Read-out strips (roughly)

Some initial observations: *) We are exercising the chip well above the “tracking” region. Lowest workable input charges are ~7 fC (normal gain) and ~4fC (double gain). Tracking thresholds are typically fC. *) Looked at channels 0-31 so far (0-63 bonded out) *) About 1/3 of loaded KPiX-7 channels look similar in gain and noise to unloaded channels *) But this noise is very high – 2000 to 2500 electrons *) Another ~1/3 of KPiX channels have somewhat higher noise, but similar gain (up to 4000 electrons, say…) [cont’d]

Initial observations cont’d *) 4 of 32 channels “dead” (comparator always firing or never firing, irrespective of input charge) *) Remainder have huge, non-gaussian noise/pickup and no response to input charge (may be swamped by the noise/pickup) *) No correlation between geometry (see slide 1) and channel behavior Not sure what we’re learning if we’re seeing 2000 electrons as baseline noise… need to think a bit about this for starters.