CDF Steps Up to the Plate

by Judy Jackson

A year ago, Fermilab Director Mike Witherell laid it on the line. The era of detector schedule slips at Fermilab was over. Collider Run II at the Tevatron would begin on time, on schedule, on March 1, 2001. Period.

"I believe we now have a schedule that we have a good chance of meeting," Witherell said in an October 1999 FermiNews story. "But it won't be easy. From here on the things with the most impact on the schedule are under the collaborations' control. Now it is up to them to step up to the plate."

Message received.

"The lab has made clear that we will have the resources we need," said CDF cospokesman Al Goshaw, in the same story. "Now that's it. That's the schedule we have to meet. If we fail this time around, we all have the message that it would be very damaging not just to Fermilab but to high-energy physics. We have a big responsibility to make this happen."

That was last October. At the time, Goshaw and CDF cospokesman Franco Bedeschi were clearly determined that the $110 million reinvention of the detector that found the top quark would finish on time. Equally clearly, they were seriously worried about whether they would succeed.

Now, a year later, the white knuckles of CDF's cospokesmen have given way to relieved smiles.

On September 7, right on schedule, CDF began rolling into the Tevatron tunnel for a six-week commissioning run. Bedeschi was in the CDF control room when the detector recorded its first test collisions, from cosmic rays in the atmosphere.

"Getting the first collisions in the detector, after five years of work, was so exciting I could hardly believe it was happening," Bedeschi said. "I went out to a grocery store and bought two bottles of champagne."

The experience was all the sweeter because, in late August, unexpected magnet problems in the Tevatron almost scuttled the commissioning run.

"There was a moment when I was afraid there would be no roll-in, with the accelerator difficulties," Bedeschi said. "It wouldn't have made sense to roll in without beam in the Tevatron. It is nice to see that the accelerator has picked up speed."

Very nice.

The commissioning run will last until about November 1. Then CDF will roll back out into the assembly hall for installation, in early December, of its long-awaited SVX II silicon detector, and final preparations for Run II.

"Last fall, when we committed to the late summer roll-in," Bedeschi said, "we were determined, but there were still many uncertainties. There was still a lot of guesswork. But now, I think we are out of the woods. All three barrels of SVX II are done. There are a lot of little things to be understood, but they are all standard problems of commissioning a complicated detector. I can now say confidently that we will be ready to go on March 1."

How did they get from last fall's white knuckles to today's confident stance?

"We all worked hard on all aspects," Bedeschi said. "When crises developed, we pulled people from everywhere. We jumped on every crisis. It was very important to have a goal and a deadline. The fact of the commissioning run schedule was an important stimulus. If it had been cancelled, momentum would have slowed. Now, it is wonderful to see things picking up speed. Professors are starting to bring their graduate students. They are getting apartments, getting settled."

Recent reports from CERN, the European Laboratory for Particle Physics, of possible hints of the long-sought Higgs boson, the particle theorized to confer mass, have upped the excitement at CDF. Whether or not the Higgs will show up in Run II at Fermilab depends directly on how many collisions the detectors can log in the time available.

Goshaw explained.

"The discovery of a 115 GeV/c2 Higgs would start with hints (few sigma effects), going through evidence (three sigma or so) and onto a solid discovery at, say, five sigma. Based on our Run II studies, combined CDF/D0 data would yield hints at about 2 inverse femtobarns (a measure of the total number of collisions observed), evidence at about five, and for discovery something like 10-15. So, depending on how well the accelerator performs, you can make an estimate of ëwhen.' If we have a good Run IIa, we could have ëevidence' by early 2004, but discovery would still require Run IIb data. We can always hope to do better when we actually have data to work with, as we did with the top. I expect we will, but for now that's the best we can say."

Bedeschi spelled out what that means for his collaborators.

"If we want an unambiguous Higgs discovery at Fermilab in Collider Run II, we had better get started," he said. "There is no time to mess around. We have a lot to do, and the search for the Higgs gives an increased urgency to a good start. It will take everything we've got."