LONG BASELINE NEUTRINO OSCILLATION EXPERIMENTS have now gotten underway with the announcement that the Super-Kamiokande detector (on the west coast of Japan) has recorded the arrival of a neutrino launched in its direction from the KEK proton accelerator 250 km away (near Tsukuba). Last year Super-Kamiokande established the important fact that neutrinos (made by cosmic rays striking the atmosphere) transform, or oscillate, from one type to another on their way through the Earth (see last week's Update 435 for more recent results). In the new experiment (dubbed "K2K") physicists attempt to confirm the oscillation phenomenon by allowing neutrinos made artificially at an accelerator to pass through a nearby detector and also the much more distant Super-Kamiokande detector, aligned so as to receive the same neutrino beam. If, for example, muon neutrinos oscillate into another type of neutrino, adjusted event rates would be different for the two detectors. (K2K website: http://neutrino.kek.jp; for background see Physics Today, February 1996.)