Kelvinox 100 operating procedures

Runs are initiated by opening the inner vacuum chamber (IVC) and the installation of a detector. Working with and around the detector and its cold hardware is a sensitive process that requires a calm hand and an acute sense of cleanliness. You can allow mess in your daily life, but not in the clean rooms! The following is the general process to prepare the fridge for uninstalling/installing detectors and the installation process itself.

1. Lower the Dewar
2. Set Up Mini Clean Room
   • Filling IVC with nitrogen gas
   • Setting up mini clean room
3. Uninstalling the Tower
4. Clean Flange
5. Tower Disassembly
   • Removing the Adapter Plate and Side Coaxes
   • Disassembling the Stack
   • Preparing the Detector for Shipment
   • Removing the Connector Lid

1. Tower Assembly
   • Installing Spacers and Connector Lid
   • Source Holder Preparation/Installation
   • Installing the Detector on Tower
   • Installing Side Coaxes and Adapter Plate
2. Installing the Tower
   • 30 mK Stage, Tower Attachment, and Thermometer Connection
   • 100 mK Stage
   • 600 mK Stage
   • Clean the Flange
   • 4 K Stage
   • Electrical Check
3. Sealing the IVC
   • Prepare Indium
   • Seal IVC

Now that the IVC has been sealed it needs to be evacuated. Once that is done, a leak check can be performed to determine if the seal prepared is sufficient. If the helium leak rate is less than 3E-8 mbar*l/s, then you can proceed with cool-down.

1. Pump Dewar Jacket
2. Pump IVC
3. Leak Check with He Gas Spray Test
4. Raise Main Bath

The first stage in cooling down to base temperatures (~ 50-70 mK) is to transfer liquid nitrogen (LN2) into the main bath. This will cool the system to 77 K. To do so, you need to prepare the main bath and the IVC. Once you transfer LN2 and are waiting for the system to cool, the He3-He4 mixture can be cleaned through the LN2 cold traps.

1. Pump and Flush Main Bath
2. Evacuate 1K Pot
3. Pump and Flush Main Bath and 1K pot
4. Adding Nitrogen Exchange Gas
5. Liquid Nitrogen Transfer
6. Cryoclean Mixture

Having cooled the system to 77 K, the next step is to cool down to 4.2 K with liquid helium (LHe). To do that, you must remove the LN2 and the nitrogen exchange gas. You then will put He exchange gas into the IVC to facilitate the cooling of the IVC when you transfer LHe and into the MB to keep the MB over-pressurized. Throughout this process, you will do several checks: leak check, resistance check, and a through-put test (to check the flow of mixture).

1. Pump out Nitrogen Exchange Gas
2. Blow out Liquid Nitrogen
3. Resistance Check at 77 K
4. Through-Put Test
5. Adding Helium Exchange Gas
6. Pump and Flush the Main Bath
7. Evacuate the 1K Pot
8. Liquid He Transfer
   • First Transfer(Testing Phonon Channels)
   • First Transfer(Testing Charge Channels Only)
   • Subsequent LHe Transfers

Now that you have transferred liquid helium to the MB, this allows the next stage of cooling to happen which will take the refrigerator down to base temperatures ( ~ 50-70 mK ). The first step in doing so is to start the 1 K pot. This will lower the temperature of the 1 K pot down to ~ 1.8 K, and then you can proceed to condensing the He3-He4 mixture and circulating it, which will provide cooling power to lower the tower and mixing chamber temperatures to base temperatures.

1. Start 1K Pot
2. Condense Mixture
   • Condensing Manually Via IGH Front Panel
   • Condensing Via Labview VI
3. Lower 1K Pot Temperature
4. Circulate Mixture
   • Circulate Manually Via IGH Front Panel
   • Circulate Via Labview VI

1. Warm Up Procedure

1. Electrical Check at the Breakout Box
2. Pump Mixture to Dump
3. Pump and Flush Main Bath
4. Fill LN2 cold trap
5. Clean LN2 Cold Trap
6. Clean LHe Cold Trap
7. Switch Cold Traps Mid-Circulation
8. Cleaning All Three Cold Traps Mid-Circulation
9. Cryo-clean Mixture
10. Evacuate LHe Transfer Tube
11. Install Striplines
12. Uninstall Striplines
13. Install Polyethylene & Lead Shield
14. Change 3He Circulation Pump Oil
15. Ordering Gas Cylinders
16. Using the Fridge Windows computer for Monitor and Control

1. Setting Up DCRC Boards
   • Changing DCRC Board IP Address
2. Zap SQUIDs and SQUID Tuning
3. IbIs Measurements
4. Complex Impedance Measurements
5. Measure Tc's
6. Flashing the Detector
7. Determining Charge Breakdown
8. Take Data
9. Process Raw Data
   • Backup Raw Data
   • View Raw Pulses
10. MIDAS

1. Fridge Troubleshooting
2. DCRC Troubleshooting
3. Data Processing and cdmsbats Troubleshooting

Old Procedure

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