Calorimeter Upgrades for the High Luminosity LHC

Calorimeter Upgrades for the High Luminosity LHC A. Straessner FSP 101 ATLAS DPG Frühjahrstagung Göttingen März, 2012

Outline Introduction: ATLAS and CMS Detectors Today Physics at the High-Luminosity Large Hadron Collider Calorimeter Upgrade Plans by CMS and ATLAS Improved Calorimeter Trigger and Readout Summary and Outlook main references: CERN-LHCC-2011-012 (ATLAS LoI) CERN-LHCC-2011-006 (CMS TP) 2

Introduction Large Hadron Collider (LHC): proton-proton collisions at up to 7-14 TeV 4 main particle detectors: ATLAS, CMS: general purpose LHCb: B-physics ALICE: heavy-ion physics 3

ATLAS and CMS Detectors at the LHC ATLAS and CMS detectors performed well in 2011 with efficient data taking: 97% - 100% of detector channels operational 91% - 93% data taking efficiency Luminosity recorded at 7 TeV centre-of-mass energy : ~5.3 fb -1 per experiment 4

L dt Evolution of LHC into High Luminosity Phase 7-8 TeV 13-14 TeV (5-7)x10 34 cm -2 s -1 luminosity leveling 10 27 cm -2 s -1 7x10 33 cm -2 s -1 1x10 34 cm -2 s -1 nominal LHC: detectors designed for these conditions 1,5 year stop long shutdown 1 ~20 fb -1 long shutdown 2 ~100 fb -1 1 year stop (2-3)x10 34 cm -2 s -1 ~400 fb -1 1,5 year stop long shutdown 3 3000 fb -1 schedule under discussion 2013/14 2018 ~2022 Year today 5

Physics at High Luminosities - Examples Properties of SM-like Higgs boson: coupling strength to fermions and gauge bosons spin, CP properties rare decays: H μμ, H Zγ Higgs self-coupling (maybe) Super-symmetry: non-sm-like Higgs bosons (h,a,h,h ± ) squarks and gluinos with ~2 TeV sparticle mass spectrum sparticle properties: spin If no Higgs boson found: resonances and deviations from SM in V L V L scattering Additional gauge bosons: W, Z with 3-6 TeV and more... indicative prospects: hep-ph/0204087v1 improvements expected 6

Challenges at High Instantaneous Luminosities Reconstruction of physics objects already deals with pile-up of proton-proton collisions: up to 24 events in 2011 Poisson mean at nominal LHC: 25 events 20 reconstructed pile-up vertices 1 reconstructed Z μμ decay Increased instantaneous luminosity increased flux of particles pile-up events dilute trigger performance trigger energy and momentum thresholds are raised accordingly Pile-up in HL-LHC Phase-1: 55-80 events Pile-up in HL-LHC phase-2: ~200 or more events 7

Motivation for Detector Upgrade Robustness of detector and readout components Replace malfunctioning components Replace detector components with limited performance at highest instantaneous luminosities Improve radiation tolerance some detectors or components are designed for only 300-1000 fb -1 Prepare for longer-term operation until ~2030 Improvements of readout and trigger systems: Keep sensitivity to rare processes in presence of increased background rates Guarantee a successful LHC physics program in High Luminosity Era 8

CMS Calorimeter Upgrade Plans possible modification of Avalanche Photo Diode readout (phase-2) possible replacement of PbWO 4 endcaps (phase-2) new photo-detectors for scintillator light collection new quartz fibers (phase-2) new photo-detectors for scintillator light collection new quartz scintillator (phase-2) + Upgrade of readout and trigger systems and DAQ 9

