View source for Matt's May 1, 2013 e-mail

 Hi all,
 
 I've been reading through your proposal for pion polarizability and have some technical questions about the instrumentation.
 
 On page 25 you talk about using start counter in the trigger but your table says that the start counter will be removed.
 Do you plan to remove the start counter?
 
 You are going to move the target forward to avoid dead regions in the FDC. However, the FDC is deadened because backgrounds
 from the target (in its current position) are unmanageable.  If you move the target it seems like this would cause major noise
 issues in the FDC.  Can you operate in the presence of this noise?  Will it affect the lifetime of the chambers?
 
 The downstream muon system consists of an iron absorber, but as best I can tell it sits in the beam line.  (Does it have a
 hole in it?)  It must or else it will act as a beam stop.  I would expect noise in  this detector to be relatively high since there
 will likely be a lot of beam scraping on the steel tube inside the FCAL.   It seems like any instrumentation that doesn't sit in
 the "shadow" of the FCAL is  going to be very hard to operate.  How close do plan (or need) to get to the beamline in the
 region behind the FCAL?
 
 To do ID you must be planning to connect tracks from the FDC to tracks reconstructed in the muon ID system.  How
 successfully can you track pions or muons through the material on the front of the forward carriage (the FCAL) and
 match them with hits in the muon detector (in the presence of the aforementioned noise)?  I see you cite a 6 cm
 scatter.  Are you including just the lead glass in this?  The true material may be significantly greater by the time
 one includes the TOF, monitoring system, steel magnetic shielding on the back of the bars, cable mass, etc.
 
 You've seem to have shown convincingly that that the kinematics works out.  I'm concerned about the ability to
 practically pull of something like a 1% absolute rate measurement for muon pairs.
 
 Is there a physics handle available on mu pi separation?  Can you study angular distributions, dependence of rate on
 target material?  Dependence of rate on beam energy?  ....anything to separate the process you are interested in from the
 mu background?
 
 Matt