How the coronavirus pandemic is affecting the world's biggest physics experiments

A 3-kilometre-long arm part of the Virgo detector for gravitational waves.

Italy's Virgo gravitational-wave detector has been forced to shut down.Credit: Claudio Giovannini/AFP/Getty

The vast, sparsely populated Argentinian Pampas would seem ideal for social distancing. In the Mendoza region, the Pierre Auger Observatory near Malargue consists of more than 1,600 car-sized plastic tanks filled with water, scattered across some 3,000 square kilometres of land that is usually visited only by grazing cattle.

Yet even here, at the world’s largest cosmic-ray observatory, the coronavirus pandemic is leaving its mark. Project manager Ingo Allekotte, a physicist who is based 1,000 kilometres south at the Bariloche Atomic Center in Argentina, says that because of a national lockdown, maintenance staff are barred from doing regular repairs at the detectors, which include replacing failed batteries. “As a result, with a longer term lack of maintenance, individual detectors will go ‘dark’,” he says. Already, the observatory has had to shut down its fluorescence detectors, which monitor the sky above for the ultraviolet flashes of cosmic rays.

Scores of other ‘big physics’ facilities and astronomical observatories around the world have had to reduce their operations or, in many cases, completely suspend them, in response to the pandemic.

In the United States, the country that now has the fastest growing number of confirmed COVID-19 cases, many large labs have had to essentially halt operations, following lockdown orders from governors or cautionary measures from their management.

Most of the US Department of Energy (DOE)’s massive network of 17 national laboratories has switched to a telecommuting mode of operation, and major experiments have been shut down. One is an accelerator that smashes gold atoms at Brookhaven National Laboratory in Upton, New York, which ended its data-taking run on 20 March. “This was 3 months earlier than planned,” says Helen Caines, a physicist at Yale University in New Haven, Connecticut, who leads the experiment.

The same fate befell the National Ignition Facility, the world’s largest laser, designed for nuclear-fusion experiments at Lawrence Livermore National Laboratory in California. But some DOE lab facilities — and in particular its synchrotron light sources and four supercomputing centres — are soldiering on, and contributing work to COVID-19 research.

Upgrades on hold

Some big-physics projects are still collecting data. Large-scale experiments run by international collaborations have long been moving towards the ability to run with minimal on-site support, as team members monitor the functioning of these projects from around the world, says Nigel Smith, the director of the SNOLAB underground facility, which aims to detect dark matter and neutrinos, near Sudbury, Canada. “The ability to remotely operate is baked into the systems,” says Smith, who is an astroparticle physicist at nearby Laurentian University. This is the case at SNOLAB, where major detectors are still running.

But even facilities that are still able to run experiments are finding that planned upgrades or construction will have to wait. Surface work is slowed, and trips down the 2,000-metre deep shaft to the SNOLAB halls are being limited. “It’s close quarters on the cage ride down”, which is not ideal for social distancing, says Mark Chen, who leads a partially finished — but already operating — neutrino experiment at the lab.

Another major underground facility, the Gran Sasso National Laboratories in central Italy, is in a similar situation. Although upgrades and construction are halted, ongoing experiments — also on neutrinos and dark matter — are still running despite the nationwide lockdown. “Experiments in Gran Sasso are designed to be run with no local attendance,” spokesperson Roberta Antolini tells Nature.

CERN, the world’s largest particle-physics experiment near Geneva, Switzerland, has had to suspend its upgrade work on the Large Hadron Collider.

Protecting staff

The Laser Interferometer Gravitational-Wave Observatory (LIGO) — with twin antennas in Livingston, Louisiana, and Hanford, Washington — and the Virgo interferometer near Pisa, Italy, both shut down on 27 March to safeguard the health of their staff. The facilities detect faint ripples in space-time known as gravitational waves, caused by massive cosmic collisions such as black-hole mergers. Virgo had already been running on a minimal staff of less than a dozen people, says Virgo spokesperson Jo van den Brand, a physicist at the National Institute for Subatomic Physics in Amsterdam. But travel to Italy has become practically impossible, and a full shutdown was the only way to protect their employees.

The observatories had planned to end their data-collecting runs at the end of April, and to start significant upgrades in May, with the aim of doubling their sensitivity and restarting in 2022. “But all of that is impossible now,” van den Brand says.

Still, LIGO and Virgo have accumulated a vast amount of data during their latest year-long run, which had started on 1 April 2019. The bounty includes 56 ‘candidate’ collision events, most of which are probably mergers of two black holes. The international LIGO–Virgo collaboration will now have busy months analysing those data, says Sebastiano Bernuzzi, a theoretical physicist at Friedrich Schiller University in Jena, Germany. Fortunately, the team is still able to use facilities such as the Leibniz Supercomputing Centre in Garching, Germany. “If high-power computing facilities and the Internet continue to operate, we should be able to keep working,” Bernuzzi says.

Business as usual

COVID-19 has not yet affected all parts of the world in a major way. In Sweden, the government has maintained a controversial business-as-usual policy. Construction at the European Spallation Source, a state-of-the-art facility for neutron beams due to open in 2025 in Lund, has carried on as planned.

The Kamioka Observatory — home to the Super-Kamiokande neutrino detector and to the Kamioka Gravitational Wave Detector (KAGRA), among other things — near Hida, Japan, has not suffered major disruptions, says Keiko Kokeyama, a physicist who works on KAGRA. Her team has continued the months-long, painstaking work of tuning up the brand new detector, which started operations in February.

And in China, where the coronavirus first emerged in the country’s central Hubei province, not all regions have been on lockdown. In the far south, the Jiangmen Underground Neutrino Observatory (JUNO), an underground detector that will contain 20,000 tonnes of mineral oil, is still under construction. “Most people are now back to work normally,” says Lei Liu, director of the JUNO project office. She estimates that the project will be delayed by up to three months, but still aims to begin the experiment in 2022.

One place that should be safe from coronavirus for now is the Amundsen–Scott South Pole Station. Flights to and from Antarctica have stopped in February as the summer season wound up. By now, the ‘winterovers’, the skeleton staff that stays at the station until the next summer, have been quarantined for long enough to be considered coronavirus-free. “As we arrived in November, the coronavirus had not yet been identified,” says John Hardin, who works on IceCube, the cosmic neutrino observatory made of sensors embedded in a cubic kilometre of ice. “It is a strange experience,” he adds. "While we are completely isolated from the spread, not being able to be there for friends and family is difficult.”

“The detector is operating and transmitting data north as usual,” says Francis Halzen, a physicist at the University of Wisconsin–Madison and spokesperson for IceCube.

doi: https://doi.org/10.1038/d41586-020-00943-3


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