Speaker
Description
The Deep Underground Neutrino Experiment (DUNE) utilizes neutrino sensors that are submerged within liquid argon to measure the electron trails left by neutrinos. The sensors require specially designed supports to ensure they remain precisely positioned even after the thermal contraction of the sensors and the cryostat that occurs during cooldown. These supports must ensure that the fragile cryostat floor is protected yet also allow the sensor planes to slip in order to avoid any damage. Further, the supports must ensure that the center of contraction is a predetermined location. These objectives are satisfied by utilizing an intermediate slip plane in the support itself that provides a lower coefficient of friction compared to the interface between the support and the cryostat floor. The design of these supports required knowledge of the coefficient of friction for a variety of materials at cryogenics. It was found that the friction associated with materials such as metals, ceramics, and polymers have all been studied very little in cryogenic environments; there is specifically not much data available relative to the static coefficient of friction associated with polymers polymers at low temperature. Therefore, a test apparatus was built to measure the static coefficient of friction of different materials. The apparatus uses a linear screw to apply a force to a test sled contained in a low temperature, moisture controlled environment. Using this test apparatus, a number of tests with different materials were carried out. Some of these results are discussed in this paper.
