Hall C isn't quite five years old, having opened its doors to researchers in the summer of 1994. Despite its relative youth, the hall is performing like a seasoned pro. Laboratory staff are currently preparing for the installation of five short experiments in the hall which will run concurrently through the end of the calendar year.

"Hall C really complements the other halls," says Don Geesaman, senior physicist at Argonne National Laboratory near Chicago, and chair of the JLab Users Group board of directors. "The program is developing just as we expected. Results from Hall C experiments are having a big impact in the field."

The $23 million hall is unique among the Laboratory's experimental facilities in its ability to accommodate a variable array of equipment for complex, extended investigations. Reconfiguration can be laborious with instrument changeovers usually taking three to four months.

"It's not just putting equipment into an empty building. You have to dismantle what's already there - then put it back to standard configuration when you're done," says Hall Leader Roger Carlini. "At Hall C we are constantly in flux - which is both a blessing and a curse. The changing and reconfiguring never ceases. That makes for interesting physics, but also for a hectic and intense life."

Of the 10 experiments conducted so far in the hall, seven have been completed, with results published in peer-reviewed journals. Three experiments have collected partial data and are expected to complete their runs in the near future. Carlini estimates that 27 Ph.D.-candidate students have obtained data from the hall's various investigations. Nine have gone on to earn doctorates in physics.

"The bottom-line metrics here are how may experiments you complete; the quality of those experiments and the resulting physics; and how many students you train," Carlini says. "Those are our 'products,' the things that matter. By those measures we're at the very top."

Unique Research In An Expensive World

In Hall C, as in the Lab's other two halls, the physics objective is nothing less than a more fundamental understanding of the nature of the atomic nucleus and of all matter.

"The world around us is made up mostly of quarks held together by their interactions," says Don Geesaman. "We're trying to see the quark structure of atomic nuclei. What we're trying to do is make quantifiable measurements of things we've had hints of. It lets us know if we have all the pieces right."

Testing those pieces, however, does not come without cost. Geesaman says that one issue Hall C users and the Lab's Program Advisory Committee must continually address is increasing expense. Because of Hall C's capabilities and its mandate to carry out one-of-a-kind experiments, the complexity of those experiments and experimental equipment was underestimated when initial budgets were devised. Now, it is difficult to economize where labor and equipment are concerned.

"We've shown we can move in the big equipment and perform experiments successfully," Geesaman notes. "But resources remain quite limited. The experiments are getting more expensive to do. That's the only issue I'm really concerned about."

Nevertheless, hall staff are prepping for the installation of a "hypernuclear" spectrometer by the end of 1999. The hall will also welcome a second-generation quasi-permanent fixture, a toroidal spectrometer, scheduled for sometime late in 2001. Other equipment is also on order, to make use of the Lab's planned 2005-2006 electron beam upgrade.

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