\section{Upgrade motivations  {\small [TK]}}

{\it 
Discussion of muon spectrometer performance at high luminosity - precision 
tracking and L1 trigger, and conclude that new detector and electronics are
needed.

Point out serious (?) performance degradation in the small
wheel region in both MDT and CSC, referring to the radiation background 
discussoin in Appendix.
Performance of the present detector should be evaluated for high lumi conditin,
either using high lumi Monte Carlo or overlay of real events.
CSC is 4 layers. 

In the L1 discussion, emphasise the importance of maintaining low $p_T$ 
threshold.
There are two issues.
the high rate of fake triggers
in the endcap region based mainly on the study using data.
Then introduce basic idea of how this can be 
mitigated by integrating the small wheel in the L1 trigger.
As the second point of trigger, discuss the pT resolution and possible 
improvement using the new small wheel.
Physics requirement asks low pT threshold (20-40 GeV), 
L1 rate should be maintained at 100 kHz.  
Need sharpening pT threshold. Here introduce 1 mrad requirement.

Finally conclude that NSW should be built and replace the present ones
as a phase-1 upgrade item in preparation to running with luminosity beyond 
the nominal luminosity.
}

