This meeting was called on short notice because of new proposals from the alignment group which must be considered quickly if they are to be incorporatedinto the P2" prototype.

Present status:  Wisconsin has received assembly drawings they believed were approved assembly drawings from Fermilab showing the frame pieces.  On machined; long extrusions are out on bid and the machining has not started yet.

Nelson made the point that these assembly drawings were not approved or released despite the fact that his name was shown in the checked and approved box (it was in error).  He also stated he is not
responsible for frame drawings so it is not possible to have "approved" drawings from Fermilab for the frame pieces.  In fact,  Nelson was not aware of the new alignment proposals made by Dave Eartly or of the potential impact on the chamber design since it had not been discussed at Fermilab.

On the wide edge of the P2" chamber the Fermilab drawing of the frame assembly showed M6 threaded holes located 38mm from the bolt center line, not 20mm as specified in the Wisconsin drawing.  No one could explain this discrepancy.

Drawings:  It was agreed that Wisconsin would be responsible for parts and services outside the chamber body (panels).  So Wisconsin drawings would be controlling for the frame and all alignment pads/plates etc.  But Fermilab is responsible for the pin holes in the panels.  However, it was agreed that we must have closer contact to ensure that alignment pin holes in the panels must match those in the frame.

Nelson described the Fermilab drawing directory location:

Alignment proposal:

 *  narrow end -- The solution agreed on 26 Mar '99 has two holes milled in the back side of the top panel.  It is difficult to perform this milling with the required accuracy.  Instead it was concluded at Fermilab that holes along the bolt centerline are preferred.  Dave proposed a large C-bracket located by the holes on bolt centerline with precision holes to mount the alignment sensor.  It was felt this
proposal did not provide sufficient mechnical stiffness; it was subject to the distortions of the frame extrusion due to the z bracket bolts.  Glueing the large C-bracket to the top panel was also rejected because an important chamber requirement is that it must be possible to disassemble the
chamber for maintenance.  Another constraint is the need to insert shims under the chamber mount bracket to compensate for chamber stackup variance.

We agreed on a rectangular block roughly 90 x 250 mmsq and 1/2" thick glued to the panel according to present drawings.  The location of this plate would be determined using a pin transfer jig and locating on the top panel holes on bolt centerline. Wisconsin will produce a drawing and an alignment plate from 1/2" jig Al plate  with the nominal holes for mounting the alignment sensor (see drawing) for the P2" prototype.

Fermilab will design and fabricate this pin transfer jig once the Wisconsin drawings are received.  Fermilab will also incorporate the location of this plate into the Fermilab drawings.

This requires two additional 0.44" clearance holes in the frame separated by 11.3+/-0.040" located symmetrically on the bolt centerline.  Wisconsin will add these holes to the P2" frames already machined and alter the frame drawings appropriately.

*  wide end -- The alignment proposal for the wide incorporated a larger footprint with 3 M6 threaded holes instead of 2 M6 threaded holes.  The larger footprint resulted in two of these holes being located exactly where the cathode FEB cables pass.  It was decided that the mounting screws should not be located in the projected path of these cables.

The new proposal used standard 6mm pins with ground spacer sleeves instead of a custom shoulder design. It was felt that the shoulder design provided significantly more stability, particularly if we have
only 2 mounting screws (instead of 3).

During the discussion it was noted that the present alignment pin on the wide end is located directly in the path of cathode cables.  We recently increased the height of this pin so the photogrammetry target will be clearly visible.  As a result these cables cannot reasonably go "over" this pin, but must go "around" it.  We will need to revisit this design during the commissioning of P2".

*  tower -- The reason for proposing a larger footprint was to increase the stability of the tower, which will be about 370mm high.  Wisconsin will produce a design for such a tower and a prototype.  Wisconsin will also estimate the stability of this tower.  The design is likely to
use a Al I-beam with welded flanges at each end.  One tower will be fabricated for the P2" prototype.

lemo connectors: It was agreed to locate the lemo connectors for the test strips on the HV side of the chambers near the narrow end of the trapezoid.  However, for the ME23/2 chambers these lemo connectors are located on the anode side near the wide end of the trapezoid.

HV connectors:  The HV connectors for P2" should be spaced 5.75" from the corner bolt hole instead of 5.4" to provide clearance for the connector shell.  This location has beenchanged inthe Wisconsin drawings and will be forwarded to the succesful bidder for machining on the long frame extrusion pieces.

 For P2" we must use the existing HV cable assemblies.  Hence the mounting plate of the connector shell must be modified to match the design approved at the 26 Mar '99 meeting.  Fermilab will modify the shells to match the approved hole pattern for P2".

For the ME1/2 chambers it was agreed to move the location of the HV connectors to the midpoint of the HV side frame extrusion or lower connectors will not interfere with the cathode electronics cooling mechanics.  It also means the the HV connector (which is the highest point of the chamber) will not interfere with the MABs.