From SURF: “CASPAR achieves first beam”

SURF logo
Sanford Underground levels

Sanford Underground Research facility

July 17, 2017
Constance Walter

Dan Robertson speaks to a group during the CASPAR first beam ribbon cutting event. Matthew Kapust.

Nearly two years after the CASPAR collaboration (compact accelerator system for performing astrophysical research) began moving into its home on the 4850 Level of Sanford Lab, it celebrated a huge milestone: first beam.

CASPAR’s accelerator at SURF


“This is a great step forward,” said Frank Strieder, an associate physics professor of physics at South Dakota School of Mines and Technology. “We’ve prepared for this for years. It’s exciting moment to have it running and to see the first beam.

“But we have to also give credit to the people who worked outside the doors,” said Strieder, the principal investigator for CASPAR. “If you can imagine, all of this equipment came down in the Yates shaft with the help of Sanford Lab staff. These are incredible people who work very hard, they supported us in every way to make this happen.”

Dan Robertson, a research assistant professor with Notre Dame, said it was a special day for the collaboration.

“Seeing the beam for the first time was really cool—the pay off for the work,” said Dan Robertson, a research assistant professor with Notre Dame. “Today we get to share this accomplishment with other people.”

Researchers with CASPAR hope to recreate the nuclear fusion processes responsible for energy generation to better understand how stars burn and what elements they create while doing so.

CASPAR is one of only two underground accelerators in the world. The other has been operating for more than 25 years at the Laboratory for Underground Nuclear Astrophysics (LUNA) in Gran Sasso, Italy.

LUNA-MV at Gran Sasso

Gran Sasso LABORATORI NAZIONALI del GRAN SASSO, located in the Abruzzo region of central Italy

“Installing and operating accelerators underground is a considerable challenge,” said Michael Wiescher, Freimann Professor of Nuclear Physics at the University of Notre Dame. “CASPAR is unique since it covers a broader energy range than the LUNA accelerator. It allows us, for the first time, to explore reactions of stellar helium burning, which take place in stars like Betelgeuse, at laboratory conditions.

“Through these studies, we will learn about the origin of oxygen and carbon as the most important ingredients of biological life in the universe, and we will learn about the mechanisms stars have developed to produce gradually heavier elements through neutron fusion processes.”

CASPAR’s 50-foot long accelerator uses radio-frequency energy to produce a beam of protons or alpha particles from hydrogen or helium gas. The ions enter the accelerating tube, which is kept at high vacuum, then are directed down the beamline using magnets. The particles crash into a target, releasing the same neutrons that fuel the nuclear reactions in stars and produce a large amount of the heavy elements.

With the achievement of first beam, the collaboration is ready to begin full operations.

“This team worked really hard to make this happen,” said Elizabeth Freer, who served as CASPAR’s project manager for four years. “It’s really exciting to see the whole team get to this point,”

Manoel Couder, an assistant professor of physics at Notre Dame, agrees. “Two years ago when we were moving in, it was like Christmas. Today, it’s like second Christmas! Now, the science starts.”

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About us.
The Sanford Underground Research Facility in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s.
LUX/Dark matter experiment at SURFLUX/Dark matter experiment at SURF

In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

Another major experiment, the Long Baseline Neutrino Experiment (LBNE)—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

Fermilab LBNE