From Lawrence Livermore National Laboratory: “Understanding the universe through neutrinos”

From Lawrence Livermore National Laboratory

July 13, 2018

Anne M Stark
stark8@llnl.gov
925-422-9799

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The xenon vessel and vacuum vessel for the next Enriched Xenon Observatory (nEXO) experiment was built at Lawrence Livermore National Laboratory. The experiment will search for an extremely rare nuclear process called neutrinoless double-beta decay (NDBD).

Determining features of the elusive particle known as a neutrino – through the observation of an extremely rare nuclear process called neutrinoless double-beta decay (NDBD) — could provide a glimpse into the nature of the universe during the earliest moments of the Big Bang.

As part of an international collaboration, Lawrence Livermore National Laboratory (LLNL) scientists have proposed the next Enriched Xenon Observatory (nEXO) experiment, a candidate for the next generation of NDBD experiments. If discovered, NDBD would demonstrate the existence of a new elementary particle, the Majorana fermion. This discovery could reshape the standard model of particle physics and lead to a better understanding of neutrinos and their impact on the evolution of the universe. The research behind the experiment appears in the journal Physical Review C.

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The Enriched Xenon Observatory 200 (EXO-200) experiment provides the basis for current work on a more sensitive detector for observing neutrinoless double beta decay (NDBD). Shown here are the EXO-200 readout wires and avalanche photodiodes used to measure induced and collected charge and scintillation light from particle decays in the detector’s main vessel. Image courtesy of SLAC National Accelerator Laboratory.

NDBD is a theoretical process with a half-life more than 10^16 times the age of the universe and could help determine whether neutrinos are their own antiparticles and explain why, from equal parts of matter and antimatter, the universe evolved into its current matter-dominated state.

The design of the nEXO detector — a 5-ton liquid xenon (Xe) time projection chamber (TPC) using 90 percent enriched 136Xe — takes advantage the best technology for the next phase of NDBD search.

“A competitive 2-order-of-magnitude increase in NDBD half-life sensitivity over current experiments is possible” using the nEXO detector, said LLNL scientist Samuele Sangiorgio, lead author of the paper. “We now have great confidence in nEXO’s design and approach, and we will be able to measure this rare event.”

Scientists expect to see only about a dozen decays in a decade-long experiment. Because of this very low signal rate, false signals from background radiation and cosmic rays must be suppressed as much as is feasible. “Understanding the backgrounds is key to a make a convincing case for a NDBD experiment, and indeed is one of the main aspects of the paper,” Sangiorgio said.

Other Livermore authors include Tyana Stiegler, Jason Brodsky. Mike Heffner and Allen House.

Other collaborators include: Brookhaven National Laboratory, Carleton University, Colorado State University, Drexel University, Friedrich-Alexander Universität Erlangen-Nürnberg, Institute of High Energy Physics Chinese Academy of Sciences, Institute for Theoretical and Experimental Physics Indiana University, Laurentian University, McGill University, Oak Ridge National Laboratory, Pacific Northwest National Laboratory, Rensselaer, SLAC National Accelerator Laboratory, Stony Brook University, TRIUMF, Universität Bern, Université de Sherbrooke, University of Alabama, University of Illinois, University of Massachusetts Amherst, University of South Dakota and Yale University.

See the full article here .


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LLNL Campus

Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration
Lawrence Livermore National Laboratory (LLNL) is an American federal research facility in Livermore, California, United States, founded by the University of California, Berkeley in 1952. A Federally Funded Research and Development Center (FFRDC), it is primarily funded by the U.S. Department of Energy (DOE) and managed and operated by Lawrence Livermore National Security, LLC (LLNS), a partnership of the University of California, Bechtel, BWX Technologies, AECOM, and Battelle Memorial Institute in affiliation with the Texas A&M University System. In 2012, the laboratory had the synthetic chemical element livermorium named after it.

