VLPC's exhibit superb characteristics as fast photon detectors for use in
a low light level application.
The sample of 4200 channels of VLPC's shows a high enough yield, and
the working devices are homogenous enough in their operating
parameters to make the use of VLPC's in large numbers feasible.
Furthermore, the relatively high yield makes it attractive to test the
devices after dicing and wirebonding,
a strategy which we plan to adopt for the 80,000 DØ fiber tracker.
Further tests, performed at Rockwell on the next generation of VLPC's,
HISTE V, show that devices manufactured from substrate grown in a
production (as opposed to experimental) facility, exhibit considerably
narrower distributions of QE and gain, and a much lower dark count
rate. We plan to characterize a sample of about 2000 channels of these
devices in the near future.