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Radiation Tolerance and Diamond Devices in the LHC Experiments

This talk discusses the motivation and research conducted by the RD42 Collaboration on radiation tolerant detector designs and materials, with a focus on diamond devices. The talk covers rate studies, diamond device development, and applications in the LHC and experiments.

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Radiation Tolerance and Diamond Devices in the LHC Experiments

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  1. RD42 Results and Status Marko Mikuž (proxy for Harris Kagan) Ohio State University for the RD42 Collaboration Vertex 2017 September 10-15, 2017 Outline of Talk • Introduction – Motivation, RD42 • Radiation Tolerance • Diamond Devices in the LHC and Experiments • Rate Studies • Diamond Device Development – 3D Diamond • Diamond Device Development – BCM’ • Summary

  2. Introduction - Motivation • Present Situation: • Innermost layers  highest radiation damage (~100 MHz/cm2) • Current detectors designed to survive ~12 months in HL- LHC •  R&D for more radiation tolerant detector designs and/or materials • Diamond as a Detector Material: • Properties: • radiation tolerance • insulating material • high charge carrier mobility • Smaller signal than in same thickness of silicon • RD42 work: • Investigation of signals in various detector designs: • pad  full diamond as a single cell readout • pixel  diamond sensor on pixel chips • 3D  strip/pixel detector with design to reduce drift distance Vertex 2017 – Asturias, Spain Harris Kagan 2

  3. Introduction - The 2017 RD42 Collaboration 130 participants 32 institutes Vertex 2017 – Asturias, Spain Harris Kagan 3

  4. Diamond as a Particle Detector Vertex 2017 – Asturias, Spain Harris Kagan 4

  5. Radiation Tolerance Vertex 2017 – Asturias, Spain Harris Kagan 5

  6. Radiation Tolerance Test Beam Setup • characterization of irradiated devices in beam tests • transparent or unbiased hit prediction from telescope Vertex 2017 – Asturias, Spain Harris Kagan 6

  7. Radiation Tolerance – Analysis Strategy • Measure signal response as a function of predicted position • Direct measurement of charge collection distance (CCD) • CCD = average distance e-h pairs drift apart under E-field • Convert CCD to mean free path (MFP) - assume ~same MFP for e,h • Damage equation: • Fit in 1/l (=1/mfp) vs f space • n number of traps • n0 initial traps in material • k damage constant • fluence • l MFP • l0 initial MFP n = n0 + kf ↓ ↓ Vertex 2017 – Asturias, Spain Harris Kagan 7

  8. Radiation Tolerance Example – 800 MeV protons • Plot single-crystal and poly on • same graph • Fit in 1/l space • Damage constant (=slope) for single-crystal and poly the same • Do the same for all energies, • species Lukas Bäni, PhD Thesis, ETH Zürich, 2017 Vertex 2017 – Asturias, Spain Harris Kagan 8

  9. Radiation Tolerance Lukas Bäni, PhD Thesis ETH Zürich, 2017 Vertex 2017 – Asturias, Spain Harris Kagan 9

  10. Radiation Tolerance Vertex 2017 – Asturias, Spain Harris Kagan 10

  11. Applications in the LHC and Experiments - beam condition/beam loss monitors - pixel detectors - 3D devices Vertex 2017 – Asturias, Spain Harris Kagan 11

  12. Diamond devices in experiments • Beam Conditions Monitors/Beam Loss Monitors • Essentially all modern collider experiments • Current generation Pixel Detectors • ATLAS Diamond Beam Monitor (DBM) • Future HL-LHC Trackers • 3D diamond • Future BCM’ • Multipad design Vertex 2017 – Asturias, Spain Harris Kagan 12

  13. Rate Studies Vertex 2017 – Asturias, Spain Harris Kagan 13

  14. Rate studies in pCVD diamond • Done at PSI - 2 yrs ago published rates up to 300kHz/cm2 • Last year w/new electronics, rates up to 10-20MHz/cm2 • Pad detector tested in ETH-Z telescope (CMS Pixels) • Electronics is prototype for HL-LHC BCM/BLM 19.8ns bunch spacing clearly visible Vertex 2017 – Asturias, Spain Harris Kagan 14

  15. Rate studies in pCVD diamond • Last year w/new electronics, rates up to 10MHz/cm2 No rate dependence observed in pCVD up to 10-15MHz/cm2 No absolute pulse height and noise calibration yet Now extending dose to 1016 n/cm2 Vertex 2017 – Asturias, Spain Harris Kagan 15

  16. Device Development – 3D Diamond Vertex 2017 – Asturias, Spain Harris Kagan 16

  17. 3D device in pCVD diamond • after large irradiation  all detector materials trap limited (mfp < 75 μm) • keep drift distances smaller than mean free path • bias and readout electrode inside detector material • same thickness Δ  same generated charge  shorter drift distance L • electrode columns drilled with 800 nm femtosecond laser • convert diamond into conductive mixture of carbon phases (~kΩ) Vertex 2017 – Asturias, Spain Harris Kagan 17

  18. 3D multi-device in pCVD diamond 3D multi-device (2015) • pCVD diamond with 3D, phantom and strip detector on single sensor • 3D column drilling & connection efficiency 92% • 3D cell size 150μm x 150μm • signal read out as ganged cells missing columns good columns Vertex 2017 – Asturias, Spain Harris Kagan 18

