Minutes of JLC CDC Subgroup Meetings



        Date and Place
         ================
      October 21, 1995 at KEK (Saturday)
 
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  Attendants:
  -----------
  K.Fujii,Y.Kurihara, N.Khalatyan, S.Sudou




    
 Wire Sag Calculation
              Simple linear formula works well:
 
       Al wire sags
         ------>  Good at the 1-st iteration and
                   improves with the number of iterations.

       W wire sags
         ------>  Left-right asymmetry could not be reproduced with
                  the nominal HV values and the nominal original
                  positions.
                  Observed asymmetry <--> about 30 V shift in the
                                          H.V. on grid wires.
      Discussions
      -----------

       i) H.V. setting
           Found one cable (H.V.) to a field wire broken.
            ----->  could have been the source of asymmetry.
   
      ii) How accuratly should we predict the sags?
           50 micron might be already good enough.
            ---- > x-t, drift field...

     iii) Sense wire electrostatic sags are harder to predict since they are
          2-nd order effects (Kurihara).

      iv) Sense wire sag about 2-x Field wire sag.       
          if E-field is the same since wire tensions are a factor
          of 2 different

       v) Even if the sense wire sags are higher-order effects, if
          they are large, there must be enough source of asymmetry in
          wires other than the sense wire
            ---- > Effects of other cells
                   (broken H.V. cables, machining errors of wire holes)

      vi) Need to study stability (Kurihara).

 
   Wire Tension Measurements 

       New magnets

          ---- >  about 3 kG at front faces.
          ---- >  about 30 G at the center of the chamber.

       Measured several wires

           Al- wires seem to start saturating.
           W - wires difficult but feasible to measure.

  
   Cosmic Ray Test. 

        Flash ADC

        Readout
          
           Noise problem -- > Follow the B-factory design:
                    --- > O.K.

        Estimate signal size.

  
  Movement

          ----- > Ask a company

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