1. GlueX collaboration meeting, Newport News, March 29-31, 2007 Discussion of the detector material budget  What is the thickness of our inner detectors (start counter, chambers)?  Where and how does it impact GlueX physics?  In what areas might we improve?

2. GlueX collaboration meeting, Newport News, March 29-31, 2007 Where do the gammas convert?

3. GlueX collaboration meeting, Newport News, March 29-31, 2007 Where do the gammas convert? Bcal (blue) Fcal FTof Cerenkov gas FDC cables FDC frames

4. GlueX collaboration meeting, Newport News, March 29-31, 2007 Consequences for reconstruction this one is reconstructed OK this event cannot be reconstructed

5. GlueX collaboration meeting, Newport News, March 29-31, 2007 Consequences for reconstruction

6. GlueX collaboration meeting, Newport News, March 29-31, 2007 Consequences for reconstruction black points: in “good cluster” peak red points: in “fragmented cluster” peak caveat: Not all “good clusters” contain the full energy of the original shower.

7. GlueX collaboration meeting, Newport News, March 29-31, 2007 Impact on physics  Multi-photon events (with  0, ’   b … ) will be hit with powers of conversion improbability in the acceptance.  Nuclear interaction lengths are a factor 2-3 longer in light materials, primarily degrades the PID capability.

8. GlueX collaboration meeting, Newport News, March 29-31, 2007 Where might we improve?

9. GlueX collaboration meeting, Newport News, March 29-31, 2007 Where might we improve?

10. GlueX collaboration meeting, Newport News, March 29-31, 2007 Where might we improve?

11. GlueX collaboration meeting, Newport News, March 29-31, 2007 Where might we improve?

12. GlueX collaboration meeting, Newport News, March 29-31, 2007 Where might we improve?