sPHENIX HCal discussion

[eric mannel <mannel AT bnl.gov>]

Folks-

Some time ago, we agreed that we would bring 24 signals out the north 
and 24 signals out the south end of the iHCal.  The implications of this 
are that we would need to run 1 16-channel and 1 8-channel cable from 
the iHCal and plug 2 8-channel iHCal channel cables into a singe 
connector on the digitizer board. This balances the cabling 
north/south.  An alternative would be to route 32 channels to one end 
and 16 channels to the other.  The implications here are which end do 
you route the 32 channels, all north or all south? 50/50 and hope you 
get all the modules correctly assembled and installed.  And just to be 
completely open, there is a small difference in timing.  For the case of 
24 North and 24 south I estimate that the timing difference is going to 
be of oder 7 nSec or ~1/2 a digitizer timing bin. If we go with with 16 
and 32 channels N/S then the difference will increase by by 3-4 nSec.  
For analysis, I don't think this is an issue, for triggering, again, I 
don't think it is an issue, but I just want it to be on the table.

The reason I am bringing this up is that Frank has sent me the lengths 
for the interior signal cables, and I want to place the order for cables 
and start assembly when they come in. Once I do that the choice is 
made.  It can be changed at the cost of dollars and time to redo cables.

I would like to get a consensus on which way to do it, so I can move 
forward next month with ordering cables and parts.

Eric


--
Eric Mannel, Ph.D.
PHENIX Group
Dept of Physics
Brookhaven National Lab.
631/344-7626 (Office)
914/659-3235 (Mobile)