JERUSALEM, Sept. 14 (Xinhua) — An international team of scientists has developed a promising advanced method for detecting low-mass dark matter, according to a statement issued by the Hebrew University of Jerusalem on Sunday.
Dark matter, due to its lack of interaction with the electromagnetic force, is an invisible substance that emits, reflects, or absorbs no light. Thus, it is undetectable by ordinary means as visible matter like stars and planets.
In the experiment QROCODILE (Quantum Resolution-Optimized Cryogenic Observatory for Dark matter Incident at Low Energy), researchers at the University of Zurich, the Hebrew University of Jerusalem, and the Massachusetts Institute of Technology wanted to design superconducting nanowire single-photon detectors, which are made of superconducting nanowires that act both as the material that dark matter will collide with and a sensor to pick up energy emerging from the collisions.
The detector can cool to just 0.1 degrees above absolute zero. Absolute zero refers to the theoretical lowest possible temperature at which a system’s atoms and molecules have their minimum possible energy and motion, equivalent to 273.15 degrees Celsius below zero.
The researchers explained that electrons form pairs called Cooper pairs in the superconducting state, which is achieved in temperatures near absolute zero. If the small amount of energy from a dark matter particle breaks the Cooper pairs in the nanowires, a tiny disturbance will be created, which produces a measurable electrical pulse.
It requires a very low amount of energy to break a Cooper pair, enabling the detector to probe low-mass dark matter candidates, according to the researchers.
The detector is currently at an early stage, demonstrating the viability of its concept, and has not yet been used to conduct dark matter searches.
During a 400-hour test run, the system achieved a very low energy threshold for a dark matter detector and set new limits on how light dark matter particles might behave.
The team plans to improve the detector’s sensitivity and move the experiment to an underground lab to reduce background noise. A larger follow-up experiment called NILE QROCODILE is already in the works. ■