Figures 2 shows the mass resolutions of the 
, J/
and 
vector mesons with the baseline copper nosecone in the
North muon arm compared to the North arm with a BeO nosecone. The sigmas of a
gaussian fit to the mass distributions are 110, 136 and 200 MeV for the copper
nosecone, and 76, 98 and 177 Mev for the BeO nosecone for , J/ and , respectively.
Figure 2: The ,
J/ and mass distributions
are shown for a copper nosecone (left) and a BeO nosecone (right). The sigma
listed is for a gaussian fit to the distributions.