Detailed Specifications for Item 1.pdf

Detailed Specifications for Item 1: One complete dry dilution refrigerator

A. Cooling Requirements:

1. Mixing chamber cooling power

a) The mixing chamber must cool below 20 millikelvin and demonstrate a cooling power greater than or equal to 12 μW at 20 millikelvin when loaded with (at a minimum) the included diagnostic thermometry and heating wiring.

b) The mixing chamber must provide at least 250 μW of cooling power at 100 millikelvin when loaded with (at minimum) the included diagnostic thermometry and heater wiring.

2. Pulse tube cooling power

a) The system must be equipped with a pulse tube with greater than 1.0 W cooling power at its 2nd stage.

3. Cooldown time and pre-cool method

a) The time to cool the bare system (diagnostic wiring only) from room temperature to below 30 millikelvin must not exceed 24 hours.

b) The pre-cooling phase must not require a liquid-nitrogen precool circuit.

B. Wiring & Instrumentation:

1. Diagnostic and utility measurement configuration

a) The system must come equipped with all necessary wiring to measure temperature at the still, 50 mK or sometimes referred to as the “cold plate”, and mixing chamber stages.

b) The system must include all necessary instrumentation and cabling to automatically measure the temperatures of all cold stages.

c) The system must include wiring + heaters to expedite warmup to room temperature at the conclusion of a cooldown.

2. User wiring

The system must include sufficient wiring capability for SMA coax as described in the options B-C.

3. Line-of-Sight (LOS) ports

a) The system must have at least 4 KF40 (or larger) line-of-sight (LOS) vacuum feedthroughs to supply options B-D.

b) The system must, in addition, have at least 2 KF50 (or larger) LOS vacuum feedthroughs.

C. Gas Handling

1. The gas handling system must be automated.

2. The necessary volume of helium-3 gas must not exceed 20 liters.

D. Inner Radiation Shielding, and Magnetic Shielding

1. The system must include a mixing chamber stage radiation shield.

2. The system must include a cryogenic magnetic shielding encompassing the mixing chamber experimental volume, thermally coupled to the mixing chamber stage. This must attenuate external DC magnetic fields by at least 40 dB in the horizontal/transverse direction. Additional magnetic shielding may be coupled to higher temperature stages if necessary.

E. Outer vacuum can, inner radiation shield assembly

The vacuum can and inner radiation shield assemblies must accommodate routine assembly/disassembly when the system is placed in a laboratory with a

2.9 m floor-to-ceiling height. Specifically, it must be possible for the vacuum can and radiation shields to be removed and replaced when the cryostat is permanently mounted on its frame.

F. Experimental Space Requirements

1. The volume available for the experimental payload at the mixing chamber must be at least 240 mm diameter and 220 mm height.

2. There must be at least 125 mm of vertical space between cold plates coupled to adjacent cooling stages.

G. Electrical Isolation

The dilution refrigerator chassis ground must be electrically isolated, i.e., capable of being “floated.”

H. Mounting and footprint

1. The system must come equipped with all necessary framing to mount the cryostat within a footprint of 2 m x 2 m and ceiling height of 2.9 m.

2. All components (cryostat, framing, gas handling system, and control instrumentation) must fit through a doorway of width 1.5 m and height 2.1 m.

Any components which must be disassembled and reassembled to accommodate this specification must be noted by the vendor.

I. Documentation

1. Baseline operating parameters (recorded at the factory) must be included in supplied documentation, including cooling powers at mixing chamber and 2nd stage pulse tube, typical temperatures of all stages (1st & 2nd stage pulse tube, still, intermediate cold plate (between still and mixing chamber), and mixing chamber), as well as helium mixture flow rates. Helium-3/4 ratio used should also be noted.

2. The values of all dilution refrigerator circuit impedances as well as the user/operator procedures for measuring their room temperature and low temperature values.

3. Required Helium-3/Helium-4 mixture ratio and total volume.

4. Commercial subsystem manuals, i.e., manuals for all included pumps, compressors, and instrumentation (pressure, temperature).

5. The vendor must provide documentation for thermometry setup and configuration, including all lead resistances, pin assignments, and calibration data.

6. The vendor must provide documentation for all other wiring, including pin assignments and part numbers for commercial mating connectors if applicable.

7. Operating procedures for the end user in the event of power failure, computer failure, or mechanical failure must be outlined and documented.

8. Operating procedures for starting (“cooldown”) and stopping (“warmup”) the system must be documented for the end user.

9. Maintenance intervals for all pumps, compressors, and pulse tube must be documented by the vendor.

10. Maintenance procedures that can be performed by the end user must be documented by the vendor.

J. Site survey

The contractor is responsible for verifying that the installation site is suitable for the dilution refrigerator and gas handling system and associated mounting frame. This includes outlining the required utilities (compressed air, cooling water, and power) for NIST (Boulder, Colorado campus).

K. Delivery and Installation

1. The contractor is responsible to delivering the system to the NIST Boulder campus.

2. The contractor must send a representative within 2 weeks of delivery to perform the installation unless a later date is agreed upon at NIST’s discretion.

3. The contractor must complete the physical installation within 5 business days of the representative’s arrival.

L. Training

The contractor must train up to 4 end users to operate the system either during or immediately after installation.

M. Warranty and Service

1. NIST requires at least a 2-year manufacturer warranty on all vendor manufactured parts and labor.

2. NIST requires at least a 1-year warranty on the cryocooler and pump systems (pulse tube, compressor(s), and vacuum pumps).

3. The contractor shall respond to e-mail support inquiries within 48 hours and determine whether field service is required within 5 business days of initial contact.

4. If the contractor determines that field service is required to repair the system, they must send a representative not more than 10 business days after determination unless otherwise agreed upon by NIST.