Dry dilution refrigerator with anti-vibration system for mK scanning probe microscopy
NPL Management Limited
Scope as published
NPL is seeking a solution for a new dry dilution refrigerator (“the system”) in which scanning probe microscopy experiments will be carried out at mK temperatures on live superconducting quantum circuits. NPL wishes to use the system for atomic scale scanning tunnelling microscopy and atomic force microscopy. As such, the system must provide a low vibration and high coherence environment (light tight mixing chamber volume). Significant emphasis will be placed on the lowest possible vibration levels that can be achieved. It is anticipated that a solution provides both a mK vibration isolation system and various vibration mitigation measures at room temperature. The scope includes the dilution refrigerator having a low-vibration experimental platform at mK temperature, the experimental wiring tree to the mK experimental platform, and any room-temperature or low-temperature vibration reducing measures, any gas handling system, vacuum pumps or electronics required to operate the system. The system does not include the scanning probe microscopy unit itself, this will be provided and integrated by NPL. In the below we denote “the mixing chamber plate” as the standard plate of the dilution refrigerator that reaches the specified temperature and cryogenic performance. We further specify an “experimental plate” which may be the same as the “mixing chamber plate” in some implementations, but it may for some vibration isolating solutions be a separate plate on which the experimental scanning probe system and apparatus is mounted. It is in that case assumed that the experimental plate is thermally anchored to the mixing chamber plate and reaches the same base temperature, and sits within the enclosed mixing chamber shielded volume. Description • A “dry” pulse tube cooled dilution refrigerator that does not use liquid nitrogen or liquid helium to achieve cooling to 4 Kelvin. • The dilution refrigerator shall reach a base temperature of 20 mK or less at the vibration-isolated experimental platform, and the dilution refrigerator shall have a cooling power at 100 mK of 400 microWatts or more. • The experimental space below the experimental plate (if not the same as the mixing chamber plate, if e.g. a mK vibration isolation solution is used) shall be at least of diameter 360 mm, with a vertical height available for custom experiments of at least 300 mm. • The experimental plate shall be able to hold an experimental load of up to at least 1.5 kg, for custom experimental apparatus NPL wishes to install. Higher load will score higher. • Of particular importance is the achieved vibration levels at the experimental plate at 20mK or less, which shall have a demonstrated vibration level both horizontally and vertically during continuous operation of the dilution refrigerator as follows: o Any individual peaks in the vibration spectrum (horizontal and vertical) measured from 10 Hz up to at least 1000 Hz not exceeding a peak-to-peak displacement of 0.5 nm/rtHz. o An integrated noise power spectral density in the frequency range 1-10 Hz shall not exceed a root mean square amplitude of 10 nmrms. o The scoring in the evaluation of supplier bids will be heavily weighted against rewarding bids that significantly exceed the above minimum requirement specifications for vibrations. o NPL recognises that laboratory vibration levels may differ and as such will set the requirement that the above vibration levels shall be achieved in factory testing, with NPL staff present during final testing to witness compliance. o Any cold vibration isolation solution must remain well-thermalised and reach a base temperature of 50 mK or less and capable of conducting the active heat loads from piezoelectric nanopositioners. In order to achieve these specifications the supplier may chose to include a range of different solutions, and may work with other suppliers to provide external (room temperature) or internal (mK) vibration isolation solutions. No such solution shall be reg…
- Deadline
- Not published
- Published
- 6 Oct 2026(yesterday)
- Contract value
- Not published
- Location
- United Kingdom
- Reference
ocds-h6vhtk-078153- First seen
- yesterday