The nominal mass window was chosen 'by eye' to maximize the number of pion candidates extracted while minimizing the backgrounds (see yield extraction page.)  I wanted to check to see how this choice of mass window would affect the measurement of A_^LL.  To this end, A_LL was calculated for two other mass windows, one narrower than the nominal window (.12 - .2 GeV) and one wider than the nominal window (.01 - .3 Gev).  The results are plotted below where the nominal window points are in black, the narrow window points are in blue and the wide window points are in red.  There is no evidence to indicate anything more than statistical fluctuations.  No systematic error is assigned for this effect.