Long lines formed outside the bunker-like home of Yale’s nuclear accelerator Saturday morning as hundreds waited to see the mammoth atom smasher one last time.

Decommissioned in 2011, the particle accelerator is set to be taken apart and removed from its home on Science Hill by spring 2015. In the first and only public tour of the nuclear physics facility, researchers at Wright Lab led groups of 35 people through the installation’s cavernous halls and into the bright blue tank that high-energy particles once zipped through.

“People have often wondered what went on in these bunker lab facilities,” said physics professor Karsten Heeger, director of Wright Lab. “When the accelerator was operational, it was not possible to conduct many tours, but now we want to take this opportunity to open up the lab and show them what we really did.”

Dedicated in 1966 under the direction of David Allan Bromley — later science advisor to former President George H.W. Bush — Wright Lab and its accelerator transformed Yale into one of the leading institutions in nuclear physics, Heeger said.

The original device was replaced by the current version in 1987. Operating at 22 million volts and propelling atoms at tens of millions of miles per hour, the machine was at the time the highest-energy tandem accelerator in the world, associate director for operations and 25-year Wright Lab veteran Jeff Ashenfelter told visiting groups.

He added that the accelerator allowed research teams to gain important insights into phenomena that ranged from the micro to the macro, from the structure of nuclei to the formation of stars.

But the existence of the massive facility was little-known, according to those interviewed.

“I had no idea we had something like this!” said Joy Chang ’94, who came down from New York with her husband and five-year-old daughter specifically to catch the tour.

Neither did Stefan Reul, who had worked in New Haven for over 10 years and drove in Saturday morning with his 17-year-old son.

“Everyone knows the Peabody [museum]. But not this,” he said, laughing.

The prospect of seeing a nuclear accelerator up close excited the over 700 people who braved the chill to get a final glimpse of the facility. Most visitors interviewed were surprised by the long lines but were willing to wait as Wright Lab staff distributed information pamphlets to the crowd.

Heeger said that he did not expect such a large turnout. Around 200 people took part when Wright Lab conducted its one previous tour that was limited to members of the Yale community, back in 2013 during University President Peter Salovey’s inauguration.

That success spurred the Wright Lab to hold this first public tour, and the interest the community showed in the science being conducted at Yale was very encouraging, Heeger said. The lab will be looking for more opportunities to share its research with the public, he added.

Attendants interviewed said that they would welcome similar outreach efforts in the future.

Chang explained that it was because of their daughter that the family decided to make the three-hour roundtrip from New York. At the age of five and a half, she already has a passion for astrophysics, Chang said.

Thirteen-year-old Michael Loalbo also came in from outside of the Elm City. Arriving from Hamden with his mum, he enthused about studying atoms in school and said he could not miss a chance to see how scientists studied them.

One visitor with a slightly different motivation was Martin Cobern GRD ’74. It has been 40 years since he obtained his Ph.D. working in this very same bunker, doing research into the structure of light nuclei.

The tours conducted by Wright Lab had a special significance for him, he said. His journey in science began on a similar tour nearly 50 years ago, when he visited the accelerator at Brookhaven National Laboratory, New York. Now, he has come goodbye.

“It’s sad to me. It’s the end of an era,” said Cobern.

The decommissioning of Yale’s particle accelerator comes as Wright Lab shifts its research focus. Heeger said that the lab will develop new detectors that will be deployed around the world to probe the nature of neutrinos and dark matter.

The bunker facility itself will be transformed to house state-of-the-art labs that will support teaching and research.