The gates on the various quantities were determined by searching for the best FOM in the two-dimensional space of the minimum and maximum value of the gate. The two edges of the gates were varied independently, and the FOM was calculated at each point to find the best cuts to use on the data. The results of the search for the best gate on the polar scattering angle, , is shown in figure .
Figure: The results of a search for the best gate on polar scattering angle, . is the lower gate, and is the upper gate. The top plot shows the effective analyzing power, , and the lower plot shows figure-of-merit (FOM).
There is often a trade-off between effective analyzing power, , and figure-of-merit, FOM, that is obvious in figure . It is generally possible to make very narrow cuts on the data and get a very good . However, this usually implies the loss of a lot of events which reduces the FOM (as defined by equation ).
Similar searches as that shown in figure were conducted for the pulse-height cuts and the velocity ratio cuts. The final gates on the data are summarized in table .
Table: Final cuts use to analyze the E385 and E387 INPOL data.
Notice that the upper limit on pulse height is listed as . This simply means that the upper limit was set high enough so as not to eliminate any events from analysis. With the gates given in table the effective analyzing power of the detector is .