Changes

=Moving the Tagger Microscope along the Focal Plane=

=Moving the Tagger Microscope along the Focal Plane=

==Coordinate System==

==Coordinate System==

There are three coordinate systems often referred to inside the Tagger Hall. They with respect to the Goniometer center (room coordinates), Tagger Magnet center (map coordinates), and the focal plane (FP coordinates). The room coordinate system has the positive z-coordinate along the beam axis with the positive y direction pointing to the ceiling of the tagger hall from the coordinates origin that is placed at the Goniometer's center, where the beamline radiator is located. Figure 1 below, taken from a presentation by Dan Sober, shows the three coordinate systems relative to one another. The map coordinate system (magnetic mapping) places the y-coordinate along the long axis of the magnet with the positive x-axis parallel to the tagger hall floor in the direction of the focal plane. the positive z-axis of the map coordinate system points toward the tagger hall ceiling. When viewed from above the map y-coordinate is offset from the room coordinate z-axis by 6.5 degrees towards the focal plane (clockwise). The focal plane coordinate system places its x-axis along the electron focal plane with zero being at an electron energy equivalent to a photon energy around 11.7 GeV. The positive x-axis points toward increasing electron energy (decreasing photon energy). The positive y-axis of the focal plane coordinate system points towards the tagger magnet and is parallel to the tagger hall floor. This leaves the focal plane positive z-axis pointing towards the tagger hall ceiling.

There are three coordinate systems often referred to inside the GlueX Tagger Hall. They are with respect to the Goniometer center (room coordinates), Tagger Magnet center (map coordinates), and the focal plane (FP coordinates). The room coordinate system has the positive z-coordinate along the beam axis with the positive y direction pointing to the ceiling of the tagger hall from the coordinates origin that is placed at the Goniometer's center, where the beamline radiator is located. Figure 1 below, taken from a presentation by Dan Sober, shows the three coordinate systems relative to one another. The map coordinate system (magnetic mapping) places the y-coordinate along the long axis of the magnet with the positive x-axis parallel to the tagger hall floor in the direction of the focal plane. the positive z-axis of the map coordinate system points toward the tagger hall ceiling. When viewed from above the map y-coordinate is offset from the room coordinate z-axis by 6.5 degrees towards the focal plane (clockwise). The focal plane coordinate system places its x-axis along the electron focal plane with zero being at an electron energy equivalent to a photon energy around 11.7 GeV. The positive x-axis points toward increasing electron energy (decreasing photon energy). The positive y-axis of the focal plane coordinate system points towards the tagger magnet and is parallel to the tagger hall floor. This leaves the focal plane positive z-axis pointing towards the tagger hall ceiling.

      

      

[[Image:Tagger_Hall_Coord.png|center|thumb|900px|Figure 1: The three coordinate systems often referred to in association with the Tagger Hall.]]

[[Image:Tagger_Hall_Coord.png|center|thumb|900px|Figure 1: The three coordinate systems often referred to in association with the Tagger Hall.]]