re: preamp ASIC spare quantities etc

[John Schaapman <jsch@phys.ualberta.ca>]

Hi Dan,
  I think another way to look at the quantity of spare ASICs needed for 
the FDC is to consider whether you want fully instrumented anode and cathode 
planes (or assembled chambers) or a fully instrumented package as spares. This
would allow testing of a chamber/package independant of the assembled detector
allowing more efficient swapping if necessary or further R and D. Then you 
may want some quantity beyond that if you want to ensure that the spare
chamber/package stays complete during the life of the experiment.
  There are also some granularity issues to consider if the number of 
channels doesn't divide evenly by eight. Has the number of anode wires 
and cathode strips per plane been fixed yet? I've seen at least two sets 
of numbers mentioned. If it hasn't been fixed yet, we'll have to use the 
highest conceivable number for channel count estimates.
  I'm not sure how the CDC spare requirements would be determined.

  Getting back to the first batch of ASICs that will be produced via 
MOSIS, the standard quantity made will be 40 ASICs. For your FDC small scale 
prototype (16ch anode, 64 ch cathode) you would need at least 10 ASICs. Is 
that correct?
  For the CDC prototype there have been 5 x 16ch HV distribution boards 
made so instrumenting all of them will take another 10 ASICs (allthough 
I've only seen a picture of one installed which would only take two 
ASICs).
  So there doesn't seem to be any need to increase the number initially 
produced above 40.
  Gerrard Visser is making 10 ( 16 ch?) postamp/shaper modules which will 
handle 20 ASICs.

John

P.S Dan - could you post the message with your questions to Mitch and his 
reply to this list. I'm sure other people will find it usefull. Thanks.


  
On Mon, 27 Nov 
2006, Daniel S. Carman wrote:

> 
> 
> John,
> 
> Thanks for the quick reply.  My understanding is that the CDC and FDC
> will use the same preamps.  We require about 1500 ASICs and I do not
> know what the number is for the CDC (significantly less).  We need
> to consider what stock of spares we want to keep around.  My approach
> is that you buy the full complement of preamps that you will need for
> the life of the experiment at t=0.  Others may have there own opinions.
> 
> 				Regards,
> 
> 					Daniel
> 
> 
> **********************************************************************
> *                                                                    *
> * Dr. Daniel S. Carman                   e-mail : carman@jlab.org    *  
> * Staff Scientist                        office : (757)-269-5586     *
> * Jefferson Laboratory                   web: www.jlab.org/~carman   *  
> *                                                                    *
> **********************************************************************
> 
> 
> 
> 

-- 
John Schaapman                   Ph: 780-492-3043
Centre for Particle Physics     Fax: 780-492-3408
CEB-158
Mailstop #615
University of Alberta            
Edmonton, AB
CANADA       T6G 2G7