Things are heating up in a race to build a new type of particle smasher known as a "super B factory." The Japanese government will invest $100 million to transform the KEKB collider at the Japanese particle-physics laboratory, KEK, in Tsukuba, into Super KEKB, which will smash electrons into positrons at 40 times the rate of the current accelerator, physicists working on the project say. Meanwhile, researchers in the United States and Italy are hoping the Italian government will soon approve plans to build a similar, competing machine.
To be spent over the next 3 years, the money granted by the Japanese government will cover only a fraction of the $350 million needed to complete the Super KEKB upgrade. Nevertheless, it suggests that the new government, which came to power in a general election last August and is led by the Democratic Party of Japan, is enthusiastic for the project, say Peter Krizan, a physicist at the Jožef Stefan Institute and University of Ljubljana in Slovenia. The project got its start under the previous government, led by the Liberal Democratic Party.
But KEK researchers are not alone in their quest for a super B factory. Researchers from Italy and the United States have proposed building in Italy a machine called SuperB using parts from a defunct accelerator in the United States. That project made a list of 14 that, according to an Italian press report, Italy's Ministry of Education, Universities and Research has drafted for the Italian government as part of its €15 billion national research plan for 2010 through 2012.
SuperB would use the massive magnets from the idle PEP-II collider at SLAC National Accelerator Laboratory in Menlo Park, California; would cost about €450 million; would smash particles at a slightly higher rate; and would used a spin-polarized electron beam, says David Hitlin, a physicist at the California Institute of Technology in Pasadena who works on the project. Researchers are hoping that the Italian government will give the project the go-ahead in the next few months, he says.
The dueling proposals continue a spirited competition that began in 1999, when PEP-II and KEKB started blasting out odd and fleeting particles called B mesons. Those particles are particularly fruitful to study because they can be used to probe a very slight asymmetry between matter and antimatter called charge-parity violation, which had only been seen before in particles called K mesons. The measurements of a few billion B mesons at the B factories enable experimenters to confirm the explanation of charge-parity violation essentially guessed by Japanese theorists Makoto Kobayashi and Toshihide Maskawa in 1972. On the basis of those measurements, Kobayashi and Maskawa shared the Nobel Prize in physics in 2008.
However, physicists are hoping that Kobayashi and Maskawa's theory isn't the final word on charge-parity violation—and it shouldn't be, given that it cannot explain the abundance of matter and dearth of antimatter in the universe. So by measuring far more B mesons and other particles, they hope to look for anomalies that might point to new physics and new massive particles that might complete the picture. That's why they want a super B factory.
Could there eventually be two super B factories? "I don't see why not," Hitlin says. "There will be zero, one, or two of these" super B factories.
*The story has been corrected. The cost of Italy's proposed national research plan would be €15 billion, not €15 million.