Requirement:
A cone structure to attach the SVT to STAR has to be developed. The cone structure has to be stiff enough to hold the detector in its aligned position throughout operation. It also has to be sufficiently rigid to carry the cable load.
Justification:
The SVT supply lines (HV, LV, water, signals) will run along the cone before distribution at the detector to keep the forward region free of material. The cable load is minimized by multiplexing on the detector. Still the cable load exceeds the detector weight by an order of magnitude.
Status:
Several graphite epoxy designs were compared. Graphite epoxy was chosen to minimize the radiation length. A solid cone was chosen to increase rigidity.
Requirement:
A light barrier to enclose the SVT has to be developed.
Justification:
The device has to be light tight.
Status:
black foam parts were chosen to enclose the structure around the air duct support
Requirement:
A support system to slide the detector into place after completion of the TPC installation has to be developed.
Justification:
The SVT will be mounted after the installment of the TPC has been finalized. That means the area of the TPC (4m along the beam) is not accessible. The SVT has to be located along the beam in the center of the TPC to an accuracy of less than 1 mm in beam direction.
Status:
A UNISTRUT system has been developed.
Requirement:
Fiducial points and adjustments have to be included in the design to allow alignment of the SVT.
Justification:
The position of the SVT has to be known to a value better than its position resolution to not degrade its performance. Because of the various stages of the installation as well as the alignment determination various gadgets have to be designed.
Status:
The detector and its assembly and installation tooling allow three different ways of adjusting the complete device throughout and after installation. Fiducial points and their location are being defined as part of the overall design.
Requirement:
A monitoring system for the SVT location has to be included in the mechanical design.
Justification:
The location and relative alignment of the detector has to be monitored during operation. Past experience with microvertex detectors has shown that displacement up to centimeters are possible (due to magnet ramping etc.)
Status:
A system comparable to the CDM system of DELPHI is being considered. This system foresees integration of capacitive probes at the end of certain selected ladders.
Requirement:
The SVT cabling plan (incl. the water and air supply) has to fit into the STAR integration plan.
Justification:
The access to the inner STAR detectors is restricted due to the design of the solenoidal magnet.
Status:
Present SVT space requirements are part of the STAR integration plan.