Calibration accuracies

ULT Rox™ sensors go through an intensive cryogenic calibration process. Each sensor comes with a downloadable calibration curve and traceability to NIST standards. Figure 1 demonstrates an example of roll‑over behavior of a calibrated ULT Rox. Calibration ensures a roll-over point beyond the calibration limit, ensuring readings down to 5 mK. It is critical to follow the installation instructions to replicate the calibration environment and wait for the sensor to fully cool down to meet accuracies at 5 mK.

¹Calibration done utilizing a noise thermometer
²[(Calibration uncertainty)² + (reproducibility)²]^0.5

Figure 1 Example of roll-off curve of one ULT Rox sensor

Temperature sensitivity

At 5 mK, ULT Rox devices typically exhibit a sensitivity of approximately 300,000 ohms/K, indicating a high responsiveness to temperature changes. Additionally, the resistance at 5 mK is around 10 kΩ. This high sensitivity means that even small temperature fluctuations result in significant changes in resistance, making the device highly effective for precise measurements in ultra-low temperature environments.

Typical sensitivity Ω/K

Figure 2 Typical sensitivity over temperature for ULT Rox sensors, showing increases responsiveness at lower temperatures

Typical resistance Ω

Figure 3 Typical resistance curve of a ULT Rox™ sensor varies from 10,000 Ω to 2,000 Ω over its operational temperature range

Performance specifications

³Recommended excitation for T < 1 K based on Lake Shore calibration procedures using a 372 AC resistance bridge temperature controller.
⁴Short-term reproducibility data is obtained by subjecting sensor to repeated thermal shocks from 305 K to 4.2 K.

Physical specifications

RX-102B-RS

Lead extensions

ULT Rox™ come standard with approximately 40 cm (16 in) lead wires. Extensions can be added to your device to extend lead length, with a variety of wire types available to suit your application. Below are the most common configurations. Refer to the Lead Extensions datasheet for the complete list.

Included mounting hardware

Each filtered ULT Rox™ sensor ships with metric brass screws. Brass screws are optimal for thermal conductivity and replicates the calibration environment for accurate measurements. Proper mounting is critical to meet specifications; see installation instructions.

• M3 brass fastener, 12 mm length
• M4 brass fastener, 14 mm length
• M3 washer
• M4 washer
• Apiezon N grease is required for installation (not included)

Temperature controller

A 372 temperature controller is required to take readings below 50 mK. Add a 3726 scanner card to increase the number of channels from 2 to 17 and provide a fully guarded signal path.