WNPPC2024 - 61st Winter Nuclear Particle Physics Conference

Design of a cryogenic capacitive liquid level sensor

18 Feb 2024, 10:30

15m

Salon AB (Hotel Chateau Bromont)

Contributed Oral Physics Beyond the Standard Model Morning 6 - Feb. 18, 2024

Speaker

Sandhya Rottoo (McGill University)

Description

The Light-Only Liquid Xenon (LoLX) experiment is designed to study scintillation light and characterize the performance of silicon photomultipliers (SiPMs) in a liquid xenon (LXe) medium. To ensure the SiPMs are functioning properly, it is necessary to verify that all of them are submerged. LoLX therefore requires a LXe level sensor. Outgassing requirements, cryogenic temperature, space constraints and the low relative permittivity of LXe (${ϵ}_{LXe}=1.85$) prohibit the use of standard liquid level sensors.

We developed a highly sensitive capacitive liquid level sensor which consists of sinusoidal electrodes inside a flexible Kapton printed circuit board. The liquid level sensor is 30 cm long with a capacitance of $35.4\pm 0.1$ pF. The capacitance is read by a FDC1004 evaluation board and an Arduino Uno, and then sent to the LoLX slow control system to be converted to a liquid level. From measurements made in sunflower oil ($\epsilon_{oil = 3.29}), we calculated that the sensitivity of the sensor in LXe will be 0.1889 ± 0.0001 pF/cm, which is orders of magnitude higher than liquid level sensors used by other groups. We plan to cross-calibrate the sensor in LXe with temperature-sensitive resistors as fixed-point sensors once it has been installed. Commissioning in LXe is planned at the next run of LoLX in March 2024.

Presentation materials

srottoo-wnppc2024.pdf

srottoo-wnppc2024.pptx