Universe Today
Scientists at the University of Minnesota College of Science and Engineering have reached a milestone with the Super Cryogenic Dark Matter Search (SuperCDMS) experiment. Located deep underground at the Sudbury Neutrino Observatory Laboratory (SNOLAB) in Canada, the world's deepest underground laboratory, this experiment is designed to detect the Universe's unseen mass, aka. Dark Matter. The SuperCDMS team recently announced that they had successfully cooled the experiment to its operational temperature, hundreds of times colder than outer space.
Formally hypothesized in the 1970s by famed astronomer Vera Rubin (for whom the Vera C. Rubin Observatory is named), Dark Matter is the mysterious mass that theoretically accounts for 85% of mass in the known Universe. Despite sixty years of ongoing study, scientists have yet to find concrete evidence of this matter or determine what it is composed of. However, the most widely accepted theory is that it is composed of large particles that interact with "normal matter" via gravity, known as the Cold Dark Matter (CDM) model.
The experiment, designed to detect Dark Matter particles already passing through Earth, consists of a four-meter-tall, four-meter-diameter (~13 x 13 ft) cylindrical enclosure made of layers of ultra-pure lead. This shielding protects the detectors inside from radiation, including neutrons and gamma-rays produced by high-energy cosmic rays passing through our atmosphere. Reaching its base temperature marks a major transition for SuperCDMS, which is 1/1000s of a degree above absolute zero (-273.15 °C; -459.67 °F), the temperature at which atomic and molecular motion ceases.
*Dark Matter in a Simulated Universe. Credit & ©: Tom Abel & Ralf Kaehler (KIPAC, SLAC)/AMNH*
Said Priscilla Cushman, a professor in the University of Minnesota School of Physics and Astronomy and the Spokesperson of SuperCDMS, in a UMN press release:
Getting to base temperature is a major milestone in a years-long campaign to build a low-background facility capable of housing our sensitive cryogenic solid-state detectors. At these extremely low temperatures, our installed detectors can now scan a whole new region of parameter space where the lightest dark matter particles may be lurking.
In addition to designing and assembling the low-background shield that protects the detectors, University of Minnesota researchers also developed the machine learning algorithms and analysis techniques. These will be used to rapidly extract dark matter signals from data once the experiment becomes operational in a few months. With the base temperature achieved, the collaboration will now move into the months-long process of detector commissioning, during which they will turn on, calibrate, and optimize each detector channel.
In addition to Dark Matter, SuperCDMS will allow scientists to study rare isotopes, study energy depositions down to the electron-volt level, and possibly discover new types of particle interactions.
Further Reading: UMN
