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Diamond Radiators for GlueX

GlueX Collaboration Meeting, Bloomington, May 9-11, 2011. Diamond Radiators for GlueX. Richard Jones, UConn Igor Senderovich, UConn Brendan Pratt, UConn James McIntyre, UConn Fridah Mokaya, UConn Chris Pelletier, UConn Jessica Hyde, E.O.Smith High School Ken Finkelstein, CHESS

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Diamond Radiators for GlueX

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  1. GlueX Collaboration Meeting, Bloomington, May 9-11, 2011 Diamond Radiators for GlueX Richard Jones, UConn Igor Senderovich, UConn Brendan Pratt, UConn James McIntyre, UConn Fridah Mokaya, UConn Chris Pelletier, UConn Jessica Hyde, E.O.Smith High School Ken Finkelstein, CHESS Yi Qiang, JLab Status Update – May 2011

  2. Outline • Review of project goals • Obstacles overcome since Jan. 2010 • New ideas under test in 2011 • Results from recent CHESS run • Remaining challenges GlueX collaboration meeting, Bloomington, May 9-11, 2011

  3. Review of project goals Diamond radiators with the following properties: thickness: 15 - 20 microns uniform area: 4 x 2 mm2 (per beam spot position) rocking curve width: < 20 mrad RMS (whole-crystal) Radiator mount with the following properties: low mass: > 98% of beam photons from diamond thermally robust: stable operation at full beam intensity vibration resistant: twist modes < 10 mrad RMS amplitude low stress: thin crystals are very susceptible to bending These two are in tension with each other GlueX collaboration meeting, Bloomington, May 9-11, 2011

  4. Accomplishments since Jan. 2010 Complementary techniques laser ablation is the standard option RCMP is the backup option (depends on SBIR funding) RCMP may be useful with laser ablation (clean ablated surface) a third possibility has re-emerged: thinning by E6 mystery facilities A lot depends on what happens in the next 12 months: Laser refurb. does not hit a show-stopper Sinmat’s interest in our project is maintained depends on SBIR funding or finding another source of funds Our collaboration with CHESS staff is maintained we should carry out the upgrade they requested We can procure a set of Element Six diamonds of our own from Diamond Radiator R&D talk, Jan. 2010 GlueX collaboration meeting: completed successfully Phase I SBIR awarded Phase I goals reached Phase II proposal submitted continues well work done, $tbd done GlueX collaboration meeting, Bloomington, May 9-11, 2011

  5. UConn student projects in 2010/2011 • Diamond radiator thinning using an excimer laser – Brendan Pratt • Controlled tensioning of carbon fiber bundles – Jessica Hyde • A direct imaging technique for vibrational analysis – Chris Pelletier • Construction of a tabletop Michelson Interferometer – Chris Pelletier • Stretched mylar films for low-stress diamond targets – James McIntyre GlueX collaboration meeting, Bloomington, May 9-11, 2011

  6. New Ideas under test in 2011 Solving problems with crystal vibrations: reduce vibrations by raising w0(ambient f ~ 1/w3) change mount to low-Z material(W wire → C fiber) test using a high-tension membrane (avoid adhesive) Investigating the causes of crystal curvature: external vs. internal stress engineering active correction into the mount Comparing intrinsic rocking curves of different grades Sinmat 9 micron thinned CVD sample ‘‘CVD single-crystal’’ vs. ‘‘electronic grade SC’’ nature of E6 ‘‘mystery 10 micron crystal’’ GlueX collaboration meeting, Bloomington, May 9-11, 2011

  7. Report on recent CHESS run New Si (331) monochromator designed to do diamond (2,2,0) diffraction asymmetric / symmetric double-bounce, expansion factor x8 uniform beam spot 10 x 10 mm2one pass per rocking curve only few hours needed for initial beamline setup stable operation over several days, minor tweaks after each fill ~ 2mrad RMS rocking curve observed in diamond (2,2,0) – best ever! New stretched mylar double-hoop mount few minutes to change out diamond targets holds diamonds of any thickness negligible attenuation of X-rays in the mylar vibration broadening of rocking curve is below limits of observation Many different samples studied: 4.5 days, 10 samples, >20 rocking curves GlueX collaboration meeting, Bloomington, May 9-11, 2011

