NuMI-L-563
                                                          R. Plunkett

	MINUTES OF THE MINOS INTEGRATION WORKING GROUP
	----------------------------------------------

		 October 17, 1999

Agenda
------

This meeting was held at RAL (actually at Cosenor's house - thanks!) and
concentrated on near detector issues with some discussion of the far 
detector when there were relevant overlaps.

Attending
---------

R. Plunkett (chair), A. Byon-Wagner, D. Ayres, J. Thron, B. Baller,
J. Nelson, E. Peterson , B. Miller , D. Michael, J. Urheim, J. Alner,
P. Adamson (apologies to anyone missed).

Item: Steel Tolerances 
-----------------------

Jeff Nelson presented a recap of the tolerance issues. Near waviness spec 
has been a concern because we might want to make the gap bigger, then the
far must follow. Once gap is set, thickness tolerances set overall length.

Collar is another concern, as it needs to be shimmed during assembly to keep it
straight. Need enough tolerance in center to deal with this. 

During assembly of 4PP, there were crunchy moments when the scintillator 
contacted, probably the collar. Recommendation is to increase the bypass 
tolerance.

Discussion:

	 The bypass tolerance is near the point where another whole strip
will be sacrificed if it is increased. A long discussion of the sag in the
columns and the collar shimming procedure showed people still think this is
a major worry. 

	The waviness problem in the near is probably small enough that it
can be dealt with by retrofits to adjust a few gaps or by plate sorting. 
(Note - a study by Rob shows it's probably less than an 8% problem). We
DECIDED not to recommend changing gap thickness.

	Earl P. proposed that we accelerate purchase of 40 planes of near
steel to see if vendor continues to have problems with the waviness (right
now several plates required rework to meet specs - but it was successful).
Because of the cost, this idea will need to be considered carefully by 
project management.

	The buildup of steel thickness tolerances may also not be a problem,
and there are ways to deal with it (by changing bolt head thickness by a 
little, e.g.). It was decided the length issue needed another iteration to
reach closure. 

Item: Near Module Layout 
------------------------

Bruce Baller recapped his presentation to the scintillator group. The main
remaining issues were the reflector connector and the module layout. It is
also possible to bisect the coil hole by moving modules around, but the 
module layout change is probably preferable.

Discussion:

Doug reported that the scintillator group prefers the reflector connector.
Action items listed below will get more information. Low intensity running
will help understand the time overlaps. 

Going to 16-wide modules looks like the preferred layout solution of this 
meeting. Project management agreed with this idea. Cost needs to be understood,
but is likely to be modest impact.

Item: Trial Near Rack Layout
-----------------------------

Rob presented the current thinking on near frontend rack layout. The number
of phototubes per rack is approx. 30, arranged in horizontal MUX boxes which
hold 4 in one level of 4.5" (for partial planes) or 6 in two levels of 4.5"
(for full planes). Numerology works out to 9 racks. The only way to do this
is to put two racks together so that only one side is accessible for each 
one. If one assumes that there is one M16 handled by one 6U VME card, and 
makes reasonable estimates of power supplies, rack monitoring, and cooling,
there are 3" left over at the bottom of the rack.

Discussion:

	The main concern voiced was that this simple census doesn't prove that
the heat can be removed from such a densely packed rack. A real airflow design
by an experienced engineer is required before we can settle. Obviously the
M16/M64 decision affects this density - first estimates by Rob show that it
would require 5 racks instead of 9, since the electronics is using up a fair
bit of space. There is discussion going on about doubling the density of
the electronics, which may be doable if the cards are long enough.

	As noted below under MUX boxes, some more space could be recovered
by fitting 6 PMT into a single row, if it can be done.

	Jonathan floated an idea to put the MUX boxes and the VME crates on
the same level. This minimizes their cable run, provides an air channel for
cool air, and gives more vertical space. The access difficulties and connection
difficulties look quite serious. 	

Item: Near Mux Boxes (with discussion of far) 
---------------------------------------------

John Alner discussed his trial horizontal Mux box design.
Useful in the near detector, he listed advantages also for
the far detector. This were:

	i) More connector space
	ii) Support bar for fiber strain relief
	iii) Easier to connect near edges (I think - notes confused)

The aluminum box is sturdy and accesses from the rear. A mu-metal shield
is integral to the tube-holding assembly.

