GlueX will use the coherent bremsstrahlung technique to produce a linearly polarized photon beam. A solenoid-based hermetic detector will be used to collected data on meson production and decays with statistics after the first year of running that will exceed the current photoproduction data in hand by several orders of magnitude. These data will also be used to study the spectrum of conventional mesons, including the poorly understood excited vector mesons and strangeonium. In order to reach the ideal photon energy of 9 GeV for this mapping of the exotic spectrum, 12 GeV electrons are required. Thus, GlueX is part for the JLab12 upgrade being finished recently and is ready for regular operation.
The emphasis of the GSI group in GlueX is the development of the GlueX-DIRC together with MIT, JLab, and Indiana University and the search for exotic strangeonium systems and the determination of their static properties, like spin-parity and decays.
Hybrid mesons, and in particular exotic hybrid mesons, provide the ideal laboratory for testing QCD in the confinement regime since these mesons explicitly manifest the gluonic degrees of freedom. Photoproduction is expected to be particularly effective in producing exotic hybrids. This is due to the fact that the quantum numbers of the lowest predicted excited modes of the flux tube, when combined with that of a virtual photon, yield exotic JPC. However, there is little data on the photoproduction of light mesons.
The current plan is to place BABAR DIRC bar boxes in front of forward calorimeter to allow for additional PID capcabilities. The GlueX PID requirements are rather similar to those of BABAR, thus the concept is comparable but updated in some important technical aspects. Currently the work is focussed on prototype optics and software. Since the timescale is rather short, GSI with its DIRC experience from PANDA joined this effort.