Requirement:
The overall experimental position resolution provided by the SVT
should be < 25 
m for both transverse directions.
Justification:
The fundamental requirement for a vertex detector is excellent
position resolution. Silicon drift detectors have been developed
with intrinsic position resolution of 10 
m for both transverse
directions. Position resolution
determines the ultimate accuracy of secondary vertex finding,
two-track resolution, momentum resolution, and efficiencies.
Simulations have shown that a position resolution of 25 
m
is adequate for the SVT.
Status:
STAR has a large SDD Research and Development program that is producing prototype SDDs with such position resolution.