TESSERACT Dilution Refrigerator BZ-2025-13

Lawrence Berkeley National Laboratory (LBNL) is conducting market research to identify sources that possess the capabilities and experience necessary to provide a dilution refrigeration system for a low-temperature application. The TESSERACT project involves the development of a highly sensitive low-temperature detector system aimed at probing extremely rare physical events. To achieve the necessary performance, the system must operate at temperatures on the order of 10 mK while also minimizing radioactive backgrounds. This dual requirement presents a unique set of technical challenges for the dilution refrigerator design. Specifically, the detector target and sensors must be enclosed within layered shielding enclosures to suppress environmental radiation. To integrate with these enclosures, the refrigerator must be equipped with shielding cans that feature a narrow-necked geometry. This allows the lower section housing the detector to extend into a pre-installed room-temperature shielding assembly. Additionally, internal shielding materials must be incorporated into the refrigerator itself, resulting in substantial static loads on the cold plate and mixing chamber. Please see the attached RFI document for more detail and response instructions.