The search by U.S. physicists for the most coveted particle of all, the so-called Higgs boson, will come to an end in September.
Researchers working at Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, had been pushing to run their 25-year-old atom smasher, the Tevatron, through 2014 in hopes of spotting the Higgs before their European counterparts could discover it with their newer, more-powerful atom smasher. But today, officials at the U.S. Department of Energy (DOE), which funds Fermilab, conveyed word to lab officials that DOE cannot come up with the additional $35 million per year to keep the Tevatron going.
"Unfortunately, the current budgetary climate is very challenging and additional funding has not been identified. Therefore … the operation of the Tevatron will end in [fiscal year 2011], as originally scheduled," wrote William Brinkman, head of DOE's Office of Science, in a letter to Melvyn Shochet, chair of DOE's High Energy Physics Advisory Panel and a physicist at the University of Chicago in Illinois. Shochet relayed the message to Fermilab officials and others in the scientific community.
Pier Oddone, director of Fermilab, had previously stressed that the lab could not forsake future experiments to keep the Tevatron going. "Given the absence of additional funding, it's the right decision," Oddone says.
Brinkman's letter is the final chapter in a long, tense tale for scientists at Fermilab. Last February, officials at the European particles physics lab, CERN, near Geneva, Switzerland, announced that their Large Hadron Collider (LHC) would be shut for all of 2012 for repairs. That opened a window for physicists at Fermilab to spot the Higgs first—although CERN officials are now considering waiting until 2013 to begin the repairs.
In August, the lab's scientific advisory panel recommended that Fermilab officials throw caution to the wind and keep running the Tevatron through 2014 even if they didn't get another dime to do so. That advice didn't sit so well with Oddone, who announced a month later that Fermilab officials could wring $15 million a year out of the lab's $410-million-a-year budget by delaying other projects but would need the additional money on top of that. In October, DOE's Particle Physics Project Prioritization Panel approved Oddone's plan, essentially a request for extra money. But the panel also said that if there was no additional money, the Tevatron should be shut down—which is what will happen.
The Higgs is key to the hypothesized explanation of how all particles gain mass, and many physicists believe that the hunt for it is the most important challenge in the field. They argue that the Tevatron would uncover the Higgs more easily than the LHC if it has a mass in the range indicated indirectly by measurements on other particles--between 121 and 144 times the mass of a proton--because of the machine's lower energy, cleaner collisions. Because the Tevatron collides protons into antiprotons, it could also probe how a new particle interacts, or "couples," to other particles in a way that would prove whether it's really the Higgs. The LHC cannot probe those connections as easily because it collides protons with protons.
"I think we presented a very good science case for continuing to run, but the fiscal realities just don't allow us to go forward," says Rob Roser, a physicist at Fermilab and co-spokesperson for the 600 researchers working with the CDF particle detector, one of two fed by the Tevatron. Roser adds that he and his colleagues feel DOE gave them a fair hearing: "They have to make very difficult decisions based on the realities. I can't fault them for that."