Hight Energy Accelerator Research Organization (KEK)

KEK is the major center for high energy experimental research in Japan. It was formed in 1997 as a combination of three laboratories: National Laboratory for High Energy Physics, Institute for Nuclear Study, and Meson Science Laboratory of University of Tokyo. It is located in the city of Tsukuba about an hour and a half from Narita Airport in Tokyo and about 70 km from the Tokyo bus station, if I'm not misreading the directions.

The two major experiments of interest to me are BELLE and K2K. BELLE is the detector in their asymmetric e+e- collider (8 GeV electron vs. 3.5 GeV positron), which hopes to make observations of the B meson (made from one bottom quark and a light anti-quark (or vice versa)) decaying through modes which violate CP symmetry (CP = charge conjugation plus parity). These observations will give clues about the nature of flavor-changing interactions, and whether or not they are described by the Standard Model or require new physics. BELLE is "competing" with a similar experiment called BaBar at SLAC.

K2K is a long baseline neutrino oscillation experiment, where a neutrino beam is created at KEK and directed towards the Super Kamiokande detector 250 km away. Past experiments at Super Kamiokande have detected solar neutrinos and atmospheric neutrinos in order to detect the oscillation of neutrinos from one flavor to another, say muon neutrino to electron neutrino. These oscillations imply that neutrinos have mass and mix with each other, inducing flavor changing similar to the quarks. Using KEK as a source of neutrinos will greatly reduce uncertainties in these observations, since one can measure the neutrino beam at the source as well as at the detector. This contrasts solar and atmospheric neutrinos where assumptions about and models of the neutrino source are required.

Of course, there is much, much more going on at KEK besides these two experiments. You should explore http://www.kek.jp to learn more.

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