From:	Paterson, James (Ewan) [jmp@slac.stanford.edu]
Sent:	Tuesday, September 08, 2009 5:55 PM
To:	ilc-ops-availability@desy.de
Subject:	Thoughts on Availability Calculations

All,
    Although the results from Availsym are complex and require careful 
interpretation, I propose we discuss some general conclusions that we might 
draw.

   1) The cases ILC115 with different energy overheads would indicate the 
cases with old RF systems in a single tunnel should be dropped in favour of 
KlyClus or DRFS. You need too large an overhead to alleviate a significant 
loss of performance. (I ignore arguments that we are not always running at 
full energy as we must be honest about the impact and the complete capital 
cost, and 1% overhead is on the order of 300 M ILCU's beyond the assumed 3% 
assumed in the RDR.)

  2)  With the present assumptions Availsym favours the KlyClus but at a level 
of accuracy where differences in capital cost, performance, tunnel safety and 
siting will be equal or more important arguments.

  3)  Availsym indicates, using the best MTTF's and optimum or realistic 
maintenance schedules, that there is a quite a significant loss of integrated 
luminosity with a single tunnel and either RF solution, BUT (At an operating 
budget of 1B per year, this could be 5% or 50 M a year) the error on the peak 
or average luminosity is greater!

THIS GROUP SHOULD NOT GO TO ALBUQUERQUE WITHOUT AT LEAST A FEW CONCLUSIONS.

                                                      Ewan