Members of the LZ crew within the LZ water tank after the outer detector set up. Credit: Matthew Kapust/Sanford Underground Research Facility
Deep beneath the Black Hills of South Dakota within the Sanford Underground Research Facility (SURF), an progressive and uniquely delicate darkish matter detector—the LUX-ZEPLIN (LZ) experiment, led by Lawrence Berkeley National Lab (Berkeley Lab)—has handed a check-out part of startup operations and delivered first outcomes.
The take-home message from this profitable startup: “We’re prepared and every little thing’s trying good,” mentioned Berkeley Lab senior physicist and previous LZ spokesperson Kevin Lesko. “It’s a posh detector with many components to it and they’re all functioning effectively inside expectations,” he mentioned.
In a paper posted on-line right now on the experiment’s web site, LZ researchers report that with the preliminary run, LZ is already the world’s most delicate darkish matter detector. The paper will seem on the web preprint archive arXiv.org later right now. LZ spokesperson Hugh Lippincott of the University of California Santa Barbara mentioned, “We plan to gather about 20 instances extra information within the coming years, so we’re solely getting began. There’s numerous science to do and it’s extremely thrilling.”
Dark matter particles have by no means truly been detected—however maybe not for for much longer. The countdown could have began with outcomes from LZ’s first 60 “stay days” of testing. These information had been collected over a three-and-a-half-month span of preliminary operations starting on the finish of December. This was a interval lengthy sufficient to substantiate that every one points of the detector had been functioning effectively.
Unseen, as a result of it doesn’t emit, take up, or scatter gentle, darkish matter’s presence and gravitational pull are nonetheless elementary to our understanding of the universe. For instance, the presence of darkish matter, estimated to be about 85 p.c of the entire mass of the universe, shapes the shape and motion of galaxies, and it’s invoked by researchers to elucidate what is thought in regards to the large-scale construction and enlargement of the universe.
Looking up into the LZ Outer Detector, used to veto radioactivity that may mimic a darkish matter sign. Credit: Matthew Kapust/Sanford Underground Research Facility
The coronary heart of the LZ darkish matter detector is comprised of two nested titanium tanks stuffed with ten tons of very pure liquid xenon and considered by two arrays of photomultiplier tubes (PMTs) in a position to detect faint sources of sunshine. The titanium tanks reside in a bigger detector system to catch particles that may mimic a darkish matter sign.
“I’m thrilled to see this complicated detector prepared to deal with the long-standing problem of what darkish matter is fabricated from,” mentioned Berkeley Lab Physics Division Director Nathalie Palanque-Delabrouille. “The LZ crew now has in hand essentially the most bold instrument to take action.”
The design, manufacturing, and set up phases of the LZ detector had been led by Berkeley Lab mission director Gil Gilchriese along side a world crew of 250 scientists and engineers from over 35 establishments from the US, UK, Portugal, and South Korea. The LZ operations supervisor is Berkeley Lab’s Simon Fiorucci. Together, the collaboration is hoping to make use of the instrument to report the primary direct proof of darkish matter, the so-called lacking mass of the cosmos.
Henrique Araújo, from Imperial College London, leads the UK teams and beforehand the final part of the UK-based ZEPLIN-III program. He labored very carefully with the Berkeley crew and different colleagues to combine the worldwide contributions. “We began out with two teams with totally different outlooks and ended up with a extremely tuned orchestra working seamlessly collectively to ship an excellent experiment,” Araújo mentioned.
An underground detector
Tucked away a few mile underground at SURF in Lead, S.D., LZ is designed to seize darkish matter within the type of weakly interacting huge particles (WIMPs). The experiment is underground to guard it from cosmic radiation on the floor that might drown out darkish matter indicators.
(Left) A schematic of the LZ detector. (Right) Illustration of LZ operation—particles work together in liquid xenon, releasing a flash of sunshine and cost which are collected by photomultiplier tube arrays at high and backside. Credit: Left schematic: LZ collaboration. Right picture: LZ/SLAC
Particle collisions within the xenon produce seen scintillation or flashes of sunshine, that are recorded by the PMTs, defined Aaron Manalaysay from Berkeley Lab, who as physics coordinator, led the collaboration’s efforts to provide these first physics outcomes. “The collaboration labored effectively collectively to calibrate and to know the detector response,” Manalaysay mentioned. “Considering we simply turned it on a couple of months in the past and through COVID restrictions, it’s spectacular now we have such vital outcomes already.”
The collisions can even knock electrons off xenon atoms, sending them to float to the highest of the chamber below an utilized electrical area the place they produce one other flash allowing spatial occasion reconstruction. The traits of the scintillation assist decide the forms of particles interacting within the xenon.
Mike Headley, government director of SURF Lab, mentioned, “The complete SURF crew congratulates the LZ Collaboration in reaching this main milestone. The LZ crew has been a beautiful companion and we’re proud to host them at SURF.”
Fiorucci mentioned the onsite crew deserves particular reward at this startup milestone, provided that the detector was transported underground late in 2019, simply earlier than the onset of the COVID-19 pandemic. He mentioned with journey severely restricted, only some LZ scientists might make the journey to assist on web site. The crew in South Dakota took glorious care of LZ.
“I’d wish to second the reward for the crew at SURF and would additionally like to precise gratitude to the big quantity of people that supplied distant assist all through the development, commissioning and operations of LZ, lots of whom labored full time from their house establishments ensuring the experiment can be successful and proceed to take action now,” mentioned Tomasz Biesiadzinski of SLAC, the LZ detector operations supervisor.
The LZ central detector within the clear room at Sanford Underground Research Facility after meeting, earlier than starting its journey underground. Credit: Matthew Kapust, Sanford Underground Research Facility
“Lots of subsystems began to come back collectively as we began taking information for detector commissioning, calibrations and science operating. Turning on a brand new experiment is difficult, however now we have an excellent LZ crew that labored carefully collectively to get us via the early phases of understanding our detector,” mentioned David Woodward from Pennsylvania State University, who coordinates the detector run planning.
Maria Elena Monzani of SLAC, the Deputy Operations Manager for Computing and Software, mentioned, “We had superb scientists and software program builders all through the collaboration, who tirelessly supported information motion, information processing, and simulations, permitting for a flawless commissioning of the detector. The assist of NERSC [National Energy Research Scientific Computing Center] was invaluable.”
With affirmation that LZ and its programs are working efficiently, Lesko mentioned, it’s time for full-scale observations to start in hopes {that a} darkish matter particle will collide with a xenon atom within the LZ detector very quickly.
A significant milestone for an underground darkish matter search experiment
More info:
D.S. Akerib et al, The LUX-ZEPLIN (LZ) experiment, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment (2019). DOI: 10.1016/j.nima.2019.163047
Projected WIMP sensitivity of the LUX-ZEPLIN (LZ) darkish matter experiment, arXiv:1802.06039v2 [astro-ph.IM] doi.org/10.48550/arXiv.1802.06039
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Lawrence Berkeley National Laboratory
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Researchers report profitable startup of darkish matter detector at underground analysis facility (2022, July 7)
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