LLNL is self-described as “a premier research and development institution for science and technology applied to national security.”[1] Its principal responsibility is ensuring the safety, security and reliability of the nation’s nuclear weapons through the application of advanced science, engineering and technology. The Laboratory also applies its special expertise and multidisciplinary capabilities to preventing the proliferation and use of weapons of mass destruction, bolstering homeland security and solving other nationally important problems, including energy and environmental security, basic science and economic competitiveness.

The Laboratory is located on a one-square-mile (2.6 km2) site at the eastern edge of Livermore. It also operates a 7,000 acres (28 km2) remote experimental test site, called Site 300, situated about 15 miles (24 km) southeast of the main lab site. LLNL has an annual budget of about $1.5 billion and a staff of roughly 5,800 employees.

LLNL was established in 1952 as the University of California Radiation Laboratory at Livermore, an offshoot of the existing UC Radiation Laboratory at Berkeley. It was intended to spur innovation and provide competition to the nuclear weapon design laboratory at Los Alamos in New Mexico, home of the Manhattan Project that developed the first atomic weapons. Edward Teller and Ernest Lawrence,[2] director of the Radiation Laboratory at Berkeley, are regarded as the co-founders of the Livermore facility.

The new laboratory was sited at a former naval air station of World War II. It was already home to several UC Radiation Laboratory projects that were too large for its location in the Berkeley Hills above the UC campus, including one of the first experiments in the magnetic approach to confined thermonuclear reactions (i.e. fusion). About half an hour southeast of Berkeley, the Livermore site provided much greater security for classified projects than an urban university campus.

Lawrence tapped 32-year-old Herbert York, a former graduate student of his, to run Livermore. Under York, the Lab had four main programs: Project Sherwood (the magnetic-fusion program), Project Whitney (the weapons-design program), diagnostic weapon experiments (both for the Los Alamos and Livermore laboratories), and a basic physics program. York and the new lab embraced the Lawrence “big science” approach, tackling challenging projects with physicists, chemists, engineers, and computational scientists working together in multidisciplinary teams. Lawrence died in August 1958 and shortly after, the university’s board of regents named both laboratories for him, as the Lawrence Radiation Laboratory.

Historically, the Berkeley and Livermore laboratories have had very close relationships on research projects, business operations, and staff. The Livermore Lab was established initially as a branch of the Berkeley laboratory. The Livermore lab was not officially severed administratively from the Berkeley lab until 1971. To this day, in official planning documents and records, Lawrence Berkeley National Laboratory is designated as Site 100, Lawrence Livermore National Lab as Site 200, and LLNL’s remote test location as Site 300.[3]

The laboratory was renamed Lawrence Livermore Laboratory (LLL) in 1971. On October 1, 2007 LLNS assumed management of LLNL from the University of California, which had exclusively managed and operated the Laboratory since its inception 55 years before. The laboratory was honored in 2012 by having the synthetic chemical element livermorium named after it. The LLNS takeover of the laboratory has been controversial. In May 2013, an Alameda County jury awarded over $2.7 million to five former laboratory employees who were among 430 employees LLNS laid off during 2008.[4] The jury found that LLNS breached a contractual obligation to terminate the employees only for “reasonable cause.”[5] The five plaintiffs also have pending age discrimination claims against LLNS, which will be heard by a different jury in a separate trial.[6] There are 125 co-plaintiffs awaiting trial on similar claims against LLNS.[7] The May 2008 layoff was the first layoff at the laboratory in nearly 40 years.[6]

On March 14, 2011, the City of Livermore officially expanded the city’s boundaries to annex LLNL and move it within the city limits. The unanimous vote by the Livermore city council expanded Livermore’s southeastern boundaries to cover 15 land parcels covering 1,057 acres (4.28 km2) that comprise the LLNL site. The site was formerly an unincorporated area of Alameda County. The LLNL campus continues to be owned by the federal government.

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