About 200 scientists gathered in Washington, DC November 2-4 to discuss the next phases of the study of a deep underground science laboratory to be located in the abandoned Homestake mine in South Dakota.
At an open session Friday afternoon, scientists, representatives of government agencies, and government officials from South Dakota described the process, the need for a Deep Underground Science and Engineering Lab (DUSEL), the technical design, and scientific opportunities DUSEL could provide.
The site-independent study group of DUSEL organized the workshop, which was sponsored by the University of California’s Institute for Nuclear and Particle Astrophysics and Cosmology. The November 3-4 sessions also received support from NSF.
With space to go as deep as 8000 feet, DUSEL would be well shielded from cosmic ray backgrounds, making it useful for a variety of physics experiments. The lab would also provide significant research opportunities in biology, geosciences, and engineering, as well as a strong education and outreach component.
The site-independent study group, which included hundreds of scientists from various disciplines, recommended strong support for deep underground science, a cross agency deep science initiative, and construction of a deep underground lab. The study group mapped out some of the compelling scientific questions that could be studied deep underground. “Deep underground science and engineering represents a new frontier,” said Bernard Sadoulet of UC Berkeley, one of the leaders of the study group.
An underground laboratory would help answer several important questions in particle physics, nuclear physics, and astrophysics, such as: What is the dark matter? What happened to the antimatter that was present at the big bang? Are protons unstable? What can neutrinos tell us? How did the universe evolve?
A quiet environment shielded from cosmic rays is crucial to detecting elusive objects such as dark matter and neutrinos as well as rare nuclear processes such as proton decay and neutrinoless double beta decay. Trying to observe dark matter at ground level would be like trying to listen to music in the middle of Manhattan, said Hitoshi Murayama of UC Berkeley. “We have to go where it’s quiet,” he said. In response to a question about the odds of DUSEL detecting dark matter, Murayama said, “My gut feeling is it’s pretty high.”
In addition to the scientific prospects, DUSEL would provide a great education and outreach opportunity, said Murayama. “This kind of science would open up young minds to new ideas,” he said.
Around the world, there is a growing interest in underground science and an increasing demand for underground labs. “Underground labs around the world are already producing exciting science opportunities,” said Art MacDonald of Queens University, Canada. Underground labs in other countries are open to US scientists, but they are already largely subscribed. DUSEL, which would be the largest and deepest underground lab in the world, would make the US a world leader in underground science, speakers at the meeting said.
DUSEL is still in the early planning stages. “Cost is an important issue,” said Jack Lightbody, deputy assistant director of the mathematical and physical sciences directorate of NSF. Reliable, responsible cost estimates will be crucial to the success of the project, he said.
Planning for DUSEL began after the Homestake gold mine announced it was closing in 2000. “Never has the closing of a business caused so much excitement in the scientific community,” said Joe Dehmer, director of the physics division of NSF. In the years since, several studies of the prospects for a deep underground lab have been conducted. After a competition between several potential sites, NSF announced on July 10 the selection of the Homestake mine near Lead, South Dakota, as the site for DUSEL. The team, headed by Kevin Lesko of UC Berkeley, was chosen to lead the design effort. They will receive $15 million over 3 years for the technical design of the laboratory.
The NSF has not yet committed funds for facility construction or development of the first suite of experiments. A rough timetable would have the earliest construction start in FY11, with construction expected to take seven or eight years. The project would cost about $500 million for the initial phase, split evenly between facility and experiments. DUSEL must go through an approval process that could take years before it can be built. “It’s not a done deal,” said Dehmer.
Governor Mike Rounds of South Dakota said that his state was enthusiastic about hosting the deep underground lab. “I have 780,000 people in my state. They are nearly unanimous in their support of this project” said Rounds. Rounds was especially excited about the lab’s outreach and education opportunities, saying that he believed it would spark children’s interest in science.
South Dakota has appropriated $19.9 million for the underground lab, which is a lot of money for South Dakota, said Rounds. “We believe in it. We want to see it move forward,” he said.
In addition to the funds from the state of South Dakota, philanthropist S. Denny Sanford has committed $70 million to the Sanford Underground Science and Engineering Laboratory. The Sanford lab, at 4850 feet below ground, will serve as the first phase of DUSEL, and should be open for science late next year. DUSEL will develop deeper levels.
Currently the mine is flooded up to a depth of 5000 feet. The water level is still rising, and the water will have to be pumped out before the deeper levels of the site can be used as a science and engineering laboratory.
Jose Alonso has recently been selected as the head of Sanford lab. Alonso is a physicist who retired in 2002 from Lawrence Berkeley National Laboratory, where he was involved with developing and managing the Bevelac project, a large accelerator facility. He also served on the management team for the Spallation Neutron Source at Oak Ridge National Lab, and since his retirement has been active in the development of the Large Hadron Collider.
Over the November 3-4 weekend, working groups from all the underground disciplines met to focus on the next phases of the project, organize the designs for the first suite of experiments, define needed research and development, explore education and outreach possibilities, and discuss coordination with existing labs and funding agencies.