New SiPMs for CMS Hadron Calorimeter CMS Hadron Calorimeter (HCAL): Barrel and endcap: brass and scintillator tiles Outer HCAL: tail catcher Optical readout fibers connected to Hybrid Photo Diodes (HPD) Noise from discharge and ion feedback overlayed to physics data analysis photocathode: γ e - PIN diode array fibers HPD HO Ring 2, 1, 0 HE HB ECAL Tracker Better performance with Silicon Photomultipliers (SiPM): Pixelated avalanche photo diodes which run in Geiger mode very high gain Gain 10 6 (x 500 of HPD) About 30% quantum efficiency (x 2 of HPD) More light (40 photo-electrons/gev), less photostatistics broadening 10% of HPD in HO replaced in 2009 remaining HPDs in HO in 2013/14 module with 18 3x3 mm 2 SiPMs SiPM 50 μm pitch Anderson - TIPP 2011 10

New SiPMs and Readout for Hadron Calorimeter Plans to replace also HPD with SiPM in HCAL barrel and endcap region (HB, HE) Better performance of SiPM w.r.t. HPD (in HE maybe not sufficient in long-term) Split signal to Time-to-Digital Converter better identification of bunch crossing improved lepton identification and pile-up suppression Pile-up mostly deposited in inner layers longitudinal segmentation of HCAL (x 4) Improved discrimination of hadrons in electron identification and trigger Improved isolation of muons Compensation of long-term radiation damage in inner layers jet fakes in electron identificaton (hadr./em. energy ratio) new SiPM readout electronics: modern μtca format synergy with CALICE @ ILC,... 11

CASTOR HF CMS Forward HCAL (HF) and CASTOR HO HE EE HB Tracker EB HF detector: steel absorber + quartz fibers Light detector with photomultiplier tubes (PMT) Muons which hit PMT window create Cerenkov light and high energy signals in forward HCAL EE 2004 Testbeam fiber bundle PMT window Replace HF phototubes in 2013/14: thinner window (<1 mm) better shielding (metal envelope) 4-way segmented anodes to reject muons hitting PMT window More radiation tolerant fibers are also considered More complete detector replacements currently evaluated for Phase-2 CASTOR: PMTs being replaced with more radiation hard version muon signal before and after selection with new 4-anode PMT 12

ATLAS Calorimeter Upgrade Plans LHC phase-0 (2013/14): Consolidation work on LAr front-end electronics: replacement of low-voltage power supplies LHC phase-1 (2017/18): New calorimeter read-out electronics and additional calorimeter trigger logic LHC phase-2 (2022): Free-running readout electronics for calorimeters New digital calorimeter trigger electronics Possible replacement of cold electronics in LAr Hadronic Endcap (HEC) Possible replacement of Forward Calorimeter (FCal) or additional forward MiniFCal 13

ATLAS LAr Calorimeter Readout LAr sampling calorimeters: E.m. barrel and endcap (lead + LAr) Hadronic endcap (copper + LAr) Forward calorimeter (copper/tungsten + LAr) LAr detectors intrinsically radiation tolerant Front-end electronics qualified for 700-1000 fb -1 Fast signal for Level-1 trigger at 40 MHz Readout of calorimeter cell information at 75 khz high-level trigger (HLT) and DAQ LAr front-end electronics: 182486 readout channels Central Trigger accept @ 75 khz Readout HTL+ DAQ @ 75 khz 14

Trigger Challenges at HL-LHC Example: ATLAS single electron trigger high efficiency of 98% with respect to offline reconstruction benchmark background rate: 20 khz E T threshold 35 GeV with unmodified detector E T threshold 27 GeV with improved calorimeter readout L=2 x 10 34 cm -2 s -1 Physics example: ~~ ~ decay gg qqqqwwχ 0 ~ 1 χ 0 1 in a simplified SUSY model ratio of total efficiency with different electron trigger thresholds: 35 GeV and 25 GeV lower threshold efficiency gain at kinematic edge 15

