1. Curtis A. Meyer 20 May, 2004 GlueX Detector Infrastructure The issue of infrastructure includes details of how we assemble the detector as a whole. How we know where things are, and monitor them, and how we service the detector under a series of failure scenarios. Curtis A. Meyer – Carnegie Mellon We have known that this was an issue since our First version of the design report. A lot of ideas Have been floated, but we have Not looked at it carefully as a collaboration until now. (1½ hour session on Friday just before lunch.)

2. Curtis A. Meyer 20 May, 2004 What do we need? In the near future, we need a plausible plan on how we assemble the detector and how we service it. We need to quickly identify bottle necks that would require early allocation of resources. We need rough costing on the infrastructure required to carry out this task. We need an updated and expanded section in our design report that reflects this work.

3. Curtis A. Meyer 20 May, 2004 The Scope of This Effort While we clearly want a plan for the entire detector, some aspects are more critical than others. We have in some sense broken the detector into four sections. (1) Upstream Region – Backwards Veto (2) Target Region – Vertex Chamber + Target (3) Inside Magnet – CDC, FDC and BCAL (4) Downstream – Cherenkov, TOF and Pb-Glass At this point in time we are focusing on (2).

4. Curtis A. Meyer 20 May, 2004 Issues Inside The Magnet We are living in a confined space from which we need to supply high voltage, low voltage, chamber gas …, and to remove heat, signals and used gas. All of the tracking devices live here, and accurate inter-calibration is crucial to the ultimate resolution of the system. Servicing these elements requires moving other detector elements

5. Curtis A. Meyer 20 May, 2004 Space Concerns 95 cm 90 cm BCAL 65 cm CDC 60cm 14cm Solenoid Have we allocated enough space for infrastructure? Move CDC in by 1-2 cm? Move BCAL out by 1-2 cm?

6. Curtis A. Meyer 20 May, 2004 Loading Issues The BCAL is ~800kg per each of 48 modules ~38000kg How is this supported by the magnet? The BCAL will settle over time as the lead flows. What can we mount the chambers to? Chamber loads on BCAL? CDC 400-700kg on endplates FDC 4 packages 200-300kg each

7. Curtis A. Meyer 20 May, 2004 Positioning Issues The chamber packages need to be aligned at the 50-100 micron level. We cannot rely on a rail system to do this, a rail system should reproduce things at the mm level. How do we achieve, maintain and monitor the desired accuracy?

8. Curtis A. Meyer 20 May, 2004 Lead Time Issues Are there long lead-time items that are required for assembly? It may be necessary to install the BCAL and let it sit for 3-6 months to settle? What is the impact on the detector installation? Do we need the entire BCAL for early assembly?

9. Curtis A. Meyer 20 May, 2004 Servicing We have made a statement in the past that we want to have access to any detector element in one shift. Is this still a valid statement? We need to catalog what failures could happen to each detector element. Estimate the chance of such a failure, and then identify what we would have to do to fix it or live with it? The FDC is probably the hardest element to get to.

10. Curtis A. Meyer 20 May, 2004 Alignment An over constrained rail system can freeze up and lock detectors in place. We need to design a flexible system that can reproduce positions to the mm level. We want a hardware solution to provide alignment at the 50-100micron level. We need a software solutions that verifies the hardware alignment. (Note that in zero-field, the chamber calibrations will be significantly different than in full field.)

11. Curtis A. Meyer 20 May, 2004 Infrastructure Meeting Agenda 11:00 – 11:10 Introduction C. Meyer 11:10 – 11:25 BCAL Installation Regina 11:25- 11:45 Discussion 11:45- 12:00 Rail Systems Ravi 12:00 – 12:30 Discussion

12. Curtis A. Meyer 20 May, 2004 A Plan We need to be able to put together a plausible and defendable plan for all of these items and include it in our design report. We need to settle space issues now so that we can begin design of the final detector elements. We can still do this with a minimum of effort, but changes get harder as we go along. All relevant parties have to sign off on our scenario and we need to be able to have a reference to make sure that we maintain consistency with it.