Diamond Radiators for GlueX Status Update – May 2011 Richard Jones, UConn Igor Senderovich, UConn Brendan Pratt, UConn James McIntyre, UConn Fridah Mokaya,

Diamond Radiators for GlueX

Status Update – May 2011

Richard Jones, UConnIgor Senderovich, UConnBrendan Pratt, UConnJames McIntyre, UConnFridah Mokaya, UConnChris Pelletier, UConnJessica Hyde, E.O.Smith High School

Ken Finkelstein, CHESS

Yi Qiang, JLab

GlueX Collaboration Meeting, Bloomington, May 9-11, 2011

GlueX collaboration meeting, Bloomington, May 9-11, 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


Review of project goals

Diamond radiators with the following properties:Diamond radiators with the following properties:1. thickness: 15 - 20 microns

2. uniform area: 4 x 2 mm2 (per beam spot position)

3. rocking curve width: < 20 rad RMS (whole-crystal)

Radiator mount with the following propertiesRadiator mount with the following properties:1. low mass: > 98% of beam photons from diamond

2. thermally robust: stable operation at full beam intensity

3. vibration resistant: twist modes < 10 rad RMS amplitude

4. low stress: thin crystals are very susceptible to bendingthin crystals are very susceptible to bending

These two are in tension with each other


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 facilitiesa third possibility has re-emerged: thinning by E6 mystery facilities

• A lot depends on what happens in the next 12 monthsthe 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 successfullycompleted successfullyPhase I SBIR awardedPhase I SBIR awardedPhase I goals reachedPhase I goals reached

Phase II proposal submittedPhase II proposal submittedcontinues wellcontinues well

work done, $tbdwork done, $tbddonedone


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


New Ideas under test in 2011 Solving problems with crystal vibrations:Solving problems with crystal vibrations:

1. reduce vibrations by raising 0 (ambient f ~ 1/(ambient f ~ 1/33))

2. change mount to low-Z material (W wire (W wire →→ C fiber) C fiber)

3.3. test using a high-tension membranetest using a high-tension membrane (avoid adhesive) (avoid adhesive)

Investigating the causes of crystal curvatureInvestigating the causes of crystal curvature:1. external vs. internal stress

2. engineering active correction into the mount

Comparing intrinsic rocking curves of different gradesComparing intrinsic rocking curves of different grades1. Sinmat 9 micron thinned CVD sample

2. ‘‘CVD single-crystal’’ vs. ‘‘electronic grade SC’’

3. nature of E6 ‘‘mystery 10 micron crystal’’


Report on recent CHESS run1.1. New Si (331) monochromator designed to do diamond (2,2,0) diffractionNew Si (331) monochromator designed to do diamond (2,2,0) diffraction

asymmetric / symmetric double-bounce, expansion factor x8asymmetric / symmetric double-bounce, expansion factor x8 uniform beam spot 10 x 10 mmuniform beam spot 10 x 10 mm22 one pass per rocking curveone pass per rocking curve only few hours needed for initial beamline setup only few hours needed for initial beamline setup stable operation over several days, minor tweaks after each fillstable operation over several days, minor tweaks after each fill ~ 2~ 2rad RMS rocking curve observed in diamond (2,2,0) – best ever!rad RMS rocking curve observed in diamond (2,2,0) – best ever!

2.2. New stretched mylar double-hoop mountNew stretched mylar double-hoop mount few minutes to change out diamond targetsfew minutes to change out diamond targets holds diamonds of any thicknessholds diamonds of any thickness negligible attenuation of X-rays in the mylarnegligible attenuation of X-rays in the mylar vibration broadening of rocking curve is below limits of observationvibration broadening of rocking curve is below limits of observation

3.3. Many different samples studied: Many different samples studied: 4.5 days, 10 samples, >20 rocking curves4.5 days, 10 samples, >20 rocking curves


Setup for diamond diffraction at CHESS

whitebeamfrom C-linebending magnet

new Si(331)monochromatorUConn design,built at CHESS

He gas

first crystal,water cooled pure Si15.3° miscut from (3,3,1)expansion factor b ~ 8at 15 keV X-ray energy

second crystalsymmetric Si(3,3,1)

monochromatic 15 keVhighly-parallel X-ray beam1cm x 1cm spot sizedispersion-matched todiamond (2,2,0) planes

Huber 4-circle gonimeter

CCDcamera


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)


SINMAT-9

(1,0,0)(0,1,0)

• 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 visibletwo line defects clearly visible


SINMAT-9

(1,0,0)

(0,1,0)

• 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 visiblecuts are clearly visible

tornflap

hangsdown


SINMAT-9

• whole-crystal rocking curve is quite bad• local rocking curve width is very goodlocal rocking curve width is very good, except near the defects• essentially all of the whole-crystal width comes from large-scale strain

CESRrefilled


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


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 GlueXThis 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 Sinmat to improve their handling of thin

samples. samples.

soso

butbut


E6-10• mystery diamondmystery 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 diffractionno 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)


E6-10• whole crystal rocking curve is extremely broadwhole 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?strain pattern somehow different in the two projections – sample moved?

““ Due to the limitation of χ angle, the sample was taken outDue to the limitation of χ angle, the sample was taken out from the holder and rotated 90 degrees before put back.”from the holder and rotated 90 degrees before put back.”

(1,1,0)

(-1,1,0)


E6-10

hasgood

regions

andnot-sogood

regions


Summary for E6-10

• Intrinsic rocking curve width close toclose 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 This crystal is usable for GlueX in one orientation.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?can we check this?

soso

butbut


E6-10• take E6-10 out of the mylar mount, place it freely resting on a posttake 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.


PRISTINE-A• 4mm x 4mm x 300m “electronic grade” single crystal ($1200 apiece)


PRISTINE-A• 4mm x 4mm x 300m “electronic grade” single crystal ($1200 apiece)


PRISTINE-B


PRISTINE-B


PLATE-A


PLATE-B


PLATE-C


PLATE-D


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 These crystals are all usable for GlueX in both orientations, both orientations, provided that they can be provided that they can be thinnedthinned..

• Stretched mylar mount did not distort these ones – no surprise – they are very stiff at 300 microns!


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


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.


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.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.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 Getting top quality diamond material is not going to be a problemis not going to be a problem..

Getting thin diamonds is Getting thin diamonds is probably not going to be a problemprobably not going to be a problem..

Getting thin diamonds to lay out flat without a rigid support behind Getting thin diamonds to lay out flat without a rigid support behind them is not going to happen. them is not going to happen. Flatness is our unsolved problem our unsolved problem..


Current ideas for radiator support• Start with a large area (6mm x 6mm x 0.3mm) CVD diamond

Use the excimer laser to cut out a rectangular hole, then

stick a thin wafer on the back

Use the excimer laser to mill out a thin section out of the

center for the beam spot

requires precise laser control

van der Waals bond might be sufficient


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


UConn diamond ablation facility


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.

Documents

Diamond Radiators for GlueX Status Update – May 2011 Richard Jones, UConn Igor Senderovich, UConn Brendan Pratt, UConn James McIntyre, UConn Fridah Mokaya,