Higher Granularity for L1 Trigger Calorimeter trigger prepares analog 4-layer sums into trigger towers Δη x Δφ = 0.1 x 0.1 Finer longitudinal and transverse granularity allows better rejection of background with pile-up 4 separate layers + e - Σ New trigger readout concept: Send analog signal to additional front-end electronics New Tower Builder Board (stbb) with digital trigger signal input radiation tolerance to 3000 fb -1 New Digital Processing System (DPS) Additional trigger logic Frontend Board TBB stbb DPS Read-out HLT/DAQ accept Calo Trigger Central Trigger Topological Trigger New Trigger Feature Extractor 16

stbb Components and Digital Processor System R&D and prototypes for key components of digital Tower Builder Board (stbb) radiation tolerant pulse shaper, delay line and Analog-to-Digital Converter (ADC, 12 bit) radiation tolerant components for fast optical link to Digital Processor System (DPS) Shaper Prototype ADC Tester Board Development of Digital Processor System based on Field Programmable Gate Arrays (FPGA) DPS prototype in ATCA format Digital filter algorithms improved pile-up suppression and identification of energy peaks more refined and better calibrated input to trigger system DPS Test Bench 17

Challenges for HL-LHC with 3000 fb -1 ATLAS LAr front-end electronics need to be replaced because of radiation tolerance and possible effects of ageing component requirements very similar to new stbb Front-end electronics of ATLAS Hadronic Endcap (HEC) may also need to be replaced mounted inside LAr cryostat difficult and risky operation to open cryostat GaAs 1μm technology qualified 10 years LHC or 1000 fb -1 PSB detector capacitance (at input) 10 yrs LHC (x safety factor) HEC wheel with preamplifier and summing boards (PSB) [n/cm 2 ] Current candidate technology: Si CMOS 250/350 nm IHP radiation tolerant and good temperature stability 18

ATLAS Current FCal FCal1 FCal2 FCal3 Plug3 IP FCal1: Cu+LAr e.m. showers FCal2/3: W+LAr hadronic showers detector concept: absorber matrix with hollow tubes gap sizes: 269 μm (FCal1) 376/508 μm (FCal2/3) 19

Limitations of Current FCal Current FCal1 will work properly up to luminosities of 1x10 34 cm -2 s -1 The FCal1 will however not work efficiently above ~3x10 34 cm -2 s -1 Reasons: Ar + ion buildup leads to field distortion and to signal distortion high HV currents lead to voltage drop heating of LAr and boiling (only at very high luminosities) +3K +2K current FCal at HL-LHC All effects related to particle rate ~peak luminosity acceptable marginal degraded 20

ATLAS sfcal for Phase-2 Solution 1: smaller 100 μm LAr gaps in FCal1 reduce ion build-up effects and HV drop replace FCal with sfcal for HL-LHC phase-2 Test beam measurement of pulse shapes in Protvino/Russia with a high-intensity proton beam 100 μm gaps 250 μm gaps proton beam FCal EMEC HEC equiv. L HL-LHC = 5x10 34 cm -2 s -1 L equiv = 10 34 cm -2 s -1 (HV corrected) L equiv = 10 34 cm -2 s -1 (HV corrected) FCal 250μm (stat. uncerty. only) FCal 100 μm (stat. uncerty. only) 21

New sfcal would require an opening of the endcap cryostat only performed if new electronics for HEC is needed Alternative solution: new MiniFCal in front of FCal 12 Cu disks and 11 diamond detector planes diamond pixels 1cm x 1cm reduces energy deposit in FCal1 by 45% ATLAS MiniFCal ~300 mm ~175 mm MiniFCal HEC FCAL HEC EMEC time in beam Neutron fluence: ~5 x 10 17 n/cm 2 (10 yr HL-LHC) Diamond sensors show strong dependence on fluence Also alternative solutions with LAr or highpressure Xenon are explored 22

Summary and Outlook High-Luminosity LHC: Further explore searches for new particles Determine properties of newly discovered particles Detector Challenges: High Luminosity = more pile-up, higher particle flux, more irradiation Upgrade Activities: Improved calorimeter readout and trigger systems R&D for forward (and endcap) calorimetry LHC Detector Upgrade performed with important German contributions, see e.g. Sessions and talks at DPG: Halbleiterdetektoren, Kalorimeter, Trigger, Myondetektoren, DAQ- Systeme,... Acknowledgements: many thanks to all ATLAS and CMS colleagues who provided information and helped preparing this presentation 23