ASIC needs for calorimetry at ATLAS and CMS

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Outline

• Detector Technologies in ATLAS and CMS• Challenges & upgrades plans• Performance requirements at LHC and HL-LHC• Readout Issues:

• Architecture and Trigger requirements• Radiation Tolerance Requirements on the Front-End

• On-going R&D and open questions• Conclusions: ASIC vs. COTS?

• We got the Higgs.

• What are the driving physics motivations for the next ~20 yrs?

• What are the challenges for the calorimeters and for their readout (i.e. for the front-end readout)?

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• Higgs properties and phenomenology (precision measurements of relatively low energy objects)

• Searches for new phenomena at the energy frontier

• We got the Higgs.

•What are the driving physics motivations for the next ~20 yrs?

• What are the challenges for the calorimeters and for their readout (i.e. for the front-end readout)?

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• We got the Higgs.

• What are the driving physics motivations for the next ~20 yrs?

• What are the challenges for the calorimeters and for their readout (i.e. for the front-end readout)?

Performance issues in a very challenging environment

• Detector technology issues

• Response and resolution requirements

• Readout:

✓ system/architecture (e.g. evolution of the trigger systems)

✓ components (e.g. aging, radiation, ...)

• EM Calorimeter (EMB/EMEC):

‣ LAr + Pb accordion

‣ ~180k readout channels

‣ ~150-180 kW on detector

• Hadronic:

‣ Barrel (Tile): Scintillating Tiles + PMT readout

‣ Endcap (HEC): LAr + Cu absorber

✦ Cryogenic GaAs ASICs (preamps+adders)

• Forward Calorimeter (FCAL):

‣ LAr tubes ( +Cu absorber in first module, W absorbers in the two hadronic modules) 3

• ECAL:

‣ PbWO4 crystals

‣ ~76k scintillators + APD/VTR photodetectors

• HCAL:

‣ Plastic scintillators + WLS fibers + HPD photodetectors

‣ Brass absorbers (HB, HE), steel return yoke (HO)

• HF:

‣ Cerenkov radiation collected with quartz fibers + PMT readout + steel absorber

Calorimeter Technologies in ATLAS and CMS

• EM Calorimeter (EMB/EMEC):

‣ Electronics aging, radiation

‣ New requirements from trigger (L1 rates and latency)

‣ Upgrade plans: trigger interface LS2, full readout LS3

• Hadronic:

‣ Electronics aging, radiation

‣ New requirements from trigger (L1 rates and latency)

‣ Upgrade plans: trigger interface LS2, full readout LS3

• Forward Calorimeter (FCAL):

‣ Potential space charge effects in LAr gaps in HL-LHC

‣ Potential upgrade in LS3 4

• ECAL:

‣ Degradation of crystal transparency induced by radiation (EE)

‣ Electronics longevity

‣ Potential new requirements from Level-1 trigger

‣ Upgrade plans for LS3

• HCAL:

‣ Discharges in HPD readout: upgrade to SiPM

‣ Depth segmentation (4 in HB, 5 in HE)

‣ Upgrade plans for LS2

• HF:

‣ Anomalous signals from muons striking PMTs

‣ Already plans to upgrade to multi-anode PMTs in LS1

Calorimeter Technology Challenges

• Maintain performance in high pileup environment

‣ Energy resolution:

‣ Fast shaping (@40ns peak time)

‣ Noise levels: ~30 MeV [EM Barrel CD=0.4-2nF]

‣ Linearity (INL): ~0.2% [EM] / ~2% [HAD]

‣ Dynamic Range: 16 bits

‣ Trigger Rates: First level of hardware trigger up to 200-500kHz / 6us @ HL-LHC

‣ Trigger performance: unprescaled ~25 GeV electrons @ 20% trigger bandwidth 5

• Maintain basic performance (similar or equivalent to ATLAS) + ...

• Under study possible improvements in:

• ECAL

‣ In ATLAS LAr EM calorimeter segmentation in pointing strip allows at some extent correlation tracks from a given PV

‣ No possible with crystal calorimetry. Under discussion possible R&D on crystals with very high timing resolution (~10ps) to discriminate between e/jets from different vertices

• HCAL

‣ 4-5 longitudinal layers in the HCAL with individual readout to optimize particle flow algorithms and improve jet energy resolution

Calorimeter Performance Requirements @ HL-LHC

Radiation Tolerance in CMS • Readout electronics and

services mounted on the backplate

‣ Cover the full fiducial area of the EE calorimeter

• Extrapolation @ HL-LHC (3000fb-1):

‣ TID: 2-3x105 Gy (η~3.0)

