Dark matter, the elusive substance that makes up about 85% of the universe’s mass, remains one of the greatest mysteries in physics. Invisible and undetectable by ordinary means, it neither emits nor absorbs light, leaving scientists with only indirect evidence of its existence. For decades, researchers have tried in vain to catch a glimpse of these elusive particles.

 

Now, an international collaboration of scientists has unveiled promising first results with a novel experiment called QROCODILE (Quantum Resolution-Optimized Cryogenic Observatory for Dark matter Incident at Low Energy). The project, led jointly by the University of Zurich and the Hebrew University of Jerusalem, involving also Cornell University, Karlsruhe Institute of Technology (KIT), and MIT, has demonstrated a new path in the search for “light” dark matter particles.

 

At the heart of QROCODILE is a cutting-edge superconducting detector capable of measuring incredibly faint energy deposits — down to just 0.11 electron-volts, millions of times smaller than the energies usually detected in particle physics experiments. This sensitivity opens an entirely new frontier: testing the existence of extremely light dark matter particles, with masses thousands of times smaller than those probed by previous experiments.

 

In a science run lasting more than 400 hours at temperatures near absolute zero, the team recorded a small number of unexplained signals. While these events cannot yet be confirmed as dark matter — they may stem from cosmic rays or natural background radiation — they already allow researchers to set new world-leading limits on how light dark matter particles interact with electrons and atomic nuclei

 

An additional strength of the experiment is its potential to detect the directionality of incoming signals. Since the Earth moves through the galactic halo, dark matter particles are expected to arrive from a preferred direction. Future upgrades could allow scientists to distinguish between true dark matter signals and random background noise, a crucial step toward a definitive discovery.

 

Prof. Yonit Hochberg of the Racah Institute of Physics at the Hebrew University, one of the project’s lead scientists, explains: "For the first time, we’ve placed new constraints on the existence of especially light dark matter. This is an important first step toward larger experiments that could ultimately achieve the long-sought direct detection.”

 

"For the first time, we’ve placed new constraints on the existence of especially light dark matter. This is an important first step toward larger experiments that could ultimately achieve the long-sought direct detection.” - Prof. Yonit Hochberg

 

The next stage of the project, NILE QROCODILE, will further enhance the detector’s sensitivity and move the experiment underground to shield it from cosmic rays. With improved shielding, larger detector arrays, and even lower energy thresholds, the researchers aim to push the boundaries of our understanding of the dark universe.

 

The research paper titled “First Sub-MeV Dark Matter Search with the QROCODILE Experiment Using Superconducting Nanowire Single-Photon Detectors” is now available in Physical Review Letters and can be accessed at https://doi.org/10.1103/4hb6-f6jl.

 

 

For a century, the Hebrew University of Jerusalem has been a beacon for visionary minds who challenge norms and shape the future. Founded by luminaries like Albert Einstein, who entrusted his intellectual legacy to the university, it is dedicated to advancing knowledge, fostering leadership, and promoting diversity. Home to over 23,000 students from 90 countries, the Hebrew University drives much of Israel’s civilian scientific research, with over 11,000 patents and groundbreaking contributions recognized by nine Nobel Prizes, two Turing Awards, and a Fields Medal. Ranked 81st globally by the Shanghai Ranking (2024), it celebrates a century of excellence in research, education, and innovation. To learn more about the university’s academic programs, research, and achievements, visit the official website at http://new.huji.ac.il/en.