Beneath the Black Hills of South Dakota, a uniquely sensitive dark matter detector has passed a start-up operations verification phase and delivered its first results, the culmination of the work of an international team that includes three researchers from the University of Alabama.

UA Department of Physics and Astronomy researchers Professors Andreas Piepke and Ion Stancu, and Assistant Professor Ryan Wang are among 250 scientists and engineers from 39 institutions collaborating on the LUX-ZEPLIN experiment, or LZ, led by Lawrence Berkeley National Lab at the Sanford Underground Research Facility in South Dakota.

Dark matter particles have never been detected, but perhaps that won’t be for very long. The countdown may have begun with the results of LZ’s first 60 “live days” of testing. The data was collected over a three-month period of initial operations beginning last December.

This was a long enough period to confirm that all aspects of the detector were working.

The results of the initial run are available on the online pre-release archive.

Invisible, because it neither emits, absorbs nor scatters light, the presence and gravitational pull of dark matter are nonetheless fundamental to understanding the universe. For example, the presence of dark matter, estimated at around 85% of the total matter in the universe, shapes the shape and motion of galaxies, and it is invoked by researchers to explain what is known about the structure. and large-scale expansion. of the universe.

Look into the LZ outer detector, used to veto radioactivity that can mimic a dark matter signal. (Matthew Kapust/Sanford Underground Research Facility)

The core of the Dark Matter Detector comprises two interlocking titanium tanks filled with 10 metric tons of pure liquid xenon and viewed by two arrays of photomultiplier-type light detectors capable of detecting faint flashes of light from interactions with subatomic particles.

Piepke participated in the multi-laboratory radioactivity screening program of detection materials to ensure that each component met the stringent requirements for dark matter searches. Additionally, his group has assembled, tested, and characterized neutron calibration sources for LZ, which help understand the detector’s response to nuclear recoil-like interactions, mimicking dark matter interactions in xenon.

Stancu created the Data Analysis and Simulation Software Management System, which integrates all the analysis and simulation code for researchers around the world. In addition, he contributed to several simulations and analysis tasks, leading to the first results.

Wang was stationed at the Sanford Underground Research Facility (SURF), and his work is key to understanding LZ’s measurement sensitivity.

He supervised the assembly of the Time Projection Chamber, a radiation detector allowing the complete 3D reconstruction of the place of the event and the integration of the detector into the underground laboratory. He also led the installation of the neutron labeling detector which identifies the otherwise indistinguishable neutron background signal. After joining UA last year, Wang became the coordinator for some critical aspects of data analysis.

“I would like to second the praise of the SURF team and would also like to express my gratitude to the large number of people who provided remote support throughout the construction, commissioning and operations of LZ, including many worked full-time from their institutions ensuring the experiment would be a success and continue to do so now,” said Tomasz Biesiadzinski of SLAC, the operations manager for the LZ detector.

This article previously appeared on the University of Alabama website and was adapted from an article by the Lawrence Berkeley National Lab.