Minutes of the Zeuthen Meeting on Front End Electronics 
   -------------------------------------------------------

    Time:             Tuesday 02/06/98, 9:30 - 10:30
    Room:             Seminar Room 2L46
    Participants:     K.Berkhan, H.Kolanoski, Z.Zhu, M.Pohl, U.Uwer


    Agenda:
      1. HV Boards
      2. Test pulse distribution
      3. Tests of Distribution Board
      4. ASD8 note
      5. Electronics Production in Zeuthen



   1. HV Boards:
   =============

   1.1 Test procedure
   ------------------
   To monitor and detect large/currents and shorts inside the
   HV groups a LCD display will be used. 
   A nano-ampere-meter together with a multiplexer is used in 
   addition to determine the leakage currents.

   From an estimation (HV= 2 kV and R=10^12 Ohms) the leakage 
   current per channel should stay below 1nA. A selection 
   threshold current can only be determined after the first tests.

   The measurement of leakage currents  should be done in 
   nitrogen. A simple gas tight box is therefore needed (-> Plexiglas). 
   Sun Hansheng should help JJ.Wang to build such a box.

 
   1.2. Cleaning
   -------------
   Outside experts have pointed to the problem that colophony 
   on the capacitors could possibly lead to increased leakage
   currents and sparking (?). In addition the outgasing of the
   soldering remains could damage the chamber(*).

   To remove any remains and also eventual finger-prints cleaning
   of the HV boards with iso-propanol was proposed. It was decided 
   NOT to start any cleaning before a test facility is available.
   
  
   1.3 HV Board assembly/production
   --------------------------------
   The exact numbers of available PCB's, capacitors, and resistors 
   are necessary to order the missing components. Mario will 
   try to summarize the available components.


   1.4 HV board cabling
   --------------------
   The HV boards of MC2  are finished. The next boards to cable are 
   5mm boards for TC. To start the length of the signal cables must 
   be defined. Mike is asked to provide these numbers based on the 
   ASD-8 distribution done by S.Lanyov.

       
   
   2. Test-pulse distribution
   -------------------------
  
   Due to different response-time of the driver a time compensation 
   of the drivers  is necessary. It is foreseen to do a compensation of
   up to +/-1ns with loops on the board.

   The board design is ready and 5 prototype PCBs will be ordered
   this week.
  
   Still open is the specification of the Harting connector: Mario
   wants to contact R.Wurth for details.  

   
   
   3. Test of power distribution Board
   -----------------------------------

   Zian Zhu will start the tests when he is back from Karlsruhe.
    

   4. ASD8 Note:
   -------------
  
   For a summary of the behaviour of the pre-amplifier certain
   measurements are still necessary:

   1. determination of the average charge of the crosstalk 
      measurement done by U.Uwer: this measurement should be 
      done by A.Schreiner. He should determine the current/rate
      for Ru and the gas used for the crosstalk measurement. 

   2. output pulse versus input charge for different thresholds
      (0.6, 0.8, 1.0) -> Mario.

   3. crosstalk measurement with coax cables -> Uli. 
 


   5. Electronic Production in Zeuthen:
   -----------------------------------

   Using the production speed of the Zeuthen workshop
      
      ASD8        : 50 Boards / day
      HV          : 50 Boards / day
      Distr.Boards: 10 Boards / day


   the production time of the ASD/HV boards and power 
   distribution boards amounts to:

      7500 ASD8 = 7.5 months  
      1300 HV   = 1.3 months
       150 Dist = 0.8 months
      -----------------------
                = 9.6 months   

   To add an additional spare time of 20% seems reasonable.       
  
   Thus the OTr needs will block the workshop for about 
   12 months. It is therefore necessary to re-evaluate the work
   shop capacities and to think of external production.
   -> Mario should contact Mr. Philip.  


   6. Next meeting:   15/06/98
   ----------------