‣ Neutrons (>100keV): 3x1014 n/cm2

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@500fb-1

Radiation Tolerance in ATLAS• Front-end readout electronics installed on crates on-detectors (LAr) and custom drawers at the top (Tile)

‣ Outer R: 280-320 cm (LAr) / 390-410 cm (Tile)

‣ Barrel Z=~290-340 cm / EndCap Z=~600cm

• Radiation Estimate Task-Force in ATLAS is re-evaluating radiation maps in the different parts of the detectors, comparing with local measurements with different radiation detectors (Report in 1 month-time scale. here only preliminary numbers)

‣ Agreement calculation/measurements ~20-30%

‣ For calorimetry higher doses in LAr EM Front-End crates [HEC excluded]

‣ Extrapolation to HL-LHC (3000fb-1):

✦ TID could be as low as ~10kRad (lower than expected)

✦ 1 MeV Si equivalent n-fluence: 1013 n/cm2 (in line with previous calculations or slightly lower)

• Real issue with radiation is Single Event Upsets @ HL-LHC

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Tile Drawers

LAr FE Crates

CMS Calorimeter Readout• Front-end ASICs:

‣ ECAL: Preamp, FP-Digitizer

‣ HCAL: QIE

‣ Serializer (GOL/GBT) and optical transmitter

• Only exception would be FE-FPGA in HCAL (?)

• Pipelines off-detectors (already presently)

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Present ECAL Readout

ATLAS Calorimeter Readout

• Mix of COTS and ASICs

‣ Preamp, Trigger readout: Discrete

‣ Shaper, SCA, SCAC, GainSel, MUX, TTC-Rx: ASIC in different technologies

‣ Serializer, ADC: COTS

• Pipelines on-detectors

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Present Readout Proposed readout for HL-LHC

• Similar?

‣ Analog FE ASIC (SiGe?)

‣ Digitizer+MUX+Serializer: ASIC? IBM 130nm? SoS?

• Pipelines off-detectors put heavier requirements on ADC and links (10Gbps single links or arrays radiation tolerant)

• [see Jingbo’s talk tomorrow]

On-going R&D on Front-End• Analog Front-end:

‣ SiGe IBM 8WL (130nm) preamplifier+shaper prototype [ATLAS LAr EM]

• Digitizers:

‣ QIE10 [CMS HCAL, ATLAS TileCal option]

‣ Nevis SAR+Pipeline - IBM 125nm 8RF [ATLAS LAr EM]

‣ Grenoble SAR - IBM 125nm 8 RF [ATLAS LAr EM]

‣ Clermont-Ferrand (LPC) - FATALIC [ATLAS TileCal option]

‣ Few independent COTS evaluations, which shows good behaviour under radiation

✦ Sensitivity of COTS devices for SEE may make the difference

• Serializers, Control Logic....:

‣ GBT project @ CERN

‣ SoC @ SMU - Peregrine SoS

‣ FPGAs ?? (can they survive SEE effects)?

• Opto-electronics:

‣ Versatile link project @ CERN [CMS HCAL]

‣ R&D in SoS (laser-driver...) @ SMU [ATLAS LAr]

‣ COTS optical modulator @ ANL [ATLAS TileCal]10

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COTS vs. ASIC• Commercial components are being developed at a much faster pace

• Many blocks could be implemented with COTS

‣ “modern” processes seem to be radiation tolerant

‣ SEE cross-sections may be fine for certain applications

‣ But...

• Analog Front-End:

‣ Very specific to the application: design of low noise, large dynamic range, high order filters with discrete components may have practical limitations (power, real estate on boards...) which an ASIC will not have likely

• Digitizers:

‣ COTS ADC are evolving fast (market growing?). Several of them can suit calorimeter requirements

‣ What an ASIC can provide? need to identify unique feature (e.g. large reduction of power, latency...). It could be argued either way

• Control/Serializers and Dataflow ICs:

‣ ASICs vs. FPGA: with increasing data throughput required FPGAs are attractive but SEE cross-sections are high and not clear they can be used even in moderate field:

✦ HCAL case of FLASH-based rad tolerant FPGAs is interesting. Scalability?11

COTS vs. ASIC• So ASIC are still required for the future upgrades of the calorimeter readouts at the

HL-LHC

• But at what extent?

• I personally believe that the calorimeter readout design should follow what other systems (trackers) have to do by necessity

‣ System on Chip: integrate as many functions as possible:

✦ Analog signal filtering

✦ ADCs

✦ Data formatting and interface to optics

✦ Signal processing (calibration and/or 0-suppression)

• That will make the ASIC case for calorimetry a real winning case.

‣ Absorb completely the complexity of the system design, while simplifying considerably the overall system design:

✦e.g. DC-DC distribution (a plague in ATLAS for long time for example), cooling...12