Scintillation Detector Development at ISIS: Current Status and Instrument Enhancement

1. Current Status of Scintillation Detector Development at ISISJeff Sykora, Erik Schooneveld, Nigel Rhodes, Martin Sharkey, Sarah Mann*, Nick Ferguson* and Giacomo Mauri(Dan Pooley, Davide Raspino, Ben Weaver*, Annabelle Brooks*,Quintino Mutamba, Johnny Boxall, John Dreyer, Stefan Howarth)*Students ICANS XXIII Chattanooga, TN 15 October 2019

2. Instrument Development at ISIS Single crystal diffraction from NiFeCoGa • Single Crystal Diffraction • Reflectometry • Powder Diffraction • SANS/SEMSANS Low angle reflection, refraction and transmission from Al2O3 Powder diffraction from NaCaAlF

3. Instrument → Detector Development at ISIS • Position Resolution • Rate capability • Size/Scalability • Cost-effectiveness • Single Crystal Diffraction • Reflectometry • Powder Diffraction • SANS/SEMSANS

4. Instrument → Detector Development at ISIS • Position Resolution • Rate capability • Size/Scalability • Cost-effectiveness • Single Crystal Diffraction • Reflectometry • Powder Diffraction • SANS/SEMSANS • Investigate novel approaches • Further develop working technology

5. Instrument → Detector Development at ISIS • Position Resolution • Rate capability • Size/Scalability • Cost-effectiveness • Single Crystal Diffraction • Reflectometry • Powder Diffraction • SANS/SEMSANS • Investigate novel approaches • Further develop working technology

6. ZnS:Ag/6LiF - Wavelength Shifting FiberBasics – An interlude n + 6Li 4He + 3H + 4.79 MeV

7. ZnS:Ag/6LiF - Wavelength Shifting FiberBasics – An interlude • Efficiency at 1.8Å • 2x0.45 = 67% • 0.25+0.45 = 40% n + 6Li 4He + 3H + 4.79 MeV • Efficiency at 9Å • 2x0.45 = 50% • 0.25+0.45 = 90%

8. Instrument Development at ISIS Single crystal diffraction from NiFeCoGa • Single Crystal Diffraction • Reflectometry • Powder Diffraction • SANS/SEMSANS

9. SXD Current Configuration

10. The 2D Solution • 2D - Crossed fibre array • Efficiency • 2 x higher lithium content scintillator front and back • High light collection • Rate capability • 4x more PMT channels (2×64 ch PMTs vs 32×1 ch PMTs)

11. Positioning2 Dimensions • Brightest fibre OR • Simple centre of gravity calculation • 7 fibres centralised on fibre with max photon density • Separate (x,y) coordinates Light distribution For a single event

12. High Resolution Prototyping • 0.5 mm fibres • 2 sets of 16 x 16 fibres • 1.5 mm pitch • 3 mm pitch • Single 64-channel FPPMT • Tested on the EMMA beamline

13. High ResolutionInterpolation 3 mm pitch Standard positioning 2 ×1 mm holes on 4mm pitch

14. High ResolutionInterpolation 3 mm pitch Standard positioning 3 mm pitch 0.75 mm positioning

15. High ResolutionTrial on SXD • 0.5 mm fibres • 32 x 32 fibres • 1.5 mm x 1.5 mm resolution • Single 64-channel FPPMT

16. SXD9,10-Diphenylanthracene Old detector (Module 6) 3mm x 3mm WSF detector (Module 1) 1.5mm x 1.5mm

17. SXD9,10-Diphenylanthracene Raw

18. SXD9,10-Diphenylanthracene Raw Normalised to pixel area

19. Full Scale Demonstrator • 1 mm fibres • 64 x 64 fibres • 3 mm pitch • 2 × 64-channel FPPMTs

20. Installation on SXD

21. “Day old” results

22. “Day old” results

23. “Day old” results • Clearly distinguish weak peaks • Higher order peaks • Satellite peak • Small crystals • FWHM = 4 µs

24. Single crystal diffraction Detector summary • We now have a cost-effective detector solution for significantly improving performance of single crystal diffractometers. • New single crystal instruments like LMX and upgrades to existing instruments like HRPD are now feasible. *With position interpolation