  19. 3D multi-device in pCVD diamond • Square cells visible • 9/99 broken readout, 15/120 field columns • Signals readout as ganged cells (strips) • Signal in 3D bigger (already by eye) than in planar • Phantom (no columns)  no pulse height Planar Strip Phantom 3D Vertex 2017 – Asturias, Spain Harris Kagan 19

  20. 3D multi-device in pCVD diamond • Measured signal (diamond thickness 525 μm): • Planar Strip ave charge (Vbias = 1000 V) 6,900e or ccd=192um • 3D ave charge (Vbias = 60 V) 13,500e or ccdeq=350-375um • For the first time collect ~75% of charge in pCVD Vertex 2017 – Asturias, Spain Harris Kagan 20

  21. Full 3D device in pCVD diamond • Tested first full 3D device in pCVD (May/Sept 2016) with three dramatic improvements • An order of magnitude more cells (1188 vs 99) • Smaller cell size (100μm vs 150μm), hole diameter (2 vs 5 μm) • Higher column production efficiency (99% vs 92%) HV bias side Readout side Vertex 2017 – Asturias, Spain Harris Kagan 21

  22. Full 3D device in pCVD diamond Full 3D Device (2016) Vertex 2017 – Asturias, Spain Harris Kagan 22

  23. 3D Diamond Pixels First 3D pixel device in pCVD (2017) [100μm x 150μm cells] Vertex 2017 – Asturias, Spain Harris Kagan 23

  24. 3D Diamond Pixels First 3D pixel device in pCVD – use CMS pixel readout chip Vertex 2017 – Asturias, Spain Harris Kagan 24

  25. 3D Diamond Pixels – Preliminary Results 3D Diamond Pixel 98.5% efficiency Planar Silicon Pixel (ref) 99.3% efficiency Vertex 2017 – Asturias, Spain Harris Kagan 25

  26. 3D Diamond Pixel – New Design Produced a 3500cell pixel prototype w/50μm x 50μm pitch • Two being produced: • Oxford (complete) • Manchester (in progress) • Can do metallization to fit • any known pixel chip • Bump bonding • CMS @Princeton • ATLAS @IFAE • Took data in August test • beam at PSI Vertex 2017 – Asturias, Spain Harris Kagan 26

  27. 3D Diamond Pixel – New Design Preliminary Results (50μmx50μm pixels) • Readout with CMS pixel readout • 6 columns (3x2) ganged together • Preliminary efficiency 99.2% • Collect >90% of charge! Vertex 2017 – Asturias, Spain Harris Kagan 27

  28. Summary • Lots of progress in diamond with HL-LHC in view • ATLAS/CMS -BCM, BLM, DBM all working in LHC • Abort, luminosity and background functionality in all LHC expts • Quantified understanding of rate effects in diamond • pCVD shows no rate effect up to 10-20MHz/cm2 @1000 V • 3D detector prototypes made great progress • 3D works in pCVD diamond; scale up worked; smaller cells worked • 3D diamond pixel devices being produced • All work as expected • Visible improvements in each step • Efficiencies look good; PH in progress H. Kagan 28 Vertex 2017 – Asturias, Spain

  29. Backup Slides Vertex 2017 – Asturias, Spain Harris Kagan 29

  30. Device Development – BCM’ - abort threshold - danger level, safety margin - luminosity Vertex 2017 – Asturias, Spain Harris Kagan 30

  31. Diamond development – BCM’ • Abort and Luminosity Functions • Abort • Require out-of-time and in-time signals above • threshold signifying beam background at the danger • Level • Danger levels can be very high • ATLAS SCT 25k/cm2/BC i.e. ~4000x lumi signal • Need to keep flexibility for threshold settings • Luminosity • Main algorithm: (absence of) in-time hits • Max sensitivity ~1.6 hits/cell • Need robust device, signal stability paramount Vertex 2017 – Asturias, Spain Harris Kagan 31

  32. Diamond development – BCM’ • Present BCM suffers from abort-lumi incompatibility • Abort thresholds can not be set higher without • abandoning lumi • Fast timing needed for abort lowers S/N thus limiting • lumi stability • Separate functions at the HL-LHC • Two fast devices from sensor to off-detector • Keep as much commonality as possible • 4 stations/side with abort, lumi-BCM’, BLM Vertex 2017 – Asturias, Spain Harris Kagan 32

  33. Diamond development – BCM’ Sensor Design Tested @PSI last week with RD42 fast amp used for Rate Studies! Vertex 2017 – Asturias, Spain Harris Kagan 33

  34. Diamond development – BCM’ • Start with RD42 fast amp used in rate studies • Designed in 130nm; will be updated to 65nm • Rise time 3-6ns; Baseline recovery time 12-18ns • Noise for 2pf input ~550e • ATLAS electronics ideas • Two preamp designs since otherwise large dynamic • range (104) needed to cover lumi and abort in same • channel • High gain for lumi; low gain for abort. Optimize gain • and speed vs SNR for lumi and abort separately • Rise time ~few ns; return to baseline 10ns • Tune parameters based on beam tests • 16 channels (8/8 lumi/abort) Vertex 2017 – Asturias, Spain Harris Kagan 34

  35. Diamond development – BCM’ Prototype test with 9.2 MHz/cm2 @PSI • Bunches 19.8ns apart clearly separated • Trigger is at 69ns • Hits in bunch before trigger not allowed Vertex 2017 – Asturias, Spain Harris Kagan 35

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