We present a measurement of the angular power spectrum of the cosmic microwave background (CMB) using data from the South Pole Telescope (SPT). The data consist of 790 deg2 of sky observed at 150 GHz during 2008 and 2009. Here we present the power spectrum over the multipole range 650 of sky observed at 150 GHz during 2008 and 2009. Here we present the power spectrum over the multipole range 650 of sky observed at 150 GHz during 2008 and 2009. Here we present the power spectrum over the multipole range 650 s = 0.9663 ± 0.0112. We detect, at ~5s significance, the effect of gravitational lensing on the CMB power spectrum, and find its amplitude to be consistent with the ?CDM cosmological model. We explore a number of extensions beyond the ?CDM model. Each extension is tested independently, although there are degeneracies between some of the extension parameters. We constrain the tensor-to-scalar ratio to be r = 0.9663 ± 0.0112. We detect, at ~5s significance, the effect of gravitational lensing on the CMB power spectrum, and find its amplitude to be consistent with the ?CDM cosmological model. We explore a number of extensions beyond the ?CDM model. Each extension is tested independently, although there are degeneracies between some of the extension parameters. We constrain the tensor-to-scalar ratio to be r s /dln k = –0.024 ± 0.013. We strongly detect the effects of primordial helium and neutrinos on the CMB; a model without helium is rejected at 7.7s, while a model without neutrinos is rejected at 7.5s. The primordial helium abundance is measured to be Yp = 0.296 ± 0.030, and the effective number of relativistic species is measured to be N eff = 3.85 ± 0.62. The constraints on these models are strengthened when the CMB data are combined with measurements of the Hubble constant and the baryon acoustic oscillation feature. Notable improvements include ns = 0.9668 ± 0.0093, r = 0.9668 ± 0.0093, r eff = 3.86 ± 0.42. The SPT WMAP data show a mild preference for low power in the CMB damping tail, and while this preference may be accommodated by models that have a negative spectral running, a high primordial helium abundance, or a high effective number of relativistic species, such models are disfavored by the abundance of low-redshift galaxy clusters.
