Photodegradation mechanisms of tetraphenyl butadiene coatings for liquid argon detectors
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Conrad_Photodegradation.pdf
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Author(s)
Jones, Benjamin James Poyner
VanGemert, J. K.
Conrad, Janet
Pla-Dalmau, A.
Date Issued
January 2013
Journal
Journal of Instrumentation
Publisher
Institute of Physics Publishing
Citation
Jones, B J P, J K VanGemert, J M Conrad, and A Pla-Dalmau. “Photodegradation Mechanisms of Tetraphenyl Butadiene Coatings for Liquid Argon Detectors.” Journal of Instrumentation 8, no. 01 (January 23, 2013): P01013–P01013.
Version
Original manuscript
Abstract
We report on studies of degradation mechanisms of tetraphenyl butadiene (TPB) coatings of the type used in neutrino and dark matter liquid argon experiments. Using gas chromatography coupled to mass spectrometry we have detected the ultraviolet-blocking impurity benzophenone. We monitored the drop in performance and increase of benzophenone concentration in TPB plates with exposure to ultraviolet (UV) light, and demonstrate the correlation between these two variables. Based on the presence and initially exponential increase in the concentration of benzophenone observed, we propose that TPB degradation is a free radical-mediated photooxidation reaction, which is subsequently confirmed by displaying delayed degradation using a free radical inhibitor. Finally we show that the performance of wavelength-shifting coatings of the type envisioned for the LBNE experiment can be improved by 10-20%, with significantly delayed UV degradation, by using a 20% admixture of 4-tert-Butylcatechol.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1088/1748-0221/8/01/p01013