Discussion:

	Questions arose about the ability to make 4-wide and 6-wide versions.
(Model shown was 3-wide). Four can be done easily, six needs thought but may
well be achievable. The mu-metal shield needs to be extended into the light-
tight volume to cover the photocathode; can this be done? J.A. will contact
Stuart to discuss shielding. 
	How are cables routed out of the box? No one was perfectly comfortable
with a bundle of RG174 because of bulk and difficulty of mass termination.
Length of cable needs to be held to 3 ft. if possible.

	Conclusion was that more information will be gathered before any 
proposal to change the far detector; this model will be used for
near detector design studies.

Item: Light Injection System 
-----------------------------

	Phil Adamson presented current plans. There are two options in the
far detector for pulser placement. Both have the system either daisy-chained
together with RS485 control lines or hooked to ethernet. Pulsers must 
illuminate the fibers, PIN diodes, and possibly monitor tubes. 

	First option has a pulser box in each frontend rack. Fibers run
30 planes in length, doing 15 planes in the relevant view. Thus each LED
illuminates 15 fibers on different planes. There are 20 LED required by
the module numerology. Please note each LED can actually handle 60 fibers.

	In the second option, pulser boxes are on midlevel. Fibers light up
60 planes. Right now component costs look comparable, with a tradeoff between
fiber runs and extra boxes being looked into. 

	For the near detector the numerology depends on the module with
choice. Need 8 LED for M64, and it's enough for M16 too. May need 2 or
more probably 3 boxes per catwalk in near ==> 2 calorimeter/1 spectrometer.
 
Discussion:

	Concern was expressed about using expensive ethernet modules for
all these connections - is that the right decision by the controls group?
It turns out that there is also a timing cable issue - fiber lengths need
to be evened out for, e.g. PIN diode delay. This needs to have its space
taken into account. 

	In far option 2, the designers were expecting to get 60 connectors
into 15" of vertical space. This could be very difficult, and the group
anticipates that 21" will be needed if this option is adopted. (It's not
the base design right now.) Near detector needs about 30 connectors/box. 

Action items were generated, as listed below.

Item:Near Cavern Width
----------------------

The change to QIE has put pressure on the cavern width in the near hall. 
Agressive choice of narrow racks, 6" for wall utilities, and 8" behind
racks just fit with no extra clearance. Also requires moving cavern over
to eliminate unused inches on magnet side of detector.

Discussion:

	The group felt cost of extra space needed to be pursued with Chris
Laughton. Options to reduce cost impact would be to only do part of the hall,
or to eliminate the DAQ room. 

NOTE: Since this meeting a request to widen the hall by 18" in the downstream
half, and to remove the DAQ room, has been submitted to project managment. - RP

Item: Survey Needs
-------------------

Dave Ayres pointed out that there is not yet a L3 manager for survey, and 
some question about the exact extent of the survey needs. The 4PP used a lot
of time and expensive equipment; we have costed cheaper equipment with some
labor help in the TDR.

Discussion:

	Doug feels strongly that there is not a need for supreme accuracy in
the survey. These are 4cm strips dominated by multiple scattering. Discussion
focused on the possibility of measuring the one important coordinate (the
transverse strip edges) with simple tape measure and jig setups. Several
ideas were advanced, like a collar jig to measure from the hole outwards. 

	It was recommended that we measure the last plane with a tape technique
to compare with what the surveyors get. 

Action Items
------------

	- Fermilab will measure the timing distribution of a reflector
connector on a module, and draw up a near detector layout using them.

	- Electronics group needs to give a PIN diode interface concept
to the the integration group - suggested by review of near electronics.

	- Integration group to communicate module layout specifics to 
Sussex ASAP.

	- Steel group to communicate scale field varies over, as it affects
survey needs.

	- Scintillator module edges to be measured with tape before plane 
raised!!!

							R. Plunkett
							9/12/99

Please note: any errors are entirely my fault and can be corrected if
necessary.