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: firstname.lastname@example.org
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
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.