Extension of the LTP temperature diagnostics to the LISA band: first results

TL;DR

This paper extends the temperature diagnostics for the LISA mission to lower frequencies down to 0.1 mHz, demonstrating thermistors can achieve high-resolution measurements without 1/f noise interference.

Contribution

It presents the first investigation into thermistor performance at ultra-low frequencies relevant to LISA, including theoretical and practical assessments.

Findings

Thermistors do not exhibit 1/f noise at 0.1 mHz.

High-resolution temperature measurements are feasible at lower frequencies.

Theoretical and practical limits of temperature sensors are established.

Abstract

High-resolution temperature measurements are required in the LTP, i.e., 10 uK/sqrt(Hz) from 1 mHz to 30 mHz. This has been already accomplished with thermistors and a suitable low noise electronics. However, the frequency range of interest for LISA goes down to 0.1 mHz. Investigations on the performance of temperature sensors and the associated electronics at frequencies around 0.1 mHz have been performed. Theoretical limits of the temperature measurement system and the practical on-ground limitations to test them are shown demonstrating that 1/f noise is not observed in thermistors even at frequencies around 0.1 mHz and amplitude levels of 10 uK/sqrt(Hz).