Neutral Beams at Fermilab
E687 and FOCUS (E831)
FOCUS (E831) is a collaboration between the University of Illinois and other groups from the
United States, Italy, Korea, Mexico, and Brazil. The FOCUS spectrometer was significantly upgraded
from E687 in the areas of lepton identification, vertexing capabilities, and data acquisition.
FOCUS obtained roughly twelve times the E687 data sample in many decay modes and a considerably
larger factor for semileptonic decays and Cabibbo suppressed decays.
With the excellent FOCUS data set, the Illinois group has produced interesting new results in the charm mixing sector. We have also studied the Dalitz structure of hadronic charm meson decays. Currently we are pursuing precision analyses of semileptonic charm meson decays and the production dynamics of charm particles from photon beams interacting with nuclear targets. We recently discovered a new s-wave interference phenomenon in
D+ ® K p m n decays. Thanks to a much larger statistical sample than was available in previous analyses, we have improved the measurement of this decay channel's form factor.
Other FOCUS Links
This material is based upon work supported by the Department of Energy under Grant Numbers 64377, 56840, 80780, 561096, DEFG02-03ER41281, DEFG02-91ER40677, and DE-SC0009932. This material is also based on work supported by the National Science Foundation under Grant Numbers PHY03-49179 and PHY04-26272. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Department of Energy or National Science Foundation.