  8. Setup for diamond diffraction at CHESS monochromatic 15 keV highly-parallel X-ray beam 1cm x 1cm spot size dispersion-matched to diamond (2,2,0) planes new Si(331) monochromator UConn design, built at CHESS CCD camera He gas second crystal symmetric Si(3,3,1) first crystal, water cooled pure Si 15.3° miscut from (3,3,1) expansion factor b ~ 8 at 15 keV X-ray energy Huber 4-circle gonimeter q, c, f, 2q white beam from C-line bending magnet GlueX collaboration meeting, Bloomington, May 9-11, 2011

  9. Sample inventory for May, 2011 run • 1 Sinmat 9 micron diamond (SINMAT-9) • 1 Element 6 “mystery” 10 micron diamond (E6-10) • 2 pristine (300 micron) CVD “electronic grade” plates, 4mm x 4mm • PRISTINE-A • PRISTINE-B • 4 pristine (300 micron) CVD type 3A SC plates, 3mm x 3mm • PLATE-A • PLATE-B • PLATE-C • PLATE-D • 1 silicon (1,1,1) 50 micron single crystal, large area (SI-SHEET) • 1 silicon (1,1,1) thick block, reflection geometry (SI-BLOCK) GlueX collaboration meeting, Bloomington, May 9-11, 2011

  10. SINMAT-9 • sample was purchased on E6 web site as “CVD single-crystal plate” (~$100) • surface normal close to (0,0,1) direction, mis-cut angle ~ 1° • sample was broken in 2 pieces during removal from thinning apparatus • X-ray image reveals why it broke where it did – two line defects clearly visible (0,1,0) (1,0,0) GlueX collaboration meeting, Bloomington, May 9-11, 2011

  11. SINMAT-9 • sample was purchased on E6 web site as “CVD single-crystal plate” (~$100) • surface normal close to (0,0,1) direction, mis-cut angle ~ 1° • sample was broken in 2 pieces during removal from thinning apparatus • X-ray image reveals break propagates into the crystal – cuts are clearly visible (1,0,0) torn flap hangs down (0,1,0) GlueX collaboration meeting, Bloomington, May 9-11, 2011

  12. SINMAT-9 • whole-crystal rocking curve is quite bad • local rocking curve width is very good, except near the defects • essentially all of the whole-crystal width comes from large-scale strain CESR refilled GlueX collaboration meeting, Bloomington, May 9-11, 2011

  13. SINMAT-9 • similar pattern is seen in the broken-off “dog-ear” chip • looks like break occurred along what was originally a growth boundary growth boundary GlueX collaboration meeting, Bloomington, May 9-11, 2011

  14. Summary for SINMAT-9 • Intrinsic rocking curve width meets GlueX spec. • Defect structure dominates the global rocking curve. • Large-scale curvature is along the defect strain axis. • This crystal is not usable for GlueX • It appears that the existing strain pattern is residual damage from the event that broke the crystal. • DOE Phase I schedule (6 months) was tough to meet. • Sinmat to improve their handling of thin samples. so but GlueX collaboration meeting, Bloomington, May 9-11, 2011

  15. E6-10 • mystery diamond – unknown crystal grade, unknown orientation • M. Frazer (E6) said it was cut with (1,1,0) direction normal to surface • no luck with that, resorted to wide-beam Laue diffraction • crystal is miscut ~5.5° away from the (0,0,1) normal – bizarre… (1,1,0) (-1,1,0) GlueX collaboration meeting, Bloomington, May 9-11, 2011

  16. E6-10 • whole crystal rocking curve is extremely broad • no evidence of localized defects, as seen in SINMAT-9. • strain pattern somehow different in the two projections – sample moved? • “Due to the limitation of χ angle, the sample was taken out from the holder and rotated 90 degrees before put back.” (-1,1,0) (1,1,0) GlueX collaboration meeting, Bloomington, May 9-11, 2011

  17. E6-10 has good regions and not-so good regions GlueX collaboration meeting, Bloomington, May 9-11, 2011

  18. Summary for E6-10 • Intrinsic rocking curve width close to GlueX spec. • Some evidence of significant defect structure. • Curvature too large to explain from mounting stress. • This crystal is usable for GlueX in one orientation. • We would need to find a way to hold it flat. • Stretched mylar mount might be responsible for creating some large-scale deformation – can we check this? so but GlueX collaboration meeting, Bloomington, May 9-11, 2011

