Sensitivity of the electret ionization chamber to fast neutrons

Pretzsch, G.; Köstel, Uwe

doi:10.1016/0167-5087(84)90259-x

Cited by 8 publications

(4 citation statements)

References 4 publications

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“…This observation is in good agreement with those of others for negative corona charged Teflon discs [32]. Also variations in the stability of potential charges such as 3% over 100 days [17], 3% over 120 days [34], 7.7% over 77 days [35], and 3% over 200 days over an extended period of time have been observed in other studies [13,40,41], which approximately validate our observations to be used in dosimetry applications. As can be seen in figure 4, the surface positive charge potential decreases rapidly at early days of storage in particular for thinner discs and then decreases with time.…”

Section: Effects Of Thickness In Negative Charge Modesupporting

confidence: 93%

“…The Teflon disc when fully charged was rapidly cooled down to room temperature by using a Peltier cooling device [31,38,39]. A post-charge annealing was applied to the charged Teflon disc at 160 • C for different durations proportional to the Teflon disc thickness (60, 150 and 300 min for 0.2, 0.5 and 1 mm Teflon disc thicknesses respectively) to achieve partial or total charge stability for long term surface potential monitoring [13,31,40,41].…”

Section: Instruments and Methodsmentioning

confidence: 99%

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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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Section: Effects Of Thickness In Negative Charge Modesupporting

confidence: 93%

Section: Instruments and Methodsmentioning

confidence: 99%

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

Sohrabi

Komijani

2018

J. Inst.

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“…These treatment protocols include post-charge annealing heat treatment, multiple heat treatment and pre-and post-charge annealing heat treatment for thick PTFE discs in the range of few millimeters. 4,5,25,[34][35][36][37] Other methods such as plasma and chemical treatments are applicable for thin PTFE films in the micrometer thickness range. 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.…”

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

confidence: 99%

“…4(b), the needle-to-PTFE disc distance was optimized to be 13 mm to uniformly deposit positive corona ions on the PTFE disc surface with an almost flat profile especially at the edges. In this study, the multiple heat treatment protocol includes different steps such as multiple charging of PTFE disc, post-charge annealing heat treatment (160 ○ C for 150 min) 5,25,34,35 and isothermal charge decay (180 ○ C for 2.5 h) 37,41 which are needed to be applied for several times to the positively charged PTFE discs. In fact, heat treatment and charging can be repeated again and again to de-trap charges with low activation energy, so that, finally, an extremely stable positively charged PTFE electret disc is obtained.…”

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

confidence: 99%

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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