Critique of the Rowe 2001 Detector Efficiency Experiment
  The Rowe 2001 experiment scattered photons from two prepared 9Be+ ions. Measurement of the scattered photons used a single photomultiplier tube (PMT). The resultant histograms appear to be a superposition of the individual ions' distribution, but that is not correct. The PMT records the convolution of the joint probability density of the ions. There are many different joint densities which yield the same PMT histograms. Each density has a different correlation. For a fixed PMT histogram the range of those correlations can be large, e.g. -0.730 to +0.997. The reported correlations based on discriminator levels and the categories 'zero bright', 'one bright', and 'two bright' are unsupported. As such the claim that the detection efficiency loophole is closed is invalid. For this experiment, the detection loophole remains open. 
Douglas G. Danforth
quant-ph