  19. E6-10 • take E6-10 out of the mylar mount, place it freely resting on a post • take a rocking curve in reflection geometry – angles are not ideal, but ... • “potato chip” large-scale curvature is still apparent. GlueX collaboration meeting, Bloomington, May 9-11, 2011

  20. PRISTINE-A • 4mm x 4mm x 300mm “electronic grade” single crystal ($1200 apiece) GlueX collaboration meeting, Bloomington, May 9-11, 2011

  21. PRISTINE-A • 4mm x 4mm x 300mm “electronic grade” single crystal ($1200 apiece) GlueX collaboration meeting, Bloomington, May 9-11, 2011

  22. PRISTINE-B GlueX collaboration meeting, Bloomington, May 9-11, 2011

  23. PRISTINE-B GlueX collaboration meeting, Bloomington, May 9-11, 2011

  24. PLATE-A GlueX collaboration meeting, Bloomington, May 9-11, 2011

  25. PLATE-B GlueX collaboration meeting, Bloomington, May 9-11, 2011

  26. PLATE-C GlueX collaboration meeting, Bloomington, May 9-11, 2011

  27. PLATE-D GlueX collaboration meeting, Bloomington, May 9-11, 2011

  28. Summary for PRISTINES / PLATES • From GlueX point of view there is no real difference between “electronic grade” and standard CVD type 3A. • No significant defect structure in any of these 5 plates. • Prices are factor of ~5 cheaper for standard type 3A. • These crystals are all usable for GlueX in both orientations, provided that they can be thinned. • Stretched mylar mount did not distort these ones – no surprise – they are very stiff at 300 microns! GlueX collaboration meeting, Bloomington, May 9-11, 2011

  29. SI-SHEET • SI-SHEET is a large circular disc of pure single-crystal silicon 50 microns thick. • sandwiched between the mylar sheets in our stretched mylar mount • transmission-mode rocking curve, taken with (3,3,1) planes GlueX collaboration meeting, Bloomington, May 9-11, 2011

  30. SI-SHEET • There is a large area where the flatness is fairly good • Leading-order distortion is quadrupole, as expected. • Center is up and to the right – was adjusted later. • Size of curvature is roughly consistent with MI images images taken at UConn. • Engineered corrections should enable us to null the quadrupole moment. GlueX collaboration meeting, Bloomington, May 9-11, 2011

  31. Summary of present status • We now know how to mount diamonds at CHESS in a flexible and non-destructive fashion, so that vibrations are not an issue. • We now have one (excessively?) thin diamond that is usable for GlueX in one orientation – but we don’t know how to hold it flat. • We have a pretty clear idea how to modify our stretched mylar mount so that it can hold thin diamonds within our flatness spec. • Getting top quality diamond material is not going to be a problem. • Getting thin diamonds is probably not going to be a problem. • Getting thin diamonds to lay out flat without a rigid support behind them is not going to happen. Flatness is our unsolved problem. GlueX collaboration meeting, Bloomington, May 9-11, 2011

  32. Current ideas for radiator support • Start with a large area (6mm x 6mm x 0.3mm) CVD diamond Use the excimer laser to mill out a thin section out of the center for the beam spot Use the excimer laser to cut out a rectangular hole, then stick a thin wafer on the back     van der Waals bond might be sufficient requires precise laser control GlueX collaboration meeting, Bloomington, May 9-11, 2011

  33. UConn diamond ablation facility • consistent operation now obtained at 192 nm (Ar + F + He gas) • recent upgrades: new chiller (rep. rate 2 Hz → 50 Hz), mirrors, safety, etc. • ablation vacuum chamber designed, constructed in UConn shop • new focusing optics • diamond mount, diamonds in-hand, first cuts in next month GlueX collaboration meeting, Bloomington, May 9-11, 2011

  34. UConn diamond ablation facility GlueX collaboration meeting, Bloomington, May 9-11, 2011

  35. Immediate Prospects • Phase II STTR grant application with Sinmat submitted in March. • CHESS collaborator Ken Finkelstein generally satisified with progress, willing to continue. • Publication presenting these results is expected this summer, probably NIM. • First diamond cuts with the laser expected this month, as soon as vacuum chamber finished. GlueX collaboration meeting, Bloomington, May 9-11, 2011

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