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Experiment Research

E01-113: Deeply Virtual Compton Scattering with CLAS at 6 GeV (e1-DVCS)

An important goal of JLab is to provide a detailed three-dimensional picture of the nucleon in terms of its quark and gluon constituents and to understand how this complex structure leads to its well known properties such as mass, spin and magnetic moment. The “e1-DVCS” experiment is the first comprehensive study in Hall B specifically focusing on this task.

The experiment required the construction of special large hardware devices, which were implemented in Hall B’s CEBAF Large Acceptance Spectrometer (CLAS) to optimize the detector’s performance for these measurements. In the experiment, the electron beam was alternately polarized parallel and anti-parallel to the beam direction. Copious amounts of data were obtained for deeply virtual Compton scattering (DVCS), which is the “flagship” of the program, and meson production (DVMP).

The first part of the experiment was run in 2005, and initial results have begun to appear. The second part of the DVCS experiment will run from October 2008 to January 2009. The goal of the second part is to more than double the statistics of the DVCS events in the same kinematical region with emphasis on extraction of helicity-dependent cross sections. There will be a new scintillation hodoscope installed in front of the DVCS Inner Calorimeter (IC). This new device will allow separation of photon and electron showers in the IC. Identification of electrons in the IC opens new physics opportunities with small angle electron scattering. 

E01-113 Technical Paper