25. Instrument Development at ISIS • Single Crystal Diffraction • Reflectometry • Powder Diffraction • SANS/SEMSANS • < 1mm position resolution • High local rates • Direct beam • High reflectivity samples • High global rates (divergent mode)

26. INTER development OLD New guide *Becky Welbourn and Max Skoda

27. INTER development New guide OLD *Becky Welbourn and Max Skoda

28. SHARD Coping with high rates • Segmented high aspect ratio 2D • Limits number of possible fibre combinations • Optically isolated rows for coarse pixilation • 2.5mm bend radius fibres for close packing Scintillator 100 µm thick steel divider

29. SHARD Coping with high rates • 1 mm fibres – 16 mm wide • 64 fibres vertically • 50-100 µm thick dividers between fibres • Individual segments • Optically divided • Strips of scintillator front and back • Walking coincidence fibre code • Single 64 chFP-PMT – partitioned FPGA Neutron beam

30. Si reflection at low angle Reflected Refracted Transmitted

31. INTERPolymer on Si Comparison to 3He tube (40 mm slit) 3He point detector Segment 3 Segment 2

32. INTERPolymer on Si Comparison to 3He tube (40 mm slit) Elevated background due to lack of shielding 3He point detector Segments 2 + 3

33. INTERPolymer on Si Comparison to 3He tube (40 mm slit) Matching error bars despite SHARD having 78% the active area of the 3He tube.

34. INTERPolymer on Si Comparison to 3He tube (40 mm slit) Matching error bars despite SHARD having 78% the active area of the 3He tube. Efficiency verified

35. SHARDRates • Local instantaneous peak rates • Single pixel peak rates linear until 16 kcps • Consistent with other ZnS:Ag/6LiF detectors

36. SHARDRates 80mm • “Local” (within beam area) instantaneous peak rates • Linear until ~160 kcps • Global (across detector) instantaneous peak rates • Limited to 320 kcps 65mm 16mm

37. Si reflection at low angle • Rate dependent neutron misplacement (ghosting) • Due to fibre coding and scintillator afterglow Reflected Refracted Transmitted

38. New hybrid fibre coding option • Optimise rate capability in a specified region • Eliminates ghosting • Keeps detector cost-effective

39. New hybrid fibre coding option • Ghosting eliminated!

40. Sub-mm resolution? • 0.5 mm fibres • 0.6 mm pitch • 30 mm wide • 64 fibres vertically • 50 µm thick dividers between fibres • Strips of scintillator front and back • Non-repeating walking coincidence fibre code • Single 64 chFP-PMT

41. Sub-mm resolution? • 200 µm slit close to the detector • ~250 µm with divergence • Integrate over time-of-flight FWHM = 0.61 mm

42. Sub-mm resolution! • 200 µm slit close to the detector • ~250 µm with divergence • Integrate over time-of-flight FWHM = 0.61 mm Apply position reconstruction algorithm?

43. Sub-mm resolution! • 200 µm slit close to the detector • ~250 µm with divergence • Integrate over time-of-flight FWHM = 0.61 mm FWHM = 0.25 mm Currently post-processing only

44. Sub-mm resolution on INTERAl2O3 block • Walking coincidence does not have ghosting!

45. Reflectometer SummaryINTER detector solution *so far

46. Reflectometer Summary • A segmented approach provides a simple, cost effective solution to increasing rate capability for reflectometers • Segments can be made in a variety of widths • Position resolution at least as good as 0.6 mm with high potential to reach 0.25 mm • An option for high resolution SEMSANS *so far

47. Instrument → Detector Development at ISIS • Position Resolution • Rate capability • Scalability • Cost-effectiveness • Single Crystal Diffraction • Reflectometry • Powder Diffraction • SANS/SEMSANS • Investigate novel approaches • Further develop working technology

48. Novel Approaches Low afterglow ZnO:Zn/6LiF Neutron

49. Novel Approaches Li-Plastic “Dead-timing” Collaboration with Sion Richards STFC Tech

50. Summary • ZnS:Ag/6LiF – WSF detectors continue to be developed and used for many techniques at ISIS. • Now have cost-effective solutions capable of handling the required count rates for • high resolution single crystal diffraction and • high resolution reflectometry. • Novel approaches to solving the inevitable challenge of very high count rates are progressing and showing promise.