The mechanical support of the detector apparatus with the requirement of easy access to inner detectors (the target, the MWPC's and the plastic veto) and upstream detector readouts, has been designed and at the time of this writing, parts of the support structure are under construction. Except for the cosmic veto house, the entire detector apparatus including the electronics is supported on a platform and can be craned in and out of the experimental area ( area). The veto house consists of a frame with layers of lead bricks and the cosmic veto detectors on the outside of the frame. The bricks prevent self-vetoing in the cosmic veto detectors due to leakage of showers through the back faces of the calorimeter modules. The veto house is equipped with a rail system on the platform and can be wheeled in to enclose the rest of the apparatus on all sides except upstream from the beam where there is a concrete wall for the shielding of the detectors from beam related events, and on the bottom where the platform is. The veto house can also be wheeled out up to five meters, thereby exposing the thermal house around the mechanical support of the calorimeter.
Figure: The support structure of the calorimeter showing the spherical steel housing, the inner calorimeter modules, the metallic cylinders enclosing the PMT's and the mechanical frame holding the housing.
The thermal house and the support of the calorimeter are equipped with their own rail system and can be wheeled out (downstream of the beam) up to 85 cm for easy access to the upstream detectors such as the beam counters, the active degrader, etc. The support of the calorimeter consists of a spherical metallic housing with holes within which fit metallic cylinders enclosing the PMT's of the calorimeter modules. The spherical housing is in turn held by a mechanical system as shown in figure . The housing is made of steel plates that have been forced into semi-spherical geometry to create two hemispheres which are then welded. The support of the twenty plastic veto staves is provided by a thin (one millimeter) carbon fiber cylinder which protects the outer MWPC. The carbon fiber cylinder also provides for smooth and easy insertions and removals of the outer chamber which is equipped with flanges and step-down rings for the support of the inner MWPC (figure 5.1). The target has its own support system with rails and can be wheeled in and out separately. This facilitates the interchange of the passive and the active target during the data taking process.
Figure: The truncated trapezoidal pyramid VT1. These are the edge shower veto detectors. There are 10 of these modules. In the process of the geodesic breakdown, this shape was produced as one HD plus one quarter of hexagon C.
Table: Properties of the trapezoidal pyramid VT1. The coordinates of slanted faces in figures and are indicated by the .
Figure: The truncated trapezoidal pyramid VT2. These are the other edge shower veto detectors. There are 10 of these modules making a total of 20 shower vetoes. VT2 is a mirror symmetry of VT1. To avoid an interference between the plastic veto detector and the shower vetos, the orginal geometries VT1 and VT2 were trimmed to produced the slanted faces shown figures and .
Table: Properties of the trapezoidal pyramid VT2.