1. Diamond Radiator Assessment Report on the CHESS run May 1-7, 2009 Richard Jones, Igor Senderovich, Franz Klein, Pawel Nadel-Turonski GlueX collaboration meeting, Newport News, May 11-13, 2009

2. 2 Run Overview April 30: install and align monochromator May 1-4: study monochromator alignment issues May 4-6: accelerator down, power short in machine May 6: start scans of BNL diamond May 7: scans with BNL diamond remounted May 8: scans of Hall B diamond – radiation damage assessment

3. GlueX collaboration meeting, Newport News, May 11-13, 2009 3 The BNL diamond It is pollen season in Connecticut

4. GlueX collaboration meeting, Newport News, May 11-13, 2009 4 The BNL diamond Optical image has “facets” that become visible when held at the right angle Surface or deep features?

5. GlueX collaboration meeting, Newport News, May 11-13, 2009 5 The BNL diamond Crystal dimensions 4mm x 4mm x 300  m

6. GlueX collaboration meeting, Newport News, May 11-13, 2009 6 CHESS beamline C Hutch Diffractometer CHESS staff member Ken Finkelstein

7. GlueX collaboration meeting, Newport News, May 11-13, 2009 7 The GlueX monochromator white beam first crystal reflects upward second crystal reflects back to horizontal

8. GlueX collaboration meeting, Newport News, May 11-13, 2009 8 The GlueX monochromator Second mono crystal hangs upside down. Gravitational strain is “large” ~ 400 nm

9. GlueX collaboration meeting, Newport News, May 11-13, 2009 9 The GlueX monochromator “ideal” monochromated beam shape actual monochromated beam shape 2009 can displace back and forth by rocking the mono angles can take rocking curves

10. GlueX collaboration meeting, Newport News, May 11-13, 2009 10 BNL diamond: first look

11. GlueX collaboration meeting, Newport News, May 11-13, 2009 11 BNL diamond: first look FWHM 200  r GlueX spec 20  r RMS

12. GlueX collaboration meeting, Newport News, May 11-13, 2009 12 BNL diamond: first look Interpretation of double-peak structure  t

13. GlueX collaboration meeting, Newport News, May 11-13, 2009 13 Diamond mounting issue Interpretation of double-peak structure xx yy  x = 200 Hz  y = 180 Hz Maybe a bad place for mechanical vibrations?

14. GlueX collaboration meeting, Newport News, May 11-13, 2009 14 Diamond mounting issue Hypothesis: maybe resonant, shift frequency add some large masses to the strings shift down the frequencies by by ~ 1 order magnitude

15. GlueX collaboration meeting, Newport News, May 11-13, 2009 15 Diamond mounting issue FWHM 800  r factor ~4 worse!

16. GlueX collaboration meeting, Newport News, May 11-13, 2009 16 Diamond mounting issue Radical approach: Get rid of the wires 1.remove diamond from wire mount 2.stick a clump of wax on the end of a post 3.stick the diamond into the wax

17. GlueX collaboration meeting, Newport News, May 11-13, 2009 17 Vibration-reduced mount FWHM 10  r consistent over entire crystal !! GlueX spec 20  r RMS

18. GlueX collaboration meeting, Newport News, May 11-13, 2009 18 Also measured  A full scan of the Hall B working diamond ( 50 micron “G50”) first comparative measurement  Was measured before in 11/2006 at CHESS – first comparative measurement!  We think the radiation dose map since 11/2006 can be extracted from Hall B logs.  First quantitative estimate of rad. damage.

19. GlueX collaboration meeting, Newport News, May 11-13, 2009 19 Status and Outlook  Hopes that the new generation of CVD diamonds from Element Six might be good enough for GlueX have been confirmed.  Existing monochromator crystals we have used at CHESS are not sufficiently rigid.  With new crystals, we can set up in a few hours and run a rocking curve in 30 min.  Wire mounting is problematic. New ideas are needed, or a more design with vibration damping. Collaboration with BNL diamond development group promises to be very fruitful for GlueX!