Maximum Likelihood Signal Extraction Method Applied to 3.4 years of
  CoGeNT Data
  CoGeNT has taken data for over 3 years, with 1136 live days of data
accumulated as of April 23, 2013. We report on the results of a maximum
likelihood analysis to extract any possible dark matter signal present in the
collected data. The maximum likelihood signal extraction uses 2-dimensional
probability density functions (PDFs) to characterize the anticipated variations
in dark matter interaction rates for given observable nuclear recoil energies
during differing periods of the Earth's annual orbit around the Sun. Cosmogenic
and primordial radioactivity backgrounds are characterized by their energy
signatures and in some cases decay half-lives. A third parameterizing variable
-- pulse rise-time -- is added to the likelihood analysis to characterize slow
rising pulses described in prior analyses. The contribution to each event
category is analyzed for various dark matter signal hypotheses including a dark
matter standard halo model and a case with free oscillation parameters (i.e.,
amplitude, period, and phase). The best-fit dark matter signal is in close
proximity to previously reported results. We find that the significance of the
extracted dark matter signal remains well below evidentiary at 1.7 $\sigma$.
