DR-TES (Dilution Refrigerator Transition Edge Sensor)

DR-TES is the acronym for Dilution Refrigerator / Transition-Edge Sensors a technological demonstrator developed at the Washington University in St. Louis. The DR-TES mission utilizes Transition-Edge Sensors (TES) to capture and analyze high-energy X-ray and gamma-ray emissions in the upper atmosphere. In the figure at left we can see a scheme of the gondola used for this flight (click to enlarge).

Cryogenic System and Dilution Refrigerator

The mission's cryogenic system includes a custom-designed dilution refrigerator (nicknamed "DR"), which cools the TES detectors to around 80 millikelvin. This setup involves a multi-step cooling process with sorption pumps that cycle helium-3 and helium-4 through a series of stages to maintain the low temperatures required for the TES detectors. A critical aspect is the system's ability to withstand temperature changes during the launch phase and sustain stable cooling during the balloon flight.

Transition-Edge Sensors and Detection Capabilities

The TES detectors are ultra-sensitive to temperature changes caused by incoming photons. These detectors operate near the superconducting transition edge, where even slight changes in temperature alter their electrical resistance. Mounted with tin absorbers, the TES can precisely capture high-energy photons and send this data to warm readout electronics. This setup allows for significant improvements in energy resolution, achieving sub-keV precision that surpasses earlier technologies.

The DR-TES mission represents a step forward in cryogenic astrophysics, providing insights that can support our understanding of high-energy processes in the universe.

Balloon launched on: 9/24/2024 at 14:44 UTC
Launch site: Scientific Flight Balloon Facility, Fort Sumner, (NM), US  
Balloon launched by: Columbia Scientific Balloon Facility (CSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon Aerostar - SF 39.57 (39.500.000 cuft)
Flight identification number: 748N
End of flight (L for landing time, W for last contact, otherwise termination time): 9/25/2024 at 00:45 UTC (L)
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 9 h 52 m
Landing site: In Mescalero Reservation, New Mexico, US

The DR-TES balloon was launched from the Ft. Sumner NASA balloon base at 14:44 UTC on September 24, as mission 748N. The balloon reached float altitude of around 131,000 feet and flew for a total of 9 hours and 52 minutes. The balloon and payload landed in the Mescalero Reservation, SW of Ruidoso, New Mexico.

The three primary objectives of the flight were verifying stable cooling during flight, achieving high-resolution data from TES detectors, and gathering spectral data to assist with future astrophysical missions.

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