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 1

FCAL detector purposes in future e+e- linear accelerators 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

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

FCAL detector designs in future e+e- linear accelerators 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 (100 Mrad/yr of EM particles), rad hard sensors sought

LumiCal sensor Yan Benhammou channels: 1 - 64 4 sectors: L2 L1 R1 R2 channels: 1 - 64 Outer active radius R = 195.2 mm 3 x 100 μm guard rings 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 Inner active radius R = 80.0 mm

LumiCal test at CERN in 2014 Yan Benhammou Energy fraction 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

Sasha Borysov 7 7

Sasha Borysov 8 8

Sasha Borysov 9 9

10 Sasha Borysov 10

Sasha Borysov 11 11

Sasha Borysov 12 12

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 13

Electronics 14 14

LumiCal readout in 2014 Yan Benhammou Signal to noise ratio ~19 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%

New readout : FLAME Yan Benhammou 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

BeamCal readout Yan Benhammou 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

Radiation Damage Studies 18 18

SLAC End-Station Test Beam (ESTB) 2 X0 pre-radiator; introduces a little divergence in shower SLAC End-Station Test Beam (ESTB) Sensor sample Not shown: 4 X0 “post radiator” and 8 X0 “backstop”

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

GaAs Charge Collection for 21 Mrad Significant charge collection loss; leakage current low at -10oC but rises somewhat with temperature 21 Mrad Exposure GaAs Sensor 21 21

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 22

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

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

SiC Charge Collection for 77 Mrad 4H SiC Sensor 98C anneal 77 Mrad Exposure Charge collection mostly above 50%; leakage current low 25 25

Silicon Diode Sensors Both n-type and p-type bulk sensors for Float-zone crystal Magnetic Czochralski crystal Most notable variation is between n-type and p-type Both develop significant leakage current, but p-type seems to maintain better charge collection (somewhat expected based on pure-EM irradiation studies from the 90s) 26 26

P Type Charge Collection after 270 Mrad @600 V, ~20% charge collection loss (60C annealing) 270 Mrad Exposure PF Si Diode Sensor 27 27

P Type I vs. Temperature; 270 Mrad Current doubling for every 7oC expected for Si Diode Qualitatively similar for all SI Diode sensors tested Note: If damage is localized in BeamCal, may not lead to unmanageable power draw even after irradiation; this is under study (see FLUKA study below) PF Si Diode Sensor 270 Mrad Exposure 28 28

P Type Charge Collection for 570 Mrad Currents roughly x2 that for 270 Mrad 570 Mrad Exposure PF Si Diode Sensor 29 29

N Type Charge Collection after 300 Mrad @600 V, ~40% charge collection loss (58C annealing) 300 Mrad Exposure NF Si Diode Sensor 30 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 31 31

BeamCal Neutrons from FLUKA 32 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 Proceeding into the simulations of the Beamcal, I would like to note that the geometric parameters of the beamcal were acquired from the ILC detailed baseline description. Additionally, we sourced our primaries from a Guinea Pig simulation of a bunch crossing. After running the FLUKA simulations, I produced several cutouts of the resulting fluences of electrons and positrons, and neutrons, at various layers in the BeamCal. It gives a good idea of what is going on inside the BeamCal. I also used the raw data to find the layers of highest fluence. Layer 8 saw the highest electron positron fluence and 12 saw the highest neutron fluence.

Layer 2 Detector - Fluence E+&E- Neutrons

Layer 4 Detector - Fluence E+&E- Neutrons

Layer 6 Detector - Fluence E+&E- Neutrons

Layer 8 Detector - Fluence E+&E- Neutrons

Layer 10 Detector - Fluence E+&E- Neutrons

Layer 12 Detector - Fluence Neutrons

Layer 14 Detector - Fluence Neutrons

Layer 16 Detector - Fluence Neutrons

Neutron Flux and BeamCal Sensor Radiation Damage SLAC Experiment T506: prototype sensor placed at shower max of electromagnetic shower induced by tungsten  shower has significant hadronic component T506 exposures in the 100-600 Mrad range used to project effects of radiation damage after multiple years of ILC running Recent discovery: FLUKA simulations suggest that damaging (non-ionizing) component of neutron energy deposition, per Mrad (i.e., per MeV of dEdX from e+-), is much higher in the BeamCal than at the T506 exposure point If damage is dominated by neutron flux (?), will have important implications for BeamCal sensor choice, given varying degrees and types (charge loss, leakage current) of radiation damage observed in T506, which would thus represent a much shorter ILC running period  Continuing to explore SLAC e- beam Sensor prototype 42 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) 43 43

Backup 44 44