Attachment A - Specifications for a Dilution Refrigerator System

Specifications for a dilution refrigerator system
This dilution refrigerator system consists of a Gas Handling System Refrigerator (hereafter referred to as GHS) and two identical He3/He4 dilution inserts.

Performance Characteristics
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Base temperature:
≤ 30mK
Cooling power:
≥ 40 µW at 100mK
Cool-down time:
≤ 2 hours to base temperature beginning from the start of condensing the mixture.
Operational temperature range, control, and stability: 30mK ≤ T ≤ 1.5K with 5% temperature control and stability over the entire range. Experimental space diameter approx. 28 mm

General Specifications
Operating Features
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The Seller shall supply a sliding seal at the top, so that the vertical position of the Dilution Refrigerator (hereafter referred to as the “DR”) insert may be adjusted without rotation with respect to a NW50 flange in the host system. We will provide general dimensions of the host systems in the figures below for the purpose of the quotations. These top loading host systems are 2 cryo-magnets, with bore of diameter of 35mm and a liquid helium refrigerator with 45mm bore. The top flange of all these hosts is an ISO NW50.
Optimized ³He/4He mixture designed to operate with an external dump. These two DR inserts must be designed to operate, with the same performance characteristics as listed above, not only with the provided GHS but also with our existing GHS. Our existing GHSs have a mixture volume of 10.5 liters. 2.8 liters of this volume corresponds to He3.
Regarding whom provides the He3/He4 mixture: Tests at the manufacturer facility to be done with their own He3/He4 mixture. DRs will be shipped with no mixture to ORNL. ORNL will load its own He3/He4 mixture when the system arrives onsite, with same volume, and same ratio composition.
One external liquid nitrogen cold trap with one dewar capable of hold times of at least 7 days.
At a minimum, pressure gauges/transducers on the dump, insert inlet, insert outlet, and pump outlet.

Control System Features
The Seller shall provide a complete control system capable of autonomous, local control of the DR system.

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A Lakeshore 372 AC Resistance Bridge controller shall be provided.

16 channel Lakeshore scanner

Auto-cool down and auto-run routines allow unattended operation. Automated cooling capability and manual override option.
Control system source code shall be provided by the seller to allow for interfacing with our software controls. The local control system shall be capable of