Progress on ILC Forward Calorimetry by the FCAL Collaboration

1. Progress on ILC Forward Calorimetry by the FCAL Collaboration AWLC17, SLAC June 26-30, 2017 Bruce Schumm UC Santa Cruz Institute for Particle Physics Representing the FCAL Collaboration

2. Yan Benhammou FCAL detector purposes in future e+e- linear accelerators • LumiCal : • Precise integrated luminosity measurements (Bhabha events) • Extend calorimetric coverage to small polar angles. Important for physics analysis • LHCal : • Extend the hadronic calorimeter coverage • BeamCal : • Measure instant luminosity • tagging of high energy electrons to suppress backgrounds to potential BSM process • shielding of the accelerator components from the beam-induced background • providing supplementary beam diagnostics information extracted from the pattern of incoherent-pair energy depositions

3. Yan Benhammou FCAL detector designs in future e+e- linear accelerators • LumiCal : • Electromagnetic sampling calorimeter • layers of 3.5 mm thick tungsten plates with 1 mm gap for silicon sensors (30 for ILC, 40 for CLIC) • LHCal : • Sampling Calorimeter • 29 layers of 16mm thickness. Absorber : tungsten or iron • BeamCal: • Sampling calorimeter based on tungsten plates (30layers for ILC, 40 layers for CLIC) • Due to large dose, rad hard sensors sought

4. ILC Layout BeamCal LHCal LumiCal CLIC Layout +Z 2450 2680 3195

5. Yan Benhammou LumiCal sensor 4 sectors: L1 R1 L2 R2 • Silicon senor, 320 mm thickness • DC coupled with read-out electronics • p+ implants in n-type bulk • 64 radial pads, pitch 1.8 mm • 4 azimuthal sectors in one tile, each 7.5 degrees • 12 tiles makes full azimuthal coverage • 40 modules were produced by Hamamatsu Outer active radius R = 195.2 mm channels: 1 - 64 Inner active radius R = 80.0 mm 3 x 100 μm guard rings

6. Yan Benhammou LumiCal test at CERN in 2014 • 4 LumiCal modules equipped with dedicated electronics (32 channels) glued on a 2.5 mm PCB • 3.5 mm between tungsten plates (fill-factor of ½) • Tested in test beam at PS with 5 GeV e-/m Energy fraction Extracted Moliere radius : 24.0 ± 0.6 (stat.) ± 1.5 (syst.) mm

7. Sasha Borysov 7

8. Sasha Borysov 8

9. Sasha Borysov 9

10. 10 Sasha Borysov

11. Sasha Borysov 11

12. Sasha Borysov 12

13. Alternative BeamCal Designs • Makes use of industrial Sapphire? • Inexpensive • Radiation tolerant (?) • But small signal (short mean free path) • Baseline Design • Standard sampling configuration • GaAs sensor planes 2013 DESY Beam Test (beam parallel to sensors) Goal is to construct and test prototype in 2018 13 Sergej Schuwalow

14. Electronics 14

15. Yan Benhammou LumiCal readout in 2014 • Development of an ASIC for the 2014 test beam • Charge amplifier shaper with different gain (MIP/electron) • 8 front end channels • Development of an 8 channel 10 bit ADC Signal to noise ratio ~19 Cross Talk < 1%

16. Yan Benhammou New readout : FLAME • FLAME: project of 16-channel readout ASIC in CMOS 130nm, front-end&ADC in each channel, fast serialization and data transmission, all functionalities in a single ASIC • FLAME prototype : • Prototype 8-channel FE+ADC ASIC • Prototype serializer ASIC First tests are encouraging : FE ok, ADC ok, basic functionality of serializer are ok

17. Yan Benhammou BeamCal readout • Firstly, BeamCal is hit by beam halo (muons) • MIP deposition, low noise electronics • Clean environment • Good for calibration • ~25ns later, BeamCal is hit by collision scattering • Large deposit energy • Physics readout Dual slope integrator for calibration signal • Integrate baseline (negative gain) • Calibration halo signal is deposited and held • Switch to physics mode, process and digitize Vop • Then integrate calibration signal and digitize Voc

18. Radiation Damage Studies 18

19. 2 X0 pre-radiator; introduces a little divergence in shower Sensor sample Not shown: 4 X0 “post radiator” and 8 X0 “backstop”

