To: Distribution 9 August 96

From: Martin Nordby

Subject: Minutes of the IR Engineering and Physics Meeting of 9 Aug 96

Hard-Copy Distribution:

Bob Bell	41	Jim Krebs	41
Lou Bertolini	LLNL L-287	Dave Kirkby	95
Gordon Bowden	26	Harvey Lynch	41
Pat Burchat	95	Tom Mattison	17
David Coward	95	James Osborn	LBL B71J
Scott Debarger	17	Eric Reuter	18
Hobey DeStaebler	17	Andy Ringwall	17
Jonathan Dorfan	17	Knut Skarpaas VIII	18
Stan Ecklund	17	John Seeman	17
Alex Grillo	95	Mike Sullivan	17
John Hodgson	12	Uli Wienands	17
Hank Hsieh	LBL B71J	Mike Zisman	LBL B71J
David Humphries	LBL 46-161	Lowell Klaisner	17
Roy Kerth	LBL 50-340	Burl Skaggs

Electronic Distribution:

Catherine Carr	Nadine Kurita	Natalie Roe	Rick Wilkins
David Coupal	Georges London	Ross Schlueter	Fran Younger
Fred Goozen	Joseph Rasonn	Joe Stieber
Rick Iverson	Jeff Richman	Jack Tanabe

Q2/4/5 Raft Update

Scott Debarger gave an update on the design of the Q2/4/5 Raft. The focus of late has been on modifying the out-board end of the Raft to fit around the Q5 Magnet Cradle. This has been done in conjunction with the Cradle design at LLNL, with 1" diameter rod-end-type supports joining the cradle to the Raft. Two rectangular structural tubes skirt the Q5 Cradle. This tubing was lowered and flared wider around Q5 to leave room for these rod-end supports. The aspect ratio of the cross-section of the Raft/Magnet combination is similar to the original design, so the overturning moment due to lateral earthquake loads is similar.

The "canoe-shaped" part of the Raft which runs under the Q4 Magnet begins the flare into the two tubes 60 mm out-board of the end of the DIRC S.O.B. magnetic shielding. This start of the flare was moved in-board to leave more room under the out-board end of Q4 for water manifolds, and to make the flare more gentle, thereby better transmitting the high bending moments across the transition.

The out-board support for the Raft is at z = 6247 mm from the I.P. This is 1/3 of the way into Q5.

Next Steps:

--Layout Q2 Shielding Plug and removal: check that the plug does not interfere with the Raft at the flare. In conjunction with this, BaBar people will work on eliminating the interference between their removal tracks and the Raft. (Catherine Carr, Ed Hajdena)

--Continue Raft analysis: finish FEA model of Raft, and check that sizes of support members are adequate. (Scott Debarger)

Raft Pier Design Concept

Martin Nordby showed a first pass at a design for concrete piers under the Q2/4/5 Raft. These replace the old A-Frame Raft Base design. The intent is to provide a more stable, yet cheaper base, that could be installed for HER commissioning in January, 1997.

The concept was sized for the backward end, leaving 300 mm clearance with respect to the volume swept by the opening of the DIRC S.O.B. door. The top of the pier is 12 inches below the bottom of the Q2/4/5 Raft, to leave room for the rolling support members at 6247 mm. This puts the top of the pier 12.4" below the elevation of the tunnel floor, so one or two steps up would be needed to get into the tunnel.

The Pier concept shown had cable trays mounted on its in-board face. These would hold D.C. cables, which exit the canoe-shaped part of the Raft under Q4. Cable trays and water manifolds are mounted on the side of the pier lying inside the PEP-II rings. This allows for easy routing of trays and pipes to the existing PEP-II infrastructure, without crossing over the beamline, or blocking access to walkways or BaBar cable routes.

On the radially inward face of the pier, the manifolding and heaters for the chilled LCW system would be mounted. This puts it as close as practical to the Support Tube entrance, but still provides direct pipe runs to the access shafts, so the chiller could be mounted upstairs in the support building.

Burl Skaggs showed layouts of a pier concept which is based on the bridge design used in the other, unused IR halls. This includes a tunnel through the pier, for access to the PPS tunnel and the inside of the ring. A further change could include burying cable ways or tubes through the concrete, so cables could be routed through an otherwise unused region. This could potentially buy back space on the hall floor which could be used for mounting racks.

The modified-bridge concept also included cut-outs for cable trays which are routed along the wall under the tunnel mouth on the south (Forward) wall. Since the top of the pier is 12 inches below the tunnel floor, the amount of concrete above these cut-outs or tunnels is less than in the standard bridge design. Burl will look into this. Another structural issue needing attention is the width of the pier. Making the pier wide reduces the possible seismic uplift loading on the dowels into the floor. However, this also uses up real estate. Therefore, the width should be reduced as much as practical (bearing in mind that the natural frequency of the pier will decrease as it is narrowed).

The permanent pier concept was generally approved by BaBar and PEP-II people as the working design. No functional or spatial interferences were known of (especially regarding the various BaBar sub-system).

Next Step:

--Fold together details from the other bridge designs into an updated pier concept. Work up a pier concept for the forward end. (Martin Nordby , Burl Skaggs)

--Layout rack locations and rough cable routing for BaBar sub-systems, using the pier concept. (Jim Krebs)

--Modify the Q2 Shielding Plug removal system, using the updated Q2/4/5 Raft design, possibly mounting off the face of the pier. (Ed Hajdena)

--Present the pier concept to the wider BaBar community at a BaBar integration meeting for approval. (Martin Nordby, Jim Krebs)

These minutes, and agenda for future meetings, are available on the Web at:

http://www.slac.stanford.edu/accel/pepii/near-ir/home.html