Investigation of Teflon Electret Detectors for Gamma Dosimetry

Pretzsch, G.; Dörschel, B.; Leuschner, A.

doi:10.1093/oxfordjournals.rpd.a081999

Cited by 14 publications

(5 citation statements)

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“…This justifies the use of the Teflon electret discs produced for different applications. The results are in good agreement with those of the negative [17,31,34,35] and positive [31,35] Teflon electret discs produced in other studies. The 67.4% and 41.9% decay observed for the positively charged Teflon discs (for 0.2 and 0.5 mm thicknesses respectively, figure 4) are extremely unacceptable for many applications especially for radiation dosimetry.…”

Section: Discussionsupporting

confidence: 91%

“…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 surfaces before its use was carefully cleaned in acetone in order to remove any possible external residues [31,33]. Each Teflon disc has attached to it 1 mm thick aluminum disc as back electrode as also applied in other studies [13,33,34]. The Teflon disc attached concentric to the rotational disc electrode was charged under the corona discharges the temperature of which was measured by a commercial non-contacting thermometer device with ±0.1 • C accuracy.…”

Section: Instruments and Methodsmentioning

confidence: 99%

“…The homo charge stability was studied via a long term monitoring method [31,34]. Each charged Teflon disc after its production was stored in a closed dark aluminum metal box.…”

Section: Instruments and Methodsmentioning

confidence: 99%

“…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%

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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: Discussionsupporting

confidence: 91%

Section: Effects Of Thickness In Negative Charge Modesupporting

confidence: 93%

Section: Instruments and Methodsmentioning

confidence: 99%

“…The homo charge stability was studied via a long term monitoring method [31,34]. Each charged Teflon disc after its production was stored in a closed dark aluminum metal box.…”

Section: Instruments and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

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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Radiation Exposure and Dose to Small Mammals in Radon-Rich Soils

Macdonald

Laverock

1998

Archives of Environmental Contamination and Toxicology

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Protection of the environment from radionuclide releases requires knowledge of the normal background levels of radiation exposure in the exposed biotic community and an estimate of the detriment caused by additional exposure. This study modeled the background exposure and dose to the lungs of small burrowing mammals from 222Rn in artificial burrows in radon-rich soils at a site in southeastern Manitoba. E-PERM chambers used to measure 222Rn in soil showed good reproducibility of measurement, with an average coefficient of variance (CV) of about 10%. Geometric mean (GM) 222Rn concentrations at nine randomly selected sites ranged from 5,490 Bq/m3 (GSD = 1.57, n = 7) to 41,000 Bq/m3 (GSD = 1.02, n = 5). Long-term monitoring of 222Rn concentrations in artificial burrows showed large variation within and between burrows and did not show consistent variation with season, orientation of the burrow opening, or levels of 226Ra in the soil. Annual GM concentrations in individual burrows ranged from 7,480 Bq/m3 (GSD = 1.60) to 18,930 Bq/m3 (GSD = 1.81) in burrows several meters apart. A grand GM of 9,990 Bq/m3 (GSD = 1.81, n = 214) was measured over the site for the year. An exposure model was constructed for five small mammal species based on their respiration rates and the number of hours spent in the burrow, active or hibernating, exposed to soil gas 222Rn, and the time spent out of the burrow exposed to atmospheric 222Rn. A background dose of 0.9 mGy/a from atmospheric 222Rn (40 Bq/m3) was estimated for a large-bodied (80 kg), nonburrowing animal living on the soil surface. The highest exposures (mJ/a) in burrowing mammals occurred in those species with the highest respiration rates. Hibernation accounted for a small fraction of total annual exposure (<5%) because of very low respiration rates during this period. Absorbed dose to lung (mGy/a) was highest in the pocket gopher and decreased in the larger animals because of larger lung mass. Using mean 222Rn concentrations from the field studies and an equilibrium factor (F) of 0.5, doses to lung ranged from 90 mGy/a in the badger to 700 mGy/a in the pocket gopher. These doses closely correspond to those estimated from published dose conversion factors (DCFs) of 1.4 mGy per mJ . h/m3 for whole lung. For the ground squirrel, the DCF approach gives an estimated dose of 300 mGy/a versus 270 using the respiratory flow rate method. Based on these results, doses exceeding 500 mGy/a may be common in mammals and birds (i.e. the burrowing owl) living in radon-rich soils. Published risk coefficients for small mammals suggest that about 17 cancers would occur in 1,000 animals at these exposure rates. Although the potential effects from these exposures were not examined in this study, the study raises questions about how the animals may respond physiologically to this largely natural stress.

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Sensitivity of the electret ionization chamber to fast neutrons

Pretzsch

Köstel

1984

Nuclear Instruments and Methods in Physics Research

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Investigation of Teflon Electret Detectors for Gamma Dosimetry

Cited by 14 publications

References 0 publications

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

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

Radiation Exposure and Dose to Small Mammals in Radon-Rich Soils

Sensitivity of the electret ionization chamber to fast neutrons

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