20. Gallium Arsenide Sensor provided by Georgy Shelkov, JINR Sn-doped Liquid-Encapsulated Czochralski fabrication 300 m thick 20

21. GaAs Charge Collection for 21 Mrad Significant charge collection loss 21 Mrad Exposure GaAs Sensor 21

22. Industrial Sapphire Sensor provided by Sergej Schuwalow Fabricated by Crystal GmbH, Berlin Layered Al-Pt-Au contact structure Current low (< 10 nA) after irradiation 22

23. Sapphire Charge Collection for 300 Mrad Low pre-irradiation charge-collection and significant charge loss after irradiation Sensors via Sergej Schuwalow, DESY Zeuthen 500 m thick Al2O3 300 Mrad Exposure 23

24. Silicon Carbide Sensor provided by Bohumir Zatko, Bratislava Schottky-barrier contacts mounted on 4H-SiC structure Epitaxial (active) layer thickness 70 m 24

25. SiC Charge Collection for 77 Mrad 4H SiC Sensor 98C anneal 77 Mrad Exposure Charge collection mostly above 50% 25

26. P Type Charge Collection after 270 Mrad @600 V, ~20% charge collection loss (60C annealing) 270 Mrad Exposure PF Si Diode Sensor 26

27. P Type I vs. Temperature; 270 Mrad Current doubling for every 7oC expected for Si Diode 270 Mrad Exposure PF Si Diode Sensor 27

28. P Type Charge Collection for 570 Mrad Currents roughly x2 that for 270 Mrad 570 Mrad Exposure PF Si Diode Sensor 28

29. N Type Charge Collection after 300 Mrad @600 V, ~40% charge collection loss (58C annealing) 300 Mrad Exposure NF Si Diode Sensor 29

30. N-Type LumiCal Prototype Fragment After annealing, charge collection at 600V likely well above 50% after 300 Mrad exposure Sensor via Sasha Borisov, Tel Aviv 300 Mrad Exposure “LumiCal” N-Type Diode Sensor 30

31. BeamCal Neutrons from FLUKA 31

32. BeamCal Simulation in FLUKA(Ben Smithers, SCIPP) • BeamCal absorbs about 10 TeV per crossing, resulting in electromagnetic doses as high as 100 Mrad/year • Associated neutrons can damage sensors and generate backgrounds in the central detector • GEANT not adequate for simulation of neutron field  implement FLUKA simulation • Design parameters from detailed baseline description (DBD) • Primaries sourced from single Guinea Pig simulation of e+- pairs associated with one bunch crossing

33. Layer 2 Detector - Fluence E+&E- Neutrons

34. Layer 4 Detector - Fluence E+&E- Neutrons

35. Layer 6 Detector - Fluence E+&E- Neutrons

36. Layer 8 Detector - Fluence E+&E- Neutrons

37. Layer 10 Detector - Fluence E+&E- Neutrons

38. Layer 12 Detector - Fluence Neutrons

39. Layer 14 Detector - Fluence Neutrons

40. Layer 16 Detector - Fluence Neutrons

41. Neutron Flux and BeamCal Sensor Radiation Damage SLAC Experiment T506: prototype sensor placed at shower max of electromagnetic shower induced by tungsten  shower has realistic hadronic component Explored radiation-hardness properties of several different Si diode and bulk solid-state (GaAs, Sapphire, SiC) sensor technologies T506 exposures in the 100-600 Mrad range (recall that maximum BeamCal dose is 100 Mrad of electromagnetic radiation) Recent discovery: FLUKA simulations suggest that damaging (non-ionizing) component of neutron energy deposition, per MeV of dEdX from e+-, is much higher in the BeamCal than at the T506 exposure point May have important implications for BeamCal sensor choice, given varying degrees and types (charge loss, leakage current) of radiation damage observed in T506 SLAC e- beam Sensor prototype 41

42. Summary • Need to do precision calorimetry in high-dose, high speed environment is driving a lot of R&D and design work • Work reasonably advanced, even at systems level • Significant use of test beams for prototype evaluation and radiation damage studies • Picture continuing to clarify (LHCal perhaps a bit behind) 42

43. Backup 43