The underground continuous electron beam accelerator ("CEBAF") at Jefferson Lab.
Enlarged version of this photo

Probing the Quirks of Quarks

A Big Boom

By the time November 1996 rolled around these problems had been solved and installation was nearing completion. But a simple cigarette lighter almost wiped out the Hall B project.

"When the project was nearing completion, there was a potentially catastrophic accident that could have reduced everything to rubble, setting the Jefferson Lab Hall B detector back several years and wiping out much of the hard work we had put into it," Stoler recalls. Each of the six Cerenkov detectors uses $10,000 worth of C4F10 gas and any leak would be costly. "To check for leaks," Stoler explains, "Jefferson Lab technicians first filled one of the detector units with a flammable argon-ethane mixture, which can be detected with electronic sniffers easily. When the tests were completed, the argon-ethane was forced out with nonflammable nitrogen. Thinking that only the nitrogen was left, a technician lit a cigarette lighter to check the gas flow. There was this huge boom and a big flame and everything on the outside of the detector melted. Miraculously, nobody was hurt and the inside of the detector and all of those fragile mirrors weren't damaged at all."

Work proceeded and Hall B was commissioned in late 1997. Sinclair says, "Hall B was the last of the halls to be commissioned, late last year. That was due in no small part to the fact that the detector is so complex and massive. However, it's worth recognizing that because people began taking the first experimental data from it in early December, this unique device — which relies on the electron to probe the nature of nuclear particles — had the honor of starting up in the 100th anniversary year of the discovery of the electron itself."

Associate Professor of Physics James Napolitano says the Jefferson Lab is but the latest example of Rensselaer's deep involvement in embracing nuclear and particle physics. "There's been a steady progression over the years to higher and higher energy levels, and we've been involved the whole way. When Paul [Stoler] came to Rensselaer in the 1960s, the physics group had started doing experiments using the Gaerttner Linear Accelerator Lab on Tibbits Avenue (see related sidebar). But its energy was too low to create new particles, except for other electrons.

"Then, when I was an undergrad here in the '70s, the group had just gotten involved with a linear accelerator that had five to six times more energy, the MIT/Bates Electron Accelerator Laboratory. It allowed them to create new matter, pions, and led to different types of studies of matter. Now, with the Jefferson Lab, we've got 10 times more energy and higher resolution. We can create and study even more types of matter, and do many different types of experiments."

Looking Ahead

Sinclair is excited about the discoveries that will be made at the Jefferson Lab. "I'm not that old, but when I was a boy there were tubes, not transistors. Who could foresee the progress that transistors have made possible? It's incredible how things have progressed. My old phone number was simply 73M. Now you can use the phone to talk with Katmandu as easily as you can talk with someone across the street.

"It would be pompous in the extreme to try to say exactly what the work carried out here will lead to, but I can't but believe for a moment that it will lead to discoveries and inventions that will make life better for humanity."

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