Cooling Workshop 11-JUNE-1998
Electronics systems in the zone between the inner and outer shielding "snouts"
			Committee Report

Presentations were made by experts from each of the subdetector groups on the
cooling requirements for the electronics systems located in the trapped
volume bounded by the end cap, the inner and outer shielding "snouts", and
the muon toroid.  In overview, the systems have the cooling provisions
listed below:
COT Repeater Cards  -  in thermal contact with a water cooled copper plate
9U VME Crates       -  rack mounted with water/air heat exchangers and fan
			trays pushing air at about 1000 CFM
Plug PMT Boxes	    -  well insulated and controlled to +- 2 F with resistive
			heater and thermoelectric cooler combination; the hot
			terminal of the Peltier plate is water cooled
CAEN HV Units	    -  air cooled with internal fans, needs 20 +- 10 C
SMD Minicrates      -  air cooled with a fan tray, asked for +- 5 C
In addition, the temperature of the chilled water (nominally 55 F) is slave to 
the dew point temperature in the first and second floor counting rooms at 
present, with the collision hall dew point yet to be added.  There no longer is
humidity control in the counting rooms and some recent weekend data showed >10 
degree F excursions of the cooling water due to humidity problems.

The main findings concerning the cooling situation in this zone are:
* 7 to 10 kW per end are being dumped into the air depending on the operating
  temperatures of the COT repeaters and the PMT boxes
* there could be very large thermal gradients top to bottom
* the only system with a tight specification on temperature range, the PMT
  boxes, is insulated and internally regulated, but the calibrations were all
  taken at 78 F in the test beam
* the relay racks systems are capable of 1 or 2 kW of refrigeration in excess 
  of that needed to cool the electronics and power supplies inside
* humidity problems in the counting rooms are causing unacceptable excursions
  in the electronics cooling water temperature

Recommendations
Of the numerous ideas discussed and possibilities explored for dealing with the 
waste heat and air cooled systems, the committee has been persuaded that a 
centralized solution with feedback and monitoring is preferred for reasons of 
cost, maintenance and reliability.  The recommendations below are directly 
derived from that point of view:
1)  Provide additional refrigeration to remove the 7 to 10kW of waste heat from
    the air which includes proportional control for the discharge temperature.
2)  Provide air circulation sufficient to overcome and control thermal
    gradients.
3)  Install temperature monitoring probes in the zone and close to the air 
    cooled systems to provide situation awareness and diagnostics for tuning.
4)  Install water/air heat exchangers on both the bottom and the top of the
    relay racks for stability of the lowest crate and to maximize the
    local refrigeration capacity.
5)  Operate the COT Repeater Card cooling plate with the standard electronics
    cooling water.
6)  Determine the temperature set point for the Plug PMT Boxes by experience.
7)  Stabilize the electronics cooling water temperature.

Observations
A number of good ideas surfaced during the workshop discussions and are 
listed here for the record.
i.	Providing additional air refrigeration and circulation can be done
	using fan, heat exchanger and duct systems which discharge into the 
	six-inch space at the face of the toroid iron.  Two 5 kW units may 
	be superior to a single 10 kW unit.
ii.	If practical, the air flow through the two relay racks could have
	the same "handedness" to enhance the circulation.
iii.	The temperature monitoring sensors recommended above could be
	additional stations on the DALLAS bus for the PMT box sensors.
iv.	The luminosity monitor system is sufficiently isolated from this
	end plug zone that the waste heate from its PMT bases can be
	removed by the flow of dry nitrogen planned for other reasons.

Participants: (some wear more than one hat, some were there by proxy)
COT		M. Binkley, K. Pitts
PMT Boxes	G. Apollinari, M. Lindgren, L. Kirsch
CAEN		G. Apollinari, (S. Zucchelli) 
VME Racks	T. Devlin, S. Orr, R. Schmitt
SMD Crates	(G. Drake), C. Drennan
I&I		R. Roser, R. Schmitt
Luminosity	J. Konigsberg
Committee	A. Byon, R. DeMaat, C. Drennan, J. Elias, S. Orr,
		K. Schuh, A. Tollestrup