List of Figures

• Upper view of the accelerator and Halls
• Schematics 3D view of CEBAF
• Exploded view of the Hall A
• Exploded view of the Hall C
• Exploded view of the Hall B
• Layers of detector in CLAS (3D view)
• Layers of detector in CLAS (2D view)
• A Cerenkov cell
• Beamline devices
• Beamline devices : before the Tagger Magnet
• Beamline devices : between the Tagger Magnet and CLAS
• Beamline devices : After CLAS
• Axes and angles in the c.m.s.
• The Möller Polarimeter in Hall B
• EPICS software and hardware layers, from [#bib:epics_a_d_g##1###]
• IOC counting loop timing (Vertical axis is in 10^-7 seconds (Scaler ticks), Horizontal is samples)
• The GUI_launch window
• The Harp GUI window
• Harp : targets and wires
• The Scaler GUI window
• Halo acquisition principle
• The Collimator GUI window
• The photon collimating system
• A collimator box
• Speed diagram for a collimator move
• The Forward Scaler GUI window
• The Converter GUI window
• Chronogram of a portion of a beam scan by the harp
• Sample TCL window : the result of a not that bad scan!
• Scan of a wide beam
• Scan of a well tuned beam
• A halo is clearly visible on this scan
• A quite good scan
• Repartition of the 144 scans over our subjective evaluation
• Cut on the non fitted scans. Removed scans appear in darker pattern
• Distribution of the reduced $\chi^2$ on the u axis sigma (large values)
• Distribution of the reduced $\chi^2$ on the u axis sigma (around 1)
•  $\chi^2$ against the subjective evaluation
• Result of the cut on $\chi^2$ over the scans
• Distribution of the error on the u axis sigma (normalized on fitted sigma)
• Cut on the error over sigma. Removed scans appear in darker pattern
• Sigma versus our subjective evaluation, not that bad
• Sigma repartition (u axis)
• Final cuts result