Requirement:
The average radiation length for all SVT material between the beam line and the full tracking region of the TPC should be 3.5% or less. Multiple Coulomb scattering and energy-loss should not degrade the performance of the SVT.
Justification:
A low-mass SVT allows the detection and tracking of charged particles to smaller momenta than possible with the TPC. Multiple Coulomb scattering and energy loss effects are directly proportional to the amount of mass particles traverse. These effects, in turn, affect position resolution and the quality of particle identification, tracking precision and track matching efficiencies.
Status:
The present SVT design leads to an average radiation length of 3.5%. The low momentum cutoff for tracking and particle identification is extended down to 50 MeV/c.