Response of parylene-coated NaI(Tl) scintillators at low temperature
1 Institut d’Astrophysique Spatiale, Bâtiment 121, Université Paris-Sud 11 and CNRS (UMR 8617), 91405 Orsay Cedex, France
2 Grupo de Física Nuclear y Astropartículas, Universidad de Zaragoza, C/Pedro Cerbuna 12 50009 Zaragoza, Spain
3 Laboratorio Subterráneo de Canfranc, Paseo de los Ayerbe s.n., 22880 Canfranc Estación, Huesca, Spain
4 Department of Physics & Center for Nuclear Physics, University of Lisbon, Av. Prof. Gama Pinto 2, 1649-003 Lisbon, Portugal
5 Fundación ARAID, C/ María de Luna 11, Edificio CEEI Aragón, 50018 Zaragoza Spain
6 Department of Physics, Slovak Technical University Ilkovicova 3, 812 19 Bratislava, Slovak Republic
a Present address: CENPA, University of Washington, US
b e-mail: email@example.com
c Present address: Service d’Astrophysique, CEA Saclay, France
Published online: 10 January 2014
Despite that it is widely used as a scintillator at room temperature, the hygroscopicity of NaI complicates its handling and limits its application for many purposes, for example as a cryogenic detector. To overcome this problem we study coating materials that can act as humidity barriers, in particular parylene, a polymer that can be deposited in very radiopure, thin and conformal layers. In this work, several NaI(Tl) samples coated with 2-5 µm parylene-C were tested at low temperature. Luminescence spectra under X-ray excitation are presented at several temperatures as well as the light output vs temperature at 1.5-300 K. Several thermoluminescence peaks were observed at around 60, 95 and 150 K during warm up to room temperature. The mechanical resistance of the coating under thermal cycles was also investigated, and we observed a degradation of the optical appearance and the light output after cooling down to about 100 mK, which compromises the reusability of the samples.
© Owned by the authors, published by EDP Sciences, 2014
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