Welcome to the g7 homepage. This experiment is an "A-" rated CLAS experiment at the Thomas Jefferson National Accelerator Facility. It is scheduled to take data in Hall B fro m September 6, 2002 to October 24, 2002.
The goal of g7 is to search for modifications of the rho meson due to the nucler medium. In other words, we will investigate differences in the rho meson mass and width when the rho meson is in a nucleus or in the vaccuum. To achieve this goal, we w ill detect the e+e- from the rho when it decays inside and outside of the target. The e+e- trigger will avoid a complicated analysis since there will be no hadronic interactions between the decay products and t he target nucleus as would be the case with pi+pi- pairs. The CLAS detector also has an excellent electron/pion discrimination to clean up the pion background. The downside to the e+e- channel is that it has a 10-5 branching ratio.
The target assembly will contain a liquid deuterium (LD2) cell and individual foils of carbon, iron, and lead. The solid targets will be positioned directly after the LD2 cell so that all of the different targets will be in the beam simultaneously. T his setup should reduce any systematic errors due to beam position. The vertex reconstruction from the CLAS analysis software will tell us which target the e+e- pair was produced in.
Useful links:
Current run plan for test June 13, 2002 (postscript 176kB, pdf 14kB).
Last update : 6/9/2002
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