltage measurement [17,[33][34][35]. It is generally known that thick and large electret discs with charge uniformity (in particular at the edges) and stability is highly desirable for dosimetry applications.…”

Section: Introductionmentioning

confidence: 99%

Surface potential stability of large-area Teflon PTFE electret dosimeters of different thicknesses

Sohrabi

Komijani

2018

J. Inst.

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The effects of charge polarity and thickness on the surface charge potential stability responses of large-area Teflon polytetrafluoroethylene (PTFE) discs electrostatically charged by a new “modified single point-to-plane corona poling rotating system” were studied. Large-area Teflon discs (6 cm diameter) with 0.2, 0.5 and 1 mm thicknesses were used to produce both negatively or positively charged Teflon discs, at the same charging conditions. The deposited charge potential stability of the Teflon discs of different thicknesses monitored by a non-contacting electrostatic voltmeter for an extended time were monitored up to 77 days. Some inter-related parameters such as surface charge potential and external electrostatic field, internal electrostatic field, surface charge density, and the storage duration were also studied. The thick large-area Teflon disc electrets produced provided a steady-state charge stability on either negative (0.2, 0.5 and 1 mm thick) or positive (1 mm thick) surface charge potentials for the long period studied. The Teflon electret discs produced demonstrated having the highest charge potential stability in thicker electrets (1 mm), either negative or positive polarity, with provision of high potential for different applications in general and radiation protection dosimetry in particular.

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