  A Search for Extraterrestrial Life (SETI), based on the possibility of
interstellar communication via laser signals, is being designed to extend the
search into the near-infrared spectral region (Wright et al, this conference).
The dedicated near-infrared (900 to 1700 nm) instrument takes advantage of a
new generation of avalanche photodiodes (APD), based on internal discrete
amplification. These discrete APD (DAPD) detectors have a high speed response
($>$ 1 GHz) and gain comparable to photomultiplier tubes, while also achieving
significantly lower noise than previous APDs. We are investigating the use of
DAPD detectors in this new astronomical instrument for a SETI search and
transient source observations. We investigated experimentally the advantages of
using a multiple detector device operating in parallel to remove spurious
signals. We present the detector characterization and performance of the
instrument in terms of false positive detection rates both theoretically and
empirically through lab measurements. We discuss the required criteria that
will be needed for laser light pulse detection in our experiment. These
criteria are defined to optimize the trade between high detection efficiency
and low false positive coincident signals, which can be produced by detector
dark noise, background light, cosmic rays, and astronomical sources. We
investigate experimentally how false coincidence rates depend on the number of
detectors in parallel, and on the signal pulse height and width. We also look
into the corresponding threshold to each of the signals to optimize the
sensitivity while also reducing the false coincidence rates. Lastly, we discuss
the analytical solution used to predict the probability of laser pulse
detection with